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MG MGB GT V8 Factory Originals Technical - LT77 gearbox vibration

Hi there,

I have an LT77 gearbox in my MGB79 with a Vitesse 3.5 engine. The gearbox have started to display vibrations at standstill thru the gearstick, @ 2500rpm while the clutch is engaged. The vibrations disappeares when the clutch is disengaged.
There is also a harshness or a diffuse vibration transmitted thru the hull of the car while driven.

Does any of you have any clues of what´s wrong.

If I do have to change or repair the gearbox. Is it possible to remove the LT witout lifting hte engine.

Thanks in advance

Erik
Erik

Erik,

sounds like a problem with the clutch or the trust plate. I never tried to remove the LT77 from my B but can not immagine that it will work without pulling the engine. You should also think upon it's wight (48.5 KGs) when trying to do so.
Before you start to dismantle everything, check the U joints of the propshaft first.

Ralph
Ralph

Erik,

By all means check all the easy things like mountings and u joints and bolts but, if the vibration is present with the gearbox in neutral with the clutch engaged then unfortunately I thing it's more likely to be a main shaft bearing and I would not drive it until you get it checked over.

Kevin.
Kevin Jackson

Eric,

It is possible to remove the LT77 box from the car without removing the engine, I've done it once under the direction of a Rover Sd1 specialist in a workshop, I think it would be difficult without the use of a hydraulic lift, and I had to use two hydraulic supports...one to hold the engine and the other to steady the gearbox.

M Barnfather

Thanks for the advice,

Seems like I´ll have to retire the car early into hibernation. I saw some adverts on E-bay where a company sold bearingkits for the LT77. It was supposed to fit the suffix D gearbox. My LT does not have any gearboxnumber at all.

Cheers
Erik
Erik

Eric,

I overhauled my LT77 and its a difficult job because the mainshaft exsist of 2 shaft which have to be fitted under a specific preload and this preload has to be set with a specific shimthickness. I overhauled mot gearboxes but this wasn't an easy one. I must say that its very smooth and also shifting is easy when cold. I saw more LT77 and most of them don't habe the bearing preload.
Regards
Peter
Peter

This thread was discussed between 29/08/2007 and 30/08/2007

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