Well I took the truck in on Tuesday to have them re-gear (from 3.55"s) and replace the inner connect/disconnect bushing. They installed new 4.10 Yukon gears with matching Master kits and I got my baby back. Took here for a run and I have to say I don't get on it too much because I want the to brake in right. Anyway, the truck is runnin like a champ with em and I love the new torque jump off the line! Can't wait to hook up to the trailer and yank that thing.........LOL


So basically I have 285 tires that are actually same size as the 33's. OEM is 31's (245's). So after intense looking around and many calculations I figure this set up will give the the best fuel mileage and torque curve that I need concerting it is mostly my around town and towing vehicle.

One issue I have ran into though that I am not quite liking is I took it for about a 3 mile drive and let her sit for a few minutes. Then we took it for a main first drive to Wal-Mart (about 25 miles away). She ran VERY quite and in fact I personally love the gears as they were so smooth and quite. Anyway go in for about a 1 hour (to let the oil cool about 40 F outside) and come out and drive it all the way back home (about 35 F now). So after I get home I jump under the truck to feel the diff's, and front is cold. Move to the rear and it's HOT. I couldn't hold my hand there too long. Jump in the truck and take it back to the shop so they can see how hot it had gotten first hand before they close. He hits it with the thermo gun and comes back with a 138 F. So he tells me to bring it back in the morning and they will check it out.

Take it back and dropped it off and they put her back up on the rack. Remove the drive line and check the pre-load. All is well and the gears are smooth as crystal......Hmmmmm

The tech calls Yukon and describes the issue and they said it sounds normal for the first drive and to give them 500 miles for a break in period. Not to cause un-needed stress and to take it easy and let them cool down after small runs.......Hmmmmm

Now I have no reason to doubt this shop or this tech as he is a Mopar nut job and builds these exact axles for personal and well as other shops. He said they are in right and he is absolutely sure of it! My question is if the pinion is shimmed too small so the pinion is to close to the ring gear and the mesh is off. I asked him this and he stated "yes" there is a possibility of that but again stated they are in there right and he is positive. With backing from Yukon and pre-load results they stated lets see what happens. Now if it blows they'll fix it and they stand by it, if it blows I know they will stand by it so I said I'll be careful as there is a warranty and I know if it will blow it will do it at that point. Lubrication was 80W-90 Conventional with Friction Modifier (soon to be changed).

It makes me uncomfortable with those hot temperatures, however the front has a disconnect on one side so the diff just spins off the drivers side and with no torque applied it checks out so no worries there.

So my question is this, has anyone replaced gearing with Yukon and measured the temp after the first 25-50 mile drive to ensure Yukon's theory?

Also what is the normal operational temperature of a worn in rear end other than nice and warm after that kind of drive?


Front Dana 60, Rear Dana 70 LS

 

I never checked my temp after I installed my gears, but I would think that there would be a higher temp during the initial break-in since there is a lot more rubbing until the gears really mesh together well. You might consider calling Randy's Ring and Pinion and just ask them your question. They know a lot about it, and could probably tell you if this sounds normal or not, and what temps you should be seeing.

 

Thanks!

That's what I was going to do, but I got a hold of a buddy of mine that has installed them and he said it sounded normal for the break in period.

 

Is there any sound/whine either speeding up or slowing down?

If not, its fine. If those gears are off even a hair you'll hear it.

The temps get hot until the metal "settles" into a pattern. Just be damn sure you are topped off with gear oil. I fill it on level ground until it dribbles out of the fill hole.

Dump the oil after the break in period and replace with new. The old will have contaminants the metal sheds during the heat cycling and pattern wearing process.

 

Those temperatures are completly normal for break in or normal driving. The differential temp will be slightly higher durring break in, but temperatures commonly range between 150-200F. Durring severe driving or when towing, diff temps may be closer to 250F. Most gear oils have a maximum recommended running temp around 280-300F.

 

so hows the truck feel off the line with the 4.10s :P do you wish you gone bigger ? like 4.56 ? jw for when i do gears

 

how much did you pay for the install? I have ben quoted anywhere from $700 to $1200 to do both axles, labor only.

 

that price sounds fair ....it isn't a cheap mod!

 

which one sounds fair? $700 or $1200?

 

That's just labor??? What is the labor rate at the shop(s)?