Technical Steering tracking (again)

[DaveMcT]

My four-wheel alignment readings always suggested that the rear axle was slightly misaligned. When fitting the new one, I tweaked it within its mounting bolts to 'correct' the misalignment.
Still pulls slightly left.
Probably the jig it was made on!

The rear hubs "could" be shimmed to the swing arm mount. BUT Fiat used over-long studs that rust so the nuts will almost certainly refuse to come off and they have four studs making any shimming more complicated.

 

[rmjbn1]

Sorry to drag this thread back into the light, I'm having an issue with rear tyre wear, and suspect toe-in on the near side rear wheel on my '54 plate 1.2 to be the cause.

They're different brands, I know. It wasn't me, I promise. It makes me feel ill: nsr toe 01.jpg
The outside tread of the near side rear (Arrowspeed) has worn down to about 2mm (3-4mm centre, 5mm inside) over 18 months / 9k miles. The previous tyre (Conti CEC3) did exactly the same, wearing the outside tread until it failed an MOT (in Jan 18, before I got the car).

There is distinct 'feathering' on the leading edge of the outside tread blocks, leading me to suspect excessive toe-in. The off side rear (Conti CEC3) shows the same symptoms, but nowhere near as much, and this tyre's about 1 year older.

In other good news, the fronts are fine (yay!), all tyres are 155/80 R13s, I keep them at 29psi front/26 rear (up to 29 with a heavy load). She brakes & handles fine, albeit with a very slight pull to the left when going straight ahead, I only really notice it on motorways.

A visual check from the rear, lining up the rear wheel until I could just see the rim, shows the NSR pointing towards the middle of the car, with more bodywork & front wheel visible on the left side compared to right: nsr toe 02.jpg

I measured -6mm across the front of the rear tyres compared to the rear, with a tape measure between the inner grooves at the highest point possible on the front & rear of the rear tyres.

I know this is not an accurate measurement of wheel alignment, but would I be right that this confirms my suspicion that excessive toe-in on the near side rear wheel is causing my car to eat this tyre this way?

If so, what next? I'm torn between:

1. Taking her for a 4-wheel alignment. I'm put off this by reading here (and on other threads/sites) that according to FIAT (and presumably most garages) there is no adjustment for toe/camber on the rear axle.
So whilst they could confirm what the issue is, they probably can't do anything about it.

2. Replacing rear bushes (possibly also springs/dampers?) to give an accurate baseline before making any further adjustments. I'm reluctant because, frankly, it seems like a lot of work and I have little faith it would help.
I fully appreciate that a 15 year-old car with 3 owners can reasonably be expected to show wear in the suspension & bushes, and it's not impossible it may even have taken a knock at some point. But my MOT has no advisories so I feel whilst the bushes might be past their best, they can't have deteriorated so much as to cause this amount of tyre wear, can they?
It also seems this problem isn't unknown on 169 Pandas, with some owners reporting it from new, so it could even be down to manufacturing tolerances?
Just to add a twist (beam) to this story, is it normal for the rear spring cups to be at different angles like this? The car was unladen on a level surface. Looks odd to me: nsr toe 03.jpg

3. I'm intruigued by the references to the triangular mounting plates on the rear axle providing some degree of adjustment.
But I assume adjusting this wouldn't get my rear wheels parallel, and I already have signs that suggest toe-in on both rear wheels. If I decrease toe-in on the left this way, I assume it would increase on the right.
Also, it sounds tricky. I don't think I have the expertise or equipment to accurately monitor any adjustments I make this way.

4. I'm most tempted to try shimming the front two studs between the left rear hub and swing arm mounting plate, to bring the front of the NSR wheel outwards, and then get the alignment tested once I've got the rear wheels more or less parallel. Or just rotate the tyres & monitor tyre wear.
I understand this isn't a very accurate way of adjusting toe, but if I could just reduce the toe-in enough to alleviate the excessive tyre wear, it would be an improvement. Plus if it doesn't work I could easily undo this step.

