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

[speedy]

hello i need help , i have dropped my irs back end by 1 spline and fitted a set of 1.5" lowered spring plates , the camber was -ve3" i followed the instructions and ovaled the holes in the rear of the spring plates using this method i have -ve 1.5 degree's of camber ,i would like -ve 1.0 degrees as am running 255 rear tires , because i have rotated the rear of the arms up in relation to the springplates the the a arms are catching the top of the spring plate just behind the top hole , this has left me with 1mm of toe in 1\2 mm each side i would like another couple of mm , i do not want to cut anymore material behind this top hole as there is not a lot there to start with and with filing the holes oval there is even less , any help or advice will be welcome or am i making a fundamental error with the method of changing the camber ,
cheers jon

[Hebster52]

I just wanted to ask if it acctually works to file up the holes and twist the trailingarm in the suspensionplate? I mean doesn't it twist the inner bushing out of line then so it wear out in no time?

Anyone who has done this and proved it to work?

[Hebster52]

Ok. Here is the deal... I did some theoretical pictures.

When the suspension is lowered the alignment of the torsionarm and trailingarm gets offset as on picture 1. This would mean that the trailingarms should be angled as stated earlier.



The best option would in my oppinion be to lift/turn the inner TA mount in proportion to the wanted lowering. In other words keeping the inner TA aligned to the torsionarm. (picture 2)



Opinions? Comments?

[Bruce2]

Originally Posted by Hebster52

I just wanted to ask if it acctually works to file up the holes and twist the trailingarm in the suspensionplate? I mean doesn't it twist the inner bushing out of line then so it wear out in no time?

Anyone who has done this and proved it to work?

This adjustment is exactly how Porsche adjusts camber on the 944, so yes it has been proven to work.

I've never heard of anyone who's worn out the inner pivot. When I used to modify stock Beetle TAs, the final step was powdercoating. This meant the inner bushings had to come out. Every one I removed was in perfect condition.

[Hebster52]

Thanks Bruce!
I definitly will have to look into the tech regarding this when I start fitting in the 944 trailingarms on my T-34 this summer.

However the rear frame have been swapped from the swing to IRS (T-3 versions without the gearboxhorns) and the torsionarms(plates) on it is the double version... I've heard that those were a 1969 one year only feature I wonder if I would benefit in using the single 1303 torsionplates instead that I have in the back on my garage?

[Bruce2]

All IRS Type 3s used the double spring plates, while Beetles went to singles in 71. I guess they thought the extra weight of a T3 warranted it. They were wrong. This has been proven by looking at a stock 944 that has single spring plates.

Instead of using Beetle spring plates, use stock 944 adjustable spring plates. Then you can use the camber adjustment Porsche designed. I adapted the 944 spring plates into my Beetle without the camber adjustment.

Single spring plates weigh less.