Technical Steering tracking (again)

[koalar]

The laser alignment tool should be adjusted for wheel runout before measurement starts. The tool is usually attached to the wheel rim at three points, so an initial reading is taken with each 'leg' at the bottom, rotating the wheel a third of a turn each time. A mid-position can then be set as a datum.
I'd hope this is done, and may well not be noticed by an observer, but may be worth watching closely, or asking how they account for an untrue rim.

I have watched. No account of runout taken. As with anything. Its down to the quality of the staff and time allowed for the job.

My previous car had alloy wheels with between .5-1mm runout on all four wheels.

worse case all the errors add up. Best case they cancel each other out. Most of the time it will be somewhere in between.

 

[rmjbn1]

A small amount of misalignment is inevitable, but they always pull left so it might be the same manufacturing issue that made the axles with a drooped spring pan.

Was it jrkitching said there are hardly any reports of rear tyre wear on the 500 section of this forum, whereas it's all too common on Pandas, and that perhaps the 500 rear axle is both better designed and manufactured? A 500 axle is getting rather tempting...

I would be surprised if any Pandas of this age had any true wheels
just noticed you are running the recommended 26psi at the rear. Depending on the tyre manufactures side wall construction. If you are spirited on roundabouts it could be tucking under slightly. I run 30 psi at the rear although its makes it a bit harsh.

Err, yes, I'm afraid I'm guilty of spirited driving on almost all twisty bits. As a result the outside shoulders of my front tyres take a hammering:

I feel my rears are wearing the outside tread, but it's not the shoulders, it's across the tread width if that make sense?


The tread depth at the grooves reduces from about 5mm inside, 3-4mm centre to 2mm outside on my rears, but is pretty uniform at 4mm across all grooves on my fronts (despite my suffering outer shoulders). Still, raising the pressure a bit on the rear sounds like a good idea, I do this with a heavy load anyway.

I can see that you are "infected" with the same pursuit of perfection that also plagues a number of us on here.

Are you sure you're retired, Jock? Sound pretty busy to me It's more the case that I would be seething at shelling out £40-50 every two years for a new tyre, but 'pursuit of perfection' sounds much better, I'll claim that from now on!

I do believe, however, in doing a job once and doing it right. Again, mostly because it means less effort and expense in the long run. Soon we'll all have Pandas better than when they left the factory at this rate!

No there was no checking of suspension, steering connections or wheels before the alignment check, so as koalar, Jock and portland_bill say, a laser 4 wheel alignment carried out this way doesn't necessarily give accurate results either.

Your analysis of too much toe-in causing the pull to the left makes sense to me, although I understand a small amount of toe-in should aid straight-line stability. With marginal toe-out on my near side rear it does seem like the pull to the left has gone. (Still not met any dual carriageway yet though).

So in the interests of science, and unless I find any better advice, I think I should persevere with my proposed taking 0.1mm shim off N/S, adding 0.1mm to O/S, get tracking checked again to see if it shows within tolerance, and see if the left pull really has disappeared. It might not be for a little while, in the meantime, any insight or advice would be very welcome.

 

[koalar]

what age is the rear tyre left side of the two photos. Looks like some deep cracks. Bet the rubber has gone quit hard ?

 

[rmjbn1]

Hi Koalar, yes I noticed that. Surprisingly, that's the newest of the tyres on my car! DOT marking is 3717, so that would make it just under 2 years old. It's an Arrowspeed. Not very impressive. It was fitted after the previous near side rear tyre failed an MOT in Jan '18, before I got the car (also worn down on the outside tread).

The 2018 MOT came with a tyre condition report which shows all tyres as Continental CEC3s, so I'm guessing the previous owner got sick of shredding decent tyres on the left rear. Might have something to do with why they got rid of her...

 

[Pugglt Auld Jock]

A 500 axle is getting rather tempting...

Are you sure you're retired, Jock? Sound pretty busy to me 'pursuit of perfection' sounds much better, I'll claim that from now on!

No there was no checking of suspension, steering connections or wheels before the alignment check, so as koalar, Jock and portland_bill say, a laser 4 wheel alignment carried out this way doesn't necessarily give accurate results either.

