Is it my Diff?

[j.fernie]

Nasty knocking from the drive train last week. A regular 'ping' that sounded like something was clipping a bolt head as everything was going round.
First thought was the UJ's on the prop shaft, but that was too easy!
Spent the weekend changing the gearbox and checking tightness on the clutch cover, but that hasn't fixed the problem either!
Adversity forces you to think, so a quick drive down my road confirmed that the frequency of the noise was speed related but not revs related. So the problem has to be behind the gearbox, and since it isn't the prop, this leaves the diff - or am I missing something?
I've known diff's grumble, but not a regular knock like this. Has anyone had similar experiences?
Any thoughts /suggestions appreciated.
Jim

[keith_h]

Re: Is it my Diff?

Am I teaching grannie to suck eggs but have you jacked the rear end up and got somebody to spin the wheels whilst you are under it. If a bolt head has come loose somewhere and is catching on something you should be able to find it. Is yours a Sierra based rear end? If so, have any of the capheads on the drive shafts worked loose and catching one of the suspension arms?

[stevejgreen]

Re: Is it my Diff?

Could be many things, but I would take a look quite soon.
I have seen a bolt, that used to secure the ring gear in place, come loose, and in the process finally detatch and find its way through the casing, meaning the complete diff needs replacing.
If you are Marina based, then the following might help: http://www.keepandshare.com/doc/4039...34-pm-81k?da=y

[cameronfurnival]

Re: Is it my Diff?

I would go with Keith's suggestion. Jack up each wheel in turn, spin it see if you can tell where the noise is coming from - obviously if its there with either wheel then it could be diff or prop - but if its just one wheel then check the brakes, backplate even the handbrake mechanism may have come adrift.

[greyV8pete]

Re: Is it my Diff?

Nasty knocking from the drive train last week. A regular 'ping' that sounded like something was clipping a bolt head as everything was going round.

Jim

Hi Jim. I had an intermittent rumble from the diff on a TR3A many years ago. A strip down revealed a piece of broken tooth from the crownwheel that had become occasionally jammed between the casing and was wearing away at the heads of the c/w securing bolts! On strip down I also found that there were two teeth missing from the c/wheel but only one tooth in the oil! As this was a common failure and the parts were the same as the Triumph 2000 I had quite a wait for replacement parts. After reassembly I found that the drive train was much smoother as the missing teeth had been causing a vibration in the transmission! To echo earlier post I would suggest investigation of your "noise" sooner rather than later. Peter.

[j.fernie]

Re: Is it my Diff?

Thanks for the comments.
Car is Marina based and I wasn't planning to let it get as far as Steve's picture. Currently "housebound" because it's poorly.
I have checked basic bits of the drive train such as prop shaft securing bolts and protrusions in the tunnel. Spinning the rear wheels doesn't help because the noise only occurs when the drive train is under load. As soon as I lift off, the noise stops.
I hadn't thought of loose brake bits where they fix to the axle. That's certainly worth a look before exposing the diff.
Jim

[CABRIOBOB]

Re: Is it my Diff?

Jim

I would remove the oil filler/level pug and drop a flexie magnet in to see if any fillings come out or use a flexie didgy camera to see inside as a very usefull tool for confined spaces, one of the best tools I ever bought saved thousands of pounds in fault finding, looking in engines/transmisson etc.

[stevejgreen]

Re: Is it my Diff?

Just wondering?

Was it your diff?

[trevor_ford]

Re: Is it my Diff?

Sounds like the same symptoms I was getting before the noises got worse and then the diff self destructed. Initially mine was only noisy on decelleration. Thank goodnes I had a spare and have now found the other one for the next time !!

[j.fernie]

Re: Is it my Diff?

It was the diff - 2 teeth missing from the pinion gear!
All rebuilt now with a new(ish) pinion and ready to go back into the car this weekend.

[stevejgreen]

Re: Is it my Diff?

Did you rebuild your own diff?
I and others have tried with ittle success. Hope it works out for you.

[Mike]

Re: Is it my Diff?

It was the diff - 2 teeth missing from the pinion gear!
All rebuilt now with a new(ish) pinion and ready to go back into the car this weekend.

How did you set the pre-load?

[j.fernie]

Re: Is it my Diff?

Sorry, can't claim any expertise here.
Having tried (and failed) to remove the hubs I accepted defeat before I damaged something and I took the axle to Ian at Apsley Transmissions (in Hemel Hempstead) who does this sort of thing for a living.
He has been in the business a long time and says he used to repair Marina axles on a regular basis. He still had the special hub puller and it was he who provided the replacement pinion (his last spare). He replaced all the diff bearings and seals but left the half shaft bearings in place as they were OK.
Whole thing took 10 days (because he was very busy) and cost less than the quoted price for a recon. diff from Rimmers.
Only time will tell if it works, but it feels right when I spin the hubs - no vibrations or grumbling noises, both of which were obvious when I was trying to take it apart.

[stevejgreen]

Re: Is it my Diff?

You dont need to remove the hubs to get the half shafts out, but the only real way to get them off is with a hydraulic press, the proper BL tool does seem to work fine. The chances are though that yu will need a press to get the bearings off.
Still if you are mobile for less than Rimmers recon diff centre price, thats a plus.

I put lots of info on

http://www.keepandshare.com/doc/4039508/morris-marina-ital-rear-axle-differential-options-pdf-may-26-2012-10-34-pm-81k?da=y