WE MAKE YOUR DIAPHRAGM STYLE CLUTCH ADJUSTABLE!!!
Use the ClutchTamer to COMPLETELY tune out any sign of a bog during a WOT launch...even from low rpm!!!
Have a bog off the line that you just can't get rid of? Want more consistency from your Drag Radials?
Raising staging rpm to minimize a bog basically works by packing more inertia energy into the rotating assy, which in turn forces the clutch to slip longer, which means the car will travel farther down the track before the engine rpm and vehicle speed can sync…that’s the point where the clutch actually locks up 1:1. Because the clutch slips to a point farther down the track where the car is traveling faster, engine rpm does not drop as low when the clutch locks up.
Think about that for a minute though…adding inertia energy to the launch...which in turn forces the clutch to slip longer against it’s maximum clamp pressure...you are basically packing more energy into the rotating assembly for the sole purpose of forcing MORE abuse on your clutch! Not only does this add a lot of un-necessary heat and wear to the clutch assy, it also makes the launch more violent than it needs to be. What most don’t realize is that after you have used that inertia energy to force the clutch to slip longer, then that spent energy has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which initially forced the clutch to slip longer now slows the car as that energy transfer reverses, now some of the engine's power is used to recharge spent inertia energy back into the rotating assy as it gains back the lost rpm. In the end, that temporary boost of torque which forced the clutch to slip longer did not actually net you any performance gain.
Ideally the clutch's holding power should be matched to the power the engine makes, with very little reserve. As an example, let's assume an engine makes 500 ft/lbs and the clutch attached to it has a capacity of 700 ft/lbs before it begins to slip. When you launch the car, that clutch is going to draw 700 ft/lbs…the 500 ft/lbs that the engine is making at wot plus another 200 ft/lbs of stored inertia energy that will cause the rotating assy to lose rpm. That extra 200 ft/lbs makes the launch more violent, but as soon engine rpm is drawn down to the point that engine rpm sync's up with vehicle speed, rpm ceases to drop and that transfer of an additional 200 ft/lbs of inertia energy stops. Remember that after you have lost the rpm and used that inertia energy, that spent energy then has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which initially made the car launch harder now slows the car, as it reverses and some of the engine's power must be used to recharge spent inertia energy back into the rotating assy. In the end, that temporary 200 ft/lb boost did not actually net you any performance gain.
Why subject your transmission and drivetrain to that extra 200 ft/lbs if it doesn't net you anything?
If that 700 ft/lb clutch were replaced with a 600 ft/lb version, the duration of clutch slip would be roughly twice as long (around 6 tenths of a second vs. 3 tenths of a second), which means the car would be traveling faster at the point where rpm and vehicle speed finally sync up...much less bog. Not only does the drivetrain see less abuse, but the engine does not lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power. It might be hard to believe, but even though the 600 ft/lb clutch slips longer and puts less stress on the drivetrain, the car will actually be quicker than it was with the 700 ft/lb clutch.
Our ClutchTamer is basically an easily adjustable way to temporarily hold back some of the clutch's clamp pressure at the throwout bearing. This allows reducing the clutch's initial torque capacity, adding just enough clutch slip to keep the engine from being pulled down/out of it's power range. The clutch still has all it's original power holding capability, but now the initial hit of the clutch can be matched to the engine's power to prevent any loss of rpm during launch. Unlike throwing extra inertia energy into the clutch assembly to force it to slip longer at maximum clamp pressure, our method gets the needed amount of clutch slip with much less wasted energy. The ClutchTamer also works great for cars that spray, as it allows choosing a clutch with enough clamp pressure to handle the spray, but allows you to dial back the initial clamp pressure as needed to prevent bogging the engine when it's running NA. The clutch still slips as needed, but now it slips against much less average clamp pressure so it‘s surfaces remain cooler and wear less. The engine no longer has to lose rpm to force the clutch to slip during launch, so the chassis never sees the additional hit from that inertia energy, and the engine won’t have to pay that spent inertia energy back. This cuts the whole give/take of rotating assy inertia right out of the launch loop all together, for a smoother, less violent, and more efficient launch! No longer do the tires have to spin to minimize the bog, less tire and clutch wear is just icing on the cake.
Slicks or radials on a manual trans car? conventional wisdom says you need a couple rotations of the tire off the line, as that's the traditional way to launch a stick car on slicks with a minimum amount of bog. Because the engine does not typically make enough torque to break the tires loose on it’s own, it needs help from a hard hitting clutch to release additional inertia energy from the engine’s rotating assy. It's the release of that extra energy that causes the engine to lose rpm just before the tires begin to spin. When the tires begin to spin the clutch no longer has to slip, basically trading less wear/tear on the clutch for more wear/tear on the tires. It’s been that way for more than 50 years now, but that’s beginning to change. We now have radials which are a much more efficient tire. Just the fact that a simple switch from slicks to radials will gain you some mph tells you the slicks eat up more power. Problem is, you can’t just bolt a set of radials on a traditional stick/slick setup and get all the benefits. The radials just won’t tolerate the violent hit or the wheel spin that the slicks needed to work effectively. If we eliminate the overly violent hit and excessive wheel spin, it becomes much easier to reap the benefits of radials. Temporarily holding back some clutch clamp pressure is the key to making radials work.