Pugglt Auld Jock- if you're reading this, hello, I hope you're well and thank you for your wee essay on tyre wear and castor/camber/toe. It's great to have the benefit of your experience, and I found it very informative (I even read the whole thing!). Thanks also for your post on your home-made alignment tool (looks great, I don't care what the others say!). I don't think I could tackle such a thing myself just yet, but with three old cars to look after (of which the Panda is the whippersnapper by quite some margin), an accurate method of monitoring wheel alignment would be very useful. Your post has given me confidence that I could do this, with the right tools.

If I do go ahead and make adjustments myself, I'd like a better idea of what's going on at the four corners. I understand the Gunson Trakrite alignment guage is just for front wheels? Is there anything similar (not too expensive) that can measure rear alignment as well?

So I'm leaning (with negative camber of course) towards option 4. Any thoughts, please? Thanks for taking the time to read this, any advice would be greatly appreciated.

 

[Pugglt Auld Jock]

There is distinct 'feathering' on the leading edge of the outside tread blocks, leading me to suspect excessive toe-in. The off side rear (Conti CEC3) shows the same symptoms, but nowhere near as much, and this tyre's about 1 year older.

In other good news, the fronts are fine (yay!), all tyres are 155/80 R13s, I keep them at 29psi front/26 rear (up to 29 with a heavy load). She brakes & handles fine, albeit with a very slight pull to the left when going straight ahead, I only really notice it on motorways.

A visual check from the rear, lining up the rear wheel until I could just see the rim, shows the NSR pointing towards the middle of the car, with more bodywork & front wheel visible on the left side compared to right

I measured -6mm across the front of the rear tyres compared to the rear, with a tape measure between the inner grooves at the highest point possible on the front & rear of the rear tyres.

I know this is not an accurate measurement of wheel alignment, but would I be right that this confirms my suspicion that excessive toe-in on the near side rear wheel is causing my car to eat this tyre this way?

If so, what next? I'm torn between:

1. Taking her for a 4-wheel alignment. I'm put off this by reading here (and on other threads/sites) that according to FIAT (and presumably most garages) there is no adjustment for toe/camber on the rear axle.
So whilst they could confirm what the issue is, they probably can't do anything about it.

2. Replacing rear bushes (possibly also springs/dampers?) to give an accurate baseline before making any further adjustments. I'm reluctant because, frankly, it seems like a lot of work and I have little faith it would help.
I fully appreciate that a 15 year-old car with 3 owners can reasonably be expected to show wear in the suspension & bushes, and it's not impossible it may even have taken a knock at some point. But my MOT has no advisories so I feel whilst the bushes might be past their best, they can't have deteriorated so much as to cause this amount of tyre wear, can they?
It also seems this problem isn't unknown on 169 Pandas, with some owners reporting it from new, so it could even be down to manufacturing tolerances?
Just to add a twist (beam) to this story, is it normal for the rear spring cups to be at different angles like this? The car was unladen on a level surface. Looks odd to me: nsr toe 03.jpg

3. I'm intruigued by the references to the triangular mounting plates on the rear axle providing some degree of adjustment.
But I assume adjusting this wouldn't get my rear wheels parallel, and I already have signs that suggest toe-in on both rear wheels. If I decrease toe-in on the left this way, I assume it would increase on the right.
Also, it sounds tricky. I don't think I have the expertise or equipment to accurately monitor any adjustments I make this way.

4. I'm most tempted to try shimming the front two studs between the left rear hub and swing arm mounting plate, to bring the front of the NSR wheel outwards, and then get the alignment tested once I've got the rear wheels more or less parallel. Or just rotate the tyres & monitor tyre wear.
I understand this isn't a very accurate way of adjusting toe, but if I could just reduce the toe-in enough to alleviate the excessive tyre wear, it would be an improvement. Plus if it doesn't work I could easily undo this step.

Pugglt Auld Jock- if you're reading this, hello, I hope you're well and thank you for your wee essay on tyre wear and castor/camber/toe. It's great to have the benefit of your experience, and I found it very informative (I even read the whole thing!). Thanks also for your post on your home-made alignment tool (looks great, I don't care what the others say!). I don't think I could tackle such a thing myself just yet, but with three old cars to look after (of which the Panda is the whippersnapper by quite some margin), an accurate method of monitoring wheel alignment would be very useful. Your post has given me confidence that I could do this, with the right tools.

