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

Rusty911

A2OC Donor
The latest A2 TDi has an undignified habit of snatching to the left as the power comes off. It's enough to catch out the unwary.

As the tyres were feathered after a few hundred miles and the steering wheel
is off, 'simples' surely: tracking must be out. A very quick check last night shows about 2 mm total toe in on front: bob on I'd have thought.

Now, I'm old enough to remember front drive cars being toe out on basis that as the power went on, the wheels would rotate somewhat around the car's centreline (in plan) so their running state under power was parallel. Downside was potentially twitchy handling as the power came off and brakes came on.

Anyway, I take it we 'are' toe in? The figure seems to be 5' +- 5'. I assume that's parallel to a total of 10' toe in across both wheels?

A quick glance doesn't show major bush failure, but will give major wiggle with a bar later. I'll also try some other wheels or at least reverse the ones I have. Pressures are fine.

I'm using old school Dunlop gauges which are blinking marvellous btw: easy to calibrate, very accurate.

Many thanks :)
 

audifan

A2OC Donor
Measurement values here


How is the camber?


Have you had a good look at the wishbones and ball joints?
 

Rusty911

A2OC Donor
Yes, that's where I got them: I just wanted to double check we are indeed toe in. I now see it does mention 'toe out' for the 20 degree measurement, suggesting toe figures are indeed 'in', which is bad(ish) for me. I need to alter the track rod ends anyway assuming wheel
isn't neatly one spline out.

I will check camber although hard to see that changing handling between throttle on / off.

Wishbones (solid) recent, rear bushes look perfect on face of it (which are the ones I'll lever around a bit to check compliance).
 

audifan

A2OC Donor
Completely check all the suspension, track rods, ball joints, steering rack mounting, wheel bearing, wheel bolts, suspension strut and spring....
 

Rusty911

A2OC Donor
Completely check all the suspension, track rods, ball joints, steering rack mounting, wheel bearing, wheel bolts, suspension strut and spring....
Well yes, in the absence of any weird suspension readings, clearly that's where I'll be heading. It's up in the air later anyway for shocks, service and gearbox oil change.

I'll also refine my rough reading from last night by popping it on the grease-plates and double checking the calibration of the Dunlops. I was rather hoping it was way off as that would address three things at once: handling, steering wheel and economy (73.4 on long gentle run: not bad but it'll do better I'm sure).

I'm obviously hunting for something that changes between power on - power off. I'm not overly worried but big believer in getting the right info up front before diving in on what might be wild goose-chases. By same token not a great player of parts-darts :).
 
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audifan

A2OC Donor
The way I'm reading the toe is EACH front wheel can be between -1' and plus 9'. There is only a total toe angle for the rear beam.
 

Howey

Member
I use the string method and set square to rear axel, its a faff and a bit "bushcraft" but does allow for visable measurement. Had good results so far!
 

Rusty911

A2OC Donor
The way I'm reading the toe is EACH front wheel can be between -1' and plus 9'. There is only a total toe angle for the rear beam.
Yes, for some reason toe is usually per wheel, odd to vary between axles though!

The fact it's a massive tolerance suggests it's actually not very critical anyway.

Easiest way to do a dirty check with the Dunlops is leave the vial on '0' and move the whole arm in and out to hit zero. That gives a gap at front or rear of the wheel at the eye-piece end. In my case, about 2.0 total toe in.

Given what's going on, I'd say that's good enough: not bad enough to cause this particular issue anyway.
 
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Rusty911

A2OC Donor
I use the string method and set square to rear axel, its a faff and a bit "bushcraft" but does allow for visable measurement. Had good results so far!
I've done this on both my early 911's (both departed). Set up using axle stands. Works really well right up until you kick one of the stands and have to start again. Even so, totally valid method and used by a lot of club racers (as are the Dunlops).

I also did the corner weights using car batteries totally my weight in driver's area, a 25mm solid bar pivoting a bit of RSJ across the front wheels. Can't help but be right.

All this laser alignment is fine, but it's not doing anything you can't DIY.
 

audifan

A2OC Donor
Sometimes the tried and tested ways are the best. Even seen people drive on wet sand to do their tracking! Its the snatching to the left that concerns me. Binding brake caliper, ball joint or wheel bearing would be my first checks. With the front wheel tolerances, as long as they are not toe out should be good. Wishbones, cross member, strut, track rods and steering rack all need to be ruled out. Could even be a gearbox differential problem. Obvious, but you do not have a directional tyre the wrong way round? Most people can access a ball of string and some garden canes but I doubt many can put their hands on a laser aligner as easily.
 

Rusty911

A2OC Donor
I think I'll be alright on checking it over thanks: original qu was just to confirm it is indeed a toe-in car, plus just in case this was a classic A2 issue of some sort.

As above: it can only be things that change between power on / off and the car otherwise drives well as far as suspension (shocks aside), brakes, steering and mechanicals are concerned. Coasts fine I think.

I'm not unduly worried as not using it, but am interested as not seen this on a relatively modern, well maintained car before . My usual quick and dirty check is to grab a front wheel and sharply jerk it back and forth. Usually soft rear a-arm bushes (which give some very odd symptoms) will allow some movement, but not this time. Equally, no tramlining, odd noises, groans or moans.

As mentioned, I'm doing shocks anyway so no doubt the cause will make itself known at this point. I do prefer to have an idea diagnoses-wise before I start.

If I hadn't done the above checks already I'd say:

1) A-arm bush or housing.
2) Tracking.
3) Tyre issues (odd wear rather than pressure as pressure would simply pull continuously).

