Rethinking springs?

I don't have any input on the universal springs, but have to ask what happened with pursuing ground control-style rear coils?

Thanks for the link I was planning on doing Moog CC253 springs on the rear with next paycheck. They're supposedly a drop in replacement 221 in/lb spring.

But some sources claim they're a variable rate spring.

Now you've given me something to think about.

Interesting. Curious as to the fitment.

Like you said, it would not be hard to make it work. You looking to get back in the stockish class?

Never thought I'd say it, but after a really tough first half of the year, I need a break from racing. Both time and money just aren't there right now. Sold off the coilovers from the Z to make ends meet and with the factory stuff back on, the car wanders and jerks on the highway so it is staying in the garage until I can figure out what's wrong with it.

The ground control rear is something I'd still like, but the fab/welding that is required is past my level of caring right now. My thought now is to source some cool alternatives for drop springs and see if single adjustable koni race shocks for a mustang works on the rear. Z is retired from autox for now (and the AE86 is being a pile of unreliable poo as usual). My main gripe about the bolt-on coilover setup was the lack of suspension droop. I found that a significantly longer stroke is really a must for cornering.

As for fronts, I'd like to work some Koni 8610's (single adjustable race dampers) into the factory housings. Maybe a coilover conversion for at least the fronts so I can get the 2.5" spring options unless I can find something off the shelf that fits into the factory perches (unlikely since they are such oddly large diameter springs).

Also, technically the relocation of the oem spring on the rear (to the spring-over-damper coilover assembly) is actually not legal for Street, Street touring, and Street Prepared as per SCCA rules. :P

what is suspension droop?

Priorities. Stick with the important stuff and the extra will fall into place.

On the topic of dampers; if you're at the right time and motivation to look into a set, Koni's annual sale goes through the end of August. Most places tend to carry the Yellows only, but others should be able to special order others and still allow a discount.

I still think the ground control rear setup is your best option for staying SCCA legal and retaining 2.5" coil convenience. But maybe consider going back to Mustang springs in the meantime? I guess I'm just wary of standard size universal springs.

Out of curiosity: Did someone challenge your decision to use those rear coilovers in autox?

Suspension droop is the distance that your suspension can travel up and down under load and off load. For instance, if you jack up the car from the rear diff and let the rear wheels hang down, the amount of droop is how far the wheels fall before they stop (max length of the shock). On stock style dampers, the droop is huge. On a coilover setup, you only get a few inches. For me, this means under heavy cornering the rear inside wheel lifts off the ground (which is bad). Things can be done to fix this, but it is always a compromise. A heavier front bar and more front spring will reduce rear lift, but also induce understeer. Removing rear sway will also reduce inner wheel lift, but will slow down transitions and make throttle steering more vague, etc. TLDR: sticky tires -> lots of lateral G's -> needs rear droop

Video footage of what happens when you lift the inside rear everywhere: https://www.youtube.com/watch?v=mFKUIP3FaXI

when one side is lifted, the diff basically stops working. Even a giken doesn't deal with lift. It spins up and once the car loses speed and plants again, it squirms. The above video is the first time I had experienced it--I thought the clutch was slipping or my diff broke. Later on, I got used to it and let off throttle when I knew it would lift to reduce the spin-up and the squirm once the car lands again. Here I had no idea so you just hear the rpms shooting up mid corner and nothing happening.

I think drop springs are just convenient even if I got back into it. As long as the height is so-so right, I'd be okay with it. I never really corner balanced the car or adjusted height often when I did have the coilover setup. 350 lb/in should be sufficient for the rears assuming I can guestimate the height. Less things that can break IMO.

No one protested the legality of my car. The car (and I) wasn't competitive enough at the national level to warrant the attention. If I were up there, I would probably get protested for it… pretty blatant. At the local level, no one cares.

Maybe I'll take some measurements this weekend while I still have the spring compressors rented and see what I can come up with. Maybe I can find something that will stop the price gouging on decent drop springs.

I'm adding helper springs to my coilovers in order to run some droop, as I've also experienced front and rear inner lifting. Its not major, but its noticeable enough for me to do something about it.

I forgot that helpers will help with that, though I never experienced front lifting. Though, my car is an NA so methinks more torque is necessary to lift that inner front :P

Springs ordered. I found that foxbody mustang shocks are too short at full extension to be usable. The stroke and compressed length should work fine, but at full extension it is ~4 inches shorter than the z31 shocks. I'm inquiring with Koni now to see if they can find me something that will fit.

One thing that may help you is modifying the OEM top shock mount

What i did with mine was separate the bushing cup and weld in a 2" by 2" piece of thick wall pipe and weld the bushing cups back on.

This lifted up the OEM Z31 shock just enough to keep things captive on my threaded collars. Its a little less extreme than a shock thats 4" shorter and can be easily done in an afternoon with a welded.

Any updates or progress on this idea?

I'm entertaining the thought of some slightly lower rear springs in the 300# range. These Mach 1 springs still tend to be a bit soft at times.

^ I've got the Ford racing "C" Front springs under the back of my car, had to trim down maybe 1.25 coils I think. the rears were a bit softer than I liked, so tried the fronts. just right!

So the spring fits into the lower perch nicely. The 11" free length is actually not long enough for the spring to stay captive at full droop on oem style shocks.

I haven't dropped the car down yet to see what the ride height is like but will do so once I finish up a few things. The 5.5"x12" springs should stay captive at full droop but might not be lowered very much (SS springs have free length of 12.5").

Possible idea is to do what James had suggested and move the shock top hat up to take up some slack, build a droop limiter in the centerline of the spring, or to fab some kind of spring retainer. It isn't off by much.

EDIT: Also found a supplier for 350 lb/in springs for 5.5x11" https://www.southwestspeed.com/?sec=…Rear%20Springs
Shipping was $20 for me.

Some pics:





Comparison pic is with an 86NA spring.