Your analysis of too much toe-in causing the pull to the left makes sense to me, although I understand a small amount of toe-in should aid straight-line stability.

As there's no urgent need I've got plenty of time to consider the merits of going with a 500 axle. It's an interesting prospect.

Retired - me? I've always been a very "busy" person either working in jobs which have "wierd" hours (the racing tyres being a good example) or working evening overtime or teaching evening classes after the day job was finished. I'm not used to just sitting back and "relaxing". When I don't have anything planned I would much prefer to go for a long walk or work in my garden. Apart from the fact I like to keep "busy" it dawned on me a while back that it seemed to be keeping me quite fit in comparison to many other retired colleagues many of whom have retired to the golf or bowling club, spend too much time in the bar and are growing big beer bellies! Before you know it I'm putting my good suit on and taking a walk up the road to the Crem for a final farewell! My 73rd birthday is rapidly approaching and I'm still mending the cars, decorating (reluctantly), gardening and generally leading an active life. I hope I can just go on like this until my allotted time is up and then, unexpectedly, go quickly.

Not surprised to have you report no pre-checks were made - I really wonder what training these operatives get?

A wee bit of toe in on rear wheels is very common as you say. Indeed I also understand it aids stability. Of course it needs to be an equal amount on both wheels!

Please do keep us updated of any future developments. I'm already having some ideas on how to check rear toe in and the rear axle relationship to the centre line of the vehicle here at home and am making paper sketches to firm up my ideas. When I construct something worthy of comment I'll post details so you can all tell me how it can't possibly work!

Kindest regards
Jock

 

[rmjbn1]

I for one will be very interested to see what you find out regarding rear toe, Jock. I'm sure the advice on this forum regarding rear axles will help to keep Pandas providing many happy miles for years to come. It seems the rear axle might be the Achilles heel (that was also his left rear, wasn't it?) of our fine little cars.

 

[koalar]

this system seem to be as fool proof as possible




there is a system which takes into account any suspension wear.

its like a 4 wheel rolling road and measures the side thrusts.


most pulling slightly to one side are due to the power steering alignment. Been a few threads on here were its taken a few tries to get it centred properly.

 

[Pugglt Auld Jock]

this system seem to be as fool proof as possible

https://www.youtube.com/watch?v=CGTHN3G_DR8


there is a system which takes into account any suspension wear.

its like a 4 wheel rolling road and measures the side thrusts.


most pulling slightly to one side are due to the power steering alignment. Been a few threads on here were its taken a few tries to get it centred properly.

Good video I enjoyed watching it. Interesting to see how the importance of thoroughly checking all the running gear before setting up to take readings is emphasized - however if what is shown on the video is all they do he's never going to pick up on a worn bottom ball joint, wheel bearing, etc. A much more vigorous and energetic procedure is required with the wheels/suspension being checked in a wheel free condition - By which I mean it needs to be jacked clear of the ground/ramp for checking. Interesting to see also that the machine itself compensates for out of true wheels by that wee forward roll before the readings are taken - run out compensation he called it. I don't see any sign of a calibration check taking place though so I believe he's relying on the machine having been calibrated accurately at some time in the past and that nothing has happened to the machine to affect that. Of course I fully concede that I'm playing devils advocate here but who's to say the apprentice didn't trip over some of it in an "absent" moment and then tell no-one?

The procedure as shown here could be done and produce a "perfect" set of "green" readings but if a worn component had been missed it would be meaningless! If there were nothing wrong with the vehicle - no worn components etc - then removing the vehicle from the ramp, driving it round the block and back on the ramp should result in another "green result". If I were paying good money to have this done I'd be "bouncing" that idea off them when I was making my booking appointment and watching closely to see the reaction.

 

[Pugglt Auld Jock]

this system seem to be as fool proof as possible

https://www.youtube.com/watch?v=CGTHN3G_DR8


there is a system which takes into account any suspension wear.

its like a 4 wheel rolling road and measures the side thrusts.


most pulling slightly to one side are due to the power steering alignment. Been a few threads on here were its taken a few tries to get it centred properly.

