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  #1  
Old 04-09-2012, 12:16 AM
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Power to primarily left wheel... malfunctioning diff?

I have a 1968 220D automatic tran. which I am trying to get into safe order for in-town trips. I don't know the mileage on the car because the odometer is broken. The car has an odd characteristic which I am hoping to get your advice on:

With the rear end of the car on jack stands, if you put it into drive, only the left wheel turns. Now, before you call me an idiot, let me explain a bit more. While in drive, it is nearly impossible to stop the left wheel to get power over to the right wheel. I almost knocked the car off the jack stands trying to wedge the left wheel and get it to stop. Eventually, with great effort, I was able to stop the left wheel, in which case the right wheel does in fact turn. But it takes some effort to keep the left wheel still. And as soon as you let go, it starts spinning and the right wheel stops. Is this normal? Is this a safety issue? Maybe this is how all differential works, but it seemed odd to me. I am not very experienced with all of this, so any advice you can provide is appreciated.
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Old 04-09-2012, 01:29 AM
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It's not out of the ordinary for only one wheel to spin with both in the air. I would check for a stuck brake on the right side, or something else making that wheel tougher to turn. The power will all tend to go to whichever wheel spins easier.
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Old 04-09-2012, 09:09 AM
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Quote:
Originally Posted by Orv View Post
It's not out of the ordinary for only one wheel to spin with both in the air. I would check for a stuck brake on the right side, or something else making that wheel tougher to turn. The power will all tend to go to whichever wheel spins easier.
Agreed.

If there is slightly more friction on one side, the opposite side will be the only one to rotate. This is not an issue if the operative word is "slightly".

However, in the case of the OP, there is some serious friction on the right side as evidenced by the amount of force necessary to stop the left wheel and get the right wheel to rotate.

I also suspect some dragging brakes on the right side.
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Old 04-09-2012, 11:19 AM
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I don't think it's the brakes

When I originally noticed the problem described above, with the car in PARK (or maybe Neutral, I don't recall), I spun the right wheel and it easily spun (and caused the left wheel to obviously spin the opposite direction). The same thing occurred if I spun the right wheel. So I don't think it is brake drag from either the normal brakes or the parking brake. But I will double check that when I get a chance. I hadn't thought about the brakes, so I definitely appreciate the advice.

Does anyone know of a problem with differentials that could cause this? And does anyone have a suggestion as to how I could test this at higher power levels? Maybe my test at idle and low speeds is just faulty, and at higher speeds/loads the problem doesn't persist.

Thanks.
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Old 04-09-2012, 01:18 PM
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A failing right side half shaft bearing or cv might also cause those symptoms.
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Old 04-09-2012, 08:34 PM
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True, it could. I can't think of anything inside the diff that could cause this, except for bad bearings, which you would hear going down the road.

Another thought -- do the rear wheels hang roughly even with the car jacked up? If you have something going on with the suspension causing one side to extend more than the other, the drive axle on that side might bind more. They aren't made to work well at really extreme angles.
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Old 04-09-2012, 08:43 PM
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Originally Posted by Orv View Post

Another thought -- do the rear wheels hang roughly even with the car jacked up? If you have something going on with the suspension causing one side to extend more than the other, the drive axle on that side might bind more. They aren't made to work well at really extreme angles.
Another thought:

The axle shafts suffer extreme angles when the back of the vehicle is lifted from the pavement with the wheels hanging. They were never designed to operate at these angles. One axle could definitely have quite a bit more friction than its twin.

If the brakes are not dragging, get the vehicle off the jacks and ignore the "problem" before you create a serious one.
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Old 04-09-2012, 11:50 PM
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Thanks for the help

You all are amazing. This is the second concern with the car that I have asked about, and both times the advice has been incredibly valuable. The "problem" was originally pointed out to me by a "mercedes" shop, so it would be ironic (and a little sad) if I was creating more of a problem than solving it. I guess it would be more $$ for them. I will definitely look into all your suggestions. Thanks for the help.
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Old 04-10-2012, 12:28 AM
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Sounds like a CV binding maybe. If jack it by supporting each hub w/ a stand so the CV's are at a normal angle, and put the tranny in gear, turn a drive wheel one way, the opposite wheel will will turn in the opposite direction.

I hear the differentials howl on the way out, you'd probably notice. If you change the oil, make sure to get the check/fill plug out before you get the drain plug out.
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