Help me adjust my tracking please?

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I've got an old, 2002 175k mile Saab 9-5 that I bought for £1000. I'm tackling as many maintenance jobs myself as possible for my own satisfaction.

The steering wheel is turned about 1cm to the right when driving in a straight line. Not such a problem, except that the driver's side front tyre gets warmer than the nearside tyre at speed. Both front tyres run warmer than the rears.
In normal driving the handling feels stable.
The old tyre that I just swapped for a winter tyre was slightly more worn towards the inner side of the tread. (3mm wear vs 4mm, perhaps.)

Pondering this, I've reached the conclusion that perhaps the offside tracking needs to be pulled in a bit to decrease the toe-in.

Before I break out the wd40 and tighten the offside track rod a half turn, can anybody spot a flaw in my plan? :-)

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226bhp said:

You can't have one wheel pointing in/out and the other not, tracking figures are from one wheel to the other, not from the centre outwards.

If you let go of the steering wheel when driving both driving wheels are tracking equal.

Yes, I understand the mechanics of tracking.
The car tracks straight if I let go of the wheel.
What I don't understand is why, if they're both tracking equally, one tyre gets warmer than the other and the tyre on that corner wears unevenly. Can you shed any light on that question?

226bhp said:

If you want to DIY it then buy some equipment and spend a day arsing about in the cold.

Me? I just take it to someone who has the correct equipment and knows what they are doing, £30 - £40? Why waste my time....

Two reasons: the personal satisfaction of doing a small job myself; and the fact that whenever I've had the tracking adjusted on previous cars, each garage had several stabs at it, usually leaving the steering wheel more badly aligned than it had been before they started. I have no confidence in the trained chimps that most garages seem to have operating the "high precision" laser alignment tools. I'm sure expert garages exist, but how many do I have to try before I find one that gets it right? The basis for this thread is that by applying a bit of logic to the symptoms it ought to be possible to improve things with a small adjustment. Maybe that premise is wrong, but I'm curious to understand why if so.

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226bhp said:

If you think that adjusting one wheel will make things ok then I would say you don't completely understand tracking.

I can't say that adjusting one wheel will make it all perfect, but based on the symptoms I'm wondering whether a tweak might help. I'm definitely not claiming to be an expert, but the steering is a mechanical linkage and I can see the general effect that adjustments to the track rods will make to the geometry of that linkage. Whether those adjustments will improve the ultimate level of grip, scrub radius characteristics or whatever other subtleties, I have no idea. I'm only wondering about a very minor tweak to the setup, not a wide-ranging re-alignment of camber, toe-in etc.

226bhp said:

If you are getting the symptoms you describe (and I have no idea how you are accurately measuring tyre temps) then as I said, something else is wrong, this could be:
Incorrect camber
Worn, bent or seized components
different tyres
You drove around a lot of roundabouts and RH bends before testing.

I'm only assessing tyre temperatures with a touch of my hand. It's not exactly scientific! However, in all my years of driving I've never noticed a tyre temperature differential like this across an axle. Quite often after fast motorway runs I'll quickly touch the hubs and tyres to see if there are any hotspots. (This habit comes from running old classic cars over the years.)

Locknut said:

Less heat in the rear tyres is due to a lighter load. (Less weight, less braking, no steering forces) A heat difference across the axle is more unusual. The right tyre (warmer tyre) had more wear on the inside, was the left tyre more evenly worn? If the wear is only on the inside of the right tyre you should check out things like ball joints etc.

Yeah, the left tyre was worn fairly evenly.
I replaced the offside balljoint last week because it was quite sloppy so I'm sure that wasn't helping things, but I didn't think to feel the tyres' temperature before doing that. (I'm mindful of the tyres because I got new winter tyres fitted last week.)

b2hbm said:

There was a thread about alignment methods recently in the Home Mechanics section;
http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Thanks for that - it seems I'm not alone in my experience of paying someone to adjust the tracking and being disappointed with the outcome.

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thebirdman said:

the car may very well track ok in a straight line but the STEERING angles won't be, ie, one wheel scrubbing on cornering and getting warm.

That makes a lot of sense! Thank you.