1QuickPro2

iTrader: (25)

I'm having a hard time finding the sweet spot on my ball diff. 1/4 turn tighter and I get no "diff action" such as a solid locked diff. 1/4 turn looser, the diff slips under load (by placing my truck on the table and holding the rear wheels and hitting the throttle to correctly set the diff and slipper). I've gone with smaller increments with the wrench such as 1/8 turns and still can't find it. Overall the diff feels tight and gritty. I've also followed the breakin process but it still feels gritty.

This is a new diff and I'm trying to install it in a Proline Pro2.... What am I doing wrong? I've gone through the diff and broken it completely down, wiped off all the grease and re-applied, and put it all back together 5-6 times... I almost feel like putting the stock diff back in.....

LasagnaCat

iTrader: (161)

http://www.rctech.net/forum/electric...er-clutch.html

Micah123

iTrader: (1)

Sounds like you need to start over with new balls. If the thrust rings and diff rings were new when you started, you can flip them and use the other side. Everything needs to be surgically clean when you assemble. Make sure to use plenty of white grease. Also pack thrust assembly with a fair amount of black grease. Not a crazy amount but not too little. After you assemble diff, tighten bolt just enough so that outdrives are touching balls. Rotate outdrives back and forth to work grease into position. Tighten a bit more and do the same. Confirm diff is smooth before further tightening. If not, something is causing a problem. Take apart and clean everything again with motor spray. If you did not tighten too tight, balls should be good to go. If you tightened too much, you may have flattened them and need to replace. Once diff is smooth and you have worked grease by rotating outdrives back and forth, go ahead and proceed to tighten until you feel that any more tightening could flatten the balls. Back off about an 1/8th and install into tranny. Set your slipper very loose and start the break in procedure by holding one tire and slowly spinning the other via the radio trigger. Not too fast, maybe like 1/4 throttle. If you are not getting enough throttle, your slipper needs to be tightened until it starts to grab enough to get the speed you need. Important to keep you slipper on the loose side until you have the ball diff set tight enough so that you do not "bark" the diff. Barking means your diff is too loose and your slipper too tight and the diff barks under load and flattens the balls..........not a good thing. After going back and forth a number of times, you will probably find your diff has loosened. Tighten as before and back off an 1/8. Redo break in procedure. Keeping the slipper on the loose side, run the car on the street or track to continue the break in process. No jumps and maybe just quarter throttle or so. All you are doing in creating a groove in the rings for the balls to run in. Lastly, check diff and adjust if necessary. Now set slipper so front of car just lifts off ground. Go run at normal speed and re check diff one last time. Anytime you adust the diff, redo the break in procedure by holding one tire and running at 1/4 throttle. Take your time and follow these hints and you should be good to go.

Bubonic-X

iTrader: (4)

Take the diff out of the car. Use 2 wrenches to put in the slots of the diff. get a towel grab the diff gear with the towel and holding the wrenches in your other hand while they are in the slots of the diff. Try with all your strength to slip the gear if it slips tighten the diff screw in 1/8 increments until you can't slip the gear with your hand and towel. When you can't slip the diff gear put it back in the car and test it as usual. If you cant get it set after that procedure. Then there is something wrong with how you built the diff...

1/4milecrazy

iTrader: (5)

That is way too much. Surgical clean, yes. White grease? No. Use diff lube. Make sure it's diff lube, its cheap enough that buying the right stuff is not going to send you to the poor house. Use as little grease as possible, with proper maintenance the grease will be getting replaced regularly. I use just enough to hold the balls in place. Grease attracts dirt, the more grease you use the more dirt the diff will hold. Don't bother breaking the diff in in the trans. Get yourself a 1/2 inch drill and chuck the diff drive in the drill and spin it both directions for a few minutes then re-tighten. I NEVER go through the break in process after initial break in. When the diffs get to a point where there is a groove in the diff ring you are ready to replace the rings.

