ShutterBug

I have a set of Rubicon take offs that the previous owner had re-geared to 4.88.

Before I put these on my JK, I want to be sure that everything was done correctly. Before I spend money taking these to a driveline shop and likely having to buy new R&Ps, I bought some Prussian Blue and did my best to get a contact pattern.

I am interested in the opinion of how this contact pattern looks. I put a "load" on the pinion by wrapping a rag around it and holding it tight.

So, the question is, do these look right or do I need to take them and have the gears replaced and properly installed?

The rear:





The front:

aro

I would say the pattern isn't exactly textbook, especially the rear 2nd picture, but that can be fixed. I'm not sure what you are asking though.

Do you want to use those R&P's and not sure if they are good? If yes, the pattern won't tell you anything about their condition. If they are not chipped, they should be ok. Sure, I guess the steel could have some kind of internal stress, but how are you gonna tell that... It depends how the original Jeep was driven off-road.

ShutterBug

No chips, no chunks. The R&P appear to be in good shape.

What I am asking is, with only these patterns to go by, were these were installed correctly. Granted, there's more to it than that. I don't have a machinists dial, so I can't tell you what the backlash is. I don't recall how many miles are on these gears (30K?), and from what I understand, they weren't wheeled too hard.

What I don't want to happen is to be 7 hours away from home and these gears blow up, when I could have taken steps to prevent that.

If they were shimmed wrong, or the pinion depth set wrong, I can't reuse this gear set because they have too many miles on them (so I am told) and would need to have them pulled, new gears installed, and everything set again.

aro

Those don't look like they were installed perfectly, but personally I wouldn't mind putting them on my Jeep. I would definitely get master kits with all new bearings, shims and crush sleeves. However, I am not an expert on differentials. As with everything used, nobody can guarantee 100% performance.

If you decide to go with new, I would take be happy to recycle them for you, and, wait... I would even pay shipping! Just PM me

Rob 12B1P

I'm no expert but the rear doesn't look right to me.

link to a chart: http://www.sierragear.com/ring-and-pinion-gear-pattern/

jtphoto JK

I would like to see the pattern on a few more teeth (minimum 1/4 of the ring gear) to get a good look at the pattern before I can make an accurate determination...

ShutterBug

*sigh*

Rob 12B1P

Sigh, did you look at the chart i linked.

ShutterBug

LOL.

Yes, I've done quite a bit of research. I've looked at a lot of different material. That's why I was looking for some expert advice.

aro

I don't know if you'll find an "expert" here. An expert is someone who deals with differentials on a regular basis. Most shops don't even have anyone like that, it's either a specialized shop, or a single individual in a few shops.

You can find informed opinions here though. In this case, an informed opinion would be that the pattern is not textbook, but that doesn't mean that the R&P are shot. Whether you want to reuse them or not, is alone your choice. Personally I would. This is my non-expert opinion, based on what I read about R&P's over the years. But then... I would do the work myself, so if I had to redo... labor is still free.