Good video I enjoyed watching it. Interesting to see how the importance of thoroughly checking all the running gear before setting up to take readings is emphasized - however if what is shown on the video is all they do he's never going to pick up on a worn bottom ball joint, wheel bearing, etc. A much more vigorous and energetic procedure is required with the wheels/suspension being checked in a wheel free condition - By which I mean it needs to be jacked clear of the ground/ramp for checking. Interesting to see also that the machine itself compensates for out of true wheels by that wee forward roll before the readings are taken - run out compensation he called it. I don't see any sign of a calibration check taking place though so I believe he's relying on the machine having been calibrated accurately at some time in the past and that nothing has happened to the machine to affect that. Of course I fully concede that I'm playing devils advocate here but who's to say the apprentice didn't trip over some of it in an "absent" moment and then tell no-one?

The procedure as shown here could be done and produce a "perfect" set of "green" readings but if a worn component had been missed it would be meaningless! If there were nothing wrong with the vehicle - no worn components etc - then removing the vehicle from the ramp, driving it round the block and back on the ramp should result in another "green result". If I were paying good money to have this done I'd be "bouncing" that idea off them when I was making my booking appointment and watching closely to see the reaction.

 

[Pugglt Auld Jock]

Wow, what happened there? two posts for the price of one click?

 

[DaveMcT]

Cars do not have a datum points at front and back that the wheels can be checked against in all directions. Why is that?

Simply checking the wheels against each other means they can all be out of alignment. At best this can only hope to get the best compromise.

 

[Pugglt Auld Jock]

Cars do not have a datum points at front and back that the wheels can be checked against in all directions. Why is that?

Simply checking the wheels against each other means they can all be out of alignment. At best this can only hope to get the best compromise.

Absolutely agree Dave. I think the best that can be achieved is to have the rear wheels exactly following the fronts (I don't mean necessarily following in the same "groove" as that would mean equal track front and rear and we know the Panda has a narrower rear track compared to the front. What I would like to achieve would be for everything to drive "straight".

This is going to be quite difficult to measure on a diy basis but my initial thoughts are that you can't use the front wheels as a datum to check rear alignment because even a very slight amount of unequal lock (either left or right) will displace the position of the tyre sidewall/wheel rims and make a nonsense!

My initial thinking was to use the end of the main hub axle because there would be an "ineffective angle" effect around the straight ahead position in regard to lateral displacement - much like the ineffective crank angle of a crankshaft and it's effect on piston movement at TDC - What I mean by this is that for a few degrees either side of straight ahead there would be an indiscernible difference in distance from the car's centre line to the end of the axle. If you always took readings with the car similarly laden and on the same piece of ground, any difference due to radial movement of the bottom wishbone should be irrelevant too?

So my idea is to use a short length of angle iron/dexion/etc which would bolt to two wheel nuts (probably straddling the axle) with a pickup point precisely in the middle to carry a long length of light weight square tubing which I can use to then rest against the rear wheel and measure the gap (front or rear, but in reality it's always going to be front) between this tube and the sidewall of the rear tyre. The angle iron bracket and square tube would then be mounted to the other side of the vehicle (thus eliminating calibration issues) and readings taken. Of course the steering wheel would be chocked to prevent any movement. Then I use my tracking gauge on the rear wheels to get actual toe in (or maybe out - whatever) and I am then armed with enough info to work out how much toe change needs to be effected (from the tracking gauge result) and where it needs to be applied (from the new tool) to start fiddling about with the hub and shims.

This is all pretty rough and in the "little grey cells" at this time but I seem to have the start of something which might work. No doubt refinement will follow as defined by the immortal words of Helmuth van Moltke "No plan of battle ever survives contact with the enemy".

More to come in time I'm sure.

 

[DaveMcT]

You cant trust the wheels so would have to measure from the wheel mounting faces. At the least you would need a 600mm length of angle iron bolted to each wheel hub.

From those you might be able to use a laser level to check the alignments.

I can see the need for all sorts of jigs and crap. You could consider a (long) length of box tube bolted under the car's centre line and measure from that to each hub.

 

[dastardly2023]

Ive checked the threads but this is a bit different.

