INNER TIRE WEAR???

[Jayman]

I'm experiencing some serious rear inner tire wear on the driver side. Can anyone run down the possibilities for me? I need know if this is a job I can handle or should I farm it out to suspension guys.
Thanks

 

[Emerald94]

Your camber is out of whack. You're probably also experiencing vibrations around 65-75 mph due the uneven wear of your rear tires.
Ford has a camber kit for the Taurus which will correct the problem.
It seems to be a common issue with our cars.

 

[sdpatt]

There is likely too great a negative camber (top of tire leaning inward) which is not adjustable with the stock suspension pieces, but there could also be too much toe-out contributing to the inner tire wear. Do you have lowering springs or sagging stock springs on your SHO? That creates more negative camber that usually requires some adjustment to get the camber back into the limits.

 

[Jayman]

Actually, I've not noticed any vibration. That does not mean it's not there though. My car is a 93 MTX with about 95k miles, stock suspension and does not appear to be sagging.
So is it my understanding then that the toe out is adjustable on the rear? Also is there a part number available for this camber kit from Ford?
Thanks for the feedback guys,
Jayman

 

[Emerald94]

Camber kit part #(Ford): E7DZ 5K751 B.
It cost me about $50.00 for it 1n 1997.

 

[Jayman]

Thanks Emerald94. I take it this kit allows you somehow to make the necessary adjustment, or just installing it will correct my problem?

 

[Emerald94]

i got mine installed at the Ford dealership because my tires were wearing funny (feathering).
A four-wheel alignment should be done at the same time.

Jayman:
Thanks Emerald94. I take it this kit allows you somehow to make the necessary adjustment, or just installing it will correct my problem?

 

[rangerj]

Installing the kit will not do the alignment. Install the kit and have a four wheel alignment done.

The current issue of Popular Mechanics has a discussion about radial tires and the causes of unusual wear.

The interesting thing is that there are some differences between the bias ply and radial tires, as far as what causes certain types of wear.

For example, wear in the center of a bias ply tire indicates overinflation. Wear in the center of a radial tire can indicate underinflation. This is per the article. Is this right?

How about some input from the tire and alignment experts on the forum. Please educate us regarding the component of our cars that takes more abuse than just about any other part!

What is the best way to "care and feed" them?

rangerj

 

[NOTAURIUS]

if youre getting inner edge wear it could also be a toe problem. The rears may be toed out causing this type of wear. The toe is adjustable with large eccentrics-use a large pair of channellocks to turn it. If the camber is out of spec youll need to adjust it, but if it is barely in spec on the negative side you will experience better handling. This is how i have my cars set up-all the way negative camber but still in spec front and rear.

 

[sdpatt]

For example, wear in the center of a bias ply tire indicates overinflation. Wear in the center of a radial tire can indicate underinflation. This is per the article. Is this right?

I have never seen a case where low inflation pressure resulted in center area wear on a radial tire. The physics of the mechanism of how the air pressure supports the mass of the car doesn't provide for a viable explantion to support that supposition. The edges of the tire have at least a tiny extra capability to support the mass of the car due to the stiffness of the sidewall. Granted, some tire designs have much more sidewall stiffness than others (run-flats). No matter, there is always a greater amount of tread support at the edge of the tire. If you have center rib wear, you should lower the tire pressure in small increments to find the pressure that results in even tread wear. For example, with the 225/55ZR16 tires size on my 7.5" wide rims, I have found over the 10 sets of replacement tires that any more than 32 psig will create the center rib wear condition. Thirty one pounds seems to be the best pressure for this size tire/wheel and the weight of my car. Some of the tires I have used are more sensitive to this effect than others, but they have all been affected.

 

[Jayman]

Matt Delbaugh:
if youre getting inner edge wear it could also be a toe problem. The rears may be toed out causing this type of wear. The toe is adjustable with large eccentrics-use a large pair of channellocks to turn it. If the camber is out of spec youll need to adjust it, but if it is barely in spec on the negative side you will experience better handling. This is how i have my cars set up-all the way negative camber but still in spec front and rear.

That is very interesting Matt. Now that 'camber' is in the forefront of my mind I've noticed that sdpatt runs -1 camber. Can you guys confirm even tire wear using these specs? When you say neg camber but still in spec, are you referring to everything else but the camber?
Thanks all

 

[sdpatt]

I run the camber at approximately -1 degrees at all four corners because it is in the limits of the alignment specs and provides additional cornering bite without sacrificing straight line traction. It does, however, tend to wear the tires unevenly. Again, some tires are more affected than others, but there is always greater wear on the inside comapred to the outside edges.

With the Eibach springs, I had to work to get the front camber back UP to -1 degrees. The lowering of the car tends to make the camber more negative with the strut-type independent suspension of the Taurus. The rear suspension is not adjustable for camber as equipped, but the driver side was at -.8 degrees and the passenger side was at -1.5 degrees. I used a little geometry and drilled new mounting holes for the passenger side upper strut mount that allowed it to match the driver side camber.

Zero camber would allow the longest and most even tire wear from inner to outer edges, but would reduce the ultimate cornering traction in the SHO's strut suspension. Negative camber greater than the -1.5(?) degree limit may aid in ultimate cornering traction, but would sacrifice straight line traction during acceleration and braking and also result in very uneven tire wear and the resultant shortened tire life.

Over the years, miles and 11 sets of tires, I have settled on -.8 to -1.0 degrees at the four coners to allow a decent compromise between the greatest driving pleasure in combination with the longest tire life. That last measure is a relative term since 30,000 miles is the longest I have been able to get out of a set of tires on my car. But then, my enjoyment of the SHO's driving dynamics may have something to do with that too.

 

[RStalveyARFF]

one thing that cures negative camber woes time and time again on the rears of these beasts is strut mounts. Often the metal sleeve breaks away, can causes the strut an 1/8+ inch to do what it wants to do. Move inward, which gives you the - camber.

 

[Jayman]

Hey Scott, that was exactly the summary I was looking for. Now that I understand 'camber' I can make an informed decision on my repair and alignment. It's funny you know, people don't like to make decisions until they understand - I understand!!!
Thanks

 

[RStalveyARFF]

Before you go and get an alignment, find out what's causing it. A stock car doesn't just go to roughly -2 degrees camber in the back for no reason. Something is broken or worn, and you'll need to find that before you work on the alignment.

 

[Jayman]

Emerald94:
Camber kit part #(Ford): E7DZ 5K751 B.
It cost me about $50.00 for it 1n 1997.

Thanks SHO91MTX. As you can see from above that is obviously the first order of business.

 

[Emerald94]

No probs! thumbs_u
FYI, that's $50.00us. It was about $80.00cdn + installation.

Jayman:

Emerald94:
Camber kit part #(Ford): E7DZ 5K751 B.
It cost me about $50.00 for it 1n 1997.

Thanks SHO91MTX. As you can see from above that is obviously the first order of business.

 

[RStalveyARFF]

sure, that's the camber correction kit. But something is worn to cause the camber to be like that.

 

[Emerald94]

Apparently the inner tire wear problem is common to a lot of Taurus (design flaw?), not just SHOs. Ford came out with the kit to correct the problem.

SHO91MTX:
sure, that's the camber correction kit. But something is worn to cause the camber to be like that.