The rear end went out of my 04 Chev 2500 crew cab yesterday. The shop who has it said they have replaced several of them on the 04s. He said it looks like the factory is overtightning the pinion gear. Anyone else had a problem with this?

Greg51


I have a 04 GMC CC that just started exhibiting a clunk on shifting in reverse.


Did you have any such symptoms?


Ron

Could you ask your shop if the rest of us with 04s should take them in and get the pinion gear checked? I have 7000 miles so far. How many miles did it take to trash your differential? Thanks for the news.

I only have 2700 miles on my truck. The way it happened is I took of with my foot in it (is there any other way) and as I did there was a loud bang and the truck jerked. After that the right rear tire was the only one spinning and boy did it spin. It soulded like I hit a pot hole (it's hard to miss them in Missouri) when I was taking off. I continued down the highway at 70 - 75 with no problems or nioses. With that I thought I may have hit a pot hole and the dif. unlocked which made the right tire spin only. About 35 miles down the road I took my exit ramp and slowed down. When I went to accelerate there was nothing there. It was like the trany was in N. I coasted to the side of the road, stopped, put it in N and then back into drive. Still nothing so I gave it a little fuel and it banged into gear. With another time of stopping and repeating what I just did I got to where I was going (only had two more miles to go) and called the nearest dealer. They took great care of me. They called a tow truck, came out to get my passengers and then gave me an 03 ext cab truck to drive while mine was being fixed. Things like that suck but with the great service I got from the dealer, which by the way was not where I purchased it, it was about as painless as it could be. Hats off to Perry Chev.

From the title, I could tell this post is "loaded".http://www.dieselplace.com/forum/smileys/HiHi.gif

Sorry! I couldn't resist!http://www.dieselplace.com/forum/smileys/Embarrased.gif

Greg51 -


Some of us with 04's have had problems with low oil levels in the rear differentials when the trucks arrived from the factory. To make matters worse, some dealerships (like mine) didn't bother to check the oil levels when our trucks were delivered to us.


Did you have a low differential oil problem with your truck? Do you have a G80 locking diff?

The rear end went out of my 04 Chev 2500 crew cab yesterday. The shop who has it said they have replaced several of them on the 04s. He said it looks like the factory is overtightning the pinion gear. Anyone else had a problem with this?


It's been a number of years since I did a ring and pinion job, but if these are anything similar, and I suspect that they are, there are a few ways to tell if that's the case. OH, is your's a G80? Was the fluid level in it checked when it came from the factory? Most of us have gotten our trucks with low differential oil levels.


Anyway, the pinion gear usually rides on two bearings with a collapsible sleeve in between. The reason being that there must be a way to set how far into the case the pinion gear rides, and thus the point where it engages the ring gear. So you start by setting a minimum torque which starts compressing the sleeve and allowing the pinion gear to go farther into the case. Then, if you've got the niffty micrometer set, you can just measure the depth, correlate that to the ring gear carrier position, and tighten the pinion until it's set. If you have to do it the old fashioned way, you paint the gears with something, used to be lead, and "read" the pattern. It takes a lot of time and is a PITA. If you can't get the pattern right within the two torque values listed, you have to take it all apart and either add or remove shims from beneath the inner bearing race on the pinion gear and start over.


I think that if the pinion were overtightened on those, there would be a noticeable "howl" from the rear end because the gears would not mesh properly. The remnants of the ring gear would show a bad pattern. As for over tightening that, IIRC the low end torque value on most of the stuff I worked on was 190 ft.lbs, it took a larger cheater bar to get that high. If you could over torque it while setting the depth, I would think the pinion gear would be broken on the shaft and stretch marks in the metal would be visible. Any crystallized areas there would indicate a faulty or bad part.


I hope some of the folks who have actually had one of these rear ends apart will comment on your post, because since I've not had one apart, I can't say for sure how they are built or if this is the way those tolerances are set. But that's the way it was done when I played with them a lot, drag racing causes a lot of rear end ratio experimentation...http://www.dieselplace.com/forum/smileys/Embarrased.gif


edit info:


Dura_Mike types faster than I do, I didn't mean to repeat his questions about whether it's a G80 or if you'd had the fluid levels checked.....http://www.dieselplace.com/forum/smileys/Confused.gifEdited by: Zeeb

It has a locking dif but I don't know if it is a G80. I keep the Attitude where it does not defuel at shift - could that have made things go bad? I removed Juice/Attitude before they came to pick it up. Just EGT and velcro left

Zeeb -


I had about 360 miles on my truck when I noticed the low diff oil. The color of the oil was a light amber with a slightly gray tint. If the pinion or differential bearings were not pre-loaded correctly would the gray tint of the oil be an indication of accelerated bearing wear? Thanks.

The dealer checked the oil levels of everything before I got the truck. I was there when they were doing the checking. They went over things quite well.

The Dodge guys have been having some problems with their AAM 11.5" rear axles. Similar stuff to what you are reporting.

Zeeb -


I had about 360 miles on my truck when I noticed the low diff oil. The color of the oil was a light amber with a slightly gray tint. If the pinion or differential bearings were not pre-loaded correctly would the gray tint of the oil be an indication of accelerated bearing wear? Thanks.








If the pre-load is wrong, you'll get wear on the gears not the bearings since the material the bearings are made of is much harder than the gear material.


Keep in mind that some gear wear is normal for a new ring and pinion set.The rear end is the primary cause for the restricted speed suggested for the first 500 miles, as well as the suggested restricted speed for the the first 500 miles of towing. That's also why the suggested change of the differential lube after it's been run for awhile, to get rid of the results of those gears wearing in.