If I do go ahead and make adjustments myself, I'd like a better idea of what's going on at the four corners. I understand the Gunson Trakrite alignment guage is just for front wheels? Is there anything similar (not too expensive) that can measure rear alignment as well?

So I'm leaning (with negative camber of course) towards option 4. Any thoughts, please? Thanks for taking the time to read this, any advice would be greatly appreciated.

Good morning rmjbn1. Your pictures do seem to show unusual wear but that lipping effect is a bit strange.

I'm very interested to read of your slight pull to the left. Portland Bill and Dave McT both report this and even after my recent replacement of struts and springs on Becky I still have this effect myself. It's very slight and easily controlled with a thumb lightly hooked into the steering wheel, but if you leave her to her own devices (especially, as you mention, on roads where you are cruising in a straight line like dual carriageways and motorways) she will gently drift away to the left. I've tried swapping over the front wheels but she still pulls left. Mrs Jock, who drives the car around town a lot, says she's no idea what I'm talking about and thinks nothing's wrong with the car!

I've done the "squinting" along the wheels bit too and my N/S/R does look as if it's very very slightly more toed in than it's O/S pal - but the effect is so slight I'm not sure - nothing like as obvious as in your picture. Of course as the front track is wider then the rear you are always going to see some of the front tyre when looking along the rears in this way. Now that you've raised this I'm going to use my tool to measure the actual toe on the rear and then my straight edge along the front and rear sidewalls of the rear tyres to compare with the fronts. There is considerable scope for inaccuracy in doing this as, because the front wheels steer, I can't rely on the visible tread as the reference point. (ie the front wheel will need to be absolutely dead ahead to get a meaningful result.) Of course none of this will be as accurate as a proper bench job (ie Hunter) but I like messing about and getting to understand what's going on. By the way my N/S/R spring pan is very slightly lower than the O/S one. Not as much as your's though and others have mentioned this too - I seem to remember that, in the instances I've read about it, that it's always been the N/S one that's lower too but the degree of "hanging down" seems to vary. I find myself wondering if this has any bearing on things? Must mean uneven wheel loading mustn't it? Could that promote the "left pull"

I suppose I should live up to my Scottish heritage by saying that probably a proper bench alignment check, with wheel loading readings, would be the only way to really understand what is going on with any of our cars but, as you say, with there being no provision for alignment adjustments to be made I'm very reluctant to shell out any dosh before I've "fiddled" away on my own and exhausted every avenue I can think of. Toe in on rear wheels is quite usual on front wheel drive vehicles but I don't know what it should be on our Pandas. So there's a wee project for me. When I built my trailer I checked the overall weight and toe bar loading with 3 bathroom scales - somehow I don't think that's going to get the job done this time!

The Trakrite would measure the rear wheel toe but would not get you much further as it doesn't tell you which of the rear wheels is out (of course both may be wrong to some extent) You need some way of comparing to the centre line of the vehicle.

I like your option 4 too - like your wee joke too! If I come up with anything of consequence I'll post it in the Panda section.

Oh, by the way, You kindly thanked me for my post about my tracking gauge (much appreciated) and you follow it saying - "looks great, I don't care what others say." I'm always interested in other's observations (even be they negative) and I don't think I'm aware of the post/posts to which you refer here. Could you point me towards them? Don't worry if you think it might hurt my feelings. Over the years I've suffered a great deal of leg pulling from friends about my tool - but it works for me so, in my eyes, they are the losers.

All the best
Jock

 

[DaveMcT]

If one wheel is out, shimming the rear hub studs is by far the best option. But you could really do with knowing where the mis-alignment lies.

The question is WHY is the wheel out of line. If its a few mm at the wheel rim (<1mm at hub mount) then it can be shimmed. But has it been crashed causing damage to the axle or body shell?

I would suggest getting it track checked with permission to work with the mechanic so you can gauge exactly how far out the wheel actually is. For example - it could be (probably is) toe out showing rear of the wheel rim is some mm inboard of the front of the wheel. It will probably be out on camber as well.

You will then know how much shim to add to the hub mounting face.

The studs will be VERY rusty so you will need a blow lamp and ideally a thread die to clean the threads. They are fine pitch so get the correct die. DO NOT try to force the nuts as the threads will strip leaving the nut spinning free. I has a second axle so was able to "borrow" a good stud but I doubt you'll get spares from Fiat.

