Tail Happy E30

#1

Hi

I searched the forums on this and most people said their e30 race cars were pretty neutral in the handling dept. Mine is not quite a SpecE30, but here is my issue and I would really appreciate some feedback.

Thanks in advance

I am chasing a pretty wild oversteer problem in my E30 325IS race car. I run the turner JS suspension with Ground control Spec e30 camber plates (for stock diameter springs) and suspension techniques swaybars. I have the rear bar set for the soft setting. The car has AKG offset trailing arm bushings in the rear and TMS delrin control arm bushings in front.

My alignment settings are as follows.

Camber -3.2 front, -2.8 in the rear

Front and Rear Toe In is 1/16" for a total of 5/32" front and rear.

I usually run cold tire pressures of 31 front and 29 rear. (Toyo RA1s 225/50/15)

I would like to get this car to be more neutral in the handling or even a tad toward understeer VS the tail out rally shape it is in now.

I was thinking of a larger adjustable sway bar for the front but I am not sure who makes a decent one. The current 22 mm suspension techniques bar is not adjustable.

I am wondering if these TMS J Stock springs
are to stiff for this car?

Thanks

Don

#2

You know more about your suspension settings than I do mine, but I’ve got the ST sways and the H+R spec springs. My rear bar is on full soft and I think the car is nicely neutral. It sounds like your thoughts about the springs may be accurate. There was a thread on here where someone posted the H+R race spring rates–you could search for that and compare them to the Turner rates.

Sasha

#3

If you can, you might want to play with the weight distribution a little bit. When I first put the cage in my car it went from nice and neutral to scary loose. I was able to fix it and bring the car back to neutral by removing the spring pads that were still underneath the rear springs. Lowering the rear that 3/8" or so made a huge difference.

#4

Another quick fix are spacers for the rear wheels. 10mm to 15mm on the rear will dial out the oversteer.

#5

#1, cold tire pressures do not matter. What’s hot? What are your temps? Don’t pay too much attention to cold temps.

Dropping the rear ride height will certainly help if you can do it.

This may not help this issue, but I bet you’d like the feel of some toe out up front (probably help turn in).

I would not go buying parts.

Try disconnecting the rear bar.

#6

I forgot to ask about shocks. Any adjustment available there?

Also, where is the car loose? Entry? Mid-corner? Track out?

#7

Check temperatures when hot. I like to see 37-38.

Don’t worry about rear camber, adjust for zero toe in the rear. Go with 1/8 toe out in front.

Lower ride height in rear by removing spring rubbers (if not already done).

Still oversteer? Add 15mm spacers to the rear.

Still oversteer? Disconnect sway bar.

Ask me how I know…

Regards, Robert Patton

#8

Robert - thanks much for the advice! Don posted this question on the BMW CR list this morning, and I jumped on it since I have the exact same problem. I tried switching over to the TMS JS setup this winter after running the spec e30 setup, and have had it out once this spring & found it nearly undriveable (it was almost boringly neutral in spec setup). I’ll try your recommendations next weekend up at Buttonwillow. I’m surprised by the rear spring pad suggestion - hadn’t heard of that before!

#9

Thanks folks for all the great suggestions.

Since I am still interested in controlling body roll, I am going to try keeping the rear
ST bar, removing the rear spring rubbers, rolling back my tire pressure, and as last resort adding the 15mm spacers to the rear.

A huge help!!

Thanks

Don

#10

Don and Steve, the Turner JS stuff used to be on the 911 police car. It is stiff and it rides like a go-cart compared to the softer Spec e30 springs and shocks. The JS stuff doesn’t bounce back on left to right switchback corners like the spec stuff. The JS is good on a smooth track, but on the bumpier tracks the spec stuff is better.

Lap times…no real difference. Could it be the driver? Good luck getting the JS stuff dialed-in.

If you know anyone looking for the JS combo I’ll sell the package for…what is a fair price? The patrs have 1.5 seasons on them and look like new.

Regards, robert Patton

PS Mike Skeen had some good advice, I just piggybacked on to his statements.

#11

Well, I removed the rear spring pads & have to say the car was nearly perfect at Buttonwillow last weekend. Still a bit of oversteer, but that’s a good thing at that track.

I had also switched diffs to a 4:10 over the winter…any thoughts on whether the diff switch might be the cause of the oversteer? Again, my problem was with mid-corner oversteer on long, high speed, 80% - 100% throttle turns at Willow Springs. I know we usually think springs & swaybars, but might a "bad" diff contribute to this?

Thanks again. I do realize I’m talking about non-spec suspension on a spec forum, and do appreciate the advice!

#12

I’ve recently installed my spec setup and the rear end is seriously loose. I’ll try out some of the suggestions in this thread. I’m surprised that such a small change like spring pads can make a difference, but I’ve been more often wrong then right. I don’t have many places to go for safe testing, but the slightest throttle during any part of a turn will kick the rear out.

Can someone look at these pics of my rear sway links and tell me if they look ok? These are pics straight from the rear of a IE bar. Is it normal for the link to be angled as such? It appears like it may be binding. There also is about a half inch left of length left on the RSB that I need to take advantage of.

IMG_2548.jpg800x600

IMG_2541.jpg800x600

#13

That’s wrong, and I’m almost sure it’s binding. I hope my terminology is good enough to help… the "link" should be more vertical, and should go in the middle of that "horseshoe" that is bolted around the swaybar end. The horseshoe thingy opens up more and the swaybar link should fit right into the crack of it. I hope that helps.

#14

mrussell wrote:

I had thought that before, but after reading through one of the sway bar threads I assumed otherwise. There appears to be two different designs from IE for the links. One where the link mounts in the ‘horseshoe’ and one on the outside of it.

Here’s the thread where I got my info and probably where I should have stayed before I crapped up Don’s thread.
http://spece30.com/component/option,com_mamboboard/Itemid,68/func,view/id,9738/catid,10/limit,10/limitstart,30/

#15

Oh, wow, that is pretty interesting. Well, I guess as long as your bolts aren’t rubbing the spring, you can eliminate that from the equation.

To echo what was said on that other thread, don’t expect much assistance or recourse from Ireland if you approach them for help… Mr. Ireland is positively hateful towards SE30 and its rules organizers, in my experience.