GSS Torque Arm / Solid Axle Conversion System
(TA/SA conversion)
'86-'91 RX-7 / Ford 8.8 DIY Kit Installation overview

CLICK HERE for TASA conversion install FAQ

Tools & Equipment Required
Here's a list of recommended tools and equipment recommended for a sucessfull installation. All are not necessary, as you may come up with alternative ways to get it done, but this will give you a general idea of what you are in for...

...basic hand tools, both metric and SAE
...measuring tape
...3/8" drill bit
...1-3/16" hole saw
...0-250 ft/lbs torque wrench

...(4) jack stands for car
...(2) jack stands for rear axle
...personal safety gear such as gloves, safety glasses, etc.
...1/2" hand drill

Supplies... Loctite
...penetrating oil
...gear oil
...friction modifier (for TracLoc or other clutch type limited slips)

Additional parts required...
We sell fabricated/rod end replacements for these parts, but our conversion package is designed to use these rubber bushed parts available from a parted out 1st gen 'RX-7...
...(2) stock rear lower control arms from a '79-'85 RX-7
...stock rear watts bellcrank and right/left watts bars from a '79-'85 RX-7

Removing your RX-7's IRS and subframe...

Prepare for rear subframe removal by raising the car about 18" off of the floor, properly supported at the OEM jacking points. Notched jackstands are preferred to prevent damage to the welded seam.
...After safely and securely supporting the car, the remove the rear tires.
...Remove any exhaust system components in the area of the rear subframe.
...Remove the driveshaft.
...Remove the brake calipers from the hubs, leaving the hoses and e-brake cables attached, then hang the calipers from the body with wire to prevent damage to the hoses.
...Remove the rotors from the hubs. Save them for possible use later.
...Remove the bolts attaching the rear shocks to the lower control arms.
...Remove the bolts attaching the sway bar end links to the lower control arms.
...Remove the lower bolt on the vertical strut near the driver's side of the center housing.
...Support the subframe by placing a floor jack under it's center.
...Remove the two large nuts, one on each side of the differential housing's "wings". The diff assembly should drop onto the subframe/jack.
...Remove the bolts from the two support struts extending away from the forward mount washers.
...Slowly remove the two remaining nuts from the forward mounts.
...Slowly lower the entire subframe and remove it from under the car.

...The original subframe, diff, axles, driveshaft, etc are no longer needed. The whole thing's not worth much if it's 4 lug. If it's either '86-'88 5 lug, 3.90, or even T-II, you should be able to sell it without much trouble.

Repositioning your RX-7's fuel lines above the rear housing...

The picture below shows how the RX-7's fuel lines will run directly over the 8.8's centersection (click on the right pic for a larger close-up view). We don't want to take a chance on a collapsed or damaged fuel line, so now's the time to move them.


If you want access to the tank end of the rubber hoses, you can get access to the top of the tank (and fuel pump) via a removable cover, located under the carpet (over the tank), in the rear hatch area. The area in the pic is located under the rear hatch carpet, just inside/back of the driver's side shock tower.

Installing the lower control arm's front pivot boxes...

Temporarily pull up the carpet and padding from the floorboard area behind the seats.
Slide the front pivot boxes onto the front studs formerly used to attach the subframe. Thread a nut onto the stud for the purpose of temporarily holding it in place.
Using the installed pivot boxes as a template, mark the remaining (16) 3/8" holes (8 per side) for drilling.
Remove the pivot boxes and drill the marked holes.
Re-install the pivot boxes.
Install the inner backing plates, bolts, and nuts. Torque them to 25 ft/lbs.
Re-install the carpeting.


Installing the Torque Arm's front yoke assembly...

Next, it's time to drill some large holes for the Torque Arm's front yoke. The front hole is located in the center of the tunnel, near the rear of the e-brake's mounting plate. The rear hole is located in the center of the tunnel, centered in the top of a raised rib. The center-to-center distance between the holes should be 12-3/4". Draw a large "+" thru the center of the holes, so that as the hole is being drilled, you will be able to make sure that the hole is not walking off-center.

Drill or die-grind both holes to a diameter of 1-3/16", the size of the rubber puck's pilot diameter.

Position the upper rubber pucks, pilot tubes, bolts, and 3" dia flatwashers over the holes, with the rubber pilot extending thru the hole. The front puck has a notch machined into it, which provides clearance for the e-brake bracket's rear bolt.


Place the rear lower rubber puck into position from the bottom side of the tunnel, over the rear bolt, with the machined slot in the rubber facing down with the e-brake cable passing thru the slot. Push the puck up onto the pilot tube extending down from above, which will hold it into place.


Push the front lower puck into position from below. Push the puck up onto the pilot tube, which will hold it into place.


Install the remaining yoke assembly from the bottom, over the bolts. Using the 1/2" flangeloc nuts provided, tighten both bolts to 60 ft/lbs.


Installing the driver's side watts anchor bracket...

Slide the large 1-1/2" dia x 5/8" thick spacer onto the large stud formerly used to hold up the passenger side of the stock RX-7 diff housing. This spacer fills the space above the bracket, shimming it down on the stud, aligning it with the flat surface of the frame rail.

Next slide the watts bracket over the same stud, while aligning with the 2 holes in the chassis. Install the chassis bolts, tightening them to 45 ft/lbs.


Next install the flat washer and nut over the stud, and tighten to 65 ft/lbs.

Installing the passenger side watts anchor bracket...

