RSAErick

I was wondering...

Would it make any sense to replace my existing progressive H&R springs with similar spring rate linear springs?

My goal would be to maximize handling on the track without having to revalve my H&R shocks (H&R coilovers). Also, I wonder if it would help prevent the tire rubbing that is being discussed here: https://rennlist.com/forums/964-forum/154663-how-much-tire-rubbing-is-too-much-pics.html

I have heard many times (noteably from Bill Gregory) that progressive springs have compromised 'turn-in' characteristics because the springs must travel through the progressive (lower spring rate) springs before getting to the higher spring rate linear portion of the springs. Even I can feel it.

But if I could replace the progressive H&R springs,
Mine are H&R 964 Coil-over:
Front 250-285 lbs/inch
Rear 265-285 lbs/inch

with linear springs of approximately the same spring rate:
Front: ~300 lbs/inch
Rear: ~350 lbs/inch

Then maybe the handling and tire rubbing will be improved.

All without revalving the shocks!?!?!?

Springs are sooooo cheap, that this could be a performance bargain if the improvement was real.

Any thoughts?

Bill Gregory

My ears were burning! LOL Moving to linear springs make quite a difference in handling. If you increase your spring rate, you really ought to revalve your shocks, at around $75? each. While I'm running fairly stiff springs now, my Bilsteins were revalved to digressive valves and new shock rates, and the combination works very nicely. Wonderful on the track, and still driveable on the street. Granted, it's a stiffer ride than stock, but really not uncomfortable. You'd think, looking at the spring rates (600 lb front, 750 lb rear) that they would be rattle-your-fillings-out stiff, but with the custom valved shocks (the work was done by Bilstein in CA), it works. I also have a roll cage, which is neccessary when using springs with those rates.

In any event, you may have to change the hats and seats you're using at the top and bottom of the springs for the new springs. ERP makes a nice kit, or the components can be bought separately. Be forewarned, some of the hardware around the springs can cost more than the springs themselves!

burgass

Bill what kind of spring are you running?
Regards

RSAErick

Bill,
Unfortunately, my shocks are made by H&R. That means that they can only be revalved by H&R.

That's one of the reasons that I was considering this 'cheap' version. If I can find linear springs of approximately the same spring rate, and of the same lenth and diameter, wouldn't they just fit in place of the progressive springs that I have now?

Maybe I'm missing something...

tonytaylor

Bill,
why do you need a roll cage?
is yours bolted or welded and have you any seam welding?

sorry for the hijack Erik.

Bill Gregory

Burgass, I have Hypercoil 2.5"x8" in front and Eibach 2.25" x 9" in back. The fronts had to be 2.5" to get over the RS shock.

Erick, I can't comment on whether new springs fit right in with what you have today. When I converted from the Porsche RS springs, the base in front could be reused, but front and rear needed new hats, and the rear needed a new base. If your existing springs are 2.25" or 2.5", you can likely reuse the hats and bases. If they are any other size, then you'll likely need new hardware (I haven't looked at the Hypercoil listing recently, in terms of the variety of widths they manufacture).

Tony, I have a Safety Devices cage, with welded feet that the cage then bolts to. No seam welding. A side benefit to the cage, beside safety, is to add stiffness to the structure, important as you get into higher spring rates.

JasonAndreas

H&R shocks are just rebadged Bilstein. There was a recent thread on the Pelican Parts BBS about it.

RSAErick

Guys,

I talked to H&R. They claim that the springs that they use on their coilovers (they are the same as the 965 H&R springs that people are putting over Bilstein HD's) are not standard size, and can NOT be replaced with 2.5" springs without changing the mounting hardware ($$$).

So much for the cheap and easy idea.

Next, I asked about revalving. They claim that the H&R shocks may contain some Bilstein components, but are NOT Bilstein shocks and can only be revalved by H&R in Germany. To do so would be MUCH more than $75 per shock, especially since they make you pay for the shipping there and back.

So, there goes my idea down in flames.

tonytaylor

I have a Safety Devices cage, I guess it's the same as yours as it sounds similar.
I have been led to believe the full welded RS clubsport cage increased shell rigidity by 70%. I doubt my welded feet/bolted cage is anywhere near that amount. Have you any idea how much rigidity is increased?
Have you changed any of the rubber bushes? I had considered rose joints but the maintainance issues put me off and I am now confused as to which bits to replace and with what.
My interest in stiffness is because I had considered running slicks but opinion seems to be the car won't stand it without a welded cage and seam welding ( and turbo hubs etc )

Erik,

If you are using the H+R coilovers then the dampers are bilstein. I had considered having my H+R coilovers revalved with linear springs and fitting monoballs but it worked out cheaper selling the H+R coilovers and buying a the cargraphic/H+Rsupercup track suspension.

Bill Gregory

Tony,

I'd expect that a fully welded cage would be stiffer, too. I know the Safety Devices cage made a difference in overall stiffness - I noticed it the first time I took it on the road. I have no more rubber bushings anywhere in the suspension. I have monoballs at the top of the shocks front and rear, and monoballs in the front A-arms, rear swing arms, and swing plates. In front, when combined with the Cup Car forks (between the steering rack and tie rod), the turn in is much crisper than stock. Still working on defining the limits in the back end.

tonytaylor

Bill,



more food for thought.

RSAErick

Interesting thought. I guess that I would consider one of the package suspension set ups if there isn't a way to assemble a better or equal system for less. Maybe this offseason.

Still, it seems like one could get custom valved shocks, monoballs, and linear springs for less than $2000-3000. I need to learn more about what it takes apparently.

Thanks.