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Old 05-08-2008, 06:32 PM
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Front-End Alignment/Rear Axle Offset

I have a 1955 Ford Customline with a Granada Rearend. When it was installed by previous owner he has it further to the left wheel well than the right wheel-well. It actually sits about 1 1/4" further to the left.

I had 4 new Radial Tires put on and the front-end aligned. Before this new alignment it was pigeon toed but run down the road without pulling. The alignment tech used a machine that had 4 gizmo's with electric cords running to his machine with a TV screen. It showed all four wheels.

He aligned the car with the right rear wheel which was the only tire green on his screen (which sits in about 1 1/4" (offset rearend). He straightened out the toe-in and all four wheels showed up green.

Now the car pulls hard left (not a gradual drift). I have to keep pressure to the right at all times. He says it is Radial run-out and should correct itself in about 200-300 miles.

Would he have to compensate the front-end alignment with the offset rearend? I'm fishing for answers.

Thanks to all for any input on this problem. Sweet-34
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Old 05-08-2008, 07:40 PM
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Quote:
He says it is Radial run-out
I'd say, Prove it What I mean is, swap tires from F to R or side to side, to "prove" that it is tire pull. I'd bet it is not.

Also, I wouldn't care to own that car with such a error in rear offset unless I fixed it first.


That "gizmos" alignment equipment is only as good as the tech,..or ...if the gizmos are even accurate. Simple equipment is more reliable IMO
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Old 05-08-2008, 08:55 PM
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Prove It!!!

He rolled the tires front to rear (directional tires) and it made no difference. Thanks~~~Ron
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Old 05-08-2008, 10:06 PM
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I have been told by a guy who has owned the local Cooper Tire dealership since 1970 that maximum allowable track offset is .5",
maximum allowable wheelbase difference is also .5"

What happens when you go beyond those values is unknown to me, but I know that if the car tracked straight (even if it crabwalked), did not pull, and did not wear tires before the alignment, and now it does, it is in the new alignment. (or MIS alignment).

"Radial runout" sounds like BS to me. Especially if you swapped tires from side to side and got no change..

I'd have a talk with the manager, and let him know that his tech is aligning front ends and letting them out with safety/drivability issues. Offer to let the manager drive the car, or take him for a ride.

Ask to see the alignment printout..many machines provide a spec sheet with before and after specs, this printout may be in your file..


later, mikey
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Old 05-09-2008, 05:55 AM
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Originally Posted by powerrodsmike
I have been told by a guy who has owned the local Cooper Tire dealership since 1970 that maximum allowable track offset is .5",
maximum allowable wheelbase difference is also .5"

What happens when you go beyond those values is unknown to me, but I know that if the car tracked straight (even if it crabwalked), did not pull, and did not wear tires before the alignment, and now it does, it is in the new alignment. (or MIS alignment).

"Radial runout" sounds like BS to me. Especially if you swapped tires from side to side and got no change..

I'd have a talk with the manager, and let him know that his tech is aligning front ends and letting them out with safety/drivability issues. Offer to let the manager drive the car, or take him for a ride.

Ask to see the alignment printout..many machines provide a spec sheet with before and after specs, this printout may be in your file..


later, mikey
In theory, "if" the F&R axle "centerlines" are exactly parallel, a rear offset should not cause a crabwalk OR a pull...but I can see how a 1-1/4" offset might screw up a "bells & whistles" gizmo machine. This all goes back to being a good mechanic and having the ability to work around an unusual situation like this car has.

If it was my car, or my customer, I would have fixed the rear offset first! That seems so bogus to not want to get the basics done correctly, before alignment. We are not talking a big job to remount the rear end correctly. Heck, if the original builder was that sloppy, what else is wrong with other items on this car??

Then after getting the rear where it belongs, I'd use my older, simple, alignment tools and "know" it was right.

I would not even go back there ....I doubt it will help...
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Old 05-09-2008, 06:30 AM
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We used offset to tune the chassis in circle track racing and it will not cause the car to pull.Now this assumes the rear end thrust alignment is correct.I.e no lead in the rearend. There is no way to use the rear tires to set caster and camber or toe in the front.These settings are independent from the rearend something was done wrong and needs corrected asap. It has nothing to do with left to right offset of the rearend, really all it does is move weight from one tire to another maybe 20 - 30 lbs.An example would be you have a 5 inch backspace wheel on the rear and have a flat and you put on a stock wheel of 3 inch backspace the car would not pull.
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Old 05-09-2008, 07:05 AM
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Before you start with bashing the guy at the alignment shop or his computer (they are about 20,000.00 without the rack we have a new Hunter 611 and get it serviced and updated every 6 months so I know quite a bit on the subject) he is most likley working on comission and getting paid about 25.00 to do the alignment on your car so to bring in a hot rod and want to pay the 50.00- 75.00 fee is expecting quite a bit of someone that does not do this type of work everyday. But if it did not pull before and it does now something is off. 1st have you checked toe with a tape and a helper? put in about 1/8" toe in. second get a caster camber gauge and check them, if it has power steering I would put 5 or so degrees of caster in it and maybe 1 degree of camber. I also would check the rear end for square I understand the offset but if it was mounted wrong in the firstplace chances are the wheelbase is different side to side. This in itself could cause a pull problem.