The "L" shaped passenger side watts anchor bracket mounts thru the bottom side of the floor pan, in the area directly below the pass side storage bin. The bracket mounts to the floor pan at two points, and to the sheet-metal "frame rail" above using a bolt-on vertical stabilizing strut.
...For the inner mounting point, we use an existing "drain" hole (actually a locating hole for the factory assembly jig), located inside the round cut-out in the matting, formerly sealed by Mazda with a large rubber plug. Remove the rubber plug, which is no longer needed.
...For the outer mounting point, we enlarge an existing small hole (hidden under the matting), located about 10" to the pass side of the above mentioned "drain" hole, between the two "dimples" in the floor pan. This small hole needs to be enlarged to 7/16", the size of the hole thru the machined pilot insert welded to the anchor bracket. An enlarged hole is shown below, in the lower left side of the picture. The view is from the passenger side of the car, looking in thru the door opening, with the rear storage bins or rear seat removed.

The sheetmetal around the two holes is clamped between the bracket's machined insert and a heavy 1-1/2" dia machined "clamp-washer" installed from above. A 7/16" dia gr8 bolt/nut is used in each hole to provide the clamping force needed to securely locate the bracket.

Intall the bracket into the large inner hole first. Be sure the machined pilot fits into the center of the hole properly, then place the "clamp-washer" over the insert from the top, recessed side down. Install the 7/16" bolt thru the washer and bracket from the bottom, then install the locking flangenut on top. Temporarily tighten the bolt/nut to around 10 ft/lbs.


Next we align the bracket's outer machined insert with the 7/16" hole we enlarged earlier. Place the "clamp-washer" over the insert from the top, recessed side down. Install the 7/16" bolt thru the washer and bracket from the bottom, then install the locking flangenut on top. Torque the bolt to 71 ft/lbs. Torquing the bolt will force the sheetmetal of the floorpan to conform to the stepped insert, insuring a perfect interference fit with no slop.

Finish torque the temporarily tightened bolt in the inner hole to 71 ft/lbs.

Next, we install the anchor stud for the bracket's support strut. Remove the rubber plug from the hole located just to the rear of the brake hose's chassis tab (center of pic below).


Fully insert the threaded end of the stud into the hole, thru into the inner hole, so that the threaded end comes out of the existing hole on the sheetmetal frame rail's inner side...


Next install the strut bar's upper end over the threaded stud. Secure w/ the 3/8" flangeloc nut provided.
Secure the strut bar's lower end to the bracket's tab, using the 3/8" bolt, washer, and flangeloc nut provided.
Torque both upper and lower strut bar bolts to 30 ft/lbs.
When installed properly, the passenger side watts anchor bracket should look like this...


Finally, 8.8 meets RX-7...

Slide the 8.8 rear with torque arm into place under the car. Use a couple of jack stands to support the axle tubes near their final location. Pull the nose of the torque arm up into place, where it can be temporarily supported by pinning it, with a bolt, to the yoke plates hanging down from the front yoke assembly.

If you are using the stock lower links from a '79-'85 RX-7, install them using their original eye bolts and nuts.

If you are using our larger rod-end style adjustable lower links, there are a few extra steps to ensure proper assembly...
...adjust each bar so that both it's ends extend from the tube an equal distance.
...install the link on the car with the left hand thread end on your left when you are facing it. This will make it easier to remember which end has the left hand threads later when you are trying to make adjustments.
...Each rod end will be spaced to the center of it's bracket using two cone shaped spacers, one on each side of the rod end. The larger side of the spacers face away from the rod end, against the inside of the bracket.
...insert the gr8 bolt, washer, and nut thru the bracket, spacers, and rod end from the outside. Install a 5/8" flange washer on the inside, and torque to ????? Repeat for the rear ends of the links.

Insert the spacer bushings into the rear shock's lower mounting holes, then slide the lower shock eyes into position between the brackets attached to the axle tubes. Install the bolts w/ washers & flange nuts, torquing each to 60 ft/lbs.

Installing the driveshaft...

This step is often overlooked, but before installing the driveshaft, be sure to grease both u-joints. Also, to protect the output shaft's rear bushing and seal, be sure to lube the slip yoke with some light oil before inserting it into the transmission.

Temporarily pull the bolt holding up the nose of the torque arm, allowing the torque arm's nose to be lowered for driveshaft installation. With the nose of the torque arm lowered, slide the driveshaft into the transmission.

Bolt the rear of the driveshaft up to the flange or yoke.
......If your 8.8 has a flange, torque the (4)12mm x 1.75 pitch (25mm long) pinion flange bolts to 60 ft/lbs ea.
......If your 8.8 has u-bolts, tighten them to a guesstimated 25 ft/lbs ea.

Pull the nose of the torque arm back up into position, between the two side plates hanging down from it's front yoke assembly. Slide the 5/8" bolt into place from the passenger side. Install the washer and self-locking nut. Torque the bolt/nut to 90 ft/lbs.

Installing the watts linkage and centering the rear...

If you are using the OEM watts linkage from a '79-'85 RX-7, your watts linkage's "bars" will need modification to properly clear and center the rear. The easiest way we have found is to simply cut the ends from the oem bars and add our custom "sleeves" to the center to correct their length and offset. We supply sleeves that are bored out to a slip fit over the cut-off ends of the stock bars, requiring only simple welding to complete the modification.
The picture below shows, installed, a stock watts linkage from a 1st gen RX-7. Note that the rods have been sleeved as described above...

If you are using our fabricated watts linkage, the supplied threaded bars are easily adjusted to center the rear under the car.

Installing the brakes and e-brake cables...

If you are using the original RX-7 brakes, this step is pretty basic, just bolt them up to the supplied brackets. Be sure to check for clearance between the rotor and any brackets or bolts that may come in contact with it.

Final inspection and safety check...

Periodic inspection and maintenance...

Keep a watch out for oil leaks from your rear, especially from it's rear cover. Not only can a leak cause component damage from low oil level, it also may indicate loose cover bolts that play a critical part in anchoring the rear of your torque arm.

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