q20v

Hey guys,
For anyone whos interested in increasing the rear roll stiffness of their type 89 chassis, read on.

Previously posted on the 20v list at rennlist.com by Bernie Benz...

"The stock 14mm dia rear anti-roll bar (RB), as pictured on Bentley Pg
42.10a, is easily replaced with the larger 4K front RB. I used a 22mm nonQ
4K RB, I believe that the 4KQ RB is 24mm, but not sure. Inasmuch as the bar
stiffness is proportional to the 4th power of the diameter, the 22mm RB will
have 6.1 times, and the 24mm RB will have 8.6 times the stiffness of the
stock 14mm RB. A 6X increase in rear roll stiffness would seem to be more
than a significant change!

Parts needed: Along with the 4K bar, aquire the 4K subframe mounting
brackets and rubber bushings which will mount the bar to the rear subframe,
and the bushing washers from the RB to the A-frame linkage. The end fitting
on the 4K bar accepts a vertical linkage rather than the horizontal ball
stud of the stock bar, so the stock link rod must be modified as follows:

Cut the lower ball joint off the rod at the point where it is welded to the
joint, retaining maximum rod length. 3/8 x 16 thread the rod end for 1 3/4"
and jam a nut against the end of the thread. 3/8 drill out the 4K cupped
bushing washers to accept the 3/8 rod and return them to either side of the
4K bar rubber link bushing. Cap off the assembly with a 3/8 lock nut.

The alignment of this new link with the RB is not perfect, but the small
missalignment is easily handled by the rubber bushing. Feedback is needed
from those who may track this mod: Can you lift a rear wheel off the ground
in hard cornering?

Bernie"

Well that pretty much sums it up, so i went ahead and did this mod and have some pics...

Donor 4000 quattro
<img src="http://pictureposter.audiworld.com/48954/dsc01577.jpg">

Roll bar removed from donor car. Measures 26mm in diameter... 11.9 times the stiffness of the old (14mm) bar!
<img src="http://pictureposter.audiworld.com/48954/dsc01578.jpg">

Old vs. new(painted red)
<img src="http://pictureposter.audiworld.com/48954/dsc01607.jpg">

Cut off ball joint and thread as per Bernie's instructions
<img src="http://pictureposter.audiworld.com/48954/dsc01609.jpg">

Assemble as so...
<img src="http://pictureposter.audiworld.com/48954/dsc01611.jpg">

And install (easier to install the bar first, then the links)
<img src="http://pictureposter.audiworld.com/48954/dsc01616.jpg">

Before
<img src="http://pictureposter.audiworld.com/48954/dsc01606.jpg">

And after
<img src="http://pictureposter.audiworld.com/48954/dsc01620.jpg">

Total cost of this project (canadian)...
4kq front roll bar from junk yard... 50$
New bushings... 35$
Assorted hardware (made my own cupped washers)... 5$

So far i've only driven it around the block and there is a noticable difference! As for whether or not it will lift a tire, i'll let you know next spring when racing starts again.

Barry

nbevins

Very cool! I think you can do this to the B4q's too?

quattro.pilot

I had asked the previous person who brought up this topic, if all the above info applied to a B4 as well. Never did get a responce, but I have a feeling it does.

Anyhow, this whole rear sway-bar thing sparked quite the thread, also unearthing the Neuspeed 19mm bar applicable to the B4. We were all still a bit unsure as to whether or not it would be TO stiff (such a large diameter) , and thus cause inherent oversteer problems. Although NO ONE has any argument for or against the 4k RB upgrade.

This is an awsome thread, and thank you for sharing it with us. Since it is relatively cheap, it makes this project affordable to dismiss; that is should the uber-oversteer issue become apparent. For myself, I would like to have a 28mm (or 29mm??) RS2 front bar matched with either the Neuspeed 19mm or a 4k 22-24mm rear bar.

check yah later

SLAB

i used the stock 4KQ mounts instead of threadding the old ones......


the 4KQ mounts i have nor RUB on the driveshavts ever so slightly....

THANKS FOR THE IDEAS!!!

quattromano

Very well done! Kudos to you! Trying to be an Audi God are you?!

snoogins

Kieth Anderson did this to his wife's 9020v, and said it became so tail-happy, it was flat out dangerous. I hope you prove otherwise.

quattro.pilot

although at about 4x the cost =(

check yah later

q20v

Just kidding, the front bar from the non-quattro 4000 is 22mm, i'll probably pick one up in the spring time and compare the two. Right now i've got the snows on, so like i said it wont be until the spring that i really get to try this thing out...
Should be a bit easier to slide the car sideways at winter solo2 events... well see

SLAB

but thats with bilstein struts, and intraz springs and virtually every suspension component NEW...

snoogins

It seems to be the best compromise between stiff, and TOO stiff. Ofcourse, if you just put a set of coil-overs on all 4 corners, the dependence on an anti-roll bar would be reduced greatly.