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Thread: Roll Center Myths and Reality by Wm. C. Mitchell

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Posts: 31-40 of 60
2013-09-13 20:20:00
I think the biggest issue that Keo and Chris have with 2JR kit is it's angle, but I'm not 100% sure without them clarifying. I just looked at the pictures and I wouldn't say the 2JR kit is as bad it's made out to be, it's just not as precisely tuned as a custom setup would be.

Update: Here is what the older one looked like:

This post explains the difference. Thanks to @Keo for finding the link.

Comparing it to the Whiteline kit for Subaru's the main thing I can see is the ball joint height is lower, while 2JR one is pretty which if is too high raises the roll center too high and causes a jacking effect. Having and adjustable one helps a ton since ride heights will vary greatly.

There are two benefits of restoring the roll center, A smaller roll couple, B helps gain negative camber as the suspension compresses.
Originally Posted by MikeK
On MacPherson strut-equipped cars, the wheel will gain negative camber under roll as long as the lower control arm is positioned less than 90 degrees relative to the strut axis. Unfortunately, many enthusiasts with MacPherson strut-equipped cars lower their cars too much and make this angle greater than 90 degrees. Beyond 90 degrees, the suspension will gain positive camber instead of negative as it compresses, significantly compromising grip (see illustration below).


I'm my opinion, it's easiest just to raise the car up, especially with rear beam's super high rollcenter and short roll couple (compared to the front). I put stock soft springs/shocks on my p11 up front, and have been driving around and noticed a good bit less body roll in moderate turns. Granted when pushing it to limits it still rolled over the front tire, but that's because the springs up front are still stupid soft.
Last edited by Vadim on 2013-09-17 at 21-54-50.
2013-09-13 20:34:19
Last edited by hammerin hank on 2013-09-30 at 11-19-49.
2013-09-13 20:51:22
Last edited by hammerin hank on 2013-09-30 at 11-20-22.
2013-09-13 21:36:53
@Vadim, close

A little less roll center and jacking and a touch of more design
2013-09-14 01:22:00
Originally Posted by hammerin

Vadim, is there a Whiteline B15 version? Comparing it to a Subie part seems like apples and oranges.

I don't believe there is one. No big company makes this stuff for us. This is why I'm happy for Joe to actually make such a product for us. Even if it might have (not saying it does) design flaws, I think it will be beneficial over stock for our cars, without very involved work that Kojima did.

I'm not sure B15 ball joint will fit on B14/B13 though, please make sure of that before purchasing.

Originally Posted by Boostlee
@Vadim, close

A little less roll center and jacking and a touch of more design

Most of their items are designed to work with very low cars, ie track cars. Thus it is that long, it would be nice if it was adjustable.
Last edited by Vadim on 2013-09-14 at 03-03-31.
2013-09-17 21:54:00
@hammerin hank

Hope this helps more in understanding

New 2JR Ball joint:

Old 2JR Ball Joint:

This post explains the difference. Basically you mess with the pivot point of the ball joint with their first design. Thanks to @Keo for finding the link to explanation.
2013-09-18 02:20:14
@Vadim, stop giving out secrets which can be found using a google search
2013-09-18 14:13:04
Originally Posted by Boostlee
@Vadim, stop giving out secrets which can be found using a google search

Actually it's a learning experience for myself. It's an online forum for information to be shared and discussed.

@hammerin hank, does it make more sense now on why Keo and @Boostlee objected to the original design? The new design actually looks pretty good and I am contemplating on getting it myself, but raising the car up (while maintaining the stiff springs) is a cheaper and better solution over all (no more scraping!), but does look like a 4x4.

That's what it comes down to, either look good but handle like crap, or look bad but handle good, or be ready to open your wallet.
2013-09-18 18:00:23
Last edited by hammerin hank on 2013-09-30 at 11-20-53.
2013-09-18 18:36:07
Sometimes I think the internet is bad.
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