Rear axle misalignment

[Aleco]

I think I've posted on this before but I can't find any threads.

I'm having real problems with the axle alignment, the near side rear wheel is very tight on the arch. I've read a lot of threads on the forum with similar problems.

I've changed all the bushes for poly and new shocks and springs all round.

I read other threads that there may have been cases of brackets mis-welded on the axle casing. Today I dropped out the axle but cannot see anything wrong on a visual inspection. How can I check the alignment of brackets on the axle or the body?

Any thoughts?

[Toledo Man]

The dimensions should be in the factory workshop manual. It is the same across the whole Dolomite range (except for the 1300fwd).

[matt of the vivas]

You sure its not the arch at fault? Could it have been replaced badly and is out of line?

In what way is the axle out of line? side to side? front to back?

Have you taken the radius arms off as well, and checked them for bends, factures, twists?

Is the shock mounting correct? The top mount has a tapered plate, it can fit 4 ways but only one is correct, that can force the spring / shock at an odd angle, can't see it moving the axle though...

Very odd.

[Pippin]

A few photos might help diagnosis of the problem ...

[gmsclassics]

We are talking about cars where the build quality was not the best, even poor by current standards. Variations in wheelbase from side to side of 1 to 1.5cm are not uncommon, although my limited experience is that later cars were better.
My blue 79 car is fine for wheelbase and location of rear axle (side to side). The mimosa 76 car has a shorter left wheelbase and the axle is biased to the left side by about 1cm. It is best to look at the gap between the wheel / tyre and the front lower edge of the inner guard. As Matt points out that avoids possibility of the location having changed for the outer wing from damage / repair damage.

The 76 car runs fatter 185.70 tyres so the issue on mine has been addresses by rolling the inner edge of the wing so that nothing will touch, even on hard cornering. I can honestly say that even with that amount of misalignment, you really cannot tell and the car drives fine, even under very hard use.

Otherwise the only way to get the rear axle side to side positioning exactly where you want it is to have adjustable upper locating arms fitted (the ones at 45 degrees to the axle). I do use one on the race car but only because it runs 195.60x14 tyres and the gaps between inner and outer arches are only a few millimetres, even with arches rolled on both sides.

I had mine made locally (mine retain polybushes and I use a hard type) but I do know of the following source in the UK

http://www.sprintspeed.co.uk/pages/prod ... uspension/

To be honest, if the tyres aren't rubbing, I'd leave well alone. Hope this helps.

Geoff

[Aleco]

Thanks for all the replies. Orginally the wheel rubbed when anyone sat in the back, so I thought the suspension and bushes were shot. That's when I poly bushed everything and fitted a set of avo coil overs. The axle alignment is still pants and because the car is slightly lower the wheel still rubs.
I really like the idea of the adjustable radius arms. I had a look on the website but I wasn't entirely clear if I could use the poly bushes I've already got and the same attachments to the axle without have to start welding on new brackets. Do you guys have any experience of these arms when not using rose joints?

[gmsclassics]

Apologies. The link I attached is for he trailing arms. It isn't these you need but the polybush ones you rightly say. I thought I had seen a source in the UK but I might have been mistaken. I did get mine adapted locally from originals by an engineer. Wasn't that expensive. Maybe that is the simplest solution. I'm away on business at present but I'll put a photo up of what I use as soon as I'm back at the end of the week

[MIG Wielder]

I
I read other threads that there may have been cases of brackets mis-welded on the axle casing. Today I dropped out the axle but cannot see anything wrong on a visual inspection. How can I check the alignment of brackets on the axle or the body?

Any thoughts?

Just as a quick check, could you measure the dimension from the upper radius arm bracket to the back face of the brake backplate ? It should be the same both sides. Then check the trailing arm dimension also from the rear of the brake back plate to the side of the radius arm. Again this should be the same each side. That would then eliminate the axle and you could look at bodywork mountings.
Tony.

[gmsclassics]

Apologies for being tardy in posting these photos. I gave the engineer an old arm which he cut, threaded (one reversed) and made the connecting piece and locknut. Trick is to ensure that the range in and out is known so it can be made long / short enough but still has enough threaded into the joining piece so it remains rigid and strong. I did have a pair made but now only use one, with a standard arm on the other side. Has been on the race car for many years now with no issues.

photo 1.JPG (123.03 KiB) Viewed 1366 times

photo 2.JPG (130.58 KiB) Viewed 1366 times

Hope this helps

Geoff

[Aleco]

That's fantastic, thanks Geoff.

The more I look and measure the more I think an adjustable rod will sort this out.

Just one more question. ....what thread did you use on the adjuster? I'm happy to do the calculations on thread loads but just thought why bother if I could copy something that's already done!

Alex

[Carledo]

Rotoflex fitted GT6 and Vitesses have the trailing link adjustable like this where the humbler models just have shims at the forward bracket on the body
On these independently sprung cars these bars control the rear tracking and errors result in an amost undriveable car but a simple adjustment can work miracles.
I,m seriously considering making a pair of adjustable bars for the Carledo, just so I can get it spot on square. As a side effect it will also make it possible to alter the diff nose angle to get that perfect too!

Steve

Ps the Carledo is also slightly out in lateral position, not a lot, maybe 3 or 4 mm nearer the O/S but it makes a big difference with 195x15s - even with the arches rolled up tight!

[sprint95m]

I'm having real problems with the axle alignment, the near side rear wheel is very tight on the arch.
Any thoughts?

Yes.....

You sure its not the arch at fault?

Matt started a thread short ago asking what the holes in the inner sills are for....

Our cars were assembled using the sills as the starting point, so axle brackets are positioned relative to these,
that is after the floor was in place of course.
The upper body was then added in stages afterwards. The tolerances used were really rather large
(for instance on Mark's unused shell one B-post had to be removed and refitted to allow proper door alignment).
viewtopic.php?f=19&t=17826&start=15 please see page 2.

In other words, I agree with Matt, I suspect one arch is the problem, perhaps even both arches.
As Dave has said the BL workshop details checking body alignment using a Churchill jig. However nowadays four wheel
alignment is mostly done electronically http://en.wikipedia.org/wiki/Wheel_alignment..........




Ian.

[gmsclassics]

In my case I was trying to fit 195.60x14 tyres to a race car which would put huge lateral forces on the axle while cornering (youTube, search for Dolomite Sprint No 20). Obviously the first point is all new hard grade polybushes and replace some annually. Once everything is tightened, i then centred the axle based on tolerances of the tyre against the inner arch, with the spring compressed to mimick cornering. I found the tight spots to be the lowest point on the inner arch at the front, and somewhere on top edge of the tyre just backwards of the centre line. Easiest way to find out if anything rubbed was to give the inner and inside of the outer arches a light spray with primer and then go for a 'spirited' drive. Any rubbing was easy to see as the primer was rubbed off. I did some bashing on the inner guard with a large hammer and using spacers between the drum and wheel, managed about 10-12mm gap each side.

That then defines how much the outer arch needs to be pulled out (after rolling the lip up/into the arch) to achieve the desired tolerance. Fortunately I didn't need to move it far to achieve a similar tolerance as on the inside.

Interestingly having done all that when a wheel sheared off in Feb and severely damaged the inner arch etc, we used the position of the wheel/tyre as the reference for welding in a replacement inner arch / boot floor and then straightening the outer arch!

Thread measurements are 16 pitch (per inch), 3/4" OD and just shy of 1 1/2" long.
Geoff