IRS alignment setting for wide rear tires

[Sandeep]

I finally have the rear end together with brakes, fenders and wheels. I drove the car down the driveway and back to settle the rear suspension so I could get a camber measurement .. it turned out to be -2.93 degrees

The 265/35/18 rear tires are only contacting the ground on the inner 3/4 of the tread (I saw the tread tracks in the snow). When I had the 195/65/15's on, I had fine tire wear but got a big problem now.

All of the rear bushings are old and I plan on converting to urethane in the next few weeks. The rear is lowered about 2" and I'd rather not re-index the spring plates. Does anyone have any suggestions as to how to correct this ? :help: Does anyone have any alignment settings for wide rear tires ?

Thanks for any suggestions.

Sandeep

[boygenius]

Do you have steel, early or late aluminum trailing arms.??

I think the aluminum arms have camber,toe and ride height adjustability.

[vujade]

if you dont have Porsche trailing arms and you are using VW arms, you could always swap sides with the arms and reverse them. This will eliminate about 3 decrees of negative camber.

[blue4400]

Originally Posted by vujade

if you dont have Porsche trailing arms and you are using VW arms, you could always swap sides with the arms and reverse them. This will eliminate about 3 decrees of negative camber.

Thats cool!! Does it affect the ride or performance??

[Panelfantastic]

Ahhh... it is sooo nice having bolted-on front pivots ! Once I had my ride height set, I just loosened them and tapped themaround until the 265's had a nice even contact patch.

Hey Vujade, my custom arms don't have a left/right. I guess somehow that little degree of twist can be left out?

[Sandeep]

Good suggestions ... I have the stock beetle arms.

Panel, where did you get the bolt on pivots ? Does anyone know if something like this exists for racing purposes ? Would be cool to be able to adjust camber at the track.

Sandeep

[vujade]

944 spring plates have camber adjustments

[Panelfantastic]

Mine wern't really intended to be "adjustable". My bus has a conversion kit that takes it from swing to IRS. This particular kit (busboys) has bolt on pivots instead of weld on. I just use the bolt on part to my advantage. If you look at the chassis on a racing 911 (I think there is a pic in the gallery), the front pivot is a hiem instead of rubber bushed and the mount is slotted vertically for adjustment. You could do something real similar on a street setup.

[Panelfantastic]

Ok, I figured out where I saw it... Feb '04 Excellence. Article near the back about tuning coilovers on a 911. Shows pics (page 146) of the slotted mount, NOT a hiem like I thought. Would be very easy to duplicate.
Sandeep, I'll try sending you a scan from the page. It shows specifically what you want to be able to do.

(I would post it, but I think that's a big copyright no-no )

[boygenius]

As long as your not doing it for profit and you list your source the copyright police shouldn't have a problem with it.

[Sandeep]

Thanks for the pic Panel. It makes sense now. I was looking on the web and found a similar pic.



This is from the Rennwerks website where they are restoring a GT2. Look at the trailing arm mounts and see how they are adjustable for camber.

Sandeep

[Sandeep]

The more I think about this, the more it makes sense .. I want to go with a coilover / 935 style springplate rear suspension in the future, and it would be cool to lower the car AND have proper camber for WIDE rear tires.

I saw a pic of a 911 RSR buildup with 17x11 rears and in the article, they lowered the rear of the car and kept the camber in check with the camber boxes.

MAKE IT SO !

Sandeep

[Rob]

Hey Sandeep,

Let me know if you are going after this. If you get a mchineshop to make the mounts, you can have them make me a set as well

Rob.

[Panelfantastic]

Yeeesss! Welcome to the dark side!
Gotta have the steamrollers out back!

What could possibly be wrong with a contact patch like this???

[boygenius]

Will my 944 late aluminum trailing arms have enough camber adjustment for 18" X 10" rears.

Which bolts adjust camber? The eccentric bolt for the sway bar or the eccentric bolt in the spring plate.