Hector_Fisher
Very Active Member
I first identified the problem with my Bullet's plastic diff cases. The plastic side where the drive cup exits would wallow out, creating big enough gaps for the internal diff fluid to leak by. Went through half a dozen diff cases that leaked out all of the diff fluid to figure out the same thing was going to keep happening and that I needed a long term, durable solution.
After purchasing a few types of tubing off the webs, I found steel capillary tubing is much truer to spec than other types of tubing. It has a very good fit with my 5mm drive cup shafts. For my case I used 5mm ID with 1mm wall thickness tubing. The sleeve is only about 5mm long, so it doesn't affect the internals of the diff. Also, most diff spurs are steel, so it would match what the other drive cup was experiencing.
The process:
Drilled out the old hole in the plastic diff case. Didn't drill all the way through on the second diff as i wanted to leave the o-ring seating surface untouched to see if it performs better than the first or if it affects service life of the o-ring in any way. Used a two part epoxy to secure the full length tube in. Once cured, I cut off the unused tube length and ground a good inside chamfer and polished the ends til they were smooth to the touch. The trick is to make sure you don't use excessive epoxy so that it "squishes" out into the tubing and to try not to mess with any o-ring seating surfaces.
First diff had already held up fine to about 10 packs. Absolutely no leaking. Very pleased with the results, and I'll try to update with either diff if I run into any issues.
After purchasing a few types of tubing off the webs, I found steel capillary tubing is much truer to spec than other types of tubing. It has a very good fit with my 5mm drive cup shafts. For my case I used 5mm ID with 1mm wall thickness tubing. The sleeve is only about 5mm long, so it doesn't affect the internals of the diff. Also, most diff spurs are steel, so it would match what the other drive cup was experiencing.
The process:
Drilled out the old hole in the plastic diff case. Didn't drill all the way through on the second diff as i wanted to leave the o-ring seating surface untouched to see if it performs better than the first or if it affects service life of the o-ring in any way. Used a two part epoxy to secure the full length tube in. Once cured, I cut off the unused tube length and ground a good inside chamfer and polished the ends til they were smooth to the touch. The trick is to make sure you don't use excessive epoxy so that it "squishes" out into the tubing and to try not to mess with any o-ring seating surfaces.
First diff had already held up fine to about 10 packs. Absolutely no leaking. Very pleased with the results, and I'll try to update with either diff if I run into any issues.
