Technical Tyre wear question

[AnthonyH]

I've found tyre wear on the inside of the front offside wheel of my Grande Punto. The front nearside tyre is fine. Back in January I changed the strut on the nearside but I didn't do the offside. I've just measured the distance between the wheel arch and the wheels to see if the car is sitting lower on the offside but it isn't.

So my question..is the tyre wear caused by the difference in the age of the struts, or some other misalignment?

(This is a different car to the one I changed subframe recently)

 

[bugsymike]

I've found tyre wear on the inside of the front offside wheel of my Grande Punto. The front nearside tyre is fine. Back in January I changed the strut on the nearside but I didn't do the offside. I've just measured the distance between the wheel arch and the wheels to see if the car is sitting lower on the offside but it isn't.

So my question..is the tyre wear caused by the difference in the age of the struts, or some other misalignment?

(This is a different car to the one I changed subframe recently)

If the bottom arm wishbone on the offside is older it's bushes may be soft allowing the wheel to sag outwards slightly giving a small degree of negative camber, not something to easily check without the right gear, much the same as general wheel alignment.
It need only be a couple of mm to make a difference.
If both sides were wearing equally on the inside of the tyre it can be tracking "toeing" outwards.
Another point is if the wheel has been changed from another position on the car etc.
Years ago we had a customer whose tyres were worn on the inside on one wheel and the offside on the other, it turned out where they parked involved a very sharp turn which scrubbed the tyres in that way.

 

[AnthonyH]

I was quite close to buying a new strut and putting that on, but now i'm thinking i need to check the wishbones/control arms. They are original to the car, i've seen their general condition, which is aged, but not checked to see if they're faulty or sagging like you mention. As far as i'm aware they are both original to the car.

I'll take a look and see.

 

[vexorg]

A good chance something is slightly bent.

A full alignment check would tell you, but you seem to like to try and see when it comes to alignment, so this could take some time to solve.

 

[bugsymike]

A good chance something is slightly bent.

A full alignment check would tell you, but you seem to like to try and see when it comes to alignment, so this could take some time to solve.

Certainly not impossible on an older car.
However I have seen worn/soft inner wishbone/bottom arm bushes cause similar issues, in some cases from oil leaking onto the bushes.
In one case a new customer came to me as her usual garage failed to locate a suspension knock on her Seat. I traced it to a front bottom suspension arm bolt which although tight to a spanner, was actually seized and not pinching the metal inner of the bush into the subframe thus allowing the arm to move causing the knock and throwing steering geometry out also.
The repair involved a new genuine Seat aluminium subframe part and bolt as impossible to do otherwise and I got her permission to undertake the job after informing her of the price, sadly she returned to her incompetent garage afterwards even though I had been 100% fair on the invoice as usual, so it just goes to show you can't help all people

 

[vexorg]

If you have changed the subframe then you'd hope there were new lower arms fitted at the same time

 

[AnthonyH]

Seems I have toe out. Both tyres have worn on the inside, it's just one tyre started with more tread so it's not as noticeable. Although maybe both control arms could have sagged. Which is the most likely?

The subframe, control arms and rods are all original to the car.

 

[bugsymike]

Seems I have toe out. Both tyres have worn on the inside, it's just one tyre started with more tread so it's not as noticeable. Although maybe both control arms could have sagged. Which is the most likely?

The subframe, control arms and rods are all original to the car.

Ah! Originally you said wear one side only.
If both bottom arm bushes old/worn they can still be affecting tyre wear.
However if you run your hand across the tread towards the middle of vehicle from outside, if tracking badly outwards as in "toe out" which can cause higher wear on the inner side of the tread you may notice it's slightly harder to push your hand in across the tread rather than out, much in the same way if you feel the teeth of a saw.
I have never been accused of being sensitive, but I can notice it.

 

[bugsymike]

Seems I have toe out. Both tyres have worn on the inside, it's just one tyre started with more tread so it's not as noticeable. Although maybe both control arms could have sagged. Which is the most likely?

The subframe, control arms and rods are all original to the car.

