Toe In / Toe Out: A2's at front? Odd handling!

Rusty911

A2OC Donor
Well, I said this was going to be a good one, and I'm not completely disappointed. Now, I have to say I've not driven it yet, so this might not be 'the' problem, but it most certainly 'a' problem.

Forgive some missing pictures, I'll do my best to explain.

The leading wishbone bushes have an internal metal element. This has an internal diameter of 15mm. A bolt passes through this with a nominal diameter of 12mm. I say nominal, the thread is 12mm, but the shank is smaller, the thread having been rolled on (I guess) rather than cut.

aaIMG_0109sm.jpg


As you can see, achieving any sort of alignment between a 12mm(ish) bolt and a 15mm hole isn't going to work. To overcome this, washers with a sintered spigot temporarily align the bush until the bolt can be tightened and the bush clamped into place between the pressed steel sub-frame and the cast aluminium console. (Bolt is from my scrap bin and not an A2 item btw).

aaIMG_0110sm.jpg


From what I can see, this clamping is what the design relies on for all working strength and alignment. Imagine what would happen if you couldn't pull the bush up tight, say, if there was a gap.

Like this:

aaIMG_0108sm.jpg


To the left is the black cast wishbone, then the end of the rubber (outer) portion of the bush, then that sintered, spigot washer. To the right is the area of the console that takes the bolt's thread. And in the middle ... well there's a great big gap. When the bolt was tight, this was pretty much invisible, but I had noticed it was possible to rotate the washer a fraction before. At that point though I hadn't received my new bushes so hadn't understood the design.

The net result is that the bush has clearly been able to move due to the complete lack of clamping force. This meant those lightweight alignment spigots in the washers had (for a while) taken the entire load of the bush until the front one had worn away, the arm moved forward a bit and started to move everywhere. As the forces are mainly in and out, when I levered the bush around I didn't see much movement as was levering up and down as that was the only place I could get a bar into. That explains why all seemed pretty much O.K. despite this issue.

I think there's actually a misalignment between steel subframe and aluminium console. I did attempt to undo all the bolts, but stopped early on as couldn't really see anything would move to that extent, the bolts were bonkers tight and I'd already established that externally (wheel in arch etc) everything looked O.K.

I elected to take a two pronged approach. The first was to turn up a 15mm OD, 12mm ID steel sleeve to go up inside the bush, just to provide initial alignment and an insurance should the bush try to move again in the future. It's not a tight fit due to the thread formation of the bolt, but it reduces a total potential play from 3mm to 1mm max.

The other was rather than trying to shift the whole subframe / console relationship, I simply turned up a 3.5mm aluminium spacer and slid it into the 'hole'.

aaIMG_0106sm.jpg


aaIMG_0107sm.jpg


Immediately I could feel the bolt clamping the bush as soon as any torque went on it.

The whole area just feels absolutely rock solid. The bushes themselves (front / rear on both sides) look and feel perfect so I'll keep the set I bought back for PYXi the FSi project.

As I say, not driven it yet, but am pretty confident that at the very least, it won't have done any harm. Out of interest, I put the tracking gauges on just as I was leaving the workshop: gone from parallel to 30' toe in, so something's moved!

Will track it up tomorrow (I think I'll start with deal parallel) and run it up the road.

Looked at the rear beam bushes last night, they are complete toast, so ended up cancelling today's MOT and have some poly ones ordered. I would have preferred O.E. style ones, but they are the 69mm versions which seem impossible to find (including genuine): everyone does 72mm.
 

Joga

A2OC Donor
Promising lead 👍. One reflektion though, wouldnt torqueing the leading screw more or less force the steel frame ear towards the wishbone and clamp it firm to the console? Hmm. I did this job myself, but dont quite remember how rigid the steel subframe was, I could be wrong.
Look forward to hear after your test drive.
 

Rusty911

A2OC Donor
Promising lead 👍. One reflektion though, wouldnt torqueing the leading screw more or less force the steel frame ear towards the wishbone and clamp it firm to the console? Hmm. I did this job myself, but dont quite remember how rigid the steel subframe was, I could be wrong.
Look forward to hear after your test drive.
That's exactly what happens, but I imagine that when everything is perfect, the bush 'just' slides up into place with its washer-chaperones, therefore the slightest tightening of the bolt clamps up the bush.

In this case, even with the bolt done up reasonably tight, the pressed steel sub-frame couldn't distort enough to clamp the bush. Luckily it looks as though no harm has been done: no stress cracks and no distortion.
 
