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Gearbox guru required

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2-3 years ago I had a problem with my 64 TR4 jumping out of second gear when not under load. After reading the forum and dismantling the Gbox I found the second gear 'Top Hat' bush was sheared. This was duly replaced and all was well with the world.

Until recently.

Same problem has re-occured.

Just had the box out and low and behold 'Top Hat' bush has sheared again.

Now thinking that sheared bush was effect rather than cause. All the rest of the innards appear fine, no missing teeth or wear marks.

However the rear gearbox mount has done its usual trick and disintegrated, could this be the cause?

Anyone got any suggestions what I should check before replacing the bush and refitting

Also whats the answer to the gbox mount, this will be the 3rd one since I 've had the car

Thanks in advance


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re g-box mount, I would first check if the engine and dif mounts are ok. I have fitted 2 Land Rover engine mounts which have a larger plate hence providing better dampening.


Edited by Geko
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The steel version is used on the later gearbox('73, metric?). I am not sure if you can retro fit to the early box.


Did you check the endfloat after fitting the top hat?


Details here: http://www.buckeyetriumphs.org/technical/Gearbox/GearboxOverhaul1/GearboxOverhaul1.htm





Edited by graeme
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On the point of rear gearbox mounting, the later gearboxes are longer (because they have a thicker front edge), Putting an engine and late gearbox into a TR4 shows that the gearbox mounts holes and the rear chassis mounts do not line up and the chassis mount holes have to be elongated to accomadate the longer box. If this is not done the front engine mounts and the rear gearbox mounts will be under constant tension and will fail. Mind you I dont see why this should stress the 2nd gear bearings. I think this is caused by inadequate oil feed to the mainshaft/ bearing surface which will eventually cause the mainshaft to "weld" itself by friction to the bearing ...and cause the breakage.. at least that happened to my box.


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