Sprnig rates vs. no rear anti-roll bar

[NigelStu]

2 Question to those who've experimented with and/or are running without a rear anti-roll bar for race, TT or HPDE.

I'm interested in hearing what spring rates people are running with NO rear bar, or stock rear bar. Especially if you've tried various bar settings (stock, non-stock, none) with your current spring rates.

1. At what rear spring rate does the rear become stiff enough that the rear bar can/should be removed? example - 400 lb/in = use adjustable rear bar. 650 lb/in, remove rear bar.
2. How is your track car set-up now? List out the FR/RR spring rates and what bars you've tried and some notes on the setup. i.e., what has been your experience with handling of the car with various rear anti-roll bar setups?

I'm looking for data/facts - In the end, I'm hoping to find what makes the car faster or easier to drive at the limit, based on a decent sample size.

Background on this question - This is for a Chump car build, so I'm very limited on what I can get away with for springs and bars. A lot of what I've read indicate no rear bar can work very well, I just want to find out where that point is so I can target to get springs at/near those rates. Or I'll find out if I need to do some mods to my current bar, or find a cab bar, etc.

[JeffRR]

Hey,

If your interested check out this thread, there was a pretty good discussion about rear bar/ no-rear bar and RS balance:

http://www.r3vlimited.com/board/showthread.php?t=95373&highlight=ride+frequency

Can you run a coil-over or are you limited to production pcs?

When your ready I can toss your #'s in my roll spread sheet to give you an idea on your ride and roll numbers. (we can compare #'s to the 350's)

You know I'm a fan of keeping total RS high and just balancing it out, just depends if you can balance it with available parts.



Hopefully someone will chime-in with direct e30 experience but I can at least toss numbers at your. (ya I'm a chassis guy at work but my e30 is seriously lacking in that department)

[gverelli]

Good question, Im interested as well. Scrolling through the thread posted above ^^, a few said 750lbs is fine?

[rwh11385]

I ran no rear bar with 475# rear ERS springs. Before doing so, back end kept wanting to step out on the track while in a corner. It was a quick fix and loved the results. Instructors were impressed with capability even with the 300/475 rates especially in the 110 deg hairpin.

My advice would be go with a good spring setup, and just undo a bolt and zip-tie the rear bar link to try it out. Easy to see how you like it, and no commitment vs. buying another bar or whatnot.

edit: I had forgotten the rates I changed to, but they are Jean's old ones below: 500/650. Only got to run them at Auto-X though, but seemed a lil faster perhaps. Friends with rates like that have good things to say about them.

[Jean]

Have been running 500front/650rear season before last, and now running 550front/675rear cabrio front and no rear bar. Seems to be working fine so far.

^ yes to try, as said above just disconnect it and see how you like it but you'll need to have a couple different springs on hand to try it out if your current ones are on the soft side .

[gverelli]

I have 850lb rear springs with no bar, have not driven the car yet so will see how it turns out. If it's too much I may have to get softer springs, maybe around 750lbs. But will see how it feels, I still plan on getting the car balanced so that may have a positive affect as well

[liquidgroove]

I have F:450 R:525 spring with Koni SA. Front has 22mm bar with M3 style mounting and rear 19mm bar. Removed the bar really helped power out the corner.

Even though car felt slower mid corner, exit speed made out for the lost. I was able to pick up 1/2 sec after disable the rear bar.

Also worked out good on my very 1st wheel to wheel race in rain.