Here's the setup...

'06 MCS JCW w/ SportPlus struts and springs
OEM FSB
Hotchkis Competition RSB (25mm) on low setting
Rear Alta end link rods to OEM length
Cabrio Braces
M7 Tuning Strut Tower Brace
Tires - Pirelli P-Zero RFTs on R113 Wheels
Alignment is set to OEM with the rears cambers to -2.5 degs

Here's my dilemma...

During AX events this year, on sweepers that I try to carry speed in, the rear end is constantly trying to swing out on me. I am counter-steering a lot to keep it in check - I mean a lot.

I consider myself to be smooth in transitions so its not from being to snappy. I know the tires aren't the greatest so it is what it is but they are 220 treadwear so they're somewhat sticky. But if it weren't for sawing on the steering wheel in some high-speed sweepers, it just feels like the car would over-rotate ever so easily.

Although I don't drive the same on the streets as in AX, on the streets, it just feels so planted and secure.

I have tried adding some extra fuel to weigh the car down but doesn't seem to help. I've tried adding air pressure and dropping air pressure in the rears to no avail.

When this occurs, it is always in a situation where I am trying to hold a steady throttle to hold/carry speed through a sweeping corner. I know it will rotate if I let off the throttle but I don't.

When I initially installed the RSB, I set it to medium. My first impressions were DAMN - Holy Oversteer Batman. But, that understeer was gone. I thought for sure I was going to over-rotate the car that day. For the next event, I changed it to low setting but it wasn't much better.

Is it possible the RSB is just TOO stiff even on the light setting?

Can the end links be lengthened a little to reduce the stiffness?

Am I just trying to go too fast?

Your input is greatly appreciated.

 

A few things:
1) softest setting is the last hole at the back of the car (just in case it's in the wrong one)
2) 2.5 degrees camber is too much on the rear of a Mini...2.5 is good on the front..try 1.5 on the rear--this should increase rear grip.
3)length of end links has no affect on the rate--adjustables are only needed to adjust corner weights with coilovers
4)--MOST IMPORTANT (after camber)--jack up the rear of the car and disconnect the swaybar end links. Try moving the bar by hand (up and down) it should move quite easily...if not it binding in the mounts (virtually all bars have this problem). If it is difficult to move--loosen the bolts that hold the mounts in place and pull one bolt out. Now place a washer between the u shaped metal bracket and the frame to space it away and free up the bar--reinstall the bolts (do both sides the same) and try moving the bar again!!! If moving freely put everything back together and give that a try. If not add a washer to the other side of the mount--usually one washer on one side will do the trick.

The camber change and the binding bar should fix your problem--that bar should work really well for autox

 

Swabar changes over vs under steer....most auto-x folks try to get pretty neutral....
But if your tires are not giving you grip...the sway bar can't do anything...your descriptions makes it sound like your tires are breaking free.....
Frankly, it sounds like you are driving to fast for your tires.

 

You might also take a look at the struts. They don't last forever. If they need replaced KONI FSDs are a good fit. I have a 22 MM adjustable set of the stiff side with FSDs and it handles like a street legal gocart.

 

I would make sure the swaybar (or some other rear suspension component) isn't binding first. What are you running in the rear with regards to toe? That could really affect the car's rotation.

Are you having issues with oversteer in corner entry or midcorner? If it's corner entry I'm guessing you're being too quick with your inputs (either hands or feet). If it's mid-corner that would point more towards something like suspension bind.

 

Thanks for the input guys. Reading all of the responses, I think I may have an issue with a binding swaybar.

There may be an issue with too much negative camber in the rear as well. The toe is good as it was set at 0.0. The guy that did the alignment is an AX'er too plus he used a brand new Hunter system to do the alignment.

I think the tire grip is good - not Dunlop Direzza Star Spec good but damned close.

The struts and springs will get replaced next year. You can count on that. The money just isn't there this year.

1qwkmini - As for the bar setting - maybe I have it wrong. I thought that the low setting was the hole closest to the bend, and not the "end" where it is cut. My thought was less length, less leverage, less torque therefore use the hole closest to the bend. Oh crap, do I have it backwards?