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Rusty911

A2OC Donor
Just to confirm, yes, this has cured the issue: yay :rolleyes:

Now tracks down the road dead straight, over bumps and lumps, on/off throttle, bends etc etc. No noises either.

This, coupled with the deep-cleaned and lubricated gear-selection trio (housing, cables, tower) has transformed the car. It's actually now quite nice to drive. Will take it on the Norfolk trip tonight which will give it a good shake down.

In the end I set the tracking to bob-on neutral in a quest for maximum economy without getting it too twitchy. Feels fine and seems to drift along on barely any throttle.

Assuming no further new issues, that leaves rear beam bearing replacement, rear hub replacement, wet-clean interior, sill cover repairs, new rear tyres, new MOT and possibly faux flaps / A2OC livery set with RS style badges. I think by time I'm at that point it'll owe me nearly £1900 and heaven knows how many hours. Sigh ... at least it's getting there and feels a lot safer than it did.

Will then decide what to do with it: probably put trade plates on PYXi the FSi and back-to-back them. Loser goes. Yorkshire FSi will be going as well, ditto TT and one more. That'll clear a bit of mental capacity / space / cash for the Austin Trophy project :cool:

Thank you all for the ideas, input and support: all very much appreciated 🙂.
 
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Joga

A2OC Donor
Good job!
Actually being able to find the root cause is rather rewarding feelingwise, isnt it?

I am not sure I understand what caused this issue in the first place.
I assume it happened when the wishbone was exchanged, right?
Was a washer between the leading bush and the console or steel subframe forgotten, or was the console and steel frame mounted with wrong distance to each other, or.
Hmm.
What is your best thoughts Barry?
 

Rusty911

A2OC Donor
Good job!
Actually being able to find the root cause is rather rewarding feelingwise, isnt it?

I am not sure I understand what caused this issue in the first place.
I assume it happened when the wishbone was exchanged, right?
Was a washer between the leading bush and the console or steel subframe forgotten, or was the console and steel frame mounted with wrong distance to each other, or.
Hmm.
What is your best thoughts Barry?
Yes, it's very satisfying to find a definite cause such as this: it's as close as you're likely to get to throwing a switch: Lurch / Don't Lurch.

My best guess is that the console and the steel subframe don't have quite the right fore-aft relationship. No evidence of accident damage, so I'd say it was previous work. I'm sure I could have slackened all bolts and pulled everything together better using the wishbone, but just didn't want to tempt fate when there was an effective risk-free and indeed, free, resolution.

If this was a £50,000 car, I'd have dropped the whole lot out, checked the bodyshell using drop measurements, measured every component and reassembled bit by bit.

As it is, I'm happy that everything is secure and that the alignment is spot on. Ultimately these are the only things that really matter.
 

Tomscar

Member
Just to confirm, yes, this has cured the issue: yay :rolleyes:

Now tracks down the road dead straight, over bumps and lumps, on/off throttle, bends etc etc. No noises either.

This, coupled with the deep-cleaned and lubricated gear-selection trio (housing, cables, tower) has transformed the car. It's actually now quite nice to drive. Will take it on the Norfolk trip tonight which will give it a good shake down.

In the end I set the tracking to bob-on neutral in a quest for maximum economy without getting it too twitchy. Feels fine and seems to drift along on barely any throttle.

Assuming no further new issues, that leaves rear beam bearing replacement, rear hub replacement, wet-clean interior, sill cover repairs, new rear tyres, new MOT and possibly faux flaps / A2OC livery set with RS style badges. I think by time I'm at that point it'll owe me nearly £1900 and heaven knows how many hours. Sigh ... at least it's getting there and feels a lot safer than it did.

Will then decide what to do with it: probably put trade plates on PYXi the FSi and back-to-back them. Loser goes. Yorkshire FSi will be going as well, ditto TT and one more. That'll clear a bit of mental capacity / space / cash for the Austin Trophy project :cool:

Thank you all for the ideas, input and support: all very much appreciated 🙂.
Glad you got it sorted Barry ... 👍👍👍
 

Merlin3046

Member
With the great benefit of hindsight, you can mimic the effect of torque reversals on the front suspension by sticking the car in gear and pushing it from the front and back alternately. So you could stick the car on a drive-on ramp and use two burly mates to rock the car back and forth while you look at what the suspension is doing from underneath (use handbrake for rear wheel investigations). If you have no ramp, lay your phone on the floor underneath the car filming upwards and repeat with two burly mates.
But as Simon says above, this is the sort of thread that absolutely makes this forum. Great detective work and great perseverance. Chapeau.
 
