Front/Rear weight distribution

#1

Don’t link me to other threads I already read them!

I haven’t gotten corner weighed yet but I’ve been told on the forums here I could never get to 50/50.

When I changed pads saturday morning I noticed my springs had lost their powder coating where they met from binding.

When I put the car on the trailer sunday afternoon I saw that I have about a 1/2 inch of travel before they bind up in the rear.

I have been trying to get as much weight in the rear as possible and have done it gram by gram. I was thinking 50/50 would be the best.

Now I’m thinking that the springs were designed for a specific weight and distribution. I think there may be an optimum distribution for the springs we are running and its on the front heavy side.

If anyone knows the spring rate that we have there must be a way to calculate the Front/Rear balance they were designed for. I am obviously to heavy in the rear right now.

#2

I can’t help myself. Spring Rate Link Opinions there say 315 front, 570-640 rear.

[quote]I haven’t gotten corner weighed yet but I’ve been told on the forums here I could never get to 50/50. [/quote]I’ve never worried about F/R 50/50, but always focus on cross weights. You CAN get those close to 50/50.

[quote]I have been trying to get as much weight in the rear as possible and have done it gram by gram. I was thinking 50/50 would be the best. [/quote]I didn’t go to any great lengths, but did put weight over the right rear when possible (battery hold-down, fire bottle).

I don’t have any setup sheets with me to tell you what my front/rear splits were. I never worried that much about it.

#3

[quote=“Steve D” post=67355]

I don’t have any setup sheets with me to tell you what my front/rear splits were. I never worried that much about it.[/quote]

Of course your didn’t. With that much talent, I wouldn’t have worried about it either. :whistle:

#4

I talked to H&R last year about our rear springs because I wanted to know why they are intentionally set up to bind after only a couple inches travel. This is an issue because there is a theory that when the rear suspension compresses so much that the spring binds, it puts tremendous force on the rtabs which can cause the various rtab adjustment systems to shift. The binding spring acts as a fulcrum.

H&R said that the additional coils were necessary to provide adequate spring height. Otherwise there would be a danger that the spring would pop out when the wheel was unloaded.

Re. front/rear weight distro. I’d aim for good corner weights and let it go at that. If you can get good corner weight while also keeping your polar moment low, that would be good too. F/R weight distro is, IMO, a 3rd priority.

E30 Springs

Spring---------------------Front(lb/in.)-------------Rear(lb/in.)

Stock 325i*-----------------------106------------------------245
Stock 325is*----------------------118------------------------265
Stock 325ix*----------------------106------------------------308
Stock M3*-------------------------114------------------------314
Stock M3--------------------------140------------------------250
Dinan Sport-----------------------172------------------------300
H&R OE Sport---------------------180------------------------380
H&R Sport-------------------------180------------------------380
H&R Sport (29664)---------------200------------------------285
H&R Race-------------------------315------------------------ 570
H&R Coilovers***----------------340------------------------380
Eibach Pro-Kit--------------------102-------------------------277
Eibach Race----------------------160-------------------------445
IE SIII----------------------------315-------------------------570
Koni Coilovers-------------------342-------------------------407
Cosmo Coilovers----------------450-------------------------560
Tokico----------------------------165-------------------------265
TMS J-Stock**-------------------680------------------------1026
Alpina(est.)---------------------~200-----------------------~350
FK 60/60 cup kit-----------------379--------------------------379
Vogtland Standard***--------115/197-----------------------360
Vogtland CS***---------------137/200-----------------------400
Vogtland--------------------------225--------------------------360
Intrax-----------------------------126--------------------------250

#5

[quote=“mcmmotorsports” post=67356][quote=“Steve D” post=67355]

I don’t have any setup sheets with me to tell you what my front/rear splits were. I never worried that much about it.[/quote]

Of course your didn’t. With that much talent, I wouldn’t have worried about it either. :whistle:[/quote]

What’s that? Sorry. I couldn’t hear you from all the Champagne spraying around me.:woohoo:

#6

I finally had a chance to look. My SE30 is 53.5% front weight with driver and 50.2% cross. By comparison, my Spec Miata is 52.2% front weighted. With coil-overs, it’s pretty easy to hit 50% cross though.

Hope that info helps.