E36 Rear Spring Rates for AutoX and Track?

[tptrsn]

Thanks jakermac and MW!!

[bostonaudi]

Asking for spring rates without context is completely useless and you're explicitely asking that we don't add context. Is your intention to simply average all the numbers posted and run that? I just don't see where you're going with this. There are knowledgeable people on here that will help you if you let them.

Agree, a better question might have been what do other drivers like, a neutral car, a tail happy car, an under steering car, etc as those lead to rate advise - a little.

Also agree conditions can dictate rates, at a track like CMP (Carolina Motorsport Park) the track has typically been very bumpy between 13 and 14 and high rates (or damper too stiff) can make the car dance all over the place in that section. Friends tell me Sebring in Florida also very bumpy, not a great place for super stiff suspension.

I built a FWD track car a while ago that was tail happy, and it tended to scare the hell out of me at times. Everyone said that was the right set up for FWD, now I know that was BS.

Get seat time and figure out what you like. Experiment.

And listen to the pros:

http://www.randypobst.com/index.cfm?...e&mag_id=15941

[JBasham]

Yes, I was parked at an HPDE this weekend next to a nice guy driving a GT4. We were talking oversteer in BMWs and he said he raced E36s forever, and they were all prone to "surprise" oversteer unless all the rear bushings were replaced with solid or near solid. His point being that I needed to do the same in my E92 daily driver post haste. He never breathed a word about spring rates or dampers, and I didn't want to be a d**k about it so I just listened. Plenty of good advice in this thread. Funny how this collective always manages to steer things that way.

[ThreeD]

Yes, I was parked at an HPDE this weekend next to a nice guy driving a GT4. We were talking oversteer in BMWs and he said he raced E36s forever, and they were all prone to "surprise" oversteer unless all the rear bushings were replaced with solid or near solid. His point being that I needed to do the same in my E92 daily driver post haste. He never breathed a word about spring rates or dampers, and I didn't want to be a d**k about it so I just listened. Plenty of good advice in this thread. Funny how this collective always manages to steer things that way.

Surprise oversteer in an E36? Lol...one of the most predictable cars I've driven...

Sent from my Nexus 5X using Tapatalk

[tptrsn]

I haven't experienced any surprise oversteer, but then again the first thing I did was replace all of my bushings with nearly solids except the RTABs, which for which I got softer poly in case some articulation is necessary in those. With the 800# springs I currently have in the rear I doubt there's very much articulation needed in that bushing, but the motion ratio does make those springs surprisingly compliant. I kind of think I would try higher rate springs just to see what they are like, but 800s are the highest I have. So I guess 800s are where I will stay...

[bostonaudi]

I've run both poly and factory RTAB's with limiters and quite frankly I think the concerns about articulation in the E36 are overblown. With 800 lb springs you should be fine. Vorshlag wrote up an article with concerns, and I have driven a car where lack of articulation with rear poly could really be felt in a negative way, the E36 doesn't seem to be bothered by poly in the RTAB.

[Hags86]

Hi All. Reviving an old thread. Looking for recommendations on spring rates and I'll try and give as much info as possible.

e36, 328i coupe.
Gutted and caged. Doing cheap endurance racing (think Lemons or Chump cars). Racing only. Only time it will be on a public road is getting it on/off the trailer.
Looking for neutral handling.
We are not allowed to run coilovers so will get some Koni inserts, probably get them custom valved to the spring rates we settle on.
Must run a street tyre. No R Specs or semi-slicks. Currently using a 320 treadwear Michelin Pilot Sport 4. Basically a decent quality road tyre.

I've done some reading/searching but the circuit recommendations (probably) all assume an R-spec tyre or stickier. Would like to get some good data from the experienced guys before I waste a bunch of time and money chasing a good combo.

(currently have OEM spec Bilstein dampers and some lowering springs that I bought cheap - no data on rates unfortunately. The car is nicely balanced but too much body roll which really dent's your confidence on high speed corners. Sway bars are 24mm front, 15mm rear)

Thanks

[aeronaut]

With the limitation of using OEM struts, I'd just start with the NASA spec3 setup, or some other E36 spec class setup that uses the OEM McP struts.

https://nasa-assets.s3.amazonaws.com...ules_Final.pdf

[tptrsn]

Do you know what the spring rates are for those? Initial googling doesn't reveal any numbers.

[aeronaut]

I don't. But, typically, spring rates for OEM struts from HR, Eibach, etc max out around 300lb/in.

[NeilM]

@Hags86: Are you going to/allowed to change the sway bars, and in the case of your non-M chassis, the front link attachment location?

Neil

[Hags86]

Yes, can change sway bars and link attachments.

[cmoody]

Definitely not coilovers, but I found that the E36 M3 Dinan+Koni setup was very capable on street, track, and autoX. It was supposedly 150/400 but also did not lower the car much, only like 1/4" or so, which keeps the front roll centers happy.