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MG MGB GT V8 Factory Originals Technical - Gearbox problem

After many years of service my LT77 is showing signs of trouble. Firstly I started to feel a small knocking through the gear lever whenever I changed into 2nd, but nothing whilst actually in 2nd. A couple hundred miles later and I have a rhythmic, speed dependent, audible clunking when in 2nd and a light rattle through the lever when changing from 3rd to 4th. Oddly enough the clunking in 2nd disappears if I apply slight pressure to the right hand side of the gear lever. I understand little about gearboxes and any clues to the cause/remedy would be more than welcome.

If it's terminal(!), which is the easiest to fit in place, the T-5 or the R380?

Many thanks, David.
David Canning

If you're doing a straight swap, the R380 is infinitely easier. You'll use the same bell housing, clutch slave, clutch mechanism, driveshaft, crossmember and probaly the gear shifter itself too.

With the T5 you have to change all of those things....
Justin

R380 without a doubt.

I'm not an expert, but I have this box in my B GT V8.

There are I believe a number of variations of the 2 wheel drive R380 however they all have the same ratios except for the version used in the DAF van which has a slightly lower 2nd gear.

The 28A has a long remote and is used in the Morgan & TVR V8

The MG RV8 used the 18A which has a short remote as do the versions of the box used for the T16 Morgan(24A), Chengdu (21A)and TVR 3.9 (20A).



Nigel Steward

Nigel, What the heck is a Chengdu ?

Mike
M Barnfather

Try http://www.austin-rover.co.uk/index.htm?huanduf.htm
greg fast

David
I had something very similar to your noises. I would first check the 4 off little (20mm dia) gromment type soft mounts on the gear change extension, top of box, they are designed to locate/clamp to main box and remove a lot of vibration.
You should be able to see/feel them with gear lever boot removed, the rubber tends to go all soft and gooey. To change them the box does not have to be removed, starter etc. does though but it is quite fiddly, you have to work from under the car.
To check, when changing gear try to lift lever. What could be happening, the underside of extension is just touching prop UJ which gives the engine speed knock. Of course I could be talking a load of rubbish, but it might help. Please feed back outcome.
Richard
Richard Evans

Thanks guys, looks like the R380 is the easiest and most economical route should all else fail.

Richard, the fact that the clunking stops if I apply light sideways pressure to the gear lever suggests you may be in the right ballpark. I'll jack the rear wheels off the ground and see if I can replicate/locate the noise in the garage.

David.
David Canning

David,
If cost is an issue you may want to consider a rebuild of your LT77.... http://stores.ebay.co.uk/Transmission-Rebuild-Kits
Pete
Pete Green

Well played Richard! Got down and dirty under the car last night, the lower 2 of the grommets that you mention have perished and allow the extension to wobble around, just enough to touch the prop UJ and make the noise.

It's amazing how elated one can feel when the prospect of spending the thick end of £2,000 turns into the cost of a couple of grommets.

I've yet to remove them but are these special grommets and if so where can I find them in the UK.

Thanks again, David.
David Canning

As a side issue, when I removed the gear lever gaiter, I noticed that the ball cap was loose (the retaining bracket and bolt nowhere to be seen).

What difference does the ball cap make and is it necessary to replace it?

Thanks David.
David Canning

David,

You can get them from Rommer Bros. http://www.rimmerbros.co.uk/cgi-bin/rimmer?sd1/transmission-manual
Plastic (original) p/n UKC854 £1.90 inc. VAT or Polyurethane (longer lasting) p/n UKC854POLY £2.29 inc. VAT

Geoff
Geoff King

Thanks Geoff, I see they do the ball cap as well. Cheers.
David Canning

David
I apoligies for not getting back to you earlier. I had to get some work done!! Anyway I see Geoff King sorted you out with the correct info
If the ball cap is missing you will proberbly also be without the anti-rattle spring and nylon plunger which engages in the side of the ball. This assembly stops the gear lever buzzing. The screw which holds the cover is clamped with a 1/4 UNC screw, the hole it locates in might have the thread stripped! A longer screw should pick up a few more threads at the bottom, with a nut on the under side to clamp it if required.
Good Luck
Richard
Richard Evans

This thread was discussed between 23/05/2005 and 27/05/2005

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