Take the new diff rings and place a piece of very fine grit sand paper and place it on a super hard smooth surface and sand the rings until all the shiny surfaces have been sanded. Use one of the outdrives to assure that the diff ring stays flat and even on the sandpaper. I prefer ball diffs over gear, maybe its the years of building ball diffs since the RC10 days.

bdyche

iTrader: (5)

The MIP diff kits use chrome steel balls and thrust balls. If you tighten the diff bolt too much when you build it the balls will crush and ruin the diff (this is why I stopped using MIP diff rebuild kits). For the easiest diff to build that will last quite a while, use carbide diff balls and a captured ceramic thrust bearing. My personal favorite is sold by Schelle, but only because they are packaged as a kit. You will need a diff bolt, nut and rings if you go that route. Avid RC and Casper RC sell captured thrust bearings as well, and all of them are great quality.

afm237

B-fast diff kit and folow the instructions, best, smoothest and longest lasting diff I have ever built. Never had any luck with MIP diff kits.

Micah123

iTrader: (1)

Most diff rebuild kits come with 2 different types of grease....typically white and black. Black grease for thrust and other for diff balls. Everyone has there preference on amount of grease but I believe you will find that heat is the cause for grease to break down vs dirt. Excess grease will be pushed out during break in. If you use the drill method, you can wipe off excess during break in. If you break in after installing in trans, excess will lube the tran gears. Probably a good idea not to use too much grease if you plan on breaking in after trans install since you do not want too much grease in the trans. I use the drill method as well but have found that by following my above procedure, diffs turn out nice and smooth. Reason for breaking in the diff is to create a race (groove) in the rings. Good idea to freshen the race after each adjustment... keeps the diff nice and smooth. No need to sand the rings but will not hurt anything if you do. OP, once you understand the concept, you will have no future problems. Pro driver stepped me thru the process and I have never had a problem since.

Mantis Toboggan

iTrader: (4)

No, diff rebuild kits have CLEAR grease. White grease is something completely different, and it wouldn't work for a diff.

Also, sanding rings is to flatten them so the diff doesn't have tight spots. This is not some second hand knowledge I got from some local, its stuff I've learned from building ball diffs for 23 years.

1QuickPro2

iTrader: (25)

What grit sand paper you recommend?

Mantis Toboggan

iTrader: (4)

800 with light pressure and figure 8 sanding motions, using the female outdrive to hold the ring. After a couple 8's check the surface of the ring, and you should be able to see the high spots of the ring. Keep sanding with light pressure until the surface is uniform. Then flip the ring and do the same to the other side of the ring, then pick one side to finish with 2000 grit. According to Fred from BFast (a master machinist of 30+ tears), this is the best way to replicate the BFast rings.

Micah123

iTrader: (1)

Hate being color blind. Looks whitish to me but definitely not the black stuff. OP, you definitely want diff grease. Was going to post that rebuild kits do not actually come with grease or diff balls but never followed through. Sanding rings is a good thing and will take the time on my next rebuild. Probably gives better grip between rings and balls as well.

Socket

iTrader: (61)

Sounds like the slipper is too tight.

1/4milecrazy

iTrader: (5)

Thank you. Like I said, since the RC10 days. These youngins just dont understand the ball diff struggle.

Back in the day cheap kmart kits and Tamiya scale cars had gear diffs. Race cars like Losi, AE, and Yokomo had ball diffs.

You do not want to wear a "race" into a diff ring. That is when they should be replaced. These are not caged bearings. When you start seeing lines then they are due for a rebuild. I take mine apart regularly to clean, re-grease, sand the rings a little and re-adjust. The minute I feel a little grit after a rebuild I replace. I will say this, I have B-Fast diffs in my B44 and they feel AMAZING. Definitely want to get some more of them.

1QuickPro2

iTrader: (25)

Can you put different brand diff balls into the MIP gear? Unfortunately I have already shelled out the cash for the MIP kit so I can't switch brands entirely. But if another brand has better/harder diff balls that I can use with my MIP kit that would be an option for me...