Front Tyre Wear

[scam75]

Evening all

Having got to the bottom of my intermittent wobbling issue I have discovered that my front tyres are quite worn on the inside, driver side slightly worse of the two.

The car is on full new suspension, is lowered about 60mm and had a full geo set up done when the suspension was put on. Tyres are about 6k miles old, Toyo T-1R's. Plenty life on the rest of the tyres but the end 10% or so is well worn down.

Is this normal with the car slammed or is something not right? Rears are wearing even.

Thoughts and contributions appreciated as usual!

Stuart

 

[simdel1]

Sounds like it's got way too much negative camber, or possibly too much toe-in.

 

[Mike_Pollock]

Toe-in would wear the outside edge surely?

 

[simdel1]

My thinking was that, due to the king-pin inclination, excess toe-in effectively increases the negative camber...and also drags this edge sideways across the tarmac.

I'm sat here on my lap top with my hands held out as if they're tyres trying to confirm my thoughts and think of a better way of getting my thoughts into text. My other half is looking at me like I'm doing something quite odd...[8D]

 

[simdel1]

...and it seems I'm completely wrong. lol

http://www.etyres.co.uk/glossary-tyre-terms?term=toe-inout

 

[Mike_Pollock]

Thinking about it a little more, lowering the front would take the angle of the wishbones closer to the horizontal, which increases the distance between hubs, which unless the track arms are lengthened the same amount, will increase the toe-in. Plus lowering the front would also increase the camper.
Both of which will lead to inner edge wear of the tyre.
Double whammy!

 

[vincematthews]

ORIGINAL: scam75
The car is on full new suspension, is lowered about 60mm and had a full geo set up done when the suspension was put on. Tyres are about 6k miles old, Toyo T-1R's. Plenty life on the rest of the tyres but the end 10% or so is well worn down.
Stuart

Where did they get the geometry settings from to do the 'setup' with that amount of lowering . . . or did they use the standard figures (which really would need modding) ?

 

[robwright]

Stuart mine did exactly the same when I bought it. So much so that the inside of one tyre wore through to the canvas without me even noticing. A quick geometry check confirmed that the camber was indeed miles out. The only adverse effect I noticed on normal (and I stress normal) driving was that the steering did not like to self centre at all. The feeling was also a little odd on full lock on reverse. A 50 quid laser alignment made everything much better and my fronts have now hardly worn at all in the last year []

 

[scam75]

Vince - No idea what settings were used. It was a place Alasdair uses in Bonnybridge.

Rob - I will get it set up again before i strike canvass!

Anyone recommend somewhere near Glasgow to do this properly?

Stuart

 

[loc944]

The guys with GT3's have used Kenny Brown in Hillington. I was planning on going after I have refreshed my suspension.

Alan.

 

[scam75]

Yeah spoke to him earlier, he's looking for £40 per hour, 2-4 hours he's quoting! Then VAT!!

I'm going to take it into Farmers in Paisley tomorrow and see if we can get any adjustment on the camber/tracking and take it from there.

Stuart

 

[loc944]

OK , maybe I won't be going there after all.
I had a steering wobble on my van a few years ago and took it into local Kwik fit, they offer a free check, fortunatly mine was only 0.5 degrees out so wasn't worth adjusting.

 

[simkin911]

CLCM Wheel Alignment,
11 Bankhead Drive,
Sighthill Industrial Estate,
Edinburgh
Tel: 0131 458 5559, Ask for Willie, the owner.

As recommended by others inc Lee (928 owner in Glasgow). Cost £50 I believe.

 

[vincematthews]

ORIGINAL: scam75
Vince - No idea what settings were used. It was a place Alasdair uses in Bonnybridge.
Anyone recommend somewhere near Glasgow to do this properly?
Stuart

Stuart, You will need to find suitable settings for a lowered car because the ordinary setup people will not know these. Maybe someone who races 944s can help?

 

[JamesBall]

Just out of interest, why do the settings change on a lowered car?

 

[vincematthews]

ORIGINAL: James Ball
Just out of interest, why do the settings change on a lowered car?

Because, as mentioned by others above, the suspension geometry will have changed when the car is lowered.
The standard car setup will have been designed to be what they consider is best compromise (for a road car) between road holding, comfort, tyre wear and other factors.

 

[JamesBall]

I can see that the suspension geometry will have changed when the car was lowered, but now that it is lowered it should be set to standard specs surely?

i.e. the act of lowering causes the alignment to go out, rather than because it is lowered it needs different specs to a car at standard ride height

 

[Mike_Pollock]

The angles between the various components are now different, so when they move, they move differently, so the compromise as Vince says needs to be different.
Minor example - if the wishbone is angled down to the wheel, when the suspension is depressed the wheel will move out slightly, but with it lowered, the wishbone angle is horizontal and then when the suspension is compressed the wheel will move slightly in....

 

[JamesBall]

That makes sense. Thanks for the explanations chaps.

 

[vincematthews]

ORIGINAL: James Ball
I can see that the suspension geometry will have changed when the car was lowered, but now that it is lowered it should be set to standard specs surely?
i.e. the act of lowering causes the alignment to go out, rather than because it is lowered it needs different specs to a car at standard ride height

ditto to what Mike says.
If nothing else is available, such as racing setup info, the standard setup would be an obvious starting point. You would then drive it under various conditions and tweek these settings until it handled the way you wanted it to, given the shorter suspension travel available. Over a period of time you would find out other things, like uneven tyre wear, which you could live with or adjust out although this in turn would effect handling and so on. Its suck it and see territory . . .
It maybe that uneven tyre wear turn out to be a price you have to accept with lowered suspension. I have an unmodified Alfa 156 which feathers its front tyres on the inside edge with the factory correct suspension setup. Fact of life or as they say, . . . . you don't get something for nothing.