JRX Pro Rebuild

[jwscab]

yup, for sure. You are supposed to mix the regular with the super slider, so one gray, one white.

[Top_Billing]

Got it. Thanks.

Does anyone have experience making the modification to the female diff half in order to use the ball bearing diff gear? The instructions originally provided by Losi are not the clearest. I'm not sure which part of the diff half needs to be cut. Is this even worth doing in the first place? Does the ball bearing diff provide a noticeable performance gain?

[jwscab]

the drawing doesn't really explain why you need to do that, but since the bearing is fatter than the gear, the center diff bearing will actually go into the the bore of that diff half, and when the diff rotates, the outer race of the bearing will spin in that half. So by trimming that edge, the bearing won't make contact with the diff half and make the diff action smoother.

as for the diff center bearing, it doesn't necessarily make the diff smoother, but it does make the diff a little more robust. rather than plastic on plastic rubbing, you now have a bearing. prevents some heat buildup. it also can make the diff gear run more true.

[scr8p]

I'm no Losi expert, but this is only needed if you don't have the thin Losi diff bearing right?

[jwscab]

I think this is with the special narrow bearings. I don't think you can fit standard width bearings at all without some custom machining.

[Top_Billing]

i have two thin bearings, but it sounds like modification needs to be done regardless. To be clear, we're talking about the inside circular edge where the bearing sits, right? And can this be done with a dremel and the right fitting?

[jwscab]

dremel will work with a sanding drum or stone. you can probably carefully use an xacto blade too to bevel it out. I'd probably use an xacto, but that's just me.

[matt1ptkn]

Yeah, that drawing has me scratching my head now. I understand the need for the bevel and the benefits of the bearing. But what I'm concerned about is the number of bearings used. So there are two bearings in this setup or just one? I think I've only ever used one bearing in mine, but it looks like there should be one in the diff gear and another one in the diff half. Now I'm worried that, after all these years, I've been building my diffs wrong. Now I feel like I need to check all my diffs; and I probably have at least 10 currently in use and I'm stuck at work for another 8 hours.

[jwscab]

Losi upgraded the diff gear with a bearing. If you built them and the diff gear fit snugly on the diff half before, then yes it would have been just one bearing and you built them right. Adding the special diff bearing requires the new diff gear and then two bearings.

[scr8p]

http://vintagelosi.com/Instructions_files/Bearing_Diff_Kit_A3020.pdf

[Top_Billing]

Losi upgraded the diff gear with a bearing. If you built them and the diff gear fit snugly on the diff half before, then yes it would have been just one bearing and you built them right. Adding the special diff bearing requires the new diff gear and then two bearings.

Just to confirm -- does the modification need to be done when using the upgraded diff gear and two thin bearings? Sorry if I'm covering old ground... just want to be sure before I start carving up vintage parts.

[jwscab]

definitely read that losi pdf Scr8p linked to. Some diff side gears already had this chamfer in place.

if the diff gear does NOT have a bearing, this modification is NOT needed.