Rallycross spring rates.

In all my research on the subject, (mostly here, specialstage, and a few other forums) I've found vastly differing opinions on the "right" spring rates for rallycross. I've come to the conclusion that there isn't a right answer but wanted your opinion anyway.

I have a '94 Protege currently on stock coils, and therefore, rates.

I need new struts badly (originals on 290k ) so while I'm replacing struts, I wanted to address the springs if I needed to. Since my struts are so far gone, I don't have any real feel as to how well the stockers are working.

Any feedback is greatly appreciated, especially if you rallycross a BG variant. (paging cghstang)

PS, the club I run with doesn't follow any NASA or SCCA Rallycross rules so our courses are typically rough and we have yumps.

I'll strongly agree with the "vastly differing opinions" conclusion.

I can tell you for sure that the Eibach lowering springs common to the BG chassis and ZX2 S/R are not what you want. If they were linear springs at the higher of their two rates they might be just right, but as progressives I didn't like them at all (on crappy roads too for that matter).

Locally the consensus seems to be that stock or slightly stiffer than stock is what works well.

My ZX-2 currently has the Ford Motorsports struts with stock ZX-2 springs. So far I like the setup. It's worked well so far for a mud fest rallyx, grass/dirt/hayfield rallyx, and a couple of autox events.

A lot of the subaru guys around here go to sti pink springs which are stiffer than stock but not outrageous.

I don't know how results usually shake out on your courses, but it's not unusual in OH or MI for scca stock class cars (non adjustable dampers with stock springs) to take first overall.

As for the yumps, I'd be thinking about your bumpstops. Replacing the stockers which are probably super hard would be a good idea but I don't know if you'd want to go with stock replacements, stiffer, or softer ones.

In the motoiq frankenmiata article they discuss using some modern foam bumpstops, same concept as the flyin miata/ FCM miata bumpstop revolution. I though about trying something along these lines to get a bit more compression travel but didn't get around to it before I swapped my springs out. Luckily the BG chassis has a decent amount of travel so hitting the bumpstops hasn't been an issue for me. It might be for you with the yumps.

You tell me if I need to consider bumpstops, this is a landing from 4 wheels off :

I was going to go with the poly bumpstops that FM uses. The ones with the Kangaroo on the package, haha, the brand name escapes.

I was thinking going with GR-2 struts paired with junkyard stock ZX2 springs. Thoughts on that set up? I like it because it should be cheap as dirt and give me a slight bump over stock Protege rates.

In reply to Carson:

Ha! I'm guessing that pic was just after the one of your avatar.

Yep.

That's the one that caked the oil pan fins too.

GR-2 struts with ZX2 springs sounds like a good setup to me.

The Ford Motorsport Tokicos are worth considereing as they're under $200 shipped for a set though you would have to get ZX2 upper mounts. I'm not sure how cheap you can find GR2s.

Are the FoMoSpoTo (ha!) struts the same that came stock on ZX2 S/R? I was under the impression that the S/R struts were shorter than other stock BG offerings.

ZX2 top mounts won't be a problem, I'll have to pull those to pull the springs in the junkyard anyway.

GR-2s are $185 shipped so not a huge difference.

I've never been able to come to a firm conclusion on the S/R struts (yes same as FoMoSpoTo).

I know that they're valved to match the S/R Eibachs (something like 177 - 297lb/in up front and 114.2 - 182.8lb/in in the rear if the interwebs can be trusted) but I don't know if they also have a shorter shaft. One inch shorter is the number I've heard thrown around. If they do, I think that when paired with stock ZX2 springs you should just be giving up some droop and gaining some compression travel when compared to stock struts.

I could get pictures/measurements of my setup at full droop and compression if you want. Here's one at close to full front compression:

The rod on the SR/FR struts is shorter so that the shorter spring : Eibach, will not become loose on full droop. Lowering the car for rally cross is not a good idea. I ran my SR in a field rally cross and once it got torn up I was dragging the botom of the car on the sod chunks. For ice racing I use stock springs and struts, no swaybars.

