Spider differential noise

[piperstan]

My 1973 124 spider with a 1979 Carburated 2 liter, which I have owned for years is now experiencing a rattling sound in the general vicinity of the differential. The noise is not always there and sometimes is more prevalent when I take it out of gear or make a left hand turnm or coast. I thought at first the sound was the exhaust pipe ratteling against metal but no sign of that. I changed the fluid in the differential (I filtered the fluid and found NO metal particles). On reassembly I found the noise was still there but sounded a little quiter.

I jacked up the rear wheels and noted there is a small amount of play between the propeller shaft coupling and the wheels - (hard to measure but perhaps 2 degrees). Also before I purchased the vehicle apparently the previous owner had installed a tow hitch -- yes!! - I have no idea what he was towing and I knew that before I purchased. After purchase I went through everything (about 10 years ago) except the differential - at that time I Installed the 2 lirer, new suspension, brakes - you name it (also rear stabilizer bar which really helped the cornering).

Any ideas on the noise or solution to isolate?

Thanks

Stan

[narfire]

The last thing I am is an expert on the fiats rear end... But I recently swapped mine out with another.
How are the bearings on the axle? when jacked up , put one had on top of tire and other on bottom , push-pull any play? No brakes on eh..
I know there will be a small amount of play when you turn the drive shaft and the gears connect in the dif. I had what I thought was more than there should be and when I took the rear inspection plate off, the pinion shaft was loose in the carrier. should be tight..no play.
I have no idea how you might check that with the older diffs though.

[piperstan]

Wheels seem tight - (with brakes off)

Thought it might be a backlash adjustment - not sure it's something I want to tackle w/o right tools. On the older models I think you have to pull the gears out after pulling the axle shafts?

Tx

[majicwrench]

Rear ends don't often rattle. If a bearing is bad it will whir or roar, consistantly. If a gear is chipped, it will also be rythmetic, constant. Rear ends, all of em, have what seems to be a LOT of play in em when you first check em out. After 32 years of looking at rear ends (cars, just cars, nothing else) I can tell you that whatever play you are feeling is normal. Methinks I would look elsewhere.
Keith

[bulldog4444]

Good evening Piperstan,
Unfortunately you may have sheered off a tooth or two on your ring and pinion gears. Actually it is the pinion that sheds a tooth. Unless you pulled the cover off when you did your fluid change, you probably would not find the broken piece. I've had my 1978 spider since 1982 and am currently on my fourth rear end. The original, two rebuilds and a swap out from a junk yard.

My last failure also sounded like either a hole in the muffler or exhaust pipe. I put one of those small recorders in the trunk and took it for a drive. You could clearly hear the growl/thump that yet again another pinion had bitten the dust. I drive my spider extremely carefully but I have put close to 340,000 miles on it. It seems they only last about 100,000 miles and then they are toast. The only way to be sure is to pull the cover and take a look. Changing out the rear end is only a couple hour job with jack stands and allows you to catch the shocks, universal joints and dough nut all at the same time.

I will keep an eye on this thread to see how you make out. Good luck!

Bulldog

[piperstan]

Bullog

Thanks - When you get over 70 you tend to not want to get into major repairs. - Definitely a good idea to put a recorder in the trunk. I'm in the middle of helping do a Jeep Wrangler workover - so the fiat may need to wait.

I will post my findings later.

Stan

[piperstan]

Kieth:

Thanks for the response - I have looked hard to find a rattle point - including taking everythink out of the trunk ( spare tire, jack etc ). ---- will just have to keep looking - The noise is moist prevalant at about 35 mph when I push in the clutch to change gears. But I can also hear it sometimes while coasting (out of gear with clutch not depressed).

I was thinking about raising the car, jack stands on rear axel - putting the car in gear and listening to the rear end for noise (carefully of course). It does not look like the exhaust system is contacting anything on the body but ... I have a non standard muffler system so it is possible that there might be something loose inside one of the components. I will probably stop by a muffler shop for consult.

Also, I have the performance springs which Internatonal Auto sells - which lower the scar to the ground (shocks repaced recently) ---- I think I need to replace the performance springs which have about 20 years on them --- probably sagging too much the car seems too low to ground and it is getting hard to steer at stop (symptom I think of the angle of tie rods to steering box). I don't know if the sagging springs would be part of the problem!

Stan

-----------------------

....Rear ends don't often rattle. If a bearing is bad it will whir or roar, consistantly. If a gear is chipped, it will also be rythmetic, constant. Rear ends, all of em, have what seems to be a LOT of play in em when you first check em out. After 32 years of looking at rear ends (cars, just cars, nothing else) I can tell you that whatever play you are feeling is normal. Methinks I would look elsewhere.
Keith[/quote]