The "Shop Mule" '85 RX-7
updates for 2010

The Shop Mule project car recently suffered a "setback"...
...more like a 10" engine / radiator setback combined with a 7" dash and 6" seat rail setback. Our goal for this modification is to be able to remove the rear bumper ballast on slick tracks, but some might use the extra room up front for a giant turbo or two. Others may want to move the firewall back to make room for a Cosmo 3 rotor engine or maybe a Supra 6cyl. It may look like radical surgery, but it's really relatively easy. When we're done, the car will still look stock on the outside. We could even use a flat hood if we wanted to...

Basically, the SBC V8 is moving back as far as possible while still being able to remove it's distributor past the base of the windshield. The cowl panel will go back on, but will be easily removable when the hood is up.

These RX-7 transmission tunnels are HUGE! This tunnel was moved back 9-1/2" and the seat brackets will be back 6", so the shifter will be closer...making it easier to reach 3rd while you are being pressed back in the seat. The original molded carpet still fits with slight alterations. The dash and pedal assembly was moved back 7" using fabricated aluminum extension panels and standoff posts.

Here's a shot of the lightened dash understructure being test fitted. The extended steering column and firewall brace bolt up just like stock. We are moving the fusebox so that it will face the door opening...much easier access. When the stock dash cover, plastic panels and carpet is added, it's all very "stock appearing".

The added seal panels are made from 18ga cold rolled sheet. The stock firewall is still there, just moved back a bit in the center for "valve cover clearance".

That ugly stock crossmember has got to go...

The engine now sits entirely behind the front axle. The radiator will be moved back as far as possible for this car, but some might use the extra room in front for a couple of turbos and an intercooler. The front motorplates we used are from a 410 Sprint Car. We also added rear bellhousing mounts to make transmission changes easier. With the engine this far back, the ugly stock crossmember is now easy to see. Since we no longer use it to mount the engine, we made some tubular replacements...

The new tubular front suspension components are quite a bit lighter than their stock counterparts, and use kevlar lined rod ends rod ends at the pivot points. The new strut bars feature aluminum (originals were solid steel), but the unseen advantage is the new optional front mounting points that allow the wheelbase to be altered for increased rollout at the strip...the left front can be moved forward about an inch, the right front can be moved back about an inch. Depending on the tree, an additional 2" of rollout can easily shave off well over a tenth from the 60' time.

If there is enough interest from others wanting to make our firewall mod, we may refine the process and produce a kit. It would require using a sawzall and mig welder, and would consist of the following...
...(2) pre-formed 18ga seal panels with flanges and spot weld holes to make it easy to seal the sides of the moved tunnel.
...(1) seal panel for the top (above the factory pinch weld) that seals up to the base of the windshield and optional mounting tabs for the wiper assembly.
...(2) 7" bolt-in .060" aluminum "upper extension panels" for the upper/horizontal/center part of the dash that include slots for re-located defroster ducts.
...(2) 7" bolt-in .060" aluminum "side extension panels" for the side mounting of the dash (near the upper door hinges).
...(5) 7" threaded aluminum extension posts to relocate the pedal assembly away from the firewall.
...(2) longer brake and clutch master cyl pushrods
...(1) re-designed upper steering column support.
...(1) steering shaft universal joint and extension tube (collapsable feature of the stock column is retained).
...(1) lower steering shaft support bearing.
...maybe even an optional tubular front subframe and steering rack conversion?

Anyone want to put a 3 rotor or even 4 rotor in one of these?
This firewall mod would make it easy
Click and drop us an e-mail if you think the firewall mod is something you would be interested in.

To go to the Shop Mule's 2009 home page, CLICK HERE
includes pictures from before the engine setback.

To go to the Shop Mule's 2014 home page, CLICK HERE
includes the later homemade bellhousing project and electric crankcase vac pump project

GSS Clutch Slipper Project CLICK HERE
quit breaking transmissions with this simple addition to your clutch pedal