Trying to run radials but having no luck? Most don't realize just how violent the launch of a lower power car can be. As an example, let's assume a car has power for 1.50 60's, but has a grabby clutch that has a capacity of 800 ft/lbs before it begins to slip. When you launch that car, the clutch is going to draw 800 ft/lbs, and the engine does not have to make 800 ft/lbs to make this possible. That clutch will draw all the torque that the engine is making at wot, then it will draw the balance of the 800 ft/lbs from stored inertia energy which will cause the rotating assy to lose rpm. Once again, that added inertia energy makes the launch much more violent than it needs to be. But remember as soon as engine rpm is drawn down to the point where engine rpm can sync up with vehicle speed, rpm no longer drops and the transfer of additional inertia energy stops. The downside to launching the car with inertia energy is that once the inertia energy is spent and the rpm lost, then that spent energy gets repaid while the engine recovers the lost rpm. The inertia energy transfer which made the car launch harder initially now slows the car, while the lost rpm is being repaid. In the end, using inertia energy to launch harder does not actually net you any performance gain!
Understanding that, now let's compare that 1.5 60' car with a grabby clutch, to a car that has power for 1.1 second 60's but does not lose rpm when it launches. If that 1.1 60' car does not lose rpm during launch, that indicates no inertia energy was used and it launched on engine power alone...
The 1.5 60' car averages 4648 lbs of thrust over the initial 60', but remember that the clutch in Car #1 draws 800 ft/lbs of energy before it begins to slip. Multiply that 800 ft/lbs by it's 1st gear ratio (3.35 for example), rear gear ratio (perhaps 4.30), factor in some drive train loss (13% sounds good) and the 28” tire’s lever moment at the contact patch, that 1.5 second 60' car easily matches the 8600 lb thrust of the 1.1 60' car during that very short period of time before the clutch locks up! That initial spike to 8600 lbs of thrust before the clutch locked up is then offset by a reduction of thrust, now below the average while the lost rpm is recovered. Even though thrust peaked at around 8600 lbs briefly, it's still just a 1.5 60' car. Add in violent pressure fluctuations at the contact patch from an unsorted chassis, it’s easy to see how a lower power car can easily upset a tire that's otherwise capable of amazing 1.1 second 60’s.
If that 800 ft/lb clutch in the 1.5 60' car were replaced with a 500 ft/lb version, the duration of clutch slip would be roughly 60% longer, which means the car would be traveling much faster at the point where rpm and vehicle speed finally sync up...much less bog. Now the tires only see a peak of around 5400 lbs of thrust instead of 8600 lbs in that brief period before the clutch locks up. Not only does the drivetrain see less abuse, but the engine does not lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power. It might be hard to believe, but even though the 500 ft/lb clutch slips longer and puts less stress on the drivetrain, the car will actually be quicker than it was with the 800 ft/lb clutch, and be much less likely to break the tires loose even with an un-sorted chassis.
Our ClutchTamer makes it easy for you to momentarily reduce the torque capacity of your clutch to match the power of your engine. This makes it possible to launch the car without ANY loss of engine rpm, which means power delivery will be very smooth without any spikes above your engine's torque output to break parts or knock the tires loose. With our ClutchTamer there is no delay on how quickly your clutch initially hits. Just dial how hard you want the clutch to initially grab to launch the car, then adjust how fast you want additional clutch pressure to come in to avoid blowing thru the clutch. If lockup occurs too early causing the car to bog, simply add lockup delay a little at a time until the bog disappears. It's that simple.
Are you a NMRA racer shimming your diaphragm PP to dial in clamp load? Now it's possible to get enough clutch slip to be competitive while eliminating the hassle of PP shims altogether. The ClutchTamer‘s "initial hit" dial will take over that job of limiting initial clamp load, while it's "secondary delay" setting basically allows more clamp to come in later to insure that you don't blow thru the clutch. This also puts you back on the proper side of the Belleville spring's "pressure curve", which means it will function as designed and actually gain a little clamp pressure over the life of the clutch disc. When you shim a diaphragm to lower the clamp, that puts you starting out at the end of it's wear capacity, resulting in pressure falling pretty quick as the disc wears. The pic below gives an idea how steep that pressure curve is...
What if that extra 200 ft/lbs is enough to break something?
