So I blew an axle seal a few months ago. Been riding my motorcycle everywhere, but as weather begins to turn, I decided to lay said motorcycle down on the first frosty morning. It will be spending the winter at the dealership while all the king's horses and all the king's men put her back together again.

The obvious cause of the blown axle seal seems to be the open differential and incorrect gearing, so I've put together an ARB locker and Yukon 4.88's. My Yukon axleshafts *should* arrive today, after a long backorder and a couple phone calls to Marlin to see if they had any updates.

Everything went well, up until the gear marking compound. How TF is that the part of this job I'm not capable of? My first pass with the stock shim and setup bearings came out clean and clear - well centered, but deep in the root. I added shims, painted on more compound, and got a Jackson Pollack painting. Alright, maybe I didn't clean up the first pass well enough. So I cleaned the R&P with Brakleen (careful to not hit the locker, since I have no idea how the wizards hiding inside might respond to harsh chemicals). Before reassembling, I put a little 90W on both the R&P so they weren't bone dry. Painted a new coat - similar terrible and unreadable result. This time, I'm thinking I had too much oil rolling around and the marking compound just flowed too easily.

So....any tips (from the folks who have actually done this, please) for a first time fool? How do I get a clean, readable pattern? All the photos I see online are like "yeah, I see that very clearly." I can't seem to replicate that clear pattern. I'm now out of the travel-sized tube of compound that came in the Yukon setup kit, so I've got to buy more. Does any work better than another? I think I read on Zuk's site that the Chevy dealership has it. The lady at the dealership had *no* idea what I was talking about, and suggested I buy it "uptown," because they "can't get it anymore."

Everything I read online basically says "paint on the marking compound, thin slightly with oil if needed" and my art-skill-lacking self can't seem to nail this one step down.

 

I've never had a need to thin the paint. I try to keep the gears as dry and clean as possible, then paint the paint on. Never had a problem.

 

Here's everything you'll ever need to know about gear setup.

http://gearinstalls.com/

 

If you go to a shop they probably just give you marking compound. Or go to an art store and buy a tube of paint. You don't want to oil up the gears just a little on the bearings. I suggest you paint and then put a wrench on the ring bolts to turn. At the same time really grip the pinion hard enough so that when you push and pull the wrench you can really get a good pattern smash.

 

Thanks guys. I suspected I just wasn't starting with a literal clean enough slate, sounds like that's the case. Figured after two consecutive fails, asking a stupid question felt better than wasting another chunk of time building it up for another bad read. Hopefully find time tomorrow to try again.

 

I also use starter fluid and spray onto the gears to clean them. Doesn't leave a residue.

 

Alright, part of my problem may be the setup. Not getting a nice, pretty, smooth blob like everything I see online and in tutorials. Am I correct in reading this as my pinion being too deep/need thinner shims?

 

I would definitely look over Zuks site and see what you can find to compare. Some brands of gearsets don't smear like you think they should.

Too me? Looks shallow and favors the heal. I'd go deeper and bring towards the toe some more.

 

Looks deep to me. Need to thin up the pinion shim.

 

Have BigBluePile and arlindsay1992 completely contradicted eachother? Or am I out of touch on what deep and shallow means?

 

Yes
No

 

Technically, deep on the ring gear would be shallow on the pinion. You generally make your judgements based on the ring gear, then the pros will confirm what they see by examining the pattern on the pinion.

On the ring gear, you don't want to be so deep (towards the bottom of the tooth) that the pattern in the paint goes off the face of the tooth. You can see your pattern has a hard line at the root where the pinion is riding off the face of the tooth. Most gear manufacturers will recommend a centered wide oval pattern. That is centered between the root and the crest of the tooth. ZUK, a highly recommended gear installer here, recommends a slight deep pattern which pushes the pattern just barely down from center towards the root of the tooth.

Take a look at the GearInstalls link BigBluePile posted. Take an average of the finished patterns in ZUK's setups and you'll see what we're talking about.

Root is the bottom of the tooth nearest where the ring gear bolts to the carrier. Crest is the tip of the tooth. Heel is the outside of the ring gear. Toe is the inside of the ring gear. Deep is when the pattern favors the root. Shallow is when the pattern favors the crest. Your two adjustments are the pinion shim and the backlash. Backlash must always be what the manufacturer specifies so really your only adjustment is pinion depth. To move the pattern deeper, add a thicker shim to move the pinion in closer to the ring gear. If the pattern is too deep, remove some shim from the pinion to move the pinion farther away from the ring gear.

 

A sincere thanks to that write up arlindsay. 👌

 

you are also gonna want to look at the pattern for both coast and drive
Diff Set up is an art form. I get wonder to save $$$ but doing it yourself can end up costing more $$$ especially when it grenades a long way from home