Gearbox thrust washers

[Tim D.]

Hi chaps,

During the RBRR I discovered I had gearbox issues.  Difficulty engaging 2nd and eventually third. Removed the gearbox when I got back and sent it off to a gearbox guru. Was interested to find out what had failed. Turned out to be a failed thrust washer under second. Purely out of interest I was wondering if this is a common fault? The gearbox had less than 10k miles on it after a full rebuild by a well known gearbox specialist. Also interestingly it turns out the gear lever had been shortened. Any idea why this might have been done?

Cheers

Tim

[bob buzzard]

Tim

I'm no expert, but I believe this is a common problem with the bronze "top-hat" bush. The upgrade to a steel part (129939X) is fully outlined in the Moss catalogue (p51).

Something I am keen to do just as soon as I can muster the considerable energy required to remove the box!

 

[dingle]

I am kind of suspicious of the steel bushing up grade. I bought a gear box that was totally "locked". An autopsy showed that the upgrade steel 2nd gear bushing had seized and was welded to the mainshaft. Maybe the oil level was low and the steel bushing is less forgiving than the bronze original. At least I was salvage the OD mainshaft to use as an alignment tool when mating OD gear boxes.

Berry

 

[YankeeTR5]

Tim,  same thing recently happened to my J-type w/brass bushings.  The steel thrust washer for second had crumbled apart...after about 5K on a rebuild.   It was a reused part so I figured it had become brittle or maybe went in reversed (no big deal) but that the stresses it undergoes were reversed and maybe that had something to do with it.  Luckily everything else, except bearings, were good enough to reuse after pulling things apart.

[deryckp]

I had problems a couple of years ago which are now resolved, but what I found was this. The steel bush replacement is only suitable for certain gears. I can't remember now which way round it is and as the gearbox is up and running in the car I can't check, but the problem lies in the position of the oil grooves. I think it is age dependent, but some gears have the oil drilling in the gear through the actual teeth of the gear, and some have it in the bottom of the machined groove immediately alongside the gear teeth. The groove in the steel bushes only lines up with one or the other of these two types of gear. My problem was with third gear, the bush welded itself to the mainshaft and stripped the teeth from third gear. I had to buy a new mainshaft and third gear, and I discovered that the oilways on the new third gear and the steel bush did not line up. I reverted to the brass bush and everything was OK.  Second gear was fine with the steel top hat.

 

Cheers,

 

Deryck