Noise from Diff
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The Elan S2 diff was completely rebuilt last year but I am noticing a clunking sound when accelerating and decelerating. It is a single 'clunk' which I initially attributed to a loose mounting. After careful inspection, all bolts are secure. The propshaft bolts are also secure. If I place the g/b in first and rock the car, I hear the same sound, possibly coming from inside the diff. I don't recall hearing this after the diff was rebuilt last year. Anybody ever hear a sound like this? Any ideas about what would cause it?
Current: 1965 S1.5 26/4004, 1966 S3 FHC 36/5192, 1958 Fiat Abarth 750GT Zagato, 1967 Brabham BT21B, 1988 Arrows A10B-04, 1991 Brun C91-001.
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
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CG901 - Second Gear
- Posts: 194
- Joined: 21 Feb 2013
Was the diff ok after the rebuild and then started clunking all of a sudden? If it's internal then maybe too much clearance between crown wheel and pinion. Maybe improper pinion depth or preload on pinion bearings. I'm in the process of rebuilding my diff right now. Apparently setting pinion depth using the crush washer can be difficult and deceptive. There is a lot to learn about this basically simple mechanical device.
Chris
Chris
67 Elan Super Safety
67 Elan +2
67 Elan +2
- seniorchristo
- Fourth Gear
- Posts: 589
- Joined: 19 Dec 2013
Chris - I believe the sound came on gradually as I don't recall exactly a start point. The rebuild was done by a very well known guy who is a know Lotus Specialist. He does a lot of them. Of course, that doesn't mean it was done correctly in my case.
Current: 1965 S1.5 26/4004, 1966 S3 FHC 36/5192, 1958 Fiat Abarth 750GT Zagato, 1967 Brabham BT21B, 1988 Arrows A10B-04, 1991 Brun C91-001.
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
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CG901 - Second Gear
- Posts: 194
- Joined: 21 Feb 2013
did you check the exhaust tube clearance with the chassis or gearbox? depending on how your exhaust system is hanged, a gradually getting loose exhaust mount may cause some acceleration/deceleration knock noise, as engine tilts in its mounts.
S4SE 36/8198
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nmauduit - Coveted Fifth Gear
- Posts: 2006
- Joined: 02 Sep 2013
If you can get the rear end safely up in the air, put it in top gear and lock the handbrake on one side by adjusting it up tight. Then get someone to rock the free wheel backwards and forwards to see if you can reproduce the sound - look for anything that moves when it shouldn't - mountings etc as others have said.
If all the other checks don't reveal anything and you still have doughnuts check one of those hasn't broken - I've had them make clunks and clicks when they've failed and its not always immediately obvious. Except when they disintegrate, of course. That's generally obvious.
Nigel F.
If all the other checks don't reveal anything and you still have doughnuts check one of those hasn't broken - I've had them make clunks and clicks when they've failed and its not always immediately obvious. Except when they disintegrate, of course. That's generally obvious.
Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
- nigelrbfurness
- Third Gear
- Posts: 372
- Joined: 04 Apr 2008
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