C64-gearbox-rebuild


C64-gearbox-rebuild

All parts for the renewed heater/aircon project have landed, including a by-pass valve for the heater matrix and components for an electric circuit to activate the by-pass when the heater flap is set to the lowest values. More about that in a later update.

Meanwhile i have started to disassemble the newly acquired spare C6x gearbox, which comes from a UK toyota celica TS of some sort and was supposed to be a C64 box (Lotus gear ratio for 6th) instead of a C60 box. The casing is stamped as a C60 box, but counting the teeth of the 6th set it is a short Lotus gear.

I have the rebuild manual for the C6x box at hand and a good youtube series to go with it.

The idea is to measure and adjust all tolerances on this spare box, refurbish it and assess its noise in comparison to my current box, which works just fine, but makes some noise on the overrun – as they all do when the miles rack up. I do track my car, but am still looking for perfection technically and cosmetically. Secondly, i want to understand how a gearbox works and want to be able to refurb them myself.

So here goes:

The 6th gear has 31/38 teeth, so .815 gear ratio, that is a C64 Lotus ratio! Wouldn’t have mind if it was the .725 C60 ratio but OEM is ok for me now.

It takes some heat and a puller to get the shifter off but no drama so far.

Next task is tolerance measurements (radial an axial) on the 5th and 6th gear to check its roller bearings and syncro’s.

All values in tolerance although the axial tolerance of the 6th gear is at the high end. May want to compare that with a C60 6th gear set.

The 6th can be pulled with a 3-jaw puller

The 5th needs a different puller, Toyota SST style. So far all tools are freely available in the hardware shop.

A third puller is required for the slider assembly of 5th and 6th.

After this stage the box can be opened. One of the support bearings wasn’t cooperative to slide out of the middle casing but it worked out in the end.

It is interesting to see that the syncro’s of 3rd and 4th are both on the ingoing shaft and can be replaced by ‘just’ pulling one bearing (4th) and the slider assembly (3rd). (After having pulled the endbearings and 5th and 6th of course to open the casing.)  By the looks of the color of the syncros i get the impression that the 3rd syncro has been replaced before.

The 2nd syncro is on the far end on the outgoing shaft so needs lots of pulling to get there. 1st gear hasn’t got one.

The reverse idler just slides in between the straight cut teeth gears of both shafts whenever selected. The other gears are in neutral at that time (not coupled gears on either end of each pair.)

Random notes and links:

http://www.armstrongfamilyblog.com/armstrongracing

http://www.armstrongfamilyblog.com/the-ar-gear-exchange.html

http://www.armstrongfamilyblog.com/armstrongracing/toyota-yaris-6-speed-swap-part-1-the-c60-tear-down