12-11-2018, 08:12 PM
Due to an increasing quantity of oil escaping from the rear hubs I took the decisions to pull out my differential and strip it down. The quantity of oil was not massive, but it was annoying as it ended up on the rims and dangerous as it was coating the brake drums.
A few things;
Firstly, I was surprised to find no evidence of the inner seals. The cups and washers were all there but no sign of a felt seal or a more modern lip seal, the adjusters are the basic type with no oil return spiral. Interestingly the axel tube was oily but certainly not swimming in oil as I thought would be the case. The car has done at least 750km since I last checked the diff oil level and it still seemed pretty good when pulled it down. I’ll be putting new lip seals back in but my takeaway lesson is that in my diff at least the oil does not readily want to move from the differential to the axel tubes.
Upon stripping the unit down, I found that the axels were in poor condition with cracks and flogged keyways. Lesson two, keep an eye on the retaining bolts and make sure they are nipped up tight, mine had obviously had some movement.
Next I found missing paper seals between the inner and outer hubs but a good glob of silicone. When re-installing I’ll be putting in a paper seal with a smear of Permatex or similar. I had considered taking the wheel nuts off and lapping the inner hub to the outer hub but not sure if that’s really necessary if the inner seals are working as planned. Any thoughts from those experienced?
The tapers inside the hubs were extensively pitted and thus needed a lot of lapping to get a sound fit of the hub to the axle. Using a coarse lapping paste I spent about 30 minutes trying to get a decent surface but the pitting was so widespread and deep that I was a long way from getting the homogenous result I was looking for. To speed things up I attached the hub removal tool and spun it with a drill (see below). I used a small screw driver to provide a linkage between the drill and the hub, if I’d had a spare ½ UNC and lathe I’d have made a more professional connection. I lapped in both directions and continually stopped to remove paste from the keyway and deposit it back on the shaft.
My question is this; will lapping in the above manner cause issues later? I have heard from people a lot more experienced than me that the lapping should be done with small side to side movements keeping the keyways semi-aligned, i.e, when lapping the movement should be no more than say 45 degrees from the final location. But I’ve also seen tapered joints lapped on lathes.
Any thoughts would be well received.
A few things;
Firstly, I was surprised to find no evidence of the inner seals. The cups and washers were all there but no sign of a felt seal or a more modern lip seal, the adjusters are the basic type with no oil return spiral. Interestingly the axel tube was oily but certainly not swimming in oil as I thought would be the case. The car has done at least 750km since I last checked the diff oil level and it still seemed pretty good when pulled it down. I’ll be putting new lip seals back in but my takeaway lesson is that in my diff at least the oil does not readily want to move from the differential to the axel tubes.
Upon stripping the unit down, I found that the axels were in poor condition with cracks and flogged keyways. Lesson two, keep an eye on the retaining bolts and make sure they are nipped up tight, mine had obviously had some movement.
Next I found missing paper seals between the inner and outer hubs but a good glob of silicone. When re-installing I’ll be putting in a paper seal with a smear of Permatex or similar. I had considered taking the wheel nuts off and lapping the inner hub to the outer hub but not sure if that’s really necessary if the inner seals are working as planned. Any thoughts from those experienced?
The tapers inside the hubs were extensively pitted and thus needed a lot of lapping to get a sound fit of the hub to the axle. Using a coarse lapping paste I spent about 30 minutes trying to get a decent surface but the pitting was so widespread and deep that I was a long way from getting the homogenous result I was looking for. To speed things up I attached the hub removal tool and spun it with a drill (see below). I used a small screw driver to provide a linkage between the drill and the hub, if I’d had a spare ½ UNC and lathe I’d have made a more professional connection. I lapped in both directions and continually stopped to remove paste from the keyway and deposit it back on the shaft.
My question is this; will lapping in the above manner cause issues later? I have heard from people a lot more experienced than me that the lapping should be done with small side to side movements keeping the keyways semi-aligned, i.e, when lapping the movement should be no more than say 45 degrees from the final location. But I’ve also seen tapered joints lapped on lathes.
Any thoughts would be well received.
Steve & Tate Davidson
Perpetual Amateur Austineers
Perpetual Amateur Austineers