…2800 lb car #1 has power for 1.5 second 60’s (1.66 G‘s), which requires a 60’ average of 4648 lbs of thrust at the tire
…2800 lb car #2 has power for 1.1 second 60’s (3.08 G’s), which requires a 60’ average of 8624 lbs of thrust at the tire
What is the "ClutchTamer"?..
...A small adjustable aluminum hydraulic cylinder that's installed on your car's clutch pedal. It allows tuning a bit of delay into the clutch's initial engagement, effectively shaving the "peak" off of the flywheel inertia torque spike as your clutch locks up. It's adjustable for exactly where in the clutch pedal's travel that it becomes active, and adjustable for rate of release from that point on. The cylinder has characteristics similar to those of a 90/10 shock, pulling it's rod out is easy, only the return stroke of the cylinder is controlled. With our ClutchTamer installed, only the final part of clutch pedal's release is slowed down, not the whole release cycle, while the rest of the clutch pedal's travel works like normal. If you are using the clutch pedal during shifts, the slipper will soften drivetrain shock during the gear changes as well. The Clutch Tamer slip controller allows you to choose a clutch with more capacity than you would normally choose. Typically that clutch would be too aggressive, but the addition of the first stage of the slip control provides the ability to apply only partial pressure initially, allowing slip. The second stage allows additional pressure to come in over time to insure lockup farther down the track. The most surprising thing that you will realize with the ClutchTamer is how much more power you will be able to put down without breaking parts!
How does the ClutchTamer work?...
...As the clutch pedal is depressed, it pulls the rod out of the attached ClutchTamer's cylinder. When the clutch pedal is released the pedal comes out completely unrestricted, until the "initial hit" dial on the cylinder's shaft contacts the dash bracket. From that point on, the rate of clutch pedal release is controlled by an adjustable orifice inside the cylinder. The rate of return is adjusted by simply spinning the cylinder's shaft "inward" (clockwise) from 0 to 10 turns of the shaft. We attach a knob to the end of the shaft to make the adjustment quick and easy. Below is our "Universal Underdash" version of the ClutchTamer installed on a typical lower dash/pedal assembly. Attaching the dash bracket requires drilling (4) 1/4" holes, but the pedal bracket installs by simply sliding onto the pedal and securing with a clamp bolt (we also have versions that install into the dash for a more integrated look)...
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How is the ClutchTamer adjusted?...
We use a simple dial type adjustment with an internal detent that is typically located within easy reach of the driver's seat. You can dial in more/less "initial hit" of the clutch without even unbuckling your belts! Here's a pic of the dash adjuster dial assembly. It features a notch milled into the threaded rod, while the round Delrin "Initial Hit" dial (center of below pic) uses a steel ball detent that's pre-loaded with a simple o-ring to keep the dial from free spinning...
Adjustment #1- Initial Clutch Hit...Adjusting the round dial on the threaded portion of the shaft changes the amount of initial clutch "hit", similar to adjusting the base pressure on an adjustable long style clutch. Initially we dial in 7 to 10 turns of "delay" (see adjustment #2), as this basically removes the secondary clutch application and allows focusing on just the initial hit. It is preferred that the clutch initially slips enough that the engine is not pulled down below it's "staged" RPM when the clutch is dumped. For this part of the adjustment we usually just make 30' to 60' test hits, no need to make a full run.
Adjustment #2- Secondary Clutch Lock-up Delay...Secondary lock-up delay is used to delay clutch lockup until the vehicle speed can catch up with engine speed. Turning the cylinder's winged dash knob (on the left in the pic above) basically changes how quickly additional clutch pressure comes in. There are 10 turns of adjustment on the knob. At "0" turns (fully counter-clockwise) our clutch pedal was delayed .181 sec, barely noticable. At "10" turns, the pedal takes about a minute to return.
The ClutchTamer is a very effective tool for eliminating a dead-hook bog. Adding air pressure and adjusting the chassis to gain wheelspeed can be effective if you run bias slicks, but you will be basing your consistency on a huge variable. How do you predict how far down the track you are going to spin your tires? You might get it right on occasion, but track temps, starting line condition, or even a change of lanes can throw your game off. Bogging or spinning with an occasional perfect run in-between, it's no wonder guys get frustrated to the point of switching to an automatic. Our solution of dead hooking combined with controlled clutch slip is an option that can be much more predictable.
We put this section together to help illustrate benefits of controlled clutch slip. It's a work in progress, hope it gives those manual trans guys who are "radial curious" a little re-assurance that the more efficient radials can be a viable choice. We know many make more power than this example, but this stuff generally scales nicely as long as there is enough clutch capacity to match engine output.
How is it possible that a car can be quicker while “wasting” energy slipping the clutch? Truth is simply that an engine can burn more fuel spinning at a higher rpm. Basically, it allows you to "make more steam" while traveling a given distance. This makes it possible to produce a surplus of energy, beyond that which is absorbed as heat in the clutch assembly. Net result being MORE power applied to the track, not less. Same reason it’s possible for an automatic car to be quicker in spite of installing a looser converter that produces more slip, power production increased at a faster rate than the increase in friction/heat.