Because I've only lowered cars, and never altered the suspension to maintain or increase ride height, and always matched strut valving with spring rates, I have some questions:

What is the effect of running a strut valved for a heavy spring and using a lighter spring?

What would happen if I were to run the stock (non S/R) ZX2 springs on the S/R struts with the shorter rod? Coil bind?

What would happen if I were to run stock ZX2 springs (longer w/ higher spring rate) on an OEM replacement like the GR-2 struts for a Protege?

Carson wrote: What is the effect of running a strut valved for a heavy spring and using a lighter spring?

The spring is overdamped to some degree.

Carson wrote: What would happen if I were to run the stock (non S/R) ZX2 springs on the S/R struts with the shorter rod? Coil bind?

This is exactly what I'm doing right now. It works fine if not quite well. No coil bind, no problems. I like it on the street and for rallyx and don't plan to change it anytime soon.

Carson wrote: What would happen if I were to run stock ZX2 springs (longer w/ higher spring rate) on an OEM replacement like the GR-2 struts for a Protege?

I wouldn't be surprised if they're valved exactly the same. The GR2s listed for the 90-94 Protege, 323, and ALL 91-96 Escorts (pony, lx, GT, wagon) are the same: 234037/8 and 234039/40 even though all those variants probably had slightly different stock springs. The wagons definitely have different rear springs but use the same strut. Which is to say that I don't think anything bad would happen.

did u ever use the zx2 springs on ur lx protege?

Have a friend with ZX2 running FR struts with stock springs with no problems.

cool, im buliding my protege for rally cross, and im going with kyb struts, and zx2 springs all round. I hope this is better that my original springs off the lx. If anyone knows if springs from other manufacturers such, as suburu, hyundai, or toyota will fit the protege struts, im open to ideas, i want the car to be able to take yumps and land nicely without bottoming out.

In reply to wizkid971:

Where are you located? The type and condition of courses used vary significantly from region to region.

I did somewhere around 18 SCCA RallyCross events last year with my ZX2 using stock springs and bumpstops with the Ford Motorsport struts discussed above at a wide variety of sites. The stock springs are fine most of the time but on the really rough stuff you will bottom out the front suspension.

I've got some ideas for improving the suspension for rallycross but since I haven't actually tried any of them yet, I won't go into them unless your interested. Stiffer springs on coilovers is the obvious one.

How would slightly stiffer (say 200-250 lb/in ?) springs work if they were a few inches longer than stock and mounted on a performance shock, of some sort? I read someplace, about a Ford Escort being rallied with longer,250 lb springs.

When I get coilovers for the ZX2, I'm planning on 225 or 250 lb/in for the front and 150 or 175 lb/in in the rear. The springs should just need to be long enough to stay seated at full droop, I'm not sure what length that will work out to. I think it will be a good improvement.

Edit: For anyone interested, there is some good food for thought on rallycross suspension setup in this thread on the Detroit RallyCross forum.

DeadSkunk wrote: How would slightly stiffer (say 200-250 lb/in ?) springs work if they were a few inches longer than stock and mounted on a performance shock, of some sort? I read someplace, about a Ford Escort being rallied with longer,250 lb springs.

When I rallycrossed the Metro, I used springs from the later gen, which had a .5mm larger diameter wire, and were an inch longer. The raised the car about an inch, maybe more, and it went through the rough stuff like it wasn't even there. Good, stiff motor mounts are always a good idea, and will preven thr car from jumping out of gear in the rough stuff.

In reply to cghstang: Im in Oklahoma. I would like to hear your ideas. I bought kyb gr2s, and now I am looking for zx2 springs. Id like the car to be a lil higher in the front if possible, Im open to everything right now. I forgot to mention, i am restricted by budget, or i would do rally shocks and springs, so i have to kind of go with a low budget setup for now and hopefully yall that have rally crossed proteges before can help with that. thanks