LT77 taper to ball races?

[cresta pa]

Ive heard that it makes for a better gearbox, any one care to comment? thanks

[richyb66]

I suppose it depends on how you define better. They already make a better LT77, the R380. I think it's a given that LT77 boxes are marginal in their standard form (particularly behind a V, but the taper bearings will resist axial load better unless you use an angular contact spherical bearing. Other boxes use spherical bearings so I suppose it should be possible to swap them but unless you could compare the specs of the different bearings, it would be hard to see if there was an advantage.

I've rebuilt quite a few 2WD LT77's (or at least the ones that had anything useful left inside) and pretty much all of them seem to have suffered due to failure / wear of the oil pump

[cresta pa]

The problem with taper bearings in a box is that when you get any wear or the shims get squeezed the shafts drop & the gear teeth mesh too deep, destoying the teeth.

[richyb66]

Yes, as seen in pretty much every LT77. I'm not sure if ball bearings are any more wear resistant than taper bearing though. I think the issue is that most of the wear has already happened well before anyone pulls the thing apart to rebuild it. The original plastic oil pump gears obviously weren't up to the job from day one and I think with metal pump internals and more modern oils, the taper bearing are now more viable that before.

Currently I'm rebuilding a Suffix C box to go in a Cobra kit. It's probably the best I've seen internally, mainly because it's a TR7 box so has had an easier life behind a 2 litre 4 pot. Despite this, it'll still get all new bearings, synchros, oil pump and I'm looking at options for a taller fifth gear set to drop the cruising rpm a bit. I work on the basis that any box that's out of a car is scrap and if it's possible to rebuild it then it's a bonus.