If the axle is bent (and you dont have 100HP wheels) the Fiat 500 axle is a straight swap. Used axles are low cost and come with integral anti roll bar. You need the 500 road springs and rubber spring mounts at both ends.
The car handles significantly better and the ride is far less choppy. It works with 13" steels or the 14" alloys. It wont work with 100HP wheels.

See here -

https://www.fiatforum.com/panda/449463-panda-169-rear-axle-rot-swap-2.html?p=4492977

https://www.fiatforum.com/panda/442...nto-2007-panda-169-a.html?442145=#post4196100

 

[portland_bill]

It is a cheap car, and it appears that Fiat were a bit slack when jigging the body and rear subframe. So repalceing bits is unlikely to fix anything.

The spring pans appear to be lower on the left on most cars I've looked at. (Thankfully not been arrested for peering under cars in car parks.) I fitted an aftermarket rear axle, which has copied an original so exactly that the left spring pan is lower (I was able to choose the best of a batch) and all the little brackets for pipes and hoses were bent, persumably transit damage on the original that was copied. It made me smile when looking at a stack of new ones, all brackets bent, all exactly the same. The consistency gave me faith in the construction of the aftermarket item, as they have obviously copied it well.

New studs for the hubs are available, as most of mine came out with the rusted on nut. If shims can be cut as a long 'E' shape, they could be slid in between hub and axle with just slackening of the nuts. This was OE on many Triumphs in the sixties, although I doubt theirs would fit. Be nice if they did, as they were available in several thicknesses, but finding some in my Father's garage would take weeks.

 

[rmjbn1]

You kindly thanked me for my post about my tracking gauge (much appreciated) and you follow it saying - "looks great, I don't care what others say." I'm always interested in other's observations (even be they negative) and I don't think I'm aware of the post/posts to which you refer here.

Good afternoon, Jock. No, sorry I only meant it as a joke. Not a very good one! I haven't seen any negative comments from forum members, I just had the impression you were used to having to defend it. Looks good to me, and if it does the job well, then what else matters?

 

[rmjbn1]

Thank you for finding the time to read & reply to my post so quickly, gents!

I think I'd already convinced myself of option 4, shimming the rear hub, but it's great to have the benefit of your experience! I've started soaking the hub studs in penetrating fluid and cleaning the threads in preparation.

I would discount option 2 altogether. If I ever need to replace anything on the rear axle I would follow DaveMcT's advice and get a recent 500 axle with ARB. I'm tempted to get one now before 500 owners find their spring pans rusting out and start driving prices up! Just don't tell anyone...

It's a good idea having alignment checked first, maybe I'm too focused on the obvious NSR toe-in. If I just shim one side to get my wheels parallel, I could end up still with OSR toe-in but now with NSR toe-out to add to the mix.

But after reading portland_bill & jrkitching's posts on the potential vagaries of Panda axle/chassis manufacture, maybe there's not much point trying too hard to get it spot on. If I can just get rid of the excessive tyre wear, I'll be happy. There are no obvious signs my car's had a shunt, but... who knows?

Haha, I agree with you, Jock, I'd rather do what I can first before forking out! I can't claim any Scottish ancestry, but my dad's from Yorkshire and they're just as bad, so I blame him!

Thank you Dave for the report on the axle swap. I was interested to see the photo where your near side spring pan is lower than the off side. And thank you PB for confirming even new aftermarket axles have this feature as well as most old cars. I wonder why? And how much it varies between cars, if others aren't as pronounced as mine? Could it have anything to do with the left pull? I'll be very interested to see what you find out from your research, Jock. Sorry for giving you extra work to do... Let's get them bathroom scales out again! I don't blame Mrs Jock for not noticing, I forget about it with most of my driving on country lanes. It's only when I hit the motorway and find a finger resting on the wheel isn't enough to prevent my Panda from slowly taking aim at the hard shoulder.

Well, I'll see if I can have a go at it this weekend and report back... Thank you all again!

