Best E30 Rally Suspension Setup

[KennyT]

Thing is, as a guy who was looking into building his own car, there are a lot of things that you will do wrong in the build. You are trying to build a wheel without looking at what others have done, or seeing how their approach works. That is fine if you have an unlimited budget, but realistically you need to get as much seat time as possible irregardless of the car you are in.

The 10k budget is the bare minimum you can build a car for, and that does not include spares. If you want to run a hodge podge team then go for it, and good luck. If you want to run a car that will finish every event short of hugging a tree then you have a lot of learning to do (again assuming little professional racing/car preparation experience).

Feel free to PM me details, and I apologize if I come off sounding like an ass. Wasting money simply sucks.

[iamsam]

Fist of all, I agree w/ rallycross being nothing more than autocross on dirt, and bot nearly as fun as rally. The experience I have is a day on a 2 mile rally track, which was a huge blast, and made me not want to ever go back to rallycross, and makes me think why anyone else does rallycross.

Second, I believe that Mike won't be plowing full-on into a $10 build immediately, he will probably practice alot at CORE (Colorado Off Road Extreme) first hopefully with a basic rally prep (shocks, stock springs, skidplate, chassis reinforcement, etc).

So I don't believe it will be a situation in which a novice rally driver and car builder is going to dive headlong into the "real deal" quite immediately.

However, KennyT, I really appreciate your experienced input, keep it coming!

[iamsam]

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?

Oh yes, both front and rear suspension is limited in rebound by the shock itself. The bump stops are in the shocks, and the shocks structurally limit the rebound of the control arms.

Technically the swaybars will ultimately limit rebound, but the shocks would have to snap in half first, which is unlikely.

[MasterOfPuppets]

Oh yes, both front and rear suspension is limited in rebound by the shock itself. The bump stops are in the shocks, and the shocks structurally limit the rebound of the control arms.

:eeek::eeek::eeek::eeek::eeek::eeek: Bump stops in the shocks!

That sounds like a recipe for repeated, incessant shock blowout! I guess I'll be rigging up some actual rubber chunks to limit travel. This is coming from someone who's BROKEN rubber bumpers, so I can't imagine that a tiny little stop inside the body of a shock is going to be sufficient. I guess E30s were never designed for off roading.

Also, KennyT - I have every plan of spectating and/or working a few events before and during the build process for this car. This is the exact opposite of a slapped together team, as the car has been bought already and I can't imagine competing it until late 2012 at the soonest. There's certainly learning to be done, and no amount of success or failure is a guarantee, but the challenge is surmountable! Keep the feedback and inputs coming as we design this sucker.

[iamsam]

:eeek::eeek::eeek::eeek::eeek::eeek: Bump stops in the shocks!

I dunno, the internal bump stops in the Bilstien shocks are pretty strong, and Bilstiens come with a lifetime warranty iirc. Besides, how much force is really pulling down on the shocks at full travel? No more than the springs can apply to the control arms, and no more impulse than the sprung weight can induce when accelerating from full compression to full extension with all the force the springs can apply.

As a matter of fact, it IS possible for the rear subframe to limit the downward travel of the trailing arms. to adjust that, you would just need to weld in some small steel plates.

Take a look at the pic below and you can see how the subframe rail impedes the trailing arm from swinging down entirely. Of course you would just have to strategically weld in some plates and maybe rubber bumpers on the plates right about at the same point as the shocks reach full extension, or when the bump stops in the shocks first start to contact. That would give you a TON more strength throughout the elastic region of the shock's internal bump stops.

[KennyT]

Concentrate on making the car reliable before making it competitive. Worry about making the car solid, reliable, and fun. The car will end up being overweight for the class, and won't handle very well with street suspension.

I'm guessing you guys will have someone else cage it.

Run stock sway bars for shakedown before your first rally and you can try dropping endlinks to change the handling.

Main areas to reinforce: Bottom of core support (do not mount skid plate to core support), front and rear strut tops, and rear subframe. Caswell broke his down in Mexico after a large jump along with his oil pan. Do not reinforce control arms or swing arms. You want those to bend/brake instead of the subframe or chassis.

Brakes: Good pads and rotors are much more important than bbk's. Carry spare pads/rotors/calipers/lines. Get some rubber heatshrink to go over the SS lines for protection. Avoid K-Sport hydraulic e-brakes and secondary 'drift' calipers.

Engine: Bone stock, overhaul cooling system. You should trust the drivetrain enough to drive the car cross country.

http://www.specialstage.com/forums/index.php <- great forum for all things rally.

Also, KennyT - I have every plan of spectating and/or working a few events before and during the build process for this car. This is the exact opposite of a slapped together team, as the car has been bought already and I can't imagine competing it until late 2012 at the soonest. There's certainly learning to be done, and no amount of success or failure is a guarantee, but the challenge is surmountable! Keep the feedback and inputs coming as we design this sucker.

Good to hear, a lot of people get overly excited and rush the first build, and end up with a less than decent car. Stop by the Team #425 service area at any of the Rally America national events and I can show you a few things.

[monkeytaco]

I approve of this thread.

[TimR]

http://www.ultraracing.com.my/Bars.asp?ID=2848 http://masonengineering.net/images/E...iffsupport.jpg M3 SB links and mount on strut, All Turner Engine and SB reinforsements, Weld on rear toe and camber plates, IJ Crankscraper, MM oil pump mods, Attach Rad. way better than stock, ITG foam filter so you can clean in the pit, Convertable springs for clearance????, adj. rear spring perches, Z3 Rack & Pinion, I almost rolled at this track but it was a Blast!!!!!