I anyone else finding their Panda is scrubbing out the inside edges of front tyres?


On both Pandas, the steering wheel is centered ok and tracking was set/checked when tyres were fitted. 1.2 had new tyres in September 2017 and tracking was set to Fiat spec. Both are scrubbed away the inside edges both about the same suggesting it's centralised but effectively toe out.

Fiat spec is 0 degrees +/- 10 minutes = wheels parallel.

Mine had done similar things but the old tyres were ditch finders so not a good comparison. I recently had 195-50-15V fitted and the tracking checked. All ok apparently. BUT the inside edges of my new tyres are warm and there is a slight pull to the left.

One Panda in the family doing this fair enough, but both is strange indeed. Especially, as mine has not been adjusted since I bought it and tyre fitter says the tracking is correct. The threads on mine are b****xd so I have new track rod ends and track rods to fit so we will see how it is with them on Fiat settings. I suspect no different but at least I will be able to make small adjustments that are not possible right now. I plan to try it at the toe in end of the scale and go from there.

2021 Panda Hybrid .. fidgety steering on a level windless main road . I have re- located the anti roll bar onto the lower front suspension control arm . Had all of the mindless B-S from the Fiat dealer .. got photos if anyone is experiencing the dreaded weird Panda steering [email protected]. I am running factory set Caster and camber with 0 mm toe in /out. camber is maybe a tad much for NORMAL driving .. I might try a tad more caster to achieve a slightly more locked in steering feel . I am a 78 year old EX = "has been." 1980 Donnington GT champion.

 

[dastardly2023]

Absolutely agree Dave. I think the best that can be achieved is to have the rear wheels exactly following the fronts (I don't mean necessarily following in the same "groove" as that would mean equal track front and rear and we know the Panda has a narrower rear track compared to the front. What I would like to achieve would be for everything to drive "straight".

This is going to be quite difficult to measure on a diy basis but my initial thoughts are that you can't use the front wheels as a datum to check rear alignment because even a very slight amount of unequal lock (either left or right) will displace the position of the tyre sidewall/wheel rims and make a nonsense!

My initial thinking was to use the end of the main hub axle because there would be an "ineffective angle" effect around the straight ahead position in regard to lateral displacement - much like the ineffective crank angle of a crankshaft and it's effect on piston movement at TDC - What I mean by this is that for a few degrees either side of straight ahead there would be an indiscernible difference in distance from the car's centre line to the end of the axle. If you always took readings with the car similarly laden and on the same piece of ground, any difference due to radial movement of the bottom wishbone should be irrelevant too?

So my idea is to use a short length of angle iron/dexion/etc which would bolt to two wheel nuts (probably straddling the axle) with a pickup point precisely in the middle to carry a long length of light weight square tubing which I can use to then rest against the rear wheel and measure the gap (front or rear, but in reality it's always going to be front) between this tube and the sidewall of the rear tyre. The angle iron bracket and square tube would then be mounted to the other side of the vehicle (thus eliminating calibration issues) and readings taken. Of course the steering wheel would be chocked to prevent any movement. Then I use my tracking gauge on the rear wheels to get actual toe in (or maybe out - whatever) and I am then armed with enough info to work out how much toe change needs to be effected (from the tracking gauge result) and where it needs to be applied (from the new tool) to start fiddling about with the hub and shims.

This is all pretty rough and in the "little grey cells" at this time but I seem to have the start of something which might work. No doubt refinement will follow as defined by the immortal words of Helmuth van Moltke "No plan of battle ever survives contact with the enemy".

More to come in time I'm sure.

Assuming you have no accident damage/ worn parts . .. the best tracking method is the coloured wire 1/2 mm thick making a parallelogram equally spaced off the front drive shaft ends and the rear hub bearing caps . This tracking method is well documented on You Tube . sounds like you head is full of the wrong stuff . what has Van Moltke go to do with suspension set ups [email protected]

 

[koalar]

2021 Panda Hybrid .. fidgety steering on a level windless main road .

Wrong section this is for pre 2012

I have re- located the anti roll bar onto the lower front suspension control arm . Had all of the mindless B-S from the Fiat dealer ..

here in the UK it would be illegal unless you informed your insurance company and they would add around 25%

got photos if anyone is experiencing the dreaded weird Panda steering [email protected].

