Very lose bolts on hub, now diff issues
Discussion
Gents,
At a recent MOT, the tester noticed grease around the rear OS wheel hub but no tear in teh CV boot. We looked at it together and found that one of the allen bolts on the back face of the hub near where the drive shaft enters the hub was so loose it had around half an inch of thread showing. The other 4 or 5 bolts were also loose. I have not had to dismantle the driveshaft or hubs yet so am not familiar with the construction or what these bolts actually do or whether them being loose could cause loss of grease.
I did have the differential changed last year by a well known TVR independent so I am guessing they forgot to tighten the bolts.
I assumed if these bolts had come right out, the half shaft would have come out from the hub.
So glad the MOT tester noticed it before I had a half shaft whipping around under my backside ! That could have been very nasty.
Oddly, since tightening the bolts, the diff now feels very clunky when doing anything other than going in a straight line but especially if rolling relatively slowly with no power applied in neutral. Feels a bit like when the limited slip is coming into action at very slow cornering speeds.
Can anyone advise how tightening these bolts could affect the diff and if the loose bolts tie up with loss of grease.
Thanks.
At a recent MOT, the tester noticed grease around the rear OS wheel hub but no tear in teh CV boot. We looked at it together and found that one of the allen bolts on the back face of the hub near where the drive shaft enters the hub was so loose it had around half an inch of thread showing. The other 4 or 5 bolts were also loose. I have not had to dismantle the driveshaft or hubs yet so am not familiar with the construction or what these bolts actually do or whether them being loose could cause loss of grease.
I did have the differential changed last year by a well known TVR independent so I am guessing they forgot to tighten the bolts.
I assumed if these bolts had come right out, the half shaft would have come out from the hub.
So glad the MOT tester noticed it before I had a half shaft whipping around under my backside ! That could have been very nasty.
Oddly, since tightening the bolts, the diff now feels very clunky when doing anything other than going in a straight line but especially if rolling relatively slowly with no power applied in neutral. Feels a bit like when the limited slip is coming into action at very slow cornering speeds.
Can anyone advise how tightening these bolts could affect the diff and if the loose bolts tie up with loss of grease.
Thanks.
If the bolts are loose the CV grease will seep out through the joint itself so that is correct.
I would tighten the bolts at both the hubs and the diff i.e. all 4 joints (note that the threads on the bolts are different at the hubs from the diff ends). Then try driving it to see if its is clunky.
If you do suspect the diff, you must first check that the 3 mounting bushes are solid. The top one especially can fail due to twisting action so use a big pry bar to test each bush. The bushes are available at TVR dealers or you can upgrade to poly bushes.
Also, if you still think the diff may be faulty, I would drain and refill with the correct quality oil as this can affect its performance.
Do all those checks before suspecting a failed diff.
I would tighten the bolts at both the hubs and the diff i.e. all 4 joints (note that the threads on the bolts are different at the hubs from the diff ends). Then try driving it to see if its is clunky.
If you do suspect the diff, you must first check that the 3 mounting bushes are solid. The top one especially can fail due to twisting action so use a big pry bar to test each bush. The bushes are available at TVR dealers or you can upgrade to poly bushes.
Also, if you still think the diff may be faulty, I would drain and refill with the correct quality oil as this can affect its performance.
Do all those checks before suspecting a failed diff.
Thanks. The bushes were changed with the diff and I wouldn't expect tightening the CV / hub bolts to suddenly cause them to be problematic.
Having lose bolts at the hub end wouldn't make the diff operate any differently would it, e.g. allowing slip there rather than through the diff ?
Will check the oil as the diff appears to be leaking as the exhaust is always wet below it.
Having lose bolts at the hub end wouldn't make the diff operate any differently would it, e.g. allowing slip there rather than through the diff ?
Will check the oil as the diff appears to be leaking as the exhaust is always wet below it.
Can you return the car to the TVR independent who did the work as the bolts should not work loose.
I’d suspect the cv joints on that drive shaft are now worn and could be causing the trouble.
Check both the drain and filler plugs are tight.
There’s also a vent tube on top of the diff that might leak oil if it’s been badly over filled but highly unlikely to be that.
When I got my new (15 year old) Diff the rear cover had been removed and new sealant applied as I was told the original can leak as they have been sat unused for so long so Central Tvr who I purchased mine from had done this to the one I chose, it was in a pile of many so I assume they did all of them as I chose one near the bottom!
I’d suspect the cv joints on that drive shaft are now worn and could be causing the trouble.
Check both the drain and filler plugs are tight.
There’s also a vent tube on top of the diff that might leak oil if it’s been badly over filled but highly unlikely to be that.
When I got my new (15 year old) Diff the rear cover had been removed and new sealant applied as I was told the original can leak as they have been sat unused for so long so Central Tvr who I purchased mine from had done this to the one I chose, it was in a pile of many so I assume they did all of them as I chose one near the bottom!
taylormj4 said:
Thanks. The bushes were changed with the diff and I wouldn't expect tightening the CV / hub bolts to suddenly cause them to be problematic.
Having lose bolts at the hub end wouldn't make the diff operate any differently would it, e.g. allowing slip there rather than through the diff ?
Will check the oil as the diff appears to be leaking as the exhaust is always wet below it.
Having loose bolts will cause the diff to function incorrectly. There will be no resistance for brief periods as the CV joint is turned one way then the other if loose. Power on and the play will be taken up, then foot off and the joint will move before braking resistance is detected by the diff. Having lose bolts at the hub end wouldn't make the diff operate any differently would it, e.g. allowing slip there rather than through the diff ?
Will check the oil as the diff appears to be leaking as the exhaust is always wet below it.
Was the diff a second hand one, reconditioned or new? Whoever did the work should be given the first opportunity to fix any mistakes. Has the indie accepted the problem? Will they check it out for you?
and no they dont come loose on their own 
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