With all this interest in tyre wear I noticed this in a relevant publication, especially as it mentions a Fiat although probably a slightly different age to yours

 

[Pugglt Auld Jock]

With all this interest in tyre wear I noticed this in a relevant publication, especially as it mentions a Fiat although probably a slightly different age to yours

Really enjoyed seeing that Mike. Although something may be bent or damaged on the OPs car, I'm with you that it's more likely to be something like "relaxed" old rubber bushings. Of course someone may have set the whole thing up poorly in the past. might be a worn ball joint? Anthony won't know until he's done a thorough examination.

Seems I have toe out. Both tyres have worn on the inside, it's just one tyre started with more tread so it's not as noticeable. Although maybe both control arms could have sagged. Which is the most likely?

The subframe, control arms and rods are all original to the car.

Anthony, your journey up the tree of knowledge continues. Another valuable lesson learned in that first impressions can be misleading and not everything wears to the same degree.

Please do let us know what you find, can't wait to find out1

 

[AnthonyH]

I had both tyres off a little while ago and took some pictures of the right hand side tyre. I also shook all of these joints and generally tried to get some unusual movement but these joints all feel rock solid to the hand, although I didn't get a crowbar on them etc.

I'm not really sure what to think, change the strut, which is older than the one on the other side? Change the rod ends and control arms both sides? I reckon I drove on that tyre for about 8,000-10,000 miles, so its had half of a usual tyre life.

 

[AnthonyH]

Ah! Originally you said wear one side only.
If both bottom arm bushes old/worn they can still be affecting tyre wear.
However if you run your hand across the tread towards the middle of vehicle from outside, if tracking badly outwards as in "toe out" which can cause higher wear on the inner side of the tread you may notice it's slightly harder to push your hand in across the tread rather than out, much in the same way if you feel the teeth of a saw.
I have never been accused of being sensitive, but I can notice it.

I had a go at this, but couldn't tell a difference, althout no doubt there is!

 

[Pugglt Auld Jock]

I had both tyres off a little while ago and took some pictures of the right hand side tyre. I also shook all of these joints and generally tried to get some unusual movement but these joints all feel rock solid to the hand, although I didn't get a crowbar on them etc.

I'm not really sure what to think, change the strut, which is older than the one on the other side? Change the rod ends and control arms both sides? I reckon I drove on that tyre for about 8,000-10,000 miles, so its had half of a usual tyre life.

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I had a go at this, but couldn't tell a difference, althout no doubt there is!

I just had a good look at a blow up of the first image and you can see Mike's effect but it's not very pronounced. Take a close look at the first tread groove in from the inner, very worn, shoulder. The edge of the groove nearest the shoulder is square and sharply defined. The edge on the other side of the groove is slightly rounded. If this effect was more pronounced then as you drag your hand across the tread from the very worn shoulder to the outside of the tread you would feel that the sharply defined edge would be resisting you whereas the rounded edge allows your palm to move easily over it. In this instance the effect is quite small but still plainly seen. It's also visible to a lesser extent on the other grooves. If you're doing this beware in case the inner shoulder has gone through to the steel cords under the tread. You can easily tear your hand to shreds on these cords - they are very sharp if exposed - as many a rookie traffic cop or apprentice mechanic can testify.

Looking at your picture of the tread again, because the lipping effect is quite slight but the inner shoulder is quite well worn, I'll take a guess that the rubber bushes on the bottom arms are "soft" Take a close look at the rear bush on both arms as they tend to wear most and give them a lever with a tyre iron or big screwdriver. Of course if you lever even a new one hard enough it'll give but if you lever just "firmly" there shouldn't be much give. Remember the rear bush is a "Voided" bush and designed to resist force applied to move it towards the vehicle centre line - Braking forces - or away from the centreline - Accelerating forces. So if you lever it in other directions the voids will let it move. Often when they are worn they'll start to split and/or detach from the metal of the fitting they are bonded to, so look carefully for that as you are levering. If they are quite well shot they can loose the bonding altogether and let the arm clatter against the subframe.

If nothing obvious turns up I think you're needing to consult with someone with professional aligning equipment. This may be a combination of wear and incorrectly set toe.

PS. I wouldn't say, without seeing it, that the strut is causing this, but it's unlikely.

