Best E30 Rally Suspension Setup

[iamsam]

So we are building a rally car. This is the starting point:


So we (MasterOfPuppets and I), and I have been contemplating these questions:

Which selection of stock springs would be best, which selection of stock or aftermarket swaybars would be best, and would Bilstien HDs work well?

The situation is this: We have a late 325is with Eibach ProKit springs and Billy Sports installed (which we will sell, too low for rally), and we need to decide the best springs to put in there. We are doing this relatively cheaply, since for now it will be entry level. For example, stock E36 325is springs (which should fit) have a higher spring rate than E30 325is stock, and would also lift the car an inch or so. Good option?

The car currently has ST adjustable swaybars. Keep the stiff swaybar, or get a softer stock swaybar?

Also, Billy HDs are included (not installed) w/ the car. I have heard these shocks are a good start. Any strong objections?

Real world experience and knowledge will be very appreciated.

Thanks guys.

[iamsam]

Swiped this from the suspension thread, E36 rates would be helpful too...

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


**= Alternate rates available
***= M3 Application

[LuckyHenriksen]

Metallica lovers eh? Right on!

And I have always wanted to build a rally E30 I will be watching this thread :)

[iamsam]

Metallica lovers eh?

Heck yes!

Although we have slight differences when it comes to Iron Maiden...

[LuckyHenriksen]

Metallica has been my all time fav group :)

[KennyT]

HDs will be fine for now, but you will want them re-valved to what the springs are. I would get some stock sways for now and get seat time before you worry about dialing in the suspension. I'm not too sure on what springs to run, I would call various companies and inquire about gravel rates.

I hope you are heading out to the Olympus Rally, or Oregon Trail. If those Bilstein Sports are in good shape I will pick them up from you.

[iamsam]

HDs will be fine for now, but you will want them re-valved to what the springs are. I would get some stock sways for now and get seat time before you worry about dialing in the suspension. I'm not too sure on what springs to run, I would call various companies and inquire about gravel rates.

I hope you are heading out to the Olympus Rally, or Oregon Trail. If those Bilstein Sports are in good shape I will pick them up from you.

The Sports have about 100k miles on them, and there is a buyer in line. But we are selling them priced accordingly w/ the miles on them. The HDs only have about 15k miles on them though.

Questions: Why stock sways over aftermarket?

Also, what is optimal for rally, more than stock ride height and more than stock spring rates? or something else? Because more height and more rate can easily be obtained with a huge selection of stock E36 springs....

[KennyT]

You want as much travel as possible, first and foremost. Bump vs Droop is determined based on driving style. If you are going flat over jumps and driving hard, more droop = more control when the car goes 'light' over bumps/crests/etc.

Is this your first rally car? Have you raced any rallies before? Have you crewed/marshalled/spectated any rallies?

[iamsam]

I have only rallied once, Mike (MasterOfPuppets) has ralliued alot with various American cars, but none of us have rallied officially/professionally, just for fun.

Me in the E30, Mike in the Jeep:

[KennyT]

First off, Rallycross is not rally in any way shape or form. It is autocross on dirt, nothing more.

If you have no car preparation experience, and no rally experience, there is no way a car you build will finish the first day of a rally. Don't take it as an insult, but advice from someone in the sport. I highly suggest either having someone else with rally experience prepare the car with your help, or buy a prepared car and run that for your first few events.

Building a car will cost roughly 10 thousand minimum. 2 or 3 for the cage work, a few more for seats, belts, helmets, trip computer, etc. You can buy a group 2 car for 5-8 ready to run.

[Simon S]

Questions: Why stock sways over aftermarket?

Also, what is optimal for rally, more than stock ride height and more than stock spring rates? or something else? Because more height and more rate can easily be obtained with a huge selection of stock E36 springs....

For one, stock sways will allow more-independent wheel suspension - better for rougher terrain. I'd be more concerned about wheels staying on ground for traction rather than reducing body roll.

Wish I could provide solid input on springs. I'd be inclined to rock stock springs - and add pads if more ground clearance was desireable. Mostly as a cheap place to 'start from'.

Skid plate obviously..

Def sub'd for your progress.

[blefevre]

For one, stock sways will allow more-independent wheel suspension - better for rougher terrain. I'd be more concerned about wheels staying on ground for traction rather than reducing body roll.

Proper damping will be hard to do without an adjustable offroad setup. But I would agree your best bet is to start soft and go from there. I am pretty sure I threw away both my front and rear swaybars but I might still have the rear around you can have. Honestly, I would disconnect the rear all together for the first few times to see how it works.

[QUKBMER]

I love rally racing,dont get me wrong i have been following it since 1984 but i really dont care to much for the african rally, acropolis rally and such. I really like the fast tracks like RAC and 1000 lakes and swedish and australia rally when it comes to off tarmac rally racing.

[MasterOfPuppets]

If you have no car preparation experience, and no rally experience, there is no way a car you build will finish the first day of a rally. Don't take it as an insult, but advice from someone in the sport. I highly suggest either having someone else with rally experience prepare the car with your help, or buy a prepared car and run that for your first few events.

Building a car will cost roughly 10 thousand minimum. 2 or 3 for the cage work, a few more for seats, belts, helmets, trip computer, etc. You can buy a group 2 car for 5-8 ready to run.

Disagree on both counts. This may be true under the assumption that a rookie car builder has no education, car building experience, fab skills, or funding; but in this case, none of these are an obstacle. I have no doubt that Sam and I can design and build a car that will be sufficiently reliable. Stage rally is not such a "bermuda triangle" of car racing that it is impossible to understand what goes on inside. The most likely thing to stop this car is my over-aggressiveness, which I will be constantly struggling to reign in.

On the second point regarding cost, I've put together an exhaustive spreadsheet totaling the costs for the car setup and I'm expecting about $6k for the car, another $2k for personal safety gear, and $2k of stuff for the co-driver. So in a sense, your $10k number is realistic. But the problem is that the $4k of safety gear needs bought regardless of build or buy, so the costs are very similar. An I'm confident that I can build a better Gp 2 car than I can buy.

For one, stock sways will allow more-independent wheel suspension - better for rougher terrain. I'd be more concerned about wheels staying on ground for traction rather than reducing body roll.

Agree, but the question is where to draw the line on anti-roll. Obviously at some point you could have too little and have excessive weight transfer in turns (like my Jeep).

Proper damping will be hard to do without an adjustable offroad setup. But I would agree your best bet is to start soft and go from there. I am pretty sure I threw away both my front and rear swaybars but I might still have the rear around you can have. Honestly, I would disconnect the rear all together for the first few times to see how it works.

Actually, in the interest of inducing oversteer, I'd probably rather have a rear and no front. Has anyone fooled around driving an E30s with an odd anti-roll bar combo, i.e. rear w/o front?

[MasterOfPuppets]

Another question, since I don't have my car to look at yet: what limits the rebound and jounce suspension travel in the E30? My guess would be bump stops in jounce, but rebound...? Is it the sway bar links and sway bar?