4 Speed Gearbox rebuild

[miked]

Rohan,
I used to use strings for lay cluster but found it easier to just turn the box over onto its flat top face. Give a little rotation on the shaft and all drops almost in place. I have little centre drill holes in the end of my dummy lay shaft. So all I do then is put my dental pick thing in the bellhousing end hole and centre the dummy lay shaft and push the real shaft in. Lot easier in my opinion. You can see all the thrust washers are there.

Cheers Mike

[rgh0]

Rohan,
I used to use strings for lay cluster but found it easier to just turn the box over onto its flat top face. Give a little rotation on the shaft and all drops almost in place. I have little centre drill holes in the end of my dummy lay shaft. So all I do then is put my dental pick thing in the bellhousing end hole and centre the dummy lay shaft and push the real shaft in. Lot easier in my opinion. You can see all the thrust washers are there.

Cheers Mike

The idea of using some thing to centre the dummy shaft in the holes sounds good. I will turn a tapered centre hole in my dummy shaft and make a short second dummy shaft to push in from the front to match it and centre the dummy shaft correctly. I attach the strings to bolts with a lock nut screwed into the centre case top cover holes and then turn the bolts and hold them with the lock nuts to wind the strings up to position the layshaft correctly, otherwise you need about 6 hands to pull up on the 4 strings and then tap in the layshaft and push out the dummy shaft

cheers
Rohan

[rgh0]

Time to correct the error I made in putting the 1/2 selector fork in backwards

Disconnected the rods from the forks and moved them all back out. I removed the small pin in the 1/2 rod as I pulled it back to ensure I did not loose it. Also check the plungers in the casing holes between the rods stayed in place.

remove reverse fork and the 1/2 fork and rotated the fork and refitted and refitted reverse fork and then slid the rods back in ensuring all the interlock pins and plungers went back in place correctly. You can see when 1st gear selected the fork boss on the 1/2 centre shaft stops at the casing

Rewired the securing bolts between rods and forks and retested that selection of all gears is still OK, gear box in neutral in this position

Now assembly of top cover. I needed to use small 1mm brass shims to bring the detent ball springs into the specified range of 8.5 to 9.5 mm above the cover

Refitted and bolted down the cover using the paper gasket and aviation gasket cement

Gear box now complete just need to swap the bell housing and gear change from the box I have removed from the Elan that is now due it overhaul to be ready as my spare. The reverse gear rod moves very easily forward until the top cover is fitted with the interlock balls and springs as no synchro hub to engage like the other gears so you need to be careful when fitting the gear change that it is still in neutral and that the drop link in the gear change cover correctly engages the cut out in the rod.

The new box will go back in with the rebuilt engine that is 75% done and that I will now get back to finishing . First race meeting since the Covid lockdowns in Victoria at the start of March 21 so I need to get a move on a a few other things I want to do to the car before then also.

cheers
Rohan

[joe7]

One thing to do when installing the shift forks and rails is to check the clearance on the 3/4 shift tube stop at 3rd to prevent overriding the syncro hub. Lotus used a few different types of "tubes". 1st was just a "tube" too short, 2nd was a "tube" with a "clip" to get the stop correct and the final reiteration was a proper length "tube".

[miked]

Thanks Joe, I was unaware of the 3 types. I sorted the clip ones with the short tube and the last correct ones. Since you mentioed on my last post, I look down the detent ball hole for the centre of the groove in the rail to make sure the thing is correct.
☺

[vstibbard]

Rohan, a great thread to follow, will you be fitting a vent to allow moisture out of the box? The std method had a drilled bolt with wobbly cover to allow it to breath on one of the front cover bolts from memory.

V

[rgh0]

Yes i have a breather bolt with the hole and metal cap . They were fitted originally on one of the rear bolts on the gear change I believe, well away from most of the oil spray from the gears and bearings being in the tail housing.

cheers
Rohan

[vstibbard]

They were although as heat rises the moistures tends to form up in the highest point of the box towards the front.

V