Quite looking forward to seeing what it is. Annoyingly both of my 'proper' jacks are under a customer's car at Rusty Workshops, giving an incentive to finish that phase of his build tomorrow so I can bring the jacks back home :rolleyes:

Will report back for future ref.
 

Rusty911

A2OC Donor
Top suspension mounts are strong candidates too, and prone to wear!
Well, between you, Graham and me we have literally covered every single moving part at the front end so odds are the culprit will be on the list somewhere 😂

Again, I can't help but feel that whatever it is must be affected by application of power as car is perfectly fine in all other regards. In light throttle conditions it's O.K. , steering has a nice feel to it and self-centres as it should.

Happily the above shocker work puts me right in the area anyway.
 

Welshboy

Member
On my A2 the toe in after changing a hub from a scrap a2 was a negative 0.25 left and negative 0.23 right with the steering wheel off centre. This was enough to trip the ABS and stability lights on the dash with the red circle flashing and dinging on moving off. Getting it changed to 0.02 L and 0.03 R with a straight steering wheel cured the abs lights after a 12 mile run.
 

Rusty911

A2OC Donor
Looks as though my initial thoughts were possibly right, unlike my Dunlops.

Took them outside where the light is better and set them up on a board: they were 30' out so must have got knocked since last used.

Also rolled car back-n-forth a few times to settle it in.

Sure enough, a total of 4mm toe OUT.

Everything else so far looks spot-on and there's zero play on anything.

I'll do the other work, dial in the tracking and try it again. If still odd I'll try some other tyres (have several wheel sets here).

Will update in due course ...
 

Rusty911

A2OC Donor
My efforts at tracking etc have come to nought: it's still lurching to the left when I come off the throttle.

Although the car's for sale on here, I'm still interested to resolve this particular issue, a) for any buyer's safety, and b) for my own curiosity.

Just to recap: power on, car pulls reasonably straight and true. Gentle power off, gentle pull to left. Sudden power off, lurch to left sometime almost violent. I can't link any particular noise to it although there are several cracks, creaks and clonks, all mild and seemingly random, none seen directly related to the time it lurches. There is one that seems fairly central just ahead of the front bulkhead which, so I will check I tightened the gearbox bottom mount post-gear oil change.

The front tyres actually came from @A2Steve 's stock (via the wheels he fitted) but have done around 400 miles on the car. There is some feathering which may or may not have been there before, but nothing else that I can see.

I've just done front shocks, drop links and serviced the top mounts and at same time bar'ed the front arm bushes and generally yanked the front wheels around: nothing obvious there.

Steering is about the right weight I think and self centres as you'd expect. The top mounts weren't as new, but in servicing them they were dismantled, cleaned and re-greased. If there was an issue here, why would it be power related?

The gearbox seems to be behaving fine and there are no signs the diff is in trouble, in trying to improve the shift quality I changed the oil (genuine Audi to correct spec) and although the oil that came out had some age, it was perfectly clean and smelt normal. I don't think there's an issue with the diff.

As supplied the tyres were in the low 20's, but I've tried all sorts of pressures since and that doesn't seem to change things.

So ... at some point I was going to try the following but would welcome any tales of fixed lurches 🙂

1) Try a different pair of wheels on the front. I've got a set of lighweights I fancy trying anyway.
2) Manually check the tracking with my alternative measuring device: one that goes between the wheels on the inside. Will photograph it: it's crude but can't help but be perfectly accurate.
3) Lift the car up again and see if there's a chance something on the subframe or steering rack could be moving.
4) Once again try yanking the front wheels fore and aft (car on ground) as hard as I can just in case it reveals something.

This isn't some very mild, 'perhaps it's there, perhaps it's not' thing. Caught unawares, it's a 'Whoa!! What the What!' sort of thing. Never had something like this where that isn't joined by a massive clonk or whatever.

I think sorting this and the gear-change would really turn this car around. As it is, it's thoroughly unpleasant to drive locally, but is absolutely fine (impressive in fact) when on a nice long motorway run. Oh yes, it also did nearly 74mpg, so the alignment and gearbox can't be 'that' bad surely?
 

Rusty911

A2OC Donor
Well, funnily enough, the other day I was studying this picture from @damadgeruk of Smurf's nether-regions ...

Smurf's Nethers

and the same thing struck me. The car has had wishbones in the past. I don't know if the rear bushes are supplied with the wishbones, but they look either recent or at least, very good. I did wonder if there was a chance that during this work the sub-frame either had been allowed to move or that is was still on the move.

I guess if I drop the under-tray and get some good lighting under there I could look for some witness marks? If none, perhaps just spray some paint over the areas where frame meets shell and take it out for a good work-out (acceleration / heavy braking etc) and re-examine?

The one good thing with work like this is you tend to do everything you find along the way, so even if they don't cure the issue when you do finally get to the bottom of it, you tend to end up with a very well sorted car. In that area anyway.
 
Seems to me from reading everything you have described is, sounding like its diff related. I have experienced the same symptom in another car. Worth spanner checking all the main bolts underneath. I experienced creaks from underload & breaking, never lateral forces, so used a breaker bar to check main bolts to get a true feel of how far tight they were done up, creak emerged, four bolt's got about a quarter turn.
Differentials can make you think something is loose / worn, but if everything else you have checked is fine, the diff is more than likely the culprit..?
 

bretti_kivi

Member
let me explain - i had some work done a long time back. I don't remember what, though I think it might have been wishbones. When accelerating, the car would pull so far to the left that the ESP light came on. There were loose bolts involved. I don't remember the details but I would definitely check the bolts over.

- Bret
 
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