Lotus Elan

trans rear seal replacement

PostPost by: GLB » Thu Oct 31, 2024 3:47 am

On my way back from LOG in Austin I developed a good leak from the rear transmission seal. I lost about 1 inch of gear oil down from the drain plug. I use a gear oil that is quite green in color so I knew it was gear oil. I had to replace the seal and did not want to remove the engine/transmission to do it. This way worked and may be of some help if you find yourself in the same situation.
I started by cleaning the mess up with spray engine cleaner. I put the car up on jack stands in the drive, removed the right seat and plug in the transmission tunnel for access. The leak was pretty obvious. I sprayed everything in the tunnel and chassis and body underside. After letting it soak I hosed it off with water. It took two cans and it came out nice. The engine cleaner did not disturb the undercoating on my metal chassis.
Removing the driveshaft was no picnic. I had to remove the front torque reaction rods and tip the diff down to get the flange far enough back to get the yoke out of the transmission. Had to lower the transmission to get it to come out and then raise it again to withdraw the shaft from the front as described in the WSM.
I then removed the yoke from the shaft by removing the u joint. The yoke had some slight wear but I polished it on my lathe and it cleaned up nicely and only removed less than one thou. The old seal was also a pain but it came out by destroying it with a chisel. Now how to get the new seal in.
I knew I could not just tap it in through the hole in the side of the chassis. I made a bar that was a sliding fit in the U joint part of the yoke and was long enough to fit between the retaining clips for the joint. In between the joint carriers in the bar I drilled and tapped a 1/2 -- 13 hole and screwed a 1/2 in rod about one foot long. Over this I fit a pipe that would extend out the back of the tunnel by the diff that I could hammer on to drive in the seal. On the part of the yoke that fit in the transmission I machined an aluminum spacer the would fit against the back of the seal and drive it home and stop on the back of the transmission housing .. see pictures.
It worked well after some fine tuning of the length of the pipe so that I could hit it. The seal went in easily but the drive shaft was a pain. Installation was the reverse of removal. New U joint and hope to top off the oil and test tomorrow. Gary
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GLB
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PostPost by: The Veg » Sat Nov 02, 2024 2:09 pm

Nice job Gary! You make it look easy. :mrgreen:
1970 Elan Plus 2 (not S) 50/2036
2012 BMW R1200GS
"It just wouldn't be a complete day if I didn't forget something!" -Me
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