To illustrate, here's some feedback on our ClutchTamer from an east coast class racer. Powered by a 302ci crate engine, stick cars like his are required to run a diaphragm clutch. This guy was having a rough time, as he was a slick racer switching to radials. With a typical 4300 launch, the radials bogged the engine to 2300rpm and 1.7x 60's. Stepping up to a 4800rpm launch in an attempt to eliminate the bog, this is what happened to his faceplated TKO...
He repaired the transmission, and I sent him an in-dash version of the ClutchTamer to try. He installed the ClutchTamer, made a few test hits in the driveway to get familiar with it, then went to the track. His immediate results were dead hooked radials and back to back 1.45 60's. This graph is from a 1.42 run...
Couple months later, he’s still putting down 1.4 60's at class weight with no transmission failures from 5200rpm launches. This increase in durability is due to two things-
1- a reduction of engine rpm loss before clutch lockup
2- spreading rpm loss over a longer time period
Both are beneficial on launch as well as after the shifts, as they team up to reduce shock to the drive train and tires.
Here's the same graph w/ a couple lines added to help illustrate those benefits. His graph is fairly easy to understand, as there is very little wheelspin to confuse things...
The added orange line is a rough representation of the engine's ability to gain rpm in 1st gear.
The 1st added vertical black line represents the launch, or beginning of clutch engagement.
The 2nd added vertical black line represents the point of clutch lockup.
The distance between the two vertical black lines represents the time it took for clutch lockup to occur.
Clutch slip duration was roughly .7 seconds, engine rpm at lockup was about 5100.
…If clutch lockup had occurred at .4 seconds, engine rpm would have been pulled down to appx 4200 on the orange line.
…If clutch lockup had occurred at .25 seconds, engine rpm would have been pulled down to appx 3500 on the orange line.
This is a bit of a simplified explanation. Reduced engine output at lower rpms would also reduce the engine's ability to gain rpm, that added power loss is not reflected here. The basic point is- the earlier clutch lockup occurs, the lower the rpm point on the orange line that the engine will have to accelerate from.
Anyone wonder why that orange line on the graph aligns with 2700rpm at launch instead of zero rpm? It's because a line representing rate of acceleration is actually even steeper before the clutch locks up. This happened because no power was used to accelerate the rotating assembly prior to clutch lockup, so more power was available to accelerate the car. Here's the same graph, with a red line added to represent acceleration rate before clutch lockup...
See how much steeper the car's acceleration rate was before clutch lockup?
This launch could have reached it's shift point even quicker if the clutch had slipped longer, as the car would have rode the trajectory of that steep red line to a higher point before switching to angle of the orange line. Same logic applies to clutch slip after the shifts, a car can simply accelerate quicker before the clutch locks up. Generally the longer you delay clutch lockup, the longer you ride a steeper acceleration rate.
The lightest clutch assy is not necessarily be the quickest when it comes to exploiting clutch slip to maximum advantage, as the clutch needs to have enough thermal capacity to absorb some slip without overheating/warping. Having plenty of clutch capacity for the task is the 1st requirement, then it's a simple matter of controlling the application of clutch pressure to match engine power. Ultra-lightweight circle track or road racing clutches will likely not be able to tolerate much slipping without permanent damage.
Diaphragm Pressure Plates-...a modern diaphragm style pressure plate actually has a lot going for it, especially for a Street/Strip application. The most noticeable advantage is less pedal pressure per pound of clamp pressure, due in part to less friction at it's pivot points. Beyond that, the diaphragm style spring design gradually gains a little clamp pressure as the disc wears to around the 1/2 way point, then clamp pressure begins to gradually work it's way back down. By the time the clutch disc needs replacement, clamp pressure is about what it was when the disc was new. Because diaphragm clamp pressure varies less over the life of the disc, you can more closely match clamp pressure to the actual application, which minimizes overall pressure required to depress the clutch pedal.
Borg & Beck and Long style pressure plates- any pressure plate that uses coil springs is going to lose clamp pressure from day 1 as the disc wears. Making matters worse, the typical way to increase clamp pressure for performance applications is to increase the coil’s spring rate, which only increases the amount of clamp pressure loss over the life of the disc. For this reason you MUST choose a coil spring pressure plate with too much clamp pressure when it's new, so that you will have enough clamp pressure to handle the engine's torque when the disc is worn! Not only does this make the clutch overly aggressive, it also dictates that the clutch pedal will be hardest to depress when the clutch disc is new. The addition of the ClutchTamer addresses the harsh engagement, as it makes it possible to dial back the initial aggressiveness that comes with excessive clamp pressure. Now it's possible to use radial tires without the added maintenance of constantly adding, then removing, shims from the pressure plate (or otherwise manually adjusting spring pressure), to keep clutch clamp pressure in it's sweet spot.
