Knowledge Base

Replacing the 5th cog, bearing and synchro on a C52 Mk1 gearbox

Replacement of 5th gear, it's needle bearing and the synchro ring.

These are the parts I bought, plus the shift fork and hub sleeve. Total price was in the region of '200 for the fork, hub sleeve, 5th gear, needle bearing, synchro ring, spacer and snap ring. (ouch) The snap ring (bottom right) was the wrong size so don't use the part number from the picture.

First jack rear of the car up, place securely on stands and drain the gear box oil (24mm socket for the drain and refill plugs). Remove the gearbox end cover, shift fork and hub sleeve as covered in Lauren's KB article. It should be looking like this at this point:

With a screwdriver and hammer tap the snap ring off the end of the shaft, it sits in a groove. You can tap it out a little way and then insert a screwdriver blade between the ring and the shaft and flick it out.

Fit a 3 inch 3 leg puller onto the end of the shaft and link the legs under the hub;

My puller didn't have a cap on it so I placed a small 10mm (cam cover) nut in the end of the shaft to prevent it screwing into the shaft. It's imperative that you make sure that the puller is on straight and the legs are well secured under the hub, if not it'll pop off and fall on your face. That and damage the hub.

Wind the puller in slowly, don't go too mental on it or again it'll pop off. The hub will give a small 'crack' as it comes loose and will then slide off easily still using the puller.

Once the hub is off 5th gear, the synchro and the spacer ring will slide off easily.

A comparison of the old and new 5th gears:

Old and new synchro rings:

Reassembly:

Push the new spacer onto the shaft.

Lubricate the needle bearing with some gearbox oil and place inside 5th gear then slide onto the shaft.

Lubricate the synchro ring and fit onto 5th gear.

Clean up the teeth on the hub and the spline on the shaft.

Fit the hub to the end of the shaft with the thickest centre ring of the hub on the outside, if you look at the second picture you will see that it is actually higher than the toothed part of the hub.

With a 22-27mm 1/2inch drive socket and extension drive the hub onto the shaft, I used a 22mm deep impact socket and it was just big enough (can't remember where or why I bought it). When the hub is far enough down the shaft refit the snap ring. According to the BGB the rings come in different thicknesses to adjust the play in 5th gear, as I refitted to old snap ring I'm not sure what size it was. I have a feeling a thicker one would have been appropriate.

Back over to Lauren's article to refit the hub sleeve and fork (10mm bolt 12ft.Ib torque). Refit the gearbox cover (12mm bolts 18ft.Ib) and refill with oil.