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Ford Mustang Forums Tech Related Brakes & Suspension

Why would rear solid axle toe be off?

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Bite Me 23.07.2010, 17:03
Took my solid axel swap to be aligned today and they tell me the rear toe is off.

Left rear 0"
Right rear is -7/32"

Anyone have any ideas? Me and ruger are thinking about it, but doesnt make much sense to either of us.
BLUE895.0 23.07.2010, 17:30
Maybe a bent axel or housing
mustangracer84 23.07.2010, 19:22
IIRC, the rear axle should be slightly (ever so) toed in on both sides, so the fact that one side is 0, and the other is toed that much would mean 1 of a couple things, most likely a bent control arm, or bad top axle bushing, or possibly something tweaked with the torque boxes on the chassis. Could be an axle tube, but I doubt it, if it's a problem in the axle, it's most likely some worn/bad bearings.
Bite Me 24.07.2010, 18:16
Brand new upper and lower control arms were installed.

Also brand new spherical bushings on the diff.

Still let's say something is off on the passenger side. Wouldn't that make the driver side toe off just as much? Since the axle is solid, moving it would cause the same opposite movement on the other side.

Also I have not felt any vibrations so a bent axle seems out of the question. A bent tube seems more likely if it is the rear end

So are you saying my axle SHOULD actually be toed about 3.5/32 on each side? I believe the factory spec is between 1/32 and 3/32 toe.

That would make sense. I think you might be on to something there. I still don't see 3/32 toe being acceptable IMO. Although I'm a freak perfectionist with a car that has pretty liberal factory tolerances.
mustangracer84 24.07.2010, 18:30
it technically needs a little toe to give you better traction at speed, as wheel road force will effectively O it out at speed (when everything is correct). Here's an easy check, with the vehicle on a flat surface, preferably with the parking brake off and the trans in neutral, as you're trying to get the rear axle to be unloaded, just supporting the weight of the car, measure the wheel gap between the front of the rear wheel well to the tire, and the back of the tire to the rear of the wheel well and compare it to the other side. I doubt you have a bent axle, however the tube is a possibility, or maybe something with the chassis mounting. It'd probably be good insurance to have the run out checked on your rims just to make sure as well.
Bite Me 26.07.2010, 14:17
I will check that out also. These are brand new wheels from summit, warrior r/t's that I got to mount my m/t's on for racing. Its entirely possible they arent right, or at least are contributing to the problem.

Anyways, I pulled my uppers off and checked them, they werent the same length. About 1/8" off. Passenger side was longer than the driver side. So I will adjust those and check again. I am hoping that was the issue, but if not they needed to be fixed anyways.
mustangracer84 26.07.2010, 15:46
I will check that out also. These are brand new wheels from summit, warrior r/t's that I got to mount my m/t's on for racing. Its entirely possible they arent right, or at least are contributing to the problem.

Anyways, I pulled my uppers off and checked them, they werent the same length. About 1/8" off. Passenger side was longer than the driver side. So I will adjust those and check again. I am hoping that was the issue, but if not they needed to be fixed anyways.

that'd definately cause issues...lol. That extra length would definately cause your angles to be off...
Bite Me 26.07.2010, 16:27
Thats what ruger was thinking in the beginning but I was 99% positve they were equal. I should know here in a few days once I get it back in and get some time to go get it checked out.

Thanks for the info, I appreciate it.
68mustang 27.07.2010, 17:23
OK how would the factory have a toe in on a solid rear axle? I'm trying to do this in my head. but if anything is not symetrical it "should" cause a vibration. ie: axle shafts, flanges, center section all have to be straight other wise there will be a vibration. Sounds like the control arms being incorrect length is the problem.
mustangracer84 27.07.2010, 17:55
essentially it's all about the road force effect on the wheels because even a solid axle flexes. At speed, the force will "push" on the wheels, and with a slight toe, you retain higher traction at higher speeds.
68mustang 28.07.2010, 20:45
I understand the axle flexing, but you said ford toed it a certain way (in i'm guessing) from the factory. And I'm wondering how they did that? I understand it will flex because of the clearances in the bearings and in the center section.
willrst 28.07.2010, 23:56
torque box?????
imajeenyas 29.07.2010, 00:11
Try another alignment shop? Just to double check?
mustangracer84 29.07.2010, 19:25
I understand the axle flexing, but you said ford toed it a certain way (in i'm guessing) from the factory. And I'm wondering how they did that? I understand it will flex because of the clearances in the bearings and in the center section.

yes, it's a factory setting, and it does vary slightly from car/truck. For example a dually f350 might have more because there's alot more rubber meeting the road, so to speak. Basically, the axle shafts and generally the axle tubes themselves are perfectly straight, it's generally cast or shimmed in the center section (where the axle tubes are fitted to). You have to remember these amounts are less than a 1/2 inch TOTAL, so the naked eye wouldn't even notice it...very small adjustments can do alot for stability and control at speed. Being that it's a solid axle, if say one control arm is longer than the other, then the side with the longer control arm would be "toed-out" and due to the solid axle, the other side would be "toed-in". This can cause an effect commonly referred to as "dog-legging" or "sidewinder", where the rear axle seems to track on a different plane than the front wheels, and it would appear to a vehicle following it that the car is literally driving sideways.
Bite Me 30.07.2010, 16:46
So, second time around, different shop.

This time in degrees.

Driver toe .15*
Pass toe .51*

Thrust angle .19*

Thrust angle before uppers were adjusted to equal length was .24*

So now I am on to checking the lower control arm mounts for issues, and checking axles for straightness. The axle tubes are not warped (checking straight edge on tubes), but could be off in the housing. If that doesnt do anything for me I am just going to drive the wheels off until its time to put 9" ends on and I will have it straightened at that point. The car has never been wrecked except front bumper in a snow bank like less than 5mph.

This was an IRS car, so upper TB's were brand new, lowers were warped but not like some cars I have seen. I wouldnt imagine that is the issue, but I might pull out some string and measure each from a central point on the car.
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