Subframe alignments! Advice required!

[Sirocco20348]

Hey guys,

Car: Mk4 Golf GTI

I had some new tyres fitted today and had a basic wheel alignment performed. What I noticed immediately was how uneven the wheel camber, castor and toe was.

This really confused me because except for toe on the front, I thought none of the other values were adjustable.

I have since read that the front and rear subframes need to be aligned correctly to even out the camber, castor and toe (rear).

Has any one has this done, and can anyone recommend a workshop that knows how to do the subframe alignments? I am located in Brisbane/Gold Coast, so any local recommendations are welcome.

[sambb]

By the look of it your front cambers are spot on and your castors are very close too. The subframes are what your front wishbones are bolted to and if they are that close, you really wouldn't bother moving them for that. Yes your rear numbers are out a little. There is not really anything you can do about that. The camber and toe at the rear are all more or less set due to the fact that you have a rigid beam axle. I know that on my Polo the beam bolts into welded on receivers that can't be moved. Your mk4 may be different. All that can be done is the use of shims that fit under the stub axles to bring the cambers and toes into line with each other. To be honest though I've seen way worse on rear beams. For a car that age that's been smacking potholes and reversing up gutters etc its not too drastically out. But believe me I do get it - it sucks when the numbers say its not all fluffy and sux to see in the data like that. You'd be surprised but I bet that if you went tommorow to a different place you'd get a different set of numbers too.

[Sirocco20348]

By the look of it your front cambers are spot on and your castors are very close too. The subframes are what your front wishbones are bolted to and if they are that close, you really wouldn't bother moving them for that. Yes your rear numbers are out a little. There is not really anything you can do about that. The camber and toe at the rear are all more or less set due to the fact that you have a rigid beam axle. I know that on my Polo the beam bolts into welded on receivers that can't be moved. Your mk4 may be different. All that can be done is the use of shims that fit under the stub axles to bring the cambers and toes into line with each other. To be honest though I've seen way worse on rear beams. For a car that age that's been smacking potholes and reversing up gutters etc its not too drastically out. But believe me I do get it - it sucks when the numbers say its not all fluffy and sux to see in the data like that. You'd be surprised but I bet that if you went tommorow to a different place you'd get a different set of numbers too.

Thanks for the reply.

In my mind I thought I would have atleast had negative camber on both my front wheels. Considering all the bushes, struts, springs, top mounts are all around 40000km from new. I also have shine springs that make the car sit up super high.

The thing that intrigues me in the castor. It's out on one side by over 1 degree.

I'm happy to be a test dummy. The car is booked is to have subframe aligned this Friday. I will post results.

[sambb]

sorry when I quickly looked the other night I hadn't realised that one side was positive. Yes you can slip the subframe. The holes in the subframe are oversized compared to the bolts and they'll be able to shift the bad subframe enough to improve things and hopefully enough to square things up. Your run of the mill aligners wont touch this though. I went to pedders when I installed eccentric adjusters into my subframes and they did that no problem. Its not just the two bolts holding the subframe to the chassis though. you also need to slacken the two bolts that go up through the crossmemeber on that side into the steering rack because these also pass through the subframe. With all four bolts slackened they'll be able to wriggle it around and hopefully help things.

[Sirocco20348]

sorry when I quickly looked the other night I hadn't realised that one side was positive. Yes you can slip the subframe. The holes in the subframe are oversized compared to the bolts and they'll be able to shift the bad subframe enough to improve things and hopefully enough to square things up. Your run of the mill aligners wont touch this though. I went to pedders when I installed eccentric adjusters into my subframes and they did that no problem. Its not just the two bolts holding the subframe to the chassis though. you also need to slacken the two bolts that go up through the crossmemeber on that side into the steering rack because these also pass through the subframe. With all four bolts slackened they'll be able to wriggle it around and hopefully help things.

I had a long talk with the wheel alignment guy associated with VW Southport. He knew exactly what I was talking about and explained the procedure to align the subframe.

He mentioned that wth the proper alignment of the caster, he thinks that the postive camber on the front will be neutralised to 0. While the negative camber will gain a little more, possibly 30'. But he made no promises of course.

He just asked for new subframe bolts because they are Stretch bolts apparently.

Ideally I should have camber plates up top. Too late to order now for this weekend event, but I will investigate options. How much front camber do you have on your polo?

[sambb]

sorry I may be misreading again but it looks to me that your front caster is only out by 25 minutes which is less than half a degree no? That's certainly fine but may come into place when the cambers are squared. With subframes adjustments, to get more caster you usually kick out the rear most side of the subframe so they might go to the side with the least caster and try to square that up with the 7 degrees on the other side. If its maxed out though in the hole, then they'd have to go to the side with 7 degrees and bring that side back to 6/1/2 degrees. In that case you'd loose a little off your peak caster but its still a good number. I run a higher front end than most too (along the lines of **** Shines teachings) and have done other roll centre raising stuff too and it works pretty well. You'll be happy once you get it sorted.

[sambb]

ok its good to have someone who knows the drill. yeah speak to VW now regarding the bolts cos they may need to order them in

[Sirocco20348]

ok its good to have someone who knows the drill. yeah speak to VW now regarding the bolts cos they may need to order them in

I ordered them yesterday, should be here today for fitment Friday.

What other things have you done to increase the roll centre? Have you thought about adjustable camber plates? Looking for opinions.

[Sirocco20348]

Front left caster is out by 70 minutes of the minimum tolerance value. So yeh not quite a degree.

[sambb]

I modified my Polos wishbones to accept Audi TT RS ball joints. These fitted the hubs aok but have a much longer stub. The ideal position for a macpherson struts lower wishbone pivots with respect to roll centre locaton is dead level (oem postion on my car) or down at the hub side. Lowering a mac strut car normally moves the roll centre down exponentially relative to the ride height drop you make but with this mod it allows you to run the car lower without adversely affecting the roll centre.