O.K.

This weekend, I'm wanting to change my stock diff. greast to oil. I have a 8ight RTR and bought the recommended losi oil to start with...

Here is my very simplisitc and probably common sense question.

Do I need to completely break the differentials down and clean all the grease out to put oil in?

I'm thinking I do - but wanted to be sure.

Thanks
Bob

yes that is the best way.

Agree with Sman....usually the best. Take 'em all apart (one at a time) remove any rubber o-rings (or any rubber products, including the bearings) and give everything a good soaking with carb cleaner or something like that. Put it all back together and fill them with the oil of your choice.

Note: Don't forget to put the rubber O-rings back and don't forget to put the grub screw back in before filling the diffs with oil......you may end up with a bit of a mess. Oh...and if they look like they need it, replace the gaskets. Better to do that now than find a nice thin line of diff oil all around the inside of your shell and chasie next time you run it.

Have fun man.

You also need to lightly grease the outdrive shafts before you stick them back through the diff housing. fill the diff about 85% of the way full with oil and work the gears back and forth a few times and let the oil settle. I usually top off with oil to the top of the planetary gears, then new gasket and screw them back together in a crossing pattern a little at a time until tight. Then i usually mark what oil I used on the diif case with a sharpie paint pen, or you can lightly scratch it in.

Thanks for the help ya'll!

After you get it done properly you can begin charging people $100 to r&r their diffs ( I have a freind at the lhs that charges $100 for this service )

People actually pay $100 to get that done?

Yes...some people are Extremely lazy and know that they would'nt do as good of job as say the crew mechanic.

pending on how bad buddy's trucks are.....and how far i have to dig/clean...ill charge that much....when it takes my bench up for at least 4-5 hours and i use all my own chemicals/oils......Im chargin for it plain and simple.

i usually spray wd-40 in there and turn the diff while holding a rag in the gears, works great and the little shims don't get lost. also before you put the grease in the diff be sure to check the mesh by tightening 2 screws across from each other and turn the diff cup slowly. the opposite side should spin the opposite way smooth with no stopping and just a tad bit of buzz of the gears teeth touching, if its too tight add another gasket, if they are clicking and sticking you need to shim under the cross pin and try again. diffs expand under heat and can separate the gears just enough to round them off and eventually grind them down to nothing. i've gone through 5 8th scale cars and diff issues and this way has worked flawlessly.

$100 straight up going rate ... if I'm low on oil I'll r&r my own diffs at the track and bum the oil I need , right now I have the oils I need for diff r&r , next time I may not ... 1000-4000wt diff oils always on the pit bench for the front diffs on bug&trug