4.10 Gearing Is In
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From: Riverton, UT
4.10 Gearing Is In
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 home (about 35 F now). So 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 (like you Widow) 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?
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 home (about 35 F now). So 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 (like you Widow) 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?
Last edited by hydrashocker; Feb 12, 2011 at 02:33 PM.
Yes! That is correct to measure much higher temperatures for the first 100 miles especially. I would strongly suggest not to get to speeds much higher than 60 mpg on the highway. Also, I'd recommend to not do any towing for the first 500 miles. You want the truck to get used to the gearing correctly and not put much stress on the gears.
Also, I'd recommend using a 75w-90 SYNTHETIC diff lube. Typically with 4.10 or 4.55 gears its going to get much hotter than 3.55 and this heat breaks down the conventional fluid much quicker. I also say 75 winter weight because it is a bit lighter and won't cause too much extra thickness to cause friction.
I'd give it another 200 miles of small trips before you start drawing conclusions about the gearing, like I've said I've used these gears a handful of times and its what I learned replacing with. You can start doing some towing after like 500 miles and also start hitting the throttle. Like you said, try and stay away from a WOT as you don't want to add a reason for your gears to get more hot.
Try and let it cool down for like 15 minutes at least before making another trip between trips. I'd do a fluid swap to synthetic ASAP to possibly avoid margin of error due to high heat already from what you're experiencing.
All wrapped up, keep an eye on it on a daily basis, but I'd really start paying attention if you still have heat like that 300 miles down the road. Shouldn't be a problem with the gears, as much as the differential breaking them in.
Also, I'd recommend using a 75w-90 SYNTHETIC diff lube. Typically with 4.10 or 4.55 gears its going to get much hotter than 3.55 and this heat breaks down the conventional fluid much quicker. I also say 75 winter weight because it is a bit lighter and won't cause too much extra thickness to cause friction.
I'd give it another 200 miles of small trips before you start drawing conclusions about the gearing, like I've said I've used these gears a handful of times and its what I learned replacing with. You can start doing some towing after like 500 miles and also start hitting the throttle. Like you said, try and stay away from a WOT as you don't want to add a reason for your gears to get more hot.
Try and let it cool down for like 15 minutes at least before making another trip between trips. I'd do a fluid swap to synthetic ASAP to possibly avoid margin of error due to high heat already from what you're experiencing.
All wrapped up, keep an eye on it on a daily basis, but I'd really start paying attention if you still have heat like that 300 miles down the road. Shouldn't be a problem with the gears, as much as the differential breaking them in.