4 Speed to 5 Speed

[JSutton1]

Getting serious about this now.

Want to have a 4 speed shaft reworked to work with 5 speed.

Question:

Can I transfer the drive flange from the 4 spd to the 5 spd trans so it matches the 4 spd drive shaft?

I saw that there is a boot that can be used to replace the original boot on the 4 speed shaft?

Thanks everyone!

Jim

Jim

[Workshop Help]

Question 1. No. Consult with your favorite drive shaft shop about using the two ends of your 4 speed shaft with a longer center piece. The LT77 drive flange is the same bolt pattern as the four speed gearbox. It is the flange on the five speed differential that is different.

Question 2. The boot you refer to is from an old Mini. Buy a couple of them and have one installed on the modified drive shaft during the Big Stretch.

I do hope you will be using the four speed differential.

Mildred Hargis

[JSutton1]

Yes I want to use the existing 4 speed rear end.

Do I understand correctly that I need to transfer drive gear for the speedometer cable to the 5 speed?

Jim

Jim

[Workshop Help]

Maybe. It is possible your LT77 may have the same speedo drive gear as the 4 speed box. Please look in your V-B catalog in the transmission section. Observe the different colored gears and their teeth number for the different 5 speed applications, then note the 4 speed item.

Remember, 4th gear on both the 4 speed and 5 speed are the same direct drive ratio. For the 3.63:1 differential, use the 4 speed speedometer drive gear.

Mildred Hargis

[JSutton1]

I plan on rebuilding the 5 speed before I install it. I did the same to the 4 speed when I restored the car. I had no troubles rebuilding the 4 speed but I have heard the 5 speed is a little more involved.

My concerns for rebuilding are that I have no idea of the condition in the 5 speed. Also want to make sure oil pump is good and that it doesnt have any damage from towing. Anything else I should look for?
Prob replace the syncros also.

I really love all the informatin available on this site. Its a big help.

Jim

Jim

[Workshop Help]

Overhauling the LT77 is no big deal. Your parts list will most likely entail; the three gaskets, the front & rear oil seal, the rear mainshaft ball bearing, (Be sure and replace it with a bearing shielded on one side to keep road grit from entering.), and the oil pump.

The condition of the synchro baulk rings depends on how they were abused. That small front mainshaft bearing should be replaced, too. The rest of the bearings and races will need close examination. You will find a pile of swarf packed into the recess below the oil pump. All this needs to be completely cleaned out.

I suggest you study the V-B catalog views of the LT77 gearbox to get an idea of what's in there. Also, study in depth the factory service manual section on gearbox overhaul and dig deep into the internet to review hands on video of the tear down. The more you study the task, the easier it will be to accomplish.

I like the LT77. It's cast iron case is very strong and very heavy. This is a good thing in my eyes as it holds everything securely in place. Being heavy, you will need a strong spouse to help hoist it back into place. On the first fill of gearbox oil, I suggest you use 1 1/2 quarts of ATF. This will clean out any remaining filth and ease the wear patterns as the new parts adjust to their neighbors. After 1500 miles of somewhat easy driving, change the oil to the Penzoil MTF in the yellow bottle.

I'm getting ahead of things here. Please report back should question arise.

Mildred Hargis

[Beans]

Most important with the LT77 'box is to get the end float of both shafts correct ...



Also check for damage on the gears especially 1st and 2nd ...



And wear on the main shaft ...



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[JSutton1]

Will report back on my progress. Thanks for all the help so far.

Jim

Jim