The Triumph Dolomite Club - Discussion Forum

I have been trying to undo the diff plug on my dolly to check and refill, to try and cure or lessen the clunk i'm getting when coming to a halt! Changed the transmission oil earlier and its no better, so diff the next best thing to try, but can't shift the damn plug! Have got a new plug ready from Rimmers as noticed it was chewed up earlier in the week, any ideas how to shift it, tried mole grips, stilson type pliers, a bit of heat, not too much as too near fuel tank, it just wont free off! Last thought is it a reverse thread?
Cheers Rich

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1981 Dolomite 1500 Auto

Personally I'd just take the diff cover off and get it in a vice or something....a much easier proposition when you're not on your back under the car lying in a puddle I would imagine!

Find the nearest fit in your metric sockets then hammer the next size down on. It might well ruin the socket but nobody uses metric do they?

The clonk is unlikely to be cured by changing the oil. More likely to be lash (in decreasing order of likelihood) in the diff, prop or gearbox.

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1978 Pageant Sprint - the rustomite, 1972 Spitfire IV - sprintfire project, 1968 Valencia GT6 II - little Blue, 1980 Vermillion 1500HL - resting. 1974 Sienna 1500TC, Mrs Weevils big brown.

Had another 3 hours at trying to free it this afternoon..no joy!! The rear diff cover at the back seems solid, it's a 1500 auto. Tried sockets, heat, various grips, and wrenches of all descriptions. Really stuck with it now as not much of the square left to grab on to. It's got to come out as last time it's in history was 2009 at 42k that was just a top up, now at 54k but 6 years on, so either bound to need changing or filling, and as I've changed all other fluids this is the only one I haven't been able to crack as yet!
Cheers Rich

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1981 Dolomite 1500 Auto

I had this problem on my Sapphire Cosworth. I ended up welding a big nut onto it.

I would stop wasting your time. If there is no evidence the oil has leaked then it wont need topping up.
There is no drain plug on these diffs so even if you get it out, you cant drain it unless you want to suck it all out somehow.
The most likely leak point is the pinion oil seal at the propshaft flange. If this is dry it isnt leaking.
The clonk you describe is either diff backlash or a prop-shaft u-j could be on the way out.
Give the filler plug a good soak with plus gas. After a day or two try again with a proper fitting 8 or 4 point socket.
You may need to file it square again if its damaged. I've never known one seize in like this.

The other guys were talking Sprint diffs which are different to the axle cases used on other dolomites.

Jonners

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Note from Admin: sadly Jon passed away in February 2018 but his humour and wealth of knowledge will be fondly remembered by all. RIP Jonners.

Jonners, just seen your post and wish I'd have left it alone! took it to local garage and they welded a nut on and got it out after 3 attempts but the threads are stripped, so someone at some time has butchered it in, which explains why the plug wouldn't budge and when it did start to go had to get screw driver behind it to help it out!! Also oil poured out so how can you over fill it and manage to ram a plug in and still have that much oil in it? Dont make sense in my eyes! So my question is what do I do now? can anybody tell me what thread the plug is and if I could possibly tap it out? If not what are my options? Heres hoping, Cheers Rich..

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1981 Dolomite 1500 Auto

Hi Rich, I've put a thread gauge on my spare 1850 diff; plug and it looks like 19TPI but the external diameter varies as the plug is tapered. But the average is 0.600 to 0.670 ins. so my guess is 3/8 in BSP(T) i.e a tapered BSP thread.
I'm not sure how one of these is tapped into the axle casing but if you P.M. trackerjack on here I'm sure he can advise. He has a lot of experience in these things. Is that O.K. please Jon ?
HTH,
Tony.

Thanks Tony,but I managed to get a tap from Cromwell tools in Coventry yesterday! I re cut thread and although not perfectly square it sealed and has not leaked a drop overnight, and have done approx 20 miles in her since! Cannot praise these guys at cromwells enough, tap they provided was as follows 3/8-18NPT HSS TAPER PIPE TAP, I just taped it off when measured against the plug tapped to that depth and job done..
Rich

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1981 Dolomite 1500 Auto

Well that was short lived! Went to garage to get car out having left her for almost 48hrs and oil on plank I had left under just in case..So back to square one, Have tapped hole again but cannot get plug to go in square, had to walk away and leave it tonight.. the problem seems to be that the plug is not going in square or far enough, so taper isn't taking effect. Dont seem to be enough material inside to cut the thread!
Rich..

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1981 Dolomite 1500 Auto

Put a wanted ad out for a second hand diff cover and filler plug...

Not a cover I dont think, the back of diff is solid, no bolts at back!! Got another new plug yesterday and re cut the thread again as noticed the thread was a bit botched at 1st turn, and been 24hrs and no leak, but took 48hrs for it to show before! Checked it twice today, and hopeful but not speaking too soon this time!
Rich

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1981 Dolomite 1500 Auto

I thought from memory that it had an axle swap once.

Jeroen

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Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

I had this same hassle on an Escort once.
Easiest way round is to get your garage to weld a nut over the top of the original thread to take a sump plug and copper washer from something modern. You only need a few tack welds to secure the nut, then use something like chemical metal to seal it.