What about pressure plates that feature centrifugal assist?...if you plan WOT shifts at hi rpms- any pressure plate that features any sort of centrifugal assist is going to hit the drivetrain hardest after the shift, making it more likely to break parts or knock the tires loose. Counterweight style clutches produce an RPM drop trace on a graph that looks like a "backwards J" with a hook at the bottom. Their sharp, near vertical drop indicates a quick loss of rpm (intense discharge of inertia energy), which transitions into a gradual "hook" near the bottom as the clutch begins to slip more. That hook area at the bottom of the "J" is where most of an adjustable's slip actually occurs. The intense vertical drop is something you have limited control over, as a centrifugal design dictates that rpm must come down before clamp pressure can be reduced. This is a big reason why SoftLoc style clutches are only marginally effective when trying to run radials, as they still have a relatively intense discharge of inertia energy just after the shift, until rpm comes down enough for the bulk of their slip to occur.
What about using the ClutchTamer with a clutchless transmission?...the basic ClutchTamer will not give you any slip after your shifts, so the current solution would be to use the ClutchTamer with a traditional adjustable PP that has a centrifugal component. This gets you the benefit of using the ClutchTamer to allow launching from a higher rpm than would otherwise be possible with a properly set up adjustable, then the centrifugal component will get you at least some form of after shift slip, even though the "backwards J" shaped rpm drop is less than optimal. The future will bring a system much like a fuel car, which will likely use some form of pneumatics or hydraulics, maybe even a stepper, to get the control needed to change that.
To exploit the benefits of a radial, you basically have a line that you don't want to cross when it comes to shocking the tire. Anything you can do to smooth out your power delivery profile is going to make it easier to operate closer to that line. Any torque peaks that you have in your power delivery need to be shaved down, which basically allows you to elevate the average amount of power you can deliver to the tire...make sense? A diaphragm PP combined with a ClutchTamer makes it possible to put together a slipper clutch that has a more diagonal/linear rpm drop trace than the typical centrifugal. This softer engagement in the instant just after the shift helps keep those radial tires stuck.
The ClutchTamer is just a brutally simple way to control a clutch. I'm sure myself and others will soon come up with more sophisticated/expensive means to get basically the same job done, you will have to wait if that's what you are looking for.
ORDERING INFORMATION "CLICK HERE"
CURRENT PRICING...
ClutchTamer Universal Kit (minor fabrication required)..............just $129!
'79-'93 Mustang below-dash 2" offset E-Z install ClutchTamer.........$149
Application specific '87-'89 Mustang in-dash ClutchTamer...............$149
Application specific '90-'93 Mustang in-dash ClutchTamer...............$149
Application specific '94-'04 Mustang in-dash ClutchTamer...............$149
Universal Under-Dash ClutchTamer (pictured above).......................$149
COMING SOON!!! More application specific dash and clutch pedal brackets to make your installation a snap!
Here's a link to our Universal Version ClutchTamer Install & Tuning Guide
NEW! ClutchTamer '79-'93 Mustang Install Guide.....(under dash version)
NEW! ClutchTamer '87-'89 Mustang Install Guide...........(in-dash version)
NEW! ClutchTamer '90-'93 Mustang Install Guide...........(in-dash version)
NEW! ClutchTamer '94-'04 SN95 Mustang Install Guide..(in-dash version)
If you have any questions or would like to place an order, click here to e-mail us or call 360-391-1208
Q- Recent trip to the track with a stock LS2/T56, 3.54 axle ratio, 4000rpm 2-step clutch dump, 28X9X15 ET Drag slicks @17psi, Lots of VHT with beautiful track prep. Both front wheels up during dead-hook, but engine bogged and dropped the front wheels back down almost instantly. Lowered tire pressure to 15psi and reset 2-step to 4500 with plans to keep increasing 2-step till either I got some tire spin or broke something, but the car ahead of me in staging blew his tranny up and dumped all of its oil all over the track, so I loaded up and headed home. Car performed below par with 1.60 60' times and consistent 7.30s at 96mph, mostly slowed by dead hooking, even bogging the car on gear changes. I may be going back to 26" slicks for this track since they put so much VHT down.
Here's what your mph/rpm would be at different clutch lockup points down the track, assuming 2.97 T56 1st gear, 3.54 diff ratio, no wheelspin, and your car accelerating at a 1.76g rate (1.45 60')...
Just to be clear, the ClutchTamer doesn't make the clutch "slippy", as the intent here is only to delay it's lockup point until your car is going fast enough that clutch lockup won't cause a bog. You still have all the original clamping pressure available to lock up the clutch, just controlling how when and how quickly that pressure is applied. RPM does not have to flare up above the staging rpm if you don't want it to. If you are afraid of hurting your clutch, you can easily adjust the ClutchTamer so that you still have most of your bog, just not as much. Much more predictable than relying on wheelspin to overcome your bog.
