1987 SDL, clunking in rear end..
 

Good morning.

I have a clunking in my rear end that I have narrowed down to specifics points in the shifts;

For example, if i were driving and removed my foot from the throttle right before the switch from 1st to 2nd, it makes a loud thunk. It also makes a similar thunk when putting in reverse from nuetral or park, although not as bad.

Is there a way to check for rear end play? Or the half shafts?

When the car is suspended on a lift and I grab one of the rear wheels, causing them to go front back, front back, I hear a not normal clack, from the diff and half shafts. I feel that this may be the cause of my noises. It seems like it would be "tighter".

Thoughts?

Thanks

No takers?

I have a random Twang "spring" noise in my '87 SDL. It is annoying, but it does not do it when the car is loaded, so I am tolerating it until it gets worse.

By tolerating I mean that I am not going to randomly start tearing things out and replacing. I have had it looked at 3 times, twice by the same shop and the say it is nothing MAJOR.

My '86 SDL has been doing this for about 65,000km (since I bought it) and hasn't gotten any worse. Mine is most noticeable when letting off the gas quickly just before it shifts. I wouldn't worry about it unless it gets worse...

Neal

A good diagnostic for the drivetrain beyond the transmission is to park the car in neutral and set the parking brake. Then reach under the car (or park on ramps if necessary) and try turning the driveshaft back and forth by hand.

This evaluates the wear in your differential and to some extent the half-axles. I had about 60 degrees of free turn before replacing the differential on the 1982 300D. A gear yoke inside the differential was severely worn.

Ken300D

Alan, thanks for the tip. I will try it out as soon as it stops raining.

I don't think it will leave me stranded. I am just real anal about noises and leaks and stuff.

Makes me wonder why I drive a 17 year old car sometimes, but I love it.

Bhatt, as I said I am not really woriied but it has gotten a bit worse over the last 10,000 miles.

Ken, can those gear yokes be replaced? Or is it too much trouble?

I'm sure its replaceable but there's a lot involved in taking a differential apart and then putting it back together again, and I'm not sure about parts availability. Then there are issues on shimming gear clearances, etc.

I went with an excellent low-mileage used differential at $135.

If you want to see pictures of the severely worn differential:

http://www.peachparts.com/shopforum/showthread.php?threadid=69421

Ken300D

Ken, I am thinking worst case scenario here, but where could I find a good used rear end?

From other little tests I have done, I really think it is the differential.

I have had the car on a lift and rotated the tires and am quite sure that there are a couple of inches difference between when the tires move and the drive shaft moves.

Not sure exactly how much, but the clunk it makes when I do this sounds a lot like the noise made when operating, although a lot less noiser.

Additionally, I have been to my indy's shop and did the same test on another 126 and there was little or no play at all.

Thanks

Got mine from Potomac German Auto in Frederick MD.

They have another store in St Augustine FL.

http://www.mbpartsonline.com/

They have an on-line search function for parts but its not totally representative of what they have in stock. If you call they will be able to tell you exactly what's in stock.

Should be able to ship a differential to you by UPS, but its heavy. It works best though to be able to look over the part you're about to buy.

Ken300D

Thanks. Will do your test first to make sure. The noise is really aggravating.

silver star had one also
 

Plantman,

When I was early in researching my noise/vibration issue, one shop had recommended a differential replacement. In a quick search I found Silver Star Recyclers ( out west somewhere) had one from an SDL, which I assume would have the correct gear ratios in it. Seems like they wanted more like $200-300 for theirs.

I've been unable to work on mine for the last 2 months (back injury), but just now getting mobile enough to start exploring. Let me know how your diagnosis goes. Two shops have looked at mine, one says axles one says differential. I need to get under it and look around myself.

Chuck

I'll be tring Ken's test tommorow and post the results. Maybe then some forum members can help me correctly diagnose.

I mean there is a few inches of play between the time you move the rear wheels and the time the actual driveshaft moves.

You start turning the wheel and then you hear a clunk, at which time the drive shaft starts to move.

If I understand correctly, if you were to move the wheels, the half shafts shoudl move at the same time, causing the driveshaft to move at identical times.

That is definitely not happening. There is a lag.

Ken, using your test, there is appox i inch of play in the rear end. When the driveshaft engages" you hear the aggravating clunk. Would you agree that it is in need of replacement? Thanks