[MasterOfPuppets]

I dunno, the internal bump stops in the Bilstien shocks are pretty strong, and Bilstiens come with a lifetime warranty iirc. Besides, how much force is really pulling down on the shocks at full travel? No more than the springs can apply to the control arms, and no more impulse than the sprung weight can induce when accelerating from full compression to full extension with all the force the springs can apply.

As a matter of fact, it IS possible for the rear subframe to limit the downward travel of the trailing arms. to adjust that, you would just need to weld in some small steel plates.

Take a look at the pic below and you can see how the subframe rail impedes the trailing arm from swinging down entirely. Of course you would just have to strategically weld in some plates and maybe rubber bumpers on the plates right about at the same point as the shocks reach full extension, or when the bump stops in the shocks first start to contact. That would give you a TON more strength throughout the elastic region of the shock's internal bump stops.

Hmmm, methinks we have a terminology mix up:

Bump stop = device to limit upward travel of the wheel

So the bump stop could see many thousands of pounds in a jump landing situation where the car sees a few Gs in an upwards direction. So tiny shock stops, warranty or not, are no good.

Also, that subframe needs bracing badly. I better brush up on my welding.

Concentrate on making the car reliable before making it competitive. Worry about making the car solid, reliable, and fun. The car will end up being overweight for the class, and won't handle very well with street suspension.

I'm guessing you guys will have someone else cage it.

Run stock sway bars for shakedown before your first rally and you can try dropping endlinks to change the handling.

Main areas to reinforce: Bottom of core support (do not mount skid plate to core support), front and rear strut tops, and rear subframe. Caswell broke his down in Mexico after a large jump along with his oil pan. Do not reinforce control arms or swing arms. You want those to bend/brake instead of the subframe or chassis.

Brakes: Good pads and rotors are much more important than bbk's. Carry spare pads/rotors/calipers/lines. Get some rubber heatshrink to go over the SS lines for protection. Avoid K-Sport hydraulic e-brakes and secondary 'drift' calipers.

Engine: Bone stock, overhaul cooling system. You should trust the drivetrain enough to drive the car cross country.

http://www.specialstage.com/forums/index.php <- great forum for all things rally.



Good to hear, a lot of people get overly excited and rush the first build, and end up with a less than decent car. Stop by the Team #425 service area at any of the Rally America national events and I can show you a few things.

Kenny, thanks for the inputs. They largely agree with what I had guessed. I plan on scouring the junkyards around here in ABQ where there's not a huge BMW following and building up a huge stock of control arms, subframes, trailing arms, trannies, diffs, brake parts, etc. for when the time comes. I do plan, however, to do most of the work on my own cage, probably everything with the exception of actually TIGing up all the joints. Since I'm moving up to the MN area soon I'll have no shortage of RA scrutineers to check my designs, hopefully even Mike Hurst himself.

And finally, I've been pretty active on specialstage, which is where questions like the OP's probably belong... ;)

[TimR]

http://www.e30tech.com/forum/showthread.php?t=95327 Missed one

[KennyT]

It never hurts to ask people familiar with the chassis. It sounds like you guys are going about things the right way, and I hope to see you guys out west in a couple weeks. A couple other cars to stick your head in are the #600 Fiesta of DVW, and #284 of Recon Rally. Both are small cars and opposite ends of the budget realm but have very good ideas for preparation and design.

Edit, Tim that skid plate is pathetic even for rallycross. You want something like this:

[TimR]

See, you showed us the real deal, i find if i state enough info someone gets the correct opinion or part, and i would be looking a a few cars way before spending any $$$$ thanks

[SlapDash]

Get in touch with Bill Doyle, of cagethis.com. He has a built E30 rally car, with several races under his belt as both a co-driver and driver and he is on his second E30 rally car.

He built my rally cage as well (I hope to hit my first stage rally this July in Maine)(slapdashracing.com).

The bottom line is reinforce everything.

Like a tank.

Listen to KennyT. Don't worry about beefing up engines and the like, build a solid car then upgrade. I started building rather than buying because I was impatient, plus, with a car you build yourself -- or have built -- you know what's in there. It's going to cost me a LOT more in the long run, but part of the fun for me is learning all this car stuff and meeting a lot of crazies along the way.

Check out the "Are there any E30 rallyists here?" thread on this forum, there's some good info in there.

Either way, good luck in the process!

[MasterOfPuppets]

Thanks for the inputs, guys. Sounds like reinforcement and plating are the rules of the day! Slapdash, went to the site... hope you can get it all put together and I look forward to seeing how it does for you. I'll try to contact the guys at cagethis, but this goes for anyone out there... if you have caged an E30 and have had it pass RA scrutineering, I would pay for a good set of pictures and dimensions of your cage. Let me know!

And keep those comments coming... I'm in full sponge mode.

[Bimmerman325i]

Sam, talk to Preston and Brendan at Flatirons Tuning. They prep professional rally cars for stage rally and are very active rallycrossers as well.

However, basic needs: tons of travel, softly sprung, very reactive low and high speed (shock speed) dampers. Tein and AST make great rally suspensions, but BillyHD and stock springs might do it well enough.