RKD in OKC

yep, 5 minutes is too long. Immediately, means stop get out measure temps. Commas in the sentence would be too long to wait.

sstrickstein

I will recheck them tonight after driving home. However, the interesting information is that after just having the alignment done, the inside edges of the tires are not getting as warm as the middle and outside. I will report back tonight.

sstrickstein

Here is the temps after my 30 mile drive home Lf 118,118.5,120 Lr 155.5,121,130,5 Rr 113.5,112.5. 105.5 Rf 114, 117.5, 117

Not surprising the tire near the exhaust was the hottest. I have a stoplight to stoplight drive of over two miles off the freeway. Probably I should do a highway stint and check them just off the exit. I think the tires hear up from the exhaust and the fans on the drivers side.

RKD in OKC

Those temps are a lot warmer. See the difference in your front tires, the outside is cooler this time. When the inside and outside don't match, the middle temp should be in the middle between them.

Wether the inside or outside is hotter or colder will be the difference between driving straight, and making a lot of turns. If consistently hot on inside or outside alignment would be suspect. Autocrossing the outside is almost always a little hotter because of all the turning. it also wears the outside corner off the tires.

How accurate is your tire gauge? Looks like left rear is low. The middle of the tread is colder and the overall temp is higher. or you were doing non-limited slip burn outs

sstrickstein

I'm going to check again Tommorow same route in reverse. But this time I plan to stop immediately off the freeway and check the tires. My thought is the left rear inside is closest to the exhaust and is effected temps tire.

sstrickstein

I put the most recent and the other two readings in a Excel spread sheet with chart. I will keep taking readings

sstrickstein

Here is my latest data.
SKMBT_36314110316000.pdf

From this data it seems:

a. the inside of the front tires is cooler than the center and outside.
b. the inside of the rear tires are warmer than the center or outside
c. the left rear tire is heated by the exhaust.

Anyone else wanna chime in?

RKD in OKC

Have you tried adjusting the pressures and see what happens to those temps?

What I call inside and outside is about 2 inches from the edge of the tire. Far enough in you are reading tread area that contacts the road. Center, of course is center.

When Adjusting the pressure an accurate gauge is important. Also it's best to overfill the tire by at least 3 psi, then bleed it down to the desired pressure. While it doesn't take but around 1 or 2 psi to zero in on getting even temps or at least linear across the tread, it takes plus or minus 3psi to change the handling feel of modern radial tires.

FredR

a] Not enough front camber or you are having too much fun in the bends!
b] probably to be expected if mostly straight line highway driving
c] an interesting observation but then your model does have the exhaust hanging around in that area. Still I would not have anticipated that might happen.

Regards

Fred

sstrickstein

The weird thing is that although I've had my alignment checked several times in the past.... the inside of my front tires are worn quite a bit. These tires are also only 1 year old. Guess the Summer heat just kills them.

928 at last

Your alignment's not done right.

76FJ55

Sounds to me like the toe is set incorrectly. inside tire wear is typical of excess toe out. the toe changes significantly with ride height and is the primary reason not to allow the alignment shop to lift the car prior to having the alignment performed.

sstrickstein

Yeah when I replaced my rack I had it aligned shortly after. Drive it about 500 miles and realigned it again. But to install the rack it was lifted and could t drive it far before the alignment. I gave a copy of the workshop manual alignment instructions to the alignment shop. I even mentioned the part about pulling the suspension down. I guess that's why they didn't charge for the second alignment.

FredR

It does not take long to scrub tyres in a significant toe out condition. If you have doubts about the suspension settlement dial in more toe-in initially and as it settles this will reduce. Setting toe-in at the max end of spec or a little bit beyond will do no harm other than make the steering response a bit sluggish until it settles but needless to say fully settled is the only way to go.

Fred

dr bob

I ended up building a couple laser-level holders that attach to the wheels for checking toe. There are some excellent guides by others that tell you how to use strings, tape measure, stuff like that to check your own. Earl Gillstrom has a step-by-step that's easy to follow and get's the job done.

I'd been to a local highly-recommended-by-928-owners shop. They let me sit under the car with the tech as adjustments were made, and according to the Hunter machine it was perfect. In less than 2000 miles, the inside front ribs on the new tires were corded. The car was well-settled when it went onto the rack. I took it back to see what was wrong, and they graciously put it back on the rack and again it showed everything fine. So even the best techs on the highly-regarded machines don't necessarily do great alignments. They may be acceptable for the station wagon but too expensive (in tires) on the 928.

Needless to say I strongly encourage folks to learn how to do their own alignment, even if just the camber and toe-in settings. Folks in or near central Oregon are welcome to come by for an alignment clinic. I need the practice it seems.


There's a thread here on RL someplace that describes some DIY alignment methods. Takes some care and patience but the results are worthwhile.