Just post them on the forum, not that it’s much use here as our arms are ductile cast iron

I am running factory set Caster and camber

It’s not adjustable as from factory. Of cause it no big deal to enlarge the holes or add a 1.5 degree bolts

with 0 mm toe in /out. camber is maybe a tad much for NORMAL driving .. I might try a tad more caster to achieve a slightly more locked in steering feel .

Most of the centring is done via the electric power steering.

I am a 78 year old EX = "has been." 1980 Donnington GT champion.

 

[koalar]

Assuming you have no accident damage/ worn parts . .. the best tracking method is the coloured wire 1/2 mm thick making a parallelogram equally spaced off the front drive shaft ends and the rear hub bearing caps . This tracking method is well documented on You Tube . sounds like you head is full of the wrong stuff . what has Van Moltke go to do with suspension set ups [email protected]

Highly unlikely to get accurate results on the panda 169 using the equally spaced off the front drive shaft ends, hub bearing caps You need to use the suspension mounts to find the centreline of the car and then measure out from this datum as you do with a race car

It’s highly unlikely a 10 year old car willl have the front wheels at 90, and rear wheels at 90 to this datum. It also unlikely the front and rear will follow exactly

10 year old Fiat alloy wheels will rarely be true.

There’s far easier and accurate ways to measure front toe the only easily adjustable that also take into account bent wheels.

 

[koalar]

2021 Panda Hybrid .. fidgety steering on a level windless main road .

No sue I understand the logic in moving the anti roll bar from the strut to the control arm

Straight flat road the ARB is doing very little just rotating in its bushes

I understand why BMW M3 moves the ARB from the control arm to the strut as the ARB is now lighter.

 

[dastardly2023]

Hi Dave. There's a big danger of me sounding like a "know it all" here, and that is most certainly not my intention. However I have worked with tyres (Firestone) in my early years and I have always been interested in them and how they interact with the vehicle. You may have read an earlier post I did where I described the tracking gauge I made myself.

You may know (so apologies if I'm telling you how to suck eggs) the appearance of the tread itself can tell you quite a lot about what's making a tyre wear - as long as that tyre has not been moved around on the vehicle of course. So lets consider we are sitting on the ground, in front of the OSF (driver's side front) wheel looking back towards the car. The first thing to consider is the overall wear pattern. Is it even across the width of the tyre or more worn in some areas than others?

Again apologies if I'm being too simple here but heavy wear in the centre but not on the shoulders is usually down to over inflation and the reverse, heavy wear on both shoulders but not the centre will be under inflation. This of course is easily rectified and eliminated in future by a weekly tyre pressure check.

Now, again sitting in front of the wheel and looking at the tread, perhaps left (outer) shoulder or right (inner) shoulder of the tyre is worn. This might be due to the suspension and wheel hub (perhaps because of wear or damage to suspension) failing to present the face of the tread squarely to the road surface. It might also be due to the tracking being incorrectly set or wear in the steering mechanism.

You tell us that it's the inner edges of the tread on both front tyres on your car which are wearing prematurely. So now have a very careful look at the tread pattern on these tyres. Lets consider the Off Side (drivers side) first. Ok, we can see wear of the inside shoulder but now look carefully at the treads over the width of the tyre. There will be, on most designs, bands of tread separated by water dispersing grooves which run right round the tyre. Look carefully at each of these bands, especially the edges of each band (some call them tread blocks). The inner and outer edges of each of these bands of tread should look the same (exhibit the same wear pattern) if your tracking is set such that it is allowing the two wheels/tyres to roll down the road parallel to one another. If you have this situation but with excessive wear on the shoulder then it's because the tyre is not being presented to the road surface squarely and it's likely the Camber angle on that wheel is incorrect. (top of tyre/wheel leaning in too much) If both front tyres are showing the same wear pattern (you seem to be saying both of your fronts are worn on the inside) then this is unlikely to be the reason as it's unlikely you will have an identical camber problem on both sides.