 

[irc]

Just a reminder to check the whole beam, not just the bits that usually break... this one looked fine on first look, just a bit crusty. However, the centre of the cup had the structural integrity of a Walkers Crisp.
Wierdly:
a) it still holds a spring just fine.
b) the other side is almost perfect.
Fortunately I have a good spare, so just the hassle of changing it over.

 

[Pugglt Auld Jock]

Good afternoon, Jock. No, sorry I only meant it as a joke. Not a very good one! I haven't seen any negative comments from forum members, I just had the impression you were used to having to defend it. Looks good to me, and if it does the job well, then what else matters?

Actually you did surprise me a little with this as I find this (our) forum to be a very supportive place to hold discussions and seek advice. But I have had to suffer some leg pulling from pals up here who are used to computerized machines and can't believe that mine can even get within a half mile of any sort of accuracy! Don't be concerned that you've caused me any offence - you haven't.

In fact you've motivated me, once I've done the rear cylinders, to drop the bottom bolts out of the shockers (another job for "The Hooligan" I suspect) and have a very careful look at the axle. I've been thinking about doing this for some time but just couldn't make my mind up what to do about preservation. However I've now decided I'm going to do the best cleanup I can with it still on the car (unless I run into problems with rear flexes when I'm doing the cylinders. In which case I'll drop the whole axle for cleaning) and then paint with the same anti rust paint I used on the front spring top plates.

Mrs Jock is deeply immersed in Eastenders just now so I just nipped out and took these snaps under Becky's rear end. Hope they are useful:







As you can see the N/S is a little lower but not as much as your's I think? I'd love to see an actual, genuine, new, Fiat one for comparison. As you can see mine doesn't look all that bad yet so I think a bit of preservation now could be time well spent.

 

[DaveMcT]

I fitted the rear springs so the wire slope was lowest at the back on both sides. Turning the springs in the pans will affect the ride height side to side but not very much. A spacer washer cut from UPVC fascia board material will provide a lift to one side. Put it between rubber cushion and car body.

The 500 axle rides level and the spring pans have equal angles. I would have used one under the 100HP but it would have needed cutting and welding with special jigs so I dropped the idea.

My 100HP has new bottom arms and new track rods inner and outer. It is tracked correctly (zero degrees) and checked at a different garage but still pulls left on motorways. I need to loosen the rear axle brackets under the chassis and see if the axle can be shifted backwards on the left and forwards on the right. I'm not hopeful because it has not changed since the axle was removed for zinc metal spraying.

Shimming both rear wheels' hub spindles is more likely to sort it.

 

[DaveMcT]

You can see there is more red rust just "above" that rusty hole. This is where the axle takes the most stress and accelerates corrosion. Clean it up and weld new metal over the pan (outside) from swing arm to about 1 o'clock on the spring pan. That will restore the strength. However, it would be impossible to do a good job on the car.

If you get the axle grist blasted and zinc metal sprayed it will outlast the Forth Bridge. Hot dip galvanise even better and probably about the same cost.

 

[irc]

That red patch is actually after I had been bashing it with a hammer - until I took the springs out it actually looked pretty good - I knocked it about a bit after I had decided the beam was scrap just for interest really.
It's off a Panda Sporting that spent a year sitting under a tree in Scotland before I bought it for parts. It passed an MOT about 6 months ago, with an advisory on corrosion, and I've only just got round to some routine maintenance.

I think that the passenger side of the beam must have been sitting in long grass or weeds, and the other side was dry, as the driver's side is solid and a lot less scabby.

 

[DaveMcT]

Jock

The whole axle will happily drop down when you remove the rear shocks. The bottom bolts are very long so loosen and spin them out with a power drill. I used copper paste end to end when replacing.

That gives great access for a clean-up. Mine looked more like @irc's (though with no ventilation) hence the 500 axle. The 100HP was not so bad but having removed one axle it was no worries doing another and having it zinc metal sprayed.

Your's looks great but if you decide to remove it, just cut the rubber brake hoses and spin the fragments off the flare nuts. They are not costly and really not worth the hassle of trying to save them. Free off the flare nuts later.

Braided hoses from body shell right back to the brake wont affect the pedal feel as the hoses are so short. Not silly money, but not the least cost option.

