85 RX-7 alignment / suspension help

So I'm building a dedicated track rat out of my old RX-7 GSL-SE. I'm hoping some of you 1st gen rx-7 gurus/racers have some advice on alignment specs and ride height (the coilovers on the front are easy, might have to cut a coil to adjust height out back)

Suspensionwise, this is what it has:

Ground Control camber plates (front)

Ground Control coilovers (front)

tokico illumina 5 way adjustable struts all around

Eibach springs all around

Suspension Techniques front swaybar

removed rear swaybar.

I think this is fairly close to what the spec7, PRO7 spec suspensions were although my spring rates are not as high. not positive tho.

The car is basically for track days & HPDE so full race specs are great.

any help/tips appreciated.

thanks.

What tires are you using?

What tracks are you running?

Camber and caster are affected by both

In reply to aussiesmg:

tires are TOYO Proxes RA-1s on 15x7 rims.

Mostly northern california tracks: Sears Point (Infenion), Laguna Seca, Thunderhill.

Check with tire rack for detailed info on the tires, do they need a lot of camber or less, etc.

I am assuming these are all fast tracks with longer straights, am I correct?

PS: get a tire pyrometer

In reply to aussiesmg:

yes, all fairly fast tracks. Laguna Seca is probably the fastest.

Plus one on the tire pyrometer.

I ran 13" Kumho Victoracers on my '79 (mostly autocross) and I maxed out the caster and camber, IIRC it was something like 4.5 deg caster and 3.5 deg camber with ~1/8" toe out. 350 inch pound front, 200 inch pound rear springs, same Illuminas, stock front sway bar, disconnected the rear. Ran the suspension raked up approx 1/2" to the front. Don't use urethane rear bushings, learned that one the hard (expensive) way.

'Doug' at Ground Control was a big help with setup.

Most of the RX7 racers that I knew took the Watts link and threw it in the garbage can, then installed their own panhard rod for axle location. The Watts tends to bind and cause sudden oversteer. Take a look at the ISC website for ideas.

In reply to fastmiata: I hear the hate for the early RX-7's watts linkage from many sources, but i just can't see it myself. My experience is that it's the rear 4 link that binds, not the watts link. As the body rolls, the 4 link's soft rubber bushings run out of compliance and suddenly become very stiff...snap oversteer. I just don't see how switching to a PB fixes that.

I've got an '85 RX-7 outside that's been converted to a torque arm...it has lower 2 links of the 4 link in the stock locations, but the upper 2 links have been removed. Still has the watts link, attached to the chassis in the stock locations. Without it's springs and shocks, it's rear axle can easily be articulated well beyond whats desired, to the point of looking more like a rock crawler. I just don't see any watts linkage bind that would likely cause sudden oversteer.

Thanks for all the input so far.

I don't actually have much money to invest in tri-links or custom rear end setups or anything right now.

Ultimately I'd probably be best to source a sorted out ex-racecar and stuff the 4port webber'd 13b I have in my ride but for now, just trying to get this puppy on track and handling as well as it can given the mods it currently has.

As far as ride height, cutting coils seems like the only way to lower the rear right?

Like so many things in the Grassroots life, performance doesn't have to be expensive. This mod works:

http://www.pbandjracing.com/rear_suspension.html

Best of all, it's dirt cheap.

If you already have Eibach rear springs, they should have one end that's 'coil bound'; it has three or four coils which touch, even when they aren't on the car. You can trim those as needed for rear ride height adjustment.

In reply to Jensenman:

great link. thx. Dirt cheap what I'm after.

Also before you eliminate original suspension pick up points be very careful about any class rules you may wish to compete in.