Q- I'm playing with a little Eagle Talon, and the clutches offered for it suck badly. Most people run a circle track style mini twin that locks up too quick and doesn't have enough inertia, so it either bogs or breaks stuff.
Q- Having an engine in the "heart of it's power band" is futile if all the power available cannot be applied to the back tire. I can drive around all day slipping my clutch and keeping my rpms at peak power, but that doesn't mean the tire is turning quicker, does it? By your reasoning, don't let out on the clutch at all, and you can keep it at the "heart of it's power band" continuously.
Does it really get your car down the track quicker if the clutch were to slip less? Lets say the example clutch above locks up earlier at .6 seconds into the run, resulting in the engine pulling down to 3500rpm at the point of clutch lockup. Now the engine is making only 400ft/lbs, gradually making it’s way back up to 4500rpms and 450ft/lbs by about .82 seconds into the run. It took .22 seconds to go from 400ft/lbs to 450, that’s an average of 25ft/lbs less torque during that .22 seconds.
There’s also an inertia advantage, as the engine benefiting from controlled clutch slip does not have to expend energy to accelerate it's rotating assy during that entire .78 seconds between launch and clutch lockup.
Q- If I wanted a delay in my clutch engagement, would it not be easier to install a restrictor in the hydraulic line?
Q-Maybe I'm missing it...but if this is physically attached...what happens when you want to change 1-2, 2-3, 3-4 and generally use the clutch again ?
Q- How does temperature affect the ClutchTamer...is it consistent and reliable?
We conducted a test for the purpose of creating a graph of the cylinder's characteristics. During the test the cylinder was connected to an actual clutch pedal in a car. The pedal was fitted with switches at the top/bottom of it's stroke, and was released from exactly the same spot each time, from against the pedal stop.
Q- How big and heavy is the ClutchTamer, is it going to weigh my car down much?
Q- Is a special clutch required?...
Extending clutch lockup time out to .7 sec is easily tolerated by the typical HD organic or Kevlar friction linings, as long as the pressure plate has sufficient clamping force to achieve clutch lockup at your current power level. Stretching lockup time out past .7 sec at full power may require a lining with more capacity, such as a Ram Powergrip HD or SPEC Stage 3. Ceramic and dual friction linings have been used with much success, but sintered iron is the preferred friction material at extreme power levels. Typical poly damped hubs are fine to around 700hp, but a point can reached where a harmonic problem occurs with the damping during slip, so solid hubs are preferred for extreme applications.
The big advantage of our ClutchTamer for a street/strip car is that it allows using a conventional style pressure plate, but low pressure / slipping last for only a short period of time. SoftLoc style racing clutches are designed to use very low base pressures which allow the clutch to initially slip, then grab, as the sintered iron lining heats up and the "Long" style pressure plate's centrifugal assist comes in. The problem with that on a street/strip car is that when you are cruising down the hiway at lower RPM in high gear or even overdrive, there is little centrifugal assist. The clutch lining also cools off, so the clutch will likely start slipping again as soon as you get into the throttle even a little. Getting under the car and adding base pressure is almost necessary before going back out on the highway to minimize additional wear. If you would rather adjust your street/strip car's clutch from the driver's seat instead of climbing under it to crank the base pressures up and down to make the transition from street to strip, the ClutchTamer might be your answer.
Our ClutchTamer works with cable clutches as well. One difference between some hydraulic and mechanical clutches is that some mechanical clutches (like the older musclecars) are not self adjusting, so they would need to monitor/adjust freeplay to keep things consistent for cutting a good lite. If you own a late model Mustang, our system is completely compatible with it's stock self adjusting mechanism.
Is it possible that a diaphragm pressure plate, when combined with the ClutchTamer, might actually have potential to outperform a much more expensive "Long Style" adjustable clutch?
Do YOU need a ClutchTamer?..
A- To prevent your current bog, either your clutch has to slip or your tires have to spin. Dropping air pressure isn't going to make much difference, at least as far as gaining enough rpm to prevent your bog. More air pressure will make a difference only if traction is reduced enough to let the tires spin, which will gain you some rpm.
.3 seconds in, 11.7mph 1590 rpm w/ 26" tire, 1476 w/ 28"
.4 seconds in, 15.6mph 2120 rpm w/ 26" tire, 1968 w/ 28"
.5 seconds in, 19.5mph 2649 rpm w/ 26" tire, 2460 w/ 28"
.6 seconds in, 23.4mph 3182 rpm w/ 26" tire, 2955 w/ 28"
.7 seconds in, 27.3mph 3713 rpm w/ 26" tire, 3448 w/ 28"
.8 seconds in, 31.2mph 4239 rpm w/ 26" tire, 3986 w/ 28"
As you can see, if your clutch locks up at .3 seconds in and the slicks are stuck to the track, the resulting bog to 1476 rpm with the 28" tire is only going to improve to 1590 rpm if you swap to the shorter 26" tire. Even if you were to spray some nitrous to help off the line, without wheelspin the rpm would be pulled below the minimum recommended 3000 unless clutch lockup is extended out to .6 seconds. If you want to carry those front tires down the track, your engine needs to be spinning fast enough at clutch lockup to make some power.
A- The 1st problem here is that the clutch just locks up too quick. More inertia may help, but until the clutch can initially slip, any added inertia is going to be dumped into the drivetrain very quickly and create a huge torque spike that can break parts.
Here's some low "2000 rpm launch" observed data from a "no-prep" test session last year. The low rpm launch is very easy on parts, but with the ClutchTamer delaying clutch lockup the rpm "flashes" higher instead of bogging, getting the engine into the "heart of it's power band" much softer/quicker...
...without the ClutchTamer connected, lockup occurred at around .132 sec while pulling the rpm down to 1700 at lockup.
...with 6-1/2 turns of delay, lockup occurred at around .624 sec with an rpm "flash" to 2857 before lockup.
...with 7 turns of delay, lockup occurred at 1.01 sec with an rpm "flash" to 3944 before lockup.
In this mode, the ClutchTamer is basically causing the clutch to act much like an automatic during a footbrake launch, much like "flashing" a torque converter.
A- I'll try to explain, but it's kind of counter-intuitive to what one typically thinks of when the subject of "clutch slip" comes up. We are not talking about a clutch that slips because it is over powered, where the engine is wildly gaining rpm, but rather a clutch that has plenty of capacity and is controlled to more closely match the output of the engine. Here’s a simplified example to illustrate…
...Lets say an engine puts out 450ft/lbs of torque WOT @ 4500rpms, it does not care if the clutch is slipping or not. If it's WOT @ 4500 and not gaining rpms, something is matching that 450ft/lbs of output with 450ft/lbs of resistance. That resistance is provided by the transmission's input shaft. Even though the clutch is slipping, the input shaft still sees 450ft/lbs, not some reduced amount due to slipping. For this example the car is finally going fast enough to match the engine’s 4500rpms by around .78 seconds into the run, where the clutch is allowed to lock up. If the car was launched at 4500rpms and maintained that WOT 4500rpms until clutch lockup, the input shaft sees 450ft/lbs for that entire time.
A- If your desire is to slow down your clutch engagement rate throughout the entire range of pedal travel, something in a clutch's hydraulic line could work. There are actually a couple of products currently available from companies like Magnus and McCleod that do exactly that, but I wouldn't recommend attending any events with pro-tree, arm drop or "flashlite" style starts with either. The downside to those devices is that they also slow the throwout bearing's initial release travel, the deadband area where the clutch travels through the "air-gap" from pedal stop to the point of initial engagement.
...Our ClutchTamer hydraulically delays clutch engagement similar to the Magnus and McCleod units, but our version is self contained and adds a mechanical reference to pedal position. This is key, as it allows setting the precise point in throwout bearing travel from where clutch engagement delay becomes active. Remember- with our ClutchTamer there is no delay in how quickly your clutch initially hits, as the throwout bearing still initially moves as quickly as you can remove your foot from the clutch pedal. From there simply dial how much unrestricted pedal travel (clutch pressure) you want to make available for launching the car, then separately adjust how quickly the pedal travels from that point, adding clutch pressure to complete lockup. If lockup occurs too early causing the car to bog, simply add a little lockup delay until the bog disappears.
A- If you are using the clutch pedal during upshifts, the ClutchTamer will be active then as well. There is great benefit to initial slip on upshifts, as it reduces shock to the drivetrain (and tire) while minimizing loss of rpm between shifts. Remember, there's enough initial pressure dialed into the clutch to launch the car from a dead stop, the delay is only on how fast additional clutch pressure comes in. Same applies on upshifts where the clutch is used. If you have a lower capacity transmission like a T5 where 3rd gear is a weak point, having an active clutch buffer on the shifts is a huge plus. During slower casual shifts, you won't even know it's there.
A- The ClutchTamer operates like a 90/10 shock, easy to pull on extension, but the return "delay" stroke is controlled by hydraulic oil passing thru an adjustable orifice. Just like the shocks on your car, the hydraulic oil inside the ClutchTamer is little affected by ambient temperature swings, with one big difference- in this application the "shock" is located inside the interior of the car, likely a much more controlled environment.
Here's some observed data from that test....