Given your wear pattern, it's more likely that your examination of the tread bands will show the inner edge of each tread block to be rounded slightly and the outer edge to be lipped. This wear pattern will form when the tyre is spending some, or all, of its time NOT rolling parallel to it's pal on the other side. Bear with me on this please. I know you believe your tracking to be correct. The wear pattern described will come about if both front wheels are toed out - ie splayed out (by even a small amount) The most likely reason for this is that the adjustment, made by adjusting the track rods where they screw into the track rod ends, is incorrect. But you know yours is right don't you, because it's been checked. By the way the opposite will be seen if there's too much toe in - ie the front wheels are "snow plowing" (wear on outside shoulders and outsides of each tread block rounded with inside edges lipped). It's not unusual to find when there's too much toe out that the inner shoulder of the O/S wheel is more worn than the inner shoulder of the N/S and where too much toe in is the problem the outside of the N/S tyre will be more worn than the outer shoulder of the O/S. This is simply due to road camber. - Think about it for a minute but just ask if you can't figure it out.

So now, perhaps, you're sitting thinking well, I do see some signs of this "lipping" effect but I know my tracking is correct, so what's going on? We have to face up to the fact that if the treads are lipping then, at least for some of the time, the two wheels/tyres are not rolling parallel! Having done more wheel alignments than I've had hot dinners my first port of call would be "show me the read out" Modern aligning rigs can produce a before and after read out which you should always request. There are many things which can interfere with the accuracy of a wheel alignment but the machine (if in good order and calibrated) can't lie. Also the technician doing the job MUST first do a thorough and rigorous check of all suspension ball joints, rubber bushings, steering swivels (macpherson strut top mounts being one such) and look for accident damage. If we assume the machine thinks it's correct then it's likely that the wheels are conforming when the vehicle is standing still but, and I've found this to be not uncommon, The suspension arms on most cars today use rubber bushings where they pivot on the chassis/subframe. These can look to be in good condition visually but in use, because of age and use, they can become "squishy" and overly flexible - There is a thriving business in "performance" poly bushes which are generally stiffer for the performance minded. If this is the problem then when just rolling along the track will be more or less OK but under braking, especially anything more than gentle braking, The drag of the retarding wheel will drag the front of the arm outwards, the bushes compress excessively and allow the wheels to toe out so giving the effect you are seeing. It's quite difficult to diagnose this one with certainty but it can be remarkable how different an otherwise OK handling vehicle can feel after renewing its suspension bushes!

A chap I used to know had a Gunson Trakrite. - I've just googled it and its still being made, now identified as a Gunson G4008 Trakrite - It consists basically of two plates with ball bearings between them (think they're ball bearings?) which you drive one wheel of the car over. The other wheel is still rolling along the ground so if both wheels aren't "tracking" parallel then the top plate slides sideways and registers it on a pointer type gauge. I've used it a number of times and found it very good because, regardless of what the vehicle manufacturer quotes as a toe in figure, the gauge will pick up if the wheels aren't rolling parallel! (I want one, It's on the wish list) I know some performance extremists intentionally introduce toe to alter handling but we're talking standard vehicles here so all i'm wanting is for the tyres to wear as slowly as possible!

I'm beginning to see spots in front of my eyes now! so maybe it's time to stop. We haven't even thought about Caster, King Pin Inclination, Toe Out on Turns and a whole lot more but this has been a start. Have a chew on it and get back to me if you like.

All good stuff so far . My 2021 Fiat Panda steering is far too light . going to add a bit of caster to gain a bit of weight . Any idea what factory caster is .

 

[dastardly2023]

No sue I understand the logic in moving the anti roll bar from the strut to the control arm

Straight flat road the ARB is doing very little just rotating in its bushes

I understand why BMW M3 moves the ARB from the control arm to the strut as the ARB is now lighter.

my Fiat Panda hybrid 2021 anti roll bar bushes are integral with the bar which does not rotate in the bushes . The subframe has to be lowered to replace the complete Anti roll bar + bushes assembly £345. Old fiat Panda £12 a pair of split slip on rubber bushes .