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Camber Plate Install

Front Suspension:  Spring Setup, Shock Setup, Ride Height Issues, Shock Travel Issues

Rear Suspension:  Spring Setup, Shock Setup

The RX7's have a problem where when you raise the car, the front wheels get positive camber.  From my talks with Dave Clark at DMS, he says there isn't enough front camber adjustment to remove the positive camber on the stock suspension.  So what do you do?  Get some adjustable camber plates.  I already knew that Ground Control made camber plates, so I called them and ordered a set.  I didn't know for sure how much positive camber you could take out, as most people install camber plates to eliminate negative camber (positive being where the tops of the wheels point out).  Then again, most racers like negative camber, so in theory I could just add negative camber as long as the Ground Control units allowed.

A week later my camber plates arrived and I must say, they look really nice.  They're not as stout as some of the KMR camber plates we use on the Porsche race cars at work, but they should do.  Very nice CNC work and a clean purple/gray anodized finish make them look clean.  They aren't marked for settings, but that doesn't matter in my case because we have the scale pad with alignment tools at work.  I am of the opinion that the marks on the camber plates can only be used as reference points, not as actual settings.  All that meaning that 1 degree on the plate (according to the marks) doesn't mean you have 1 degree of camber.  But, 1 degree on the camber plate might mean .5 degrees on the car, so you can use that as a reference point. Either way, why do I care.. all this doesn't affect me.  Ground Control told me over the phone that I'd have to do some "light filing" to make the camber plates fit.  Sure enough, just like I expected, the term "light filing" means you have to butcher the shock tower.  You can get away with light filing if you want, as the filing is to make the bolt-holes line up.  The adjustment however is severely limited unless you cut the shock tower out - you'll see what I mean in the picture.

After 30 minutes of "light filing" with a cut-off wheel, a hand file and a drill, the shock tower was cut to fit the camber plate.  The install wasn't that hard, but I had to make a lot of marks on the car before I just went cutting away.  The GC plates come with some shitty 6mm allen head bolts - 6mm being the bolt thickness, not the head/wrench size.  I threw out the allen bolts and got some 10.9 grade 8mm bolts which can take more torque.  Not only that, but I had to file the holes big enough to make the plates fit (apparently GC makes one camber plate, for all Gen RX7's so they don't exactly bolt right up) which in turn, made the shitty 6mm bolts almost fall through the holes.  That was about it really. I torqued the bolts to 17 ft/lbs which is just a random guess that felt right, but that'll have to due.

You can see the newly cut-out shock tower.  Without all the cutting, the bolts on the right side don't clear the tower and the actual sliding plate won't slide forward.  The bolts in the picture are the 6mm bolts GC provided, notice how the upper right bolt is about to fall through the hole.  Bigger bolts and bigger washers solved that problem. 

Specs:

Shocks - GAB Adjustables, all four corners.

Front Springs - Eibach ERS Race Springs.  Two springs per shock.  Primary Spring: 800.250.750, or 8" tall with a 750lbs spring rate.  Tender Spring: 500.250.250/550.   

Rear Springs - Eibach ERS Race Springs.  Two springs per shock.  Primary Spring: 800.250.550.  Tender Spring: 500.250.250/550.

Sway Bars - Stock.

Bushings - Stock replacements.

Notes:

- The GAB shocks had to be turned to fit in the camber plate bearing, something Ground Control forgot to tell me.. figures.  The shock shaft at the top is too thick in diameter to fit through the bearing, so they need to be turned down a little to fit through the bearing.  25 bucks at a machine shop fixed this.

-  The GAB shocks aren't tall enough in the front.  With the collars turned all the way up, not only are the front tender springs half-way compressed, but the shock shaft is fully extended.  The ride height is really close, about a half inch lower than desired, but there is no droop travel (actually, there's about a half-inch) at all so when you enter a corner under a hard load, the car wants to lift wheels.  Yeah, this looks cool like the Touring cars you see on Speedvision, but the car doesn't have much traction with three wheels touching the ground.

- To fix the shock travel/height problem, I got some 3/8" polyethylene and made a spacer that fits between the camber plate and shock tower.  Now the car sits about a half-inch higher, but it also allowed me to lower the shock collars a half-inch to give the shocks more droop travel.

Front shocks:

Rear Shocks: