Preparing my for car the next season of having fun at my not so local racetrack. Planning to swap out the open differential for a plate LSD. Got a hold of a used complete pumpkin with less miles on it than my car has. This one looked better than the one on my car as well. Decided to swap the pumpkins around as I'd like to have my spare pumpkin with less wear. I took the newer shinier pumpkin, opened the lid to check everything was OK inside and started to clean away the original gasket. Decided that a proper gasket would be better than the sticky stuff, at least if the lid will be going off again. Made a gasket out of 1.2mm gasket paper, filled it up with oil and made the swap.
Now, as both my differentials are the welded crown wheel type, I have to get a new or used bolted final drive to be able to fit an LSD. This means that I have to remove the pinion completely in order to match the new crown wheel with the new pinion. I could not find much information about this online, so figured I'd create some content to try to explain how I removed all parts from the pumpkin. Getting it all back together correctly will be a different story.
If you're lucky and have a bolted crown wheel, you are blessed and do not need to do all this in order to install your LSD. If you're like me, unlucky, and like to see how things are put together, here is how I did it. Remember to mark what parts come from what side, as the differential bearings and circlips are part of the backlash adjustment.
Parts Overview
Differential Bearing Assembly Sketch
Pinion Assembly Sketch
First I drained the unit of fluid, cracked the back lid open 8x M10 bolts, 16mm head.
Next I pulled the output flanges out, made a small bracket to fit a glide hammer to it. These did not require a lot of force to pull out.
Then I yanked the shaft seals out. These were pretty easy to get out using a spanner and putting half the open end under the seal and using the edge of the output flange "hole" in the differential as a fulcrum.
If you are removing the pinion to replace the final drive, now is probably the most fitting time to undo the 65mm double hex nut holding the pinion in place. I used a hammer and wedged it between the differential and the bottom part of the housing to lock it in place. Secured the housing to a large table using a screw clamp. Then a 65mm socket and a 3/4" ratchet with a 2m pipe as leverage to loosen and remove the nut. This nut is secured with thread locking compound, looked like green loctite. Heating the nut with a torch helps here. Also, this nut does not have links threads like the one connecting the differential to the driveshaft.
I then used a large circlip plyer to remove the inner circlips holding the differential bearings, a light tap on the bearing race helps if these are stuck.
When removing the differential bearings, any rust on the surface for the shaft seal will halt the bearing. These bearings have a clearance fit and if there is no rust on the surface, will slide out easily.
Now the differential can be rotated so the shaft for the planet wheels is vertical and removed from the pumpkin.
Put the pumpkin on its back, with the surface for the lid down against the table. Then hold the pinion while tapping the spline shaft, mine took some force to come out.
I used an internal bearing puller to remove the outer races of the pinion bearings. The front bearing race did not require too much force to pull out. For the rear bearing race, I used two aluminum bars against the surface for the lid as a brace for the bearing puller. This was because it did not seem like a good idea to put the bearing puller forces against the internal lubrication channels of the housing. The rear bearing race required some force to pull out, its also easy to lock the bearing puller on a different edge than the bearing here, so check your tool position before pulling. Behind this race, there was a shim on my diff. This is probably where to adjust the pinion position in relation the the crown wheel to get the teeth meshing correct.
For the inner race of the rear pinion bearing I used a bearing splitter. There is just enough air between the race and the pinion to get it wedged between. I tightened the splitter up pretty good, and started to heat the race with a torch. I then used a hammer on the splitter to try to shock the bearing loose, this was probably necessary because I was a sissy with the torch. After some heating and hammering the bearing started to come off, this was by far the tightest fit of all the bearings and took a lot of force to move.
If anyone has a better way to remove these parts from the pumpkin, please post it so the next guy can benefit from it. I know I could have used it.
That's it, now to get an LSD, some bearings and a new final drive!
Now, as both my differentials are the welded crown wheel type, I have to get a new or used bolted final drive to be able to fit an LSD. This means that I have to remove the pinion completely in order to match the new crown wheel with the new pinion. I could not find much information about this online, so figured I'd create some content to try to explain how I removed all parts from the pumpkin. Getting it all back together correctly will be a different story.
If you're lucky and have a bolted crown wheel, you are blessed and do not need to do all this in order to install your LSD. If you're like me, unlucky, and like to see how things are put together, here is how I did it. Remember to mark what parts come from what side, as the differential bearings and circlips are part of the backlash adjustment.
Parts Overview
Differential Bearing Assembly Sketch
Pinion Assembly Sketch
First I drained the unit of fluid, cracked the back lid open 8x M10 bolts, 16mm head.
Next I pulled the output flanges out, made a small bracket to fit a glide hammer to it. These did not require a lot of force to pull out.
Then I yanked the shaft seals out. These were pretty easy to get out using a spanner and putting half the open end under the seal and using the edge of the output flange "hole" in the differential as a fulcrum.
If you are removing the pinion to replace the final drive, now is probably the most fitting time to undo the 65mm double hex nut holding the pinion in place. I used a hammer and wedged it between the differential and the bottom part of the housing to lock it in place. Secured the housing to a large table using a screw clamp. Then a 65mm socket and a 3/4" ratchet with a 2m pipe as leverage to loosen and remove the nut. This nut is secured with thread locking compound, looked like green loctite. Heating the nut with a torch helps here. Also, this nut does not have links threads like the one connecting the differential to the driveshaft.
I then used a large circlip plyer to remove the inner circlips holding the differential bearings, a light tap on the bearing race helps if these are stuck.
When removing the differential bearings, any rust on the surface for the shaft seal will halt the bearing. These bearings have a clearance fit and if there is no rust on the surface, will slide out easily.
Now the differential can be rotated so the shaft for the planet wheels is vertical and removed from the pumpkin.
Put the pumpkin on its back, with the surface for the lid down against the table. Then hold the pinion while tapping the spline shaft, mine took some force to come out.
I used an internal bearing puller to remove the outer races of the pinion bearings. The front bearing race did not require too much force to pull out. For the rear bearing race, I used two aluminum bars against the surface for the lid as a brace for the bearing puller. This was because it did not seem like a good idea to put the bearing puller forces against the internal lubrication channels of the housing. The rear bearing race required some force to pull out, its also easy to lock the bearing puller on a different edge than the bearing here, so check your tool position before pulling. Behind this race, there was a shim on my diff. This is probably where to adjust the pinion position in relation the the crown wheel to get the teeth meshing correct.
For the inner race of the rear pinion bearing I used a bearing splitter. There is just enough air between the race and the pinion to get it wedged between. I tightened the splitter up pretty good, and started to heat the race with a torch. I then used a hammer on the splitter to try to shock the bearing loose, this was probably necessary because I was a sissy with the torch. After some heating and hammering the bearing started to come off, this was by far the tightest fit of all the bearings and took a lot of force to move.
If anyone has a better way to remove these parts from the pumpkin, please post it so the next guy can benefit from it. I know I could have used it.
That's it, now to get an LSD, some bearings and a new final drive!