 

[AnthonyH]

I just had a good look at a blow up of the first image and you can see Mike's effect but it's not very pronounced. Take a close look at the first tread groove in from the inner, very worn, shoulder. The edge of the groove nearest the shoulder is square and sharply defined. The edge on the other side of the groove is slightly rounded. If this effect was more pronounced then as you drag your hand across the tread from the very worn shoulder to the outside of the tread you would feel that the sharply defined edge would be resisting you whereas the rounded edge allows your palm to move easily over it. In this instance the effect is quite small but still plainly seen. It's also visible to a lesser extent on the other grooves. If you're doing this beware in case the inner shoulder has gone through to the steel cords under the tread. You can easily tear your hand to shreds on these cords - they are very sharp if exposed - as many a rookie traffic cop or apprentice mechanic can testify.

Looking at your picture of the tread again, because the lipping effect is quite slight but the inner shoulder is quite well worn, I'll take a guess that the rubber bushes on the bottom arms are "soft" Take a close look at the rear bush on both arms as they tend to wear most and give them a lever with a tyre iron or big screwdriver. Of course if you lever even a new one hard enough it'll give but if you lever just "firmly" there shouldn't be much give. Remember the rear bush is a "Voided" bush and designed to resist force applied to move it towards the vehicle centre line - Braking forces - or away from the centreline - Accelerating forces. So if you lever it in other directions the voids will let it move. Often when they are worn they'll start to split and/or detach from the metal of the fitting they are bonded to, so look carefully for that as you are levering. If they are quite well shot they can loose the bonding altogether and let the arm clatter against the subframe.

If nothing obvious turns up I think you're needing to consult with someone with professional aligning equipment. This may be a combination of wear and incorrectly set toe.

PS. I wouldn't say, without seeing it, that the strut is causing this, but it's unlikely.

As i read this it did feel like a penny dropped, and the rear control arm bushes are going to have sagged. I can't confirm now as the tyres are back on, but i'll check asap and some new control arms may be the order of the day. I didn't picture those bushes because i didn't think they were part of the problem.

I had a fair old fight getting the the arms off my other car recently, hopefully I won't have to drop the subframe but we'll see.

With all this interest in tyre wear I noticed this in a relevant publication, especially as it mentions a Fiat although probably a slightly different age to yours

I've just read through your practical motorist and mortorcycle pages from 1956, thanks for that. I wonder if being a mechanic was easier or harder back then?

 

[bugsymike]

I've just read through your practical motorist and mortorcycle pages from 1956, thanks for that. I wonder if being a mechanic was easier or harder back then?

Not sure , I was only 3 years old then, ask Jock

 

[Pugglt Auld Jock]

Not sure , I was only 3 years old then, ask Jock

I'd have been 10 so just starting to mess about with the estate machinery and I think I'd have had my first motor cycle for bombing around the fields with. Completely ignorant of what made them all work but just knew they all went better with no silencers fitted

 

[bugsymike]

I'd have been 10 so just starting to mess about with the estate machinery and I think I'd have had my first motor cycle for bombing around the fields with. Completely ignorant of what made them all work but just knew they all went better with no silencers fitted

I used to think that too , though not sure if true on the two stroke Francis Barnetts though, but my mates 350 Ariel Red Hunter sounded good on a straight pipe.

 

[AnthonyH]

I've ordered new control arms and rod ends from GSF. The price is actually better for all those parts than I could get on ebay. It qualifies for free delivery too, but i'll be going past there tomorrow anyway, so i'll pick them up. Sadly next Wednesday is the earliest I could start this job.

I suppose I could have had a go at putting new bushes in there, but these are 16 years old and probably not worth trying to repair.

 

[bugsymike]

I've ordered new control arms and rod ends from GSF. The price is actually better for all those parts than I could get on ebay. It qualifies for free delivery too, but i'll be going past there tomorrow anyway, so i'll pick them up. Sadly next Wednesday is the earliest I could start this job.

I suppose I could have had a go at putting new bushes in there, but these are 16 years old and probably not worth trying to repair.

You can press bushes in at home on many suspension parts , but it is a job again easier with special tools or an Hydraulic Garage Press.
(Fortunately for me I still have mine )

 

[AnthonyH]

I saw someone on YouTube using a g clamp to put bushes in, but I reckon the saving in money will be outweighed by the extra difficulty. So I'm saving that for another time. I'd consider changing rear axle bushes as the axle isn't so easily replaced.