Your best bet is to go to a local chassis shop that deals in this sort of thing everyday. Pay them 150.00-200.00 to make the car drive down the road without fighting it.
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Old 05-09-2008, 07:21 AM
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Something is very wrong here- other than the offset.

A THRUST ANGLE alignment is performed by ascertaining/knowing the rear axle(s) is square to the chassis. You then proceed to set the front off of this value. If the rear tires are not within spec, you are simply over riding the machine.

Square the rear housing (tram, tape or frame machine). The machine will let you know if the housing is bent.

Offsetting a rear for racing purposes has no bearing regarding this.
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Old 05-09-2008, 08:59 AM
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Let's go back to Square #1

First off.....I figured wrong. I did some more measuring and found these measurements. The offset on rear axle about 5/8". The wheelbase is off 1/4". The toein is 1/8". Maybe this will find the help I need.

Sorry for the misinformation. All suggestions appreciated!!!~~~~Sweet-34
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Old 05-09-2008, 09:23 AM
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I can live with 1/4" on the wheelbase now get the car up in the air and get it square if it has MII front end the lower control arms are fixed so go from the grease fittings to the center of the rear axle flanges (with a plumb bob dropped to measure to) and see how far out of square the car is. Do this front to back and in an X this will give you the correct WB and the X will tell you how far out of square the chassis is. If you have a rear 4 bar you can adjust it out if it is a leaf you might be in for a little cutting and welding either way the car can be fixed. Get the rear end square with the front then set the front end and the car will drive fine.
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Old 05-09-2008, 10:23 AM
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Stock Ford Suspension

This car has a stock '55 Ford Front Suspension and a 1976 Granada rearend that bolted right in without cutting and using the stock '55 Ford leaf springs and shocks.

The wheelbase was measured from center of rear hub to center of front hub on both sides with only 1/4' difference.

Keep them ideas and suggestions coming~~~~Sweet-34
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Old 05-09-2008, 10:45 AM
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I would go from the lower ball joint to measure the WB, the spindle has to be dead center to check WB and if the toe or caster is different it will give you a false reading.
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Old 05-09-2008, 12:31 PM
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Rechecked Wheelbase

I measured from the lower ball-joint to the rear spring perch on each side.....there is 1/16" variance. Doesn't look like that would cause any problem. The offset is only 5/8-3/4" which doesn't sound like that would give any problem in lining up the front. Tech checked caster and camber and said they were within specs. It was very pigeon toed and he reset to 1/8" toe-in. I checked that also and it is right.

It did not pull to the left with the old radial tires, but both were worn on the outside due to to much toe-in.

Now it pulls (not drift) to the left. I have to keep the steering wheel held with slight pressure to the right. If I let go of the wheel the car immediately goes to the left.

Hope this helps other in trying to help locate the problem. Thank you for your time and suggestions-34
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Old 05-09-2008, 12:52 PM
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At this point, I'd be checking caster. Caster differences on comparing each front wheel can and will cause a pull.

"set to specs". That can be misleading. Let's say the specs for that car is 1-1/2 degrees positive with a tolerance of "plus or minus" a half degree. Then have one wheel at 1 degree and the other reading 2 degrees. It still is withing the specs...sort of...but most specs will also limit how much difference is allowed, to prevent that much.

I'd go with a caster check again...especially if it is pulling "up" the crown in the road...meaning, to the left. I am basing this only on your post that said the new tires were moved to the back, and it did not help.
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Old 05-09-2008, 03:22 PM
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Caster/Camber Specs

I was just told that when you put Radials on these old Fords that you need to adjust the Caster to Positive as they were set at Negative from the factory for the old Bias-Ply tires.

Anyone know what the specs should be with all Radials on the car? Caster and Camber!!!!

Anyone been through it and can share what they did and how it worked out? Thanks~~~~~Sweet-34
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