Update - Well, according to this image, I have it set to full stiff. DUH!!! No wonder the car is trying to spin my *** around.

 

Good thing you found that picture!!!
Farther from the bend=longer leaver arm and easier to twist (softer spring rate)
Closer to the bend=shorter leaver arm and harder to twist (higher spring rate)
Give the mount spacing a try to free up the bar (you will notice the difference) and try -1.5 rear camber.

Cheers

 

Without front camber plates the 25mm hollow bar should be great.
Hopefully the hole and camber change will make a large improvement.
Also double check for binding, as was suggested. I had a 25mm bar bind up and totaled my 2003 MCS.

 

One suggestion....
Check the production date on the tires....
There are some very old tires around...and when I see a person state RFT, I wonder if they picked them up as a "deal", often used from another owner who had them sitting for a few years (common).....there are 10 year old OEM tires available in the marketplace....buyer beware.
Do check for binding....but the fact you said you had a change in the under steer/oversteer feel when installed makes me wonder....

 

Maybe off the wall suggestion:
I had a similar problem, steer to the right, back end would kick out.
I went back out to the shop that did work on my car to ask if they did any work on the back end and they said "no" only the front end. And low and behold, a missing bolt from the ball joint to the hub.
Maybe worth checking if you haven't found something obvious. My driver side front control arm was missing one of the two bolts that hold the ball joint to the hub, which allowed the front wheel to understeer excessively.
I assume if your problems are with left steer, check the Right front control arm.

 

People jump on the big bars all the time but IMO a 19mm bar with a GOOD alignment is the better set-up. So more front camber, less rear camber.

- Andrew

 

I'm fairly happy with my 19mm swaybar. Middle setting and the inside rear wheel wants to lift off the ground when entering a driveway a bit too fast Went to the track a couple times since I had it and I like the handling, I "drifted" when taking a corner too fast after overtaking in the straight line, but the car feel so solid that I never feel like I'm in danger of losing it completely.

 

Yup...
I find a bigger than stock, but not "freaking huge" bar is good for balanced handling....
But many folks seem to go by the addadge, more=better...but it is all a compromise!!

 

Well you have the right sway bar for the car as we've done plenty over the years and found the Hsport Comp bar to be far the best for the R53.

Now your -2.5 camber is way too much, and if you have that my guess is your toe is out of wack and I'd suggest doing an alignment before messing with more new parts. Also if your running high rear tire pressures, or don't have enough grip, or super stiff shocks you can cause more rotation.

 

Thanks for the added input guys.

I'm hoping to get under the car tomorrow or Friday and check things out.

One thing that both my sons were noticing is that it has never dog-legged but they can see it sliding on me. This leads me to believe it may be a seized mount.

Tay - I'll be sure to check the front end as you suggested.

I will report my findings but the camber will have to be adjusted back to -1.5. The printout shows toe is set a 0.0 so I am confident its not a toe issue. In fact, all alignment parameters are in the green - even the -2.5 on the camber which is max. I'll get my guy to redo the alignment and back off on the rear camber.

As for the tires, they're fairly new. I did pick them up on a deal (more like a steal) mounted on a set of perfect condition R113s and TPMS (which I don't need) for $1250. The tires are all week 19 of 2012 and had about 6000 miles on them when I got them. A very generous dad bought them for his son's R56 which was ultimately sold.

As for tire pressure, I have been running them at 32psi and shoulder marking demonstrates that to be good.

 

Well, I went under the car today.

-The RSB is not stuck or seized. It moves just fine.
-I moved the end links to the soft setting. I'll have to see how the car responds at the next AX.
-No missing hardware noted.

So, all that's left is getting the camber adjusted back to -1.5. I hope to get this done before the next event.

Hmm!!!

 

Keep us updated!

 

I love my Comp bar full stiff. I have yet to spin it in the 8 or so AX's this year. But it could be that I am not going fast enough.

 

i have a 19mm solid bar i think, and its set to hardest setting, still cant get the rear to swing out no matter how hard i push!

what does it actually take? jerking the wheel right at 40mph?

 

I think run flats are ONLY good for running flat , period.