 

[DaveMcT]

That red patch is actually after I had been bashing it with a hammer - until I took the springs out it actually looked pretty good - I knocked it about a bit after I had decided the beam was scrap just for interest really.
It's off a Panda Sporting that spent a year sitting under a tree in Scotland before I bought it for parts. It passed an MOT about 6 months ago, with an advisory on corrosion, and I've only just got round to some routine maintenance.

I think that the passenger side of the beam must have been sitting in long grass or weeds, and the other side was dry, as the driver's side is solid and a lot less scabby.

That red patch is exactly where Mrs Dave's axle was getting thin. It was a clear line of deeper corrosion an inch or two inboard of the swing arm. The main metal is at least 2mm thick so even my (very) unpracticed hand would be able to stick weld a decent job. The big issue is trapping rust inside the repair.

 

[irc]

That red patch is exactly where Mrs Dave's axle was getting thin. It was a clear line of deeper corrosion an inch or two inboard of the swing arm. The main metal is at least 2mm thick so even my (very) unpracticed hand would be able to stick weld a decent job. The big issue is trapping rust inside the repair.

Yep, if it wasn't for the state of the spring pan centre ("ventilation" - I like it!) I'd probably try repairing it, but it's just too crispy.

 

[rmjbn1]

Thank you for the photos Jock. Does Mrs Jock know how famous she is amongst Panda owners, I wonder?

I was also thinking of getting the lower shocker bolts out just to get the rear springs out for access to treat the spring pan. After seeing irc's I think I will!

I think the N/S pan looks lower on my car than on Jock's. I did wonder if the way the spring was installed might have an effect, but the orientation is the same both sides. It's not very clear in the photo, but the paint markings (blue & green) on the lowest visible coil are both facing the rear of the car. It seems most, if not all, Pandas have this feature to some degree, but could it be causing the rear tyre wear I'm seeing? There's no obvious difference in ride height N/S to O/S.

I have a selection of M10 washers of different thicknesses to shim the rear hub. Would shim washers on the studs be good, do you think, or should it be a plate between the hub and swing arm mount?

 

[DaveMcT]

Yep, if it wasn't for the state of the spring pan centre ("ventilation" - I like it!) I'd probably try repairing it, but it's just too crispy.

The middle really takes no weight just the cush rubbers need a point to hit.

If it was mine, the grinder and cup brush would be out to see just how bad it really is. If flat or simply curved steel will fit, then weld in some repair plates. 2mm on the spring pan hole and 3mm on the front side.

If the compound curved areas are shot then it would be too much trouble. But yours has not gone through under the spring so probably servicable.

 

[portland_bill]

I have a selection of M10 washers of different thicknesses to shim the rear hub. Would shim washers on the studs be good, do you think, or should it be a plate between the hub and swing arm mount?

Washers will take all the contact at just the washers, whereas a proper shim plate will spread the load across the surface. Ideally a shim plate should be a tapering thickness, difficult to achieve.

I found some examples from Triumphs. I can't remember how thick they are, but more than one can be fitted. These will not work for the Panda, but do illustrate the principle.
https://rimmerbros.com/Item--i-138640
https://rimmerbros.com/Item--i-118825

 

[rmjbn1]

Thank you pb. I suspected shim plates would be best, but I'm struggling to find any that would be a good fit between the front of the rear hub and the mounting plate. There's a locating peg between the two front studs, so any shim plate would need three cut-outs. I think I'd struggle to fabricate such a plate myself from such thin metal, presumably <1mm. (Anyone with a background in precision engineering fancy making these? DaveMcT? Dac69er? We could make a really really really small fortune)

On the other hand, most 10M shim washers I've found have quite a small outer diameter (typically 16mm), so not ideal either. If it stops raining this weekend, I'm going to try with the washers I have and see what the results are like.

 

[The Panda Nut]

Suggest checking camber also. But be careful if buying camber bolts I bought some EIbach bolts and found them to be the wrong size. I think they should be M12 sized but dont quote me on this. I have also been told that top mounts cause this. Recent purchase for our 169 suggests the ones I got from S4P were poor quality and need doing again to stop graunching noises...

My experience is that there are very very few places that can properly do steering alignment checks. I had to revisit one large chain no fewer than 8 times not that long ago to get a job done properly. STS Holborn Tyres seem to have the proper equipment and have been consistently good however.