04-28-2004, 10:07 AM
Join Date: Dec 2001
Location: Cleveland Heights, Ohio
OPinions are like --- ----- and everyones got them, BUT-here si what I think is the best way to build a diff for a Tc3 and now a pro4. And there will be lots of opinions here!!
For running Mod I do think it beneficial to sand the diff rings with 600 grit. I gave up-resanding used diss. I flip it over and then toss-em.
For stock-I just make sure they are clean.
I build the thrust assembly witha BIG doughnut of Associated black grease and push the balls into it. I then put a thin bead on top and put the top washer in place.
ON the gear-I put a good size drop in every hole that the diff balls go into with Associated Stealth lube. There are other diff lubes that build a smoother diff-but who cares if you have to overtighten the diff to get it tight. I want my diffs to feel like they are loose as a goose when rotating opposing wheels, but be locked when hlding the spur. NO grease on the rings!!!
I then place all the balls into the gear and usually put a small layer of stealth lube on my finger tip to help pick them up. I usually clean my finger tips with motor spray before starting too. Sick-but oh-well. I used to clean Karts when I was a kid with acetone-so I am already toxic.
I assemble the diff and spin the diff halves together untill I get them to seat lightly. I now spin the gear untill I feel the action get buttery smooth. Now I spent the next few minutes slowly tightening and rotaing the gear till my finers turn red and I leave sufficent DNA behind on the gear. I hold the diff halves with my Parma allen wrenches in one hand and spin the gear with the other. When i thik they are locked-the front more than the rear-I install them and check them with wheels on, diff halves tight. Etc. Time consuming-but the best.
Anyways-The final step is to either run them in by putting the right wheels on the table and letting the left ones spin and them do the other side-or do it on the track. NEVER let a diff slip audibly with a mod in it. Bye-bye diff balls and rings.
Ialso have used the Associted diff spring over the HPI one. I thnk it helps.
but one thing I have noticed-is you really need to tighten the diffs in the Pro4 more than you think is enough because they do loosen up. I think they stop loosening once yu finally have them tight enough to get sufficient pressure on the assembly to keep the nut from backing off (i.e. compress the diff spring enough)