"0" turns = .181 sec delay (+/- .006 sec deviation over 10 strokes)
"1" turns = .194 sec delay (+/- .005 sec deviation over 10 strokes)
"2" turns = .224 sec delay (+/- .005 sec deviation over 10 strokes)
"3" turns = .285 sec delay (+/- .001 sec deviation over 10 strokes)
"4" turns = .395 sec delay (+/- .001 sec deviation over 10 strokes)
"4-1/2" turns = .673 sec delay (+/- .003 sec deviation over 10 strokes)
"5" turns = .811 sec delay (+/- .005 sec deviation over 10 strokes)
"6" turns = 1.708 sec delay (+/- .012 sec deviation over 10 strokes)
With the cylinder completely removed from the pedal, the deviation was .011 sec over 10 strokes. This was attributed to the pedal returning at a rate that was faster than the foot could be removed from the pedal, introducing a bit of human inconsistency into the results. Conclusion? it's possible that your car will actually be MORE consistent with a clutch slipper.
A- The ClutchTamer is made from a small featherweight 1" diameter aluminum cylinder that is only 10-1/2" long. The entire kit ships in a small 2"x5"x14" box, it's shipping weight is only 1.8 lbs, including the box and packing material! Because of the small size and weight of the package, 2 day Priority shipping within the USA adds only $10. Worldwide 1st class postage is also very affordable at only $22.
A- your clutch still needs to be able to hold more torque than your engine can produce. After meeting your clutch capacity requirements, extending the duration of clutch slip does not necessarily mean you will experience more actual clutch wear. In fact if you are currently launching at 5000+ to avoid a bog, it's very likely that adding the ClutchTamer could actually reduce your clutch wear. How you ask? A traditional drag style launch uses excessive launch rpm to basically delay clutch lockup to a point farther down the track. With the ClutchTamer you can launch from a point just below your torque peak WITHOUT LOSING ANY RPM AT ALL! Here's an example of how that's possible…
…A launch from 6500 dropping to 4000 .5 seconds later at clutch lockup represents about 22 revolutions of full pressure clutch slip.
…A launch from 4500 maintaining 4500 rpm thru .5 seconds represents less than 19 revolutions of gradually increasing clutch pressure. That’s also 500 less rpm loss, so the engine is likely pulling from a higher point in it’s power curve. Why the hell would you want to put your clutch thru all that hi rpm slipping when you could have the same amount of lockup delay from a lower rpm with less actual clutch slip?
Keep in mind that delaying lockup to .7 sec or more during normal street driving will have no noticeable effect on clutch wear or durability, as typical release times during casual use without a delay often exceed 1 sec.
...The 1st answer comes from a difference in how cars are typically staged. With an adjustable clutch, staging rpm by design has to be lower, with the goal of getting enough initial clutch slip to launch the car. Often called “driving into the clutch”, as the engine gradually gains enough rpm to achieve clutch lockup by about .8 to 1.0 seconds into the run. During this entire .8 to 1.0 second time period, some of the engine’s power is used to accelerate the rotating assembly. The addition of the ClutchTamer makes it possible to raise staging rpm, while still getting the needed clutch slip, effectively reducing the time/energy spent accelerating the rotating assy.
...The 2nd answer comes in what happens in that instant just after a shift. Being rpm based, the adjustable clutch reaches maximum clamp pressure at the shift points. Engine speed must then drop sharply, until rpm is low enough to allow the clutch to slip. With a data logger, this rpm drop will show up on the graph looking much like a backwards “J”. The sharp vertical drop actually indicates an intense discharge of inertia energy (torque spike), which often releases itself as a spike in wheelspeed. The rounded hook at the bottom of the “J” indicates the more gradual transition period from torque spike, to clutch slip, to clutch lockup. With a ClutchTamer in place, rpm drop after a shift using the clutch pedal looks more like a diagonal line from shift to clutch lockup. This spreads the sharp drop in rpm over a longer time period, effectively reducing the intensity of that torque spike after the shift.
...Then there’s a difference in how easily the clutch transitions from “street” to “strip” modes. With the adjustable clutch, you typically need to be able to crawl under the car, as raising/lowering base pressure is key to making the transition. This usually means tools, jacking up the car, getting dirty and cleaning up. With the ClutchTamer, no need to change a thing for the drive back home. If you do need to make an adjustment, you can do it while sitting in the driver’s seat. If you already have an adjustable clutch, adding the ClutchTamer can make switching street/strip modes much easier.
...If your car breaks drivetrain parts- the ClutchTamer can soften that flywheel inertia induced torque spike that results when the clutch is suddenly released.
...If your car dead hooks and pulls your engine down out of it's power range- the ClutchTamer can help keep the rpm up where more power is made.
...If you race on un-prepped surfaces- low rpm launches without a bog will make your car much quicker overall.
...If you would like to make your manual trans bracket car more consistent- a slight clutch pedal delay can help minimize human inconsistency.