Rear axle alignment

[Kanerr]

Since I couldn't find anything with the search function, I'm creating a new topic.

 

Do you guys know if you can align the rear axle? My axle sits 5mm to the right and is not centered. If it is not fixable with an alignment, I know the axle is bend and will replace it with another one.

 

Its about a MK2 Fabia 1.2TSI from 2010.

 

Cheers guys.

[xman]

From my experience (2013 estate) the rear axle mounting points on the floorpan appeared to be welded in place and so no adjustment possible. It sounds like your car received a big knock on one side and either the floor distored or the rear axle beam got bent.

 

Car body workshops have tools that can measure and straighten things up.

[Kanerr]

Exactly what I thought. Thanks xman!

[J.R.]

4 hours ago, Kanerr said:

Since I couldn't find anything with the search function, I'm creating a new topic.

 

Do you guys know if you can align the rear axle? My axle sits 5mm to the right and is not centered. If it is not fixable with an alignment, I know the axle is bend and will replace it with another one.

 

Its about a MK2 Fabia 1.2TSI from 2010.

 

Cheers guys.

Where and how are you taking the measurements?

 

However you take them, are you saying that the RH dimension is 5mm more (or less) than the left hand one?

 

That would indicate an offset of 2.5mm which may even be within tolerance and is so small as to be beyond the measuring capabilities of most of us.

 

A simple lateral offset of small magnitude with the toe angles and L/R wheelbase measurements being correct is not going to have any noticeable effect on the vehicle.

[Kanerr]

Thats true, left wheel is 5mm more to the inside. The right wheel pokes 5mm more out. The reason I want to get this fixed is because the right wheel rubs the arch a lot, and I mean A LOT! I'm on a KW V2 coilover set and at the rear maxed out. I know from the factory the rear axle is not centered but this is a bit too much in my opinion. Maybe other wheels then :(

[Kobayashi]

Might not help but you could try a Rear Anti Roll on tightest setting if one available Could improve tyre wear but might still be out a few mm

[Kanerr]

Tyre wear is not the issue here, it seems to wear perfectly. I just want to fix the rubbing of the tyre/wheel on the outer arch of the right side.

[sepulchrave]

You'll have to replace the beam axle, it's obviously been bent somehow.

[xman]

I think you'll find that 5mm offset is within Skoda manufacturing tolerances for skoda suspension setups and all approved tyre and wheel sizes. The OP's suspension mods and/or oversize tyres or aftermarket wheels are likely beyond or incorrect to Skoda specs. What I am saying is I have my doubts a new beam axle would fix the offset. A bent axle would push the tyre geometry inward rather than outwards. So its probably just manufacturing tolerances on floor pan mounts plus beam axle dimensions.

 

If one side is 5mm different to the other, then its out only 2.5mm from centre. So floor and axle being 1.25mm each out could be sufficient to get this shift.

 

Long shot but try checking bushes for wear or offset.

 

But for a sub 2.5mm clearance in the outer arch, obviously either tyres are too wide or the wheels are the incorrect offset (ET), are they aftermarket? And you haven't fitted spacers?

Edited 30 October, 2020 by xman

[sepulchrave]

My reading is that the total misalignment is actually 10mm, and that's way out, I sense that the car may have been spun and slammed into a kerb at the back end.

I'm not saying the beam mounts aren't bent but straightening them out would mean jigging the shell whereas the OP can replace the beam easily himself.

I would not accept the situation and do nothing as xman suggests.

[J.R.]

2.5mm offset from the nominal centre line position, assuming that the bodywork, wings and inner wings are spot on, in reality there are tolerances on everything and a standard vehicle would have a wheel envelope designed to take all of these at their worst case and still have probably 12mm to spare to allow for dynamic loading, tyre deflection etc.

 

2.5mm is almost certainly within the manufacturers tolerances not that they will give a measurement for what the OP has measured, it would be a product of all the other dimensions and their tolerance limits (maximum & minimum material condition)

 

The axle beam may have distorted mountings from a kerbing, but equally the floorpan mounts may be distorted, the axle beam probably being stronger, were the OP to blindly change the axle it may make no difference at all, it could even become worse according to the where the mounting points of the replacement are within the tolerances.

 

Its something that comes up frequently when modifying a vehicle and the answer is usually shimming or modifying of the mounting points to achieve a central position, were it me I would be more concerned with its relationship to the front wheels and not the relationship of wider rear wheels to the bodywork.

[sepulchrave]

You could only shim the mounts if you also trimmed the bushes.

The beam is a bendy torsion bar but one of the radius arms may well have been bent, I don't see how you could know what was what unless you tried to fit a new beam, this would highlight any problem with the mounts because it would be reluctant to fit.

[J.R.]

Correct, there is an Elephant in the room though.

 

If you are correct and the beam has been bent it would increase the wheel clearance to the outside arch, the OP's right wheel is rubbing, if the presumed bent axle beam is replaced he could have the left wheel rubbing as well!!!

 

The best way to know what is what is to establish a centre line datum and take measurements from that, also from both front wheels with them tracked parallel and facing directly ahead, this itself can be checked with reference to the datum centre line.

 

String, chalkline, plumbob, spirit level and flat floor needed, or spend money on a 4 wheel alignment check with someone competent and trustworthy.

[J.R.]

Just now, J.R. said:

Correct, there is an Elephant in the room though.

 

If you are correct and the radius arm has been bent by sliding into a kerb it would increase the wheel clearance to the outside arch, the OP's right wheel is rubbing, if the presumed bent axle beam is replaced he could have the left wheel rubbing as well!!! Of course it could equally have hit an obstruction and been knocked to a toe out alignment but the car swopping ends regularly would alert the driver to that!

 

The best way to know what is what is to establish a centre line datum and take measurements from that, also from both front wheels with them tracked parallel and facing directly ahead, this itself can be checked with reference to the datum centre line.

 

String, chalkline, plumbob, spirit level and flat floor needed, or spend money on a 4 wheel alignment check with someone competent and trustworthy.