Here we go Again! Noisy diff.this time

[FranklinLeicester]

Over the past few months my 1300 (Marina)Roadster has been making a roaring noise from the back end on the over-run. Since I put the hood up after several months of open motoring the noise has got really bad. On jacking the car up and "driving" it there was no noise under these unloaded conditions but when I switched off and let it freewheel to a stop there were all sorts of whirring and grinding noises. There seems to be quite a lot of free play when turning the prop-shaft and when holding one wheel and turning the other, plus quite loud clonks, but, I am not dead sure how much free play is acceptable. Having surveyed the past sagas on this subject on the forum I see I am not the first to suffer diff. probs. Should I strip it down to see if it is a bearing problem before finding another diff or complete axle? I only have a modest engine so I won't need any fancy up-rated kit. However,I see that all sorts of Triumph alternatives have been used. Any advice welcome Except "take the hood off"! Franklin Woodcock.

[stevejgreen]

Re: Here we go Again! Noisy diff.this time

There is no sure way to find out what is going on inside without looking, but for a first step, and it might be too late, try draining and refilling the axle with Hypoy.

Removing the diff centre is a bit of a pain as you need to pull both half shafts partly out at the same time. You need a bit of garage width. It will give you a chance to check the wheel bearings and seals. Everything can be done from under the car.
The diff centre assy carries all the components that wear (in the centre of the diff) so once out you can diagnose the problem but it certainly sounds like a tired, worn gear set.
If you have read past comments about rebuilding diffs yourself you will know it is not an easy task. You can buy the complete gearset but the added cost of a professionally rebuilt unit will pay dividends in peace of mind IMHO.
The TR7 swap works for a 1.8 diff, but for a 1.3, depending as to which of the two ratios you have, will come from a 1300 or 1500 Dolomite. Not the Sprint that uses a different axle. Both are listed by Rimmers as stock who will exchange the old unit. So you can be back on the road in just one day.
It may be time to consider your driving habits, as the lower ratio diff will give lower revs for A road driving and apart from the crownwheel and pinions is dimensionally identical.

You could risk a second hand axle, they are around, but you will be in the hands of the vendor and may end up needing a new diff centre anyway. Again all that would be needed is to swap the centre in situ. You might even be able to eBay your old centre and axle as being repairable.

I hope all this helps.

[FranklinLeicester]

Re: Here we go Again! Noisy diff.this time

OK Steve, thanks for this info. I'll set about it tomorrow and see what goes on inside. In the meantime I'll consider any offers of replacement diff/axle that come along.

[CABRIOBOB]

Re: Here we go Again! Noisy diff.this time

I have been advised that a MG Midget rear axle is the same diff as Marina 1300 but I can not guarantee this.
See item on ebay 170528064478

[lil_red_roadster]

Re: Here we go Again! Noisy diff.this time

MG Midget is the A type axle...totally different to the Triumph-derived Marina axle. IIRC BMC used the A type axle & gearbox on Midgets, A35, Minor etc...usually along with an A series engine. The B type axle & gearbox went in the MGB, Oxford and others, often with a B (or C) series engine...spooky or what..! I'm not saying for sure that it won't fit but I'd be pleasantly surprised if it did.

[stevejgreen]

Re: Here we go Again! Noisy diff.this time

If only....
The Midget A type axle ratio 4.11 sounds right but the axle itself has a different centre assy and spring hangers etc. Always assuming the axle track is about correct as well.
You might has well tackle a Dolomite Sprint axle install with all the work involved.
The Midget and Minor used 4" PCD wheels so that would be another cost to consider.
That is not to mention that Jez has got it right for the applications for an A type axle IMHO.

[donsayers]

Re: Here we go Again! Noisy diff.this time

Small triumph axles had the same diff as the marina; Toledo non sprint Dolomites (Better choice of ratios from this too, the auto has a nice high ration and fits.), 4 speed TR7 and Herald for instance. Reconditioned units are available from Rimmer Bros. I dare say a second hand one could be tracked down. Try Quiller Triumph.

By the time a diff has got that noisy it is well on the way out, and the casing will be full of wear particles and chips of gear tooth; these must be all removed or they will wreck a new diff in short order.

[FranklinLeicester]

Re: Here we go Again! Noisy diff.this time

Thanks for this further info chaps, keep it coming! Spent all morning stripping the thing down but can't get the hubs of even with a big puller. Ah well it's never easy!.

[stevejgreen]

Re: Here we go Again! Noisy diff.this time

You dont necessarily need to get the hubs off. You might be able to just undo the bearing retainers and slide the hub and halfshaft out together.

You only really need to remove the hubs if you are changing oil seals and bearings etc.

[FranklinLeicester]

Re: Here we go Again! Noisy diff.this time

Steve, I like the sound of that. I've just had a look at the job again to fully understand what you are saying. I have taken the 4 screws and nuts off that hold the backplate to the axle but I can't see anything else either on the outside or behind the backplate that would release the hub. Am I missing something obvious?

[stevejgreen]

Re: Here we go Again! Noisy diff.this time

Not the best way to communicate but if you have not given the hub a sharp pull by now and pulled the half shaft out....
If you have not got a slide hammer, a crude way is to use the weight of a wheel and tyre partly bolted on to the hub and given a few sharp tugs.
I have got a tame tyre fitter locally and I have borrowed his slide hammer before.

[FranklinLeicester]

Re: Here we go Again! Noisy diff.this time

Right, can't do anything now till Monday so I'll give it a go with the wheel trick first then try to borrow a slide hammer if that doesn't work.

[b_caswell]

Re: Here we go Again! Noisy diff.this time

B oh no I mean Franklin, You will need to disconnect the hydraulics as the back plate comes with the half shaft and bearing.
If the wheel bearings seem ok its worth repacking them when it all goes back together.

[FranklinLeicester]

Re: Here we go Again! Noisy diff.this time

Thanks for all this help. The shafts came out very easily, one by gently pulling on the back plate, the other by attaching the brake drum and a gentle tug. The diff has got a chipped tooth on the pinion. I now know that my diff is a high ratio 3.6. Morals of the story are:- 1 never go by a workshop manual 2 Read the forum history thoroughly before proceeding. Now on the look out for a replacement diff. At the moment I am on the case with a couple on ebay, but if anybody has got a spare going begging I would be very interested. Thanks again for all your help. Franklin

[stevejgreen]

Re: Here we go Again! Noisy diff.this time

Congrats and comiserations. Once everything is moving its a quick job.
Interesting its a 3.63, not a standard 1.3 axle.

Don's advice on meticulous cleaning now applies as you will have many tiny bits of steel in all sorts of places.
Once you get a working diff centre back in place, fill it with Hypoy and set out for a short trip. Drain and refill it whilst its hot and repeat a couple of times and you should be OK.

If you are looking at the Marina/Ital Caterham diff on eBay, it looks sound. Both on eBay will be a week and a half before you will get them! Dont forget a new gasket!

Rimmers on the other hand claim to have stock and you can have it in place for the bank holiday sunshine!

I do not have shares or have any connection with Rimers.