Looked at the rear beam bushes last night, they are complete toast, so ended up cancelling today's MOT and have some poly ones ordered. I would have preferred O.E. style ones, but they are the 69mm versions which seem impossible to find (including genuine): everyone does 72mm.
Glad you found the problem in the end, i bet that was a relief it was nothing worse.

Just picking up on the rear axle bushes, I'm about to pull the trigger on a set of Febi bushes that have an indicated 72mm outside diameter on ebay yet your saying they should be 69mm?
 

Rusty911

A2OC Donor
With the great benefit of hindsight, you can mimic the effect of torque reversals on the front suspension by sticking the car in gear and pushing it from the front and back alternately. So you could stick the car on a drive-on ramp and use two burly mates to rock the car back and forth while you look at what the suspension is doing from underneath (use handbrake for rear wheel investigations). If you have no ramp, lay your phone on the floor underneath the car filming upwards and repeat with two burly mates.
But as Simon says above, this is the sort of thread that absolutely makes this forum. Great detective work and great perseverance. Chapeau.
I did lever the front wheels back and forth, but there must have been just enough grab to withstand this, which shows how much is going through suspension as a matter of course during normal driving. I'm still amazed there wasn't more clonking going on, although the seemly random one has now gone. In fact, the car is now driving tight as tight as once the rear bushes are done, it'll be running on virtually new suspension throughout.

It's just done 'the Norfolk trip' so Sussex, Norfolk, Sussex (360 miles): all fine and 75.4mpg this time. Getting better, bit by bit.
 

Rusty911

A2OC Donor
Glad you found the problem in the end, i bet that was a relief it was nothing worse.

Just picking up on the rear axle bushes, I'm about to pull the trigger on a set of Febi bushes that have an indicated 72mm outside diameter on ebay yet your saying they should be 69mm?
I was pretty confident the actual shell was O.K. and that after that everything is fixable. Even so, the fact it was effectively free and very easy once found was great.

As for the rear bushes, yes, almost all listings show them as being 72mm and this doesn't seem to change with the year. Nevertheless, the poly bush people list a 69mm version, and the eBay seller where I got the Febi 72mm's insisted on having the reg 'as there are two sorts'. Ironically he then confirmed I definitely needed the 72's, only for it to become clear I needed the 69's once the axle was part dropped.

All I can suggest is that you measure before buying, but the odds seem pretty high you'll be on 72's anyway.

Oh yes, even Audi (TPS) supplied me 72's as well.
 
I was pretty confident the actual shell was O.K. and that after that everything is fixable. Even so, the fact it was effectively free and very easy once found was great.

As for the rear bushes, yes, almost all listings show them as being 72mm and this doesn't seem to change with the year. Nevertheless, the poly bush people list a 69mm version, and the eBay seller where I got the Febi 72mm's insisted on having the reg 'as there are two sorts'. Ironically he then confirmed I definitely needed the 72's, only for it to become clear I needed the 69's once the axle was part dropped.

All I can suggest is that you measure before buying, but the odds seem pretty high you'll be on 72's anyway.

Oh yes, even Audi (TPS) supplied me 72's as well.
Is it not a case of two different materials and, one being more firmer than the conventional rubber type hence, the larger diameter rubber bush..? I should imagine the poly type will fit relatively easy to the rubber type, my poly on gearbox mount went on a treat without busting a blood vessel... (diesel type), an upgrade I'm very pleased with the result and without any unwanted additional vibration.
 

Rusty911

A2OC Donor
Is it not a case of two different materials and, one being more firmer than the conventional rubber type hence, the larger diameter rubber bush..? I should imagine the poly type will fit relatively easy to the rubber type, my poly on gearbox mount went on a treat without busting a blood vessel... (diesel type), an upgrade I'm very pleased with the result and without any unwanted additional vibration.
No, you can get poly's in both 72mm and 69mm.

Therefore, if ordering just be careful to check which ones you have upfront: best to jack the car up, have a quick measure with some verniers, and take the opportunity to spray some penetrating fluid around as well. You don't have to worry about hugely accurate measuring. In my case as soon as I got the verniers close it was very clear I had something smaller than 72mm!
 
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