Gear box rebuild day. The bearings I ordered arrived from RD Enterprises right on time (I had already ordered a complete gasket kit and the two oil seals). I headed over to Drew's shop (he has more tools & is better equipped than my shop) where he already had the gear box. Classic Drew, he had everything laid out and plastic down on a work bench to dismantle the gear box. We both had read the workshop manual and reviewed the exploded view of parts a number of times.
The question I posted on this forum about replacing the bearings got minimal response but two people brought up using a dummy shaft to remove and install the lay shaft. A couple of people said to leave the gear box alone. Thought about this a number of times, don't touch it, but the input shaft had a lot of play in it and now was the time to install new bearings, not later on when I would have to take the trans out again. Besides, it was leaking some oil and I wanted to try and minimize that.
I'll start by saying I'm glad I ventured down this path of rebuild. The input shaft bearings were very loose and the probable reason was the large nut holding the speedometer gear and main gear box shaft was not tightened to spec. As a matter of fact, it was several turns too loose causing the shaft to move back and forth, hence the reason for the sloppy bearings. Over all the gearbox was in very good condition. All the gears looked great (was rebuilt in 1984) and the syncro's all looked good. No metal in the bottom of the box.
We dismantled everything except the reverse gear shaft. Each and every step was photographed and I'm glad we did as there were a number of times we needed to go back and refer to the photos to make sure of the location of things.
Most of the rebuild was straight forward and anyone with fine mechanical skills, patience, a good memory, the factory manual and a decent shop with a press could do this. Couple of things needed to be paid attention to: there are some very small pieces that fit in locations that aren't so obvious. Loosing them or misplacing them would be easy. The syncro's need to be assembled in a very specific way and have a number of moving parts that require detailed attention. The removal of the lay shaft went easier then we thought including replacing all the roller bearings and reinstalling the lay shaft.
At the end of the re-assembly we realized that we didn't put one of the syncro's back together properly so the entire gearbox was disassembled again (we are now very good at this) and then reassembled. Before safety wiring the shift rod bolts we went thru all the gears while turning the input shaft. Everything was functioning very smoothly and we were very proud of ourselves until 4th gear........
When we put the gear shift lever into 4th gear there was a metal to metal rubbing noise. We went over it again and again, re-read the shop manual, had fiber optic lights in the gear box trying to figure out what wasn't right. We were almost ready to disassemble the gear box again when I asked Drew for a beer. Time to think it over with a cold one. We had been at this for 7 hours and needed perspective. On the second beer we realized the steel ball detents and springs weren't installed and they would prevent the fourth gear rod from moving too far forward and not allow any metal to rub. A dry install (no gaskets with sealant) proved this right. Phew!
Cleaned all the surfaces that had gaskets, trimmed a few gaskets as they didn't quite fit, used 832 sealant on both sides and put sealant on all bolts as the go thru the gearbox and are prime for leaking. Installed the two shaft seals. All that needs to be done now is paint the entire gear box and install!
Chancer had responded in my other gearbox bearing post that you don't need a press (
lotus-gearbox-f37/replacing-bearings-speed-gear-box-t34411.html). Some pin punches, drifts and cold chisels are all you need. I would say that is correct, plus some skill and patience!
- 4 speed gear box to be dismantled
- Shift rods
- See that small pin. Don't loose it!
- Shift rod order. One of them has a sleeve
- This nut was several turns too loose
- Gear and syncro order
- Location of needle bearing to be replaced
- Pressing bearing on
- Installing needle bearings
- Input shaft oil seal