There are other components needing a "break in" period, but that's one of the primary ones.

after reading all the post about low levels,i decided to go check mine..well guess what? it was lowhttp://www.dieselplace.com/forum/smileys/Thumbs Down.gif,i topped it off with some synthetic 75w90 i had left over from another project..i only have 210 miles on it,i will mention it to the dealer when they install my bed liner monday.http://www.dieselplace.com/forum/smileys/Wink.gif.

What was your build date or the the last 5 digits of your VIN?


I would like to know how close yours is to mine..http://www.dieselplace.com/forum/smileys/Ermm.gif

Zeeb -


I had about 360 miles on my truck when I noticed the low diff oil. The color of the oil was a light amber with a slightly gray tint. If the pinion or differential bearings were not pre-loaded correctly would the gray tint of the oil be an indication of accelerated bearing wear? Thanks.








If the pre-load is wrong, you'll get wear on the gears not the bearings since the material the bearings are made of is much harder than the gear material.


Keep in mind that some gear wear is normal for a new ring and pinion set.The rear end is the primary cause for the restricted speed suggested for the first 500 miles, as well as the suggested restricted speed for the the first 500 miles of towing. That's also why the suggested change of the differential lube after it's been run for awhile, to get rid of the results of those gears wearing in.


There are other components needing a "break in" period, but that's one of the primary ones.








If the pinion bearing preload is too tight, it will burn up the pinion bearings. This could easily happen without causing any damage to the gears at all.

If the pinion bearing preload is too tight, it will burn up the pinion bearings. This could easily happen without causing any damage to the gears at all.





That's true, I suppose I should have made that more clear, it's just that most of the ones I've seen with pre-load problems have usually been too loose allowing the pinion gear to "wander".


If one accepts the judgment of the shop mentioned above that they are over torqued, then that would apply. But I think you'd get a break in the pinion shaft before you ever realized the thing had a problem.


That's why I was wondering if he could provide more info on the failure.

The shop said they had to order a new shaft. I assume they were talking about the pinion shaft.

I think large tapered roller bearings can handle lots of load. Increased preload is just more load to a large bearing. On the other hand, too loose a bearing will not handle the load of a ring and pinion, and failure can happen.


This really is a large ring and pinion and a huge pair of roller bearings. I think if the pinion can turn, the bearings can probably handle the load.


I guess I'd be quicker to implicate a failed crush sleeve (loosening preload) than excess preload.

The shop said they had to order a new shaft. I assume they were talking about the pinion shaft.


Well there have been some others post with good comments, but my question would be what shaft?


Ring and pinion gears come as a set, with the pinion shaft being an integral part of the gear. It's all one piece.


You don't put a used piece in one place and new in the other because the used one will have a wear pattern established, and the odds of it howling are really high.

Ever think you should just get a bicyclehttp://www.dieselplace.com/forum/smileys/Ermm.gif? The rental truck I was given to drive while my truch was in the shop was an 03 chevy ext cab with only 15000 miles on it. Well I was on my way to a meeting this morning and around 60 miles away from home it quit runninghttp://www.dieselplace.com/forum/smileys/Confused.gif. Left me stranded along side the road and no Onstar which I have in my truck. Good thing I had my cell phone with me.


I'll question the mechanic on what actually happened to my truck when I pick it up and post the results.

I had a chance to call my dealer and discuss the problem with the rear end of my truck. He said there is a pin - he calls it - about the thickness of a highlighter marker that holds everything together. That pin is what breakes and yes they have had a lot of problems with this. Evidently there was a point in time where this was a problem (don't know the dates) but Chev knows about it and has fixed the problem at the factory. This doesn't make much sence to me but I am not a machanic - hopefully it will make sence to some of you. If it was just something to tight I would think Chev would contact those truck owners to let them know there is a problem so we could have it looked athttp://www.dieselplace.com/forum/smileys/Ermm.gif???

Hi, Guys.


Question from (an obviously not too auto mechanically inclined) newbie--


1) How do I check my fluid level in my rear diff? I have an 04 2500HD Dura/Ali.


2) I've got 3,000 miles on it. If I check it and it's low, or if I just want to change out the OEM fluid, what is the best brand/type/weight of fluid to buy to put in there?


3) Do I need to check/replace the fluid in my front diff, too? (i.e. have you all found that the front fluid level is low from the factory, too)?


Thanks for your help, and pardon my naivete.


~Terel

Got my truck back today. Although they have been having problems with the "pin" in the rear end that is not what broke on my truck. The left rear axle shaft broke off inside the carrier. They said it broke claen like it had been cut with a saw. Guess these Duramaxes do have a lot of torquehttp://www.dieselplace.com/forum/smileys/Approve.gif.

Greg51,


Glad you got your ride back. Yes the Dmax does have a bunch of torque. One would suspect that a manufacturing flaw was responsible for the axle problem.


Carry on....http://www.dieselplace.com/forum/smileys/Cool.gif

Terel, you should check the front and the rear diff's. There is a fill plug on the front and the oil should be just below the fill hole. The rear differental cover on the back has a fill hole about half way up and I just fill the front and rear to the bottom of the fill holes when the diff's are hot.

Terel, you should check the front and the rear diff's. There is a fill plug on the front and the oil should be just below the fill hole. The rear differental cover on the back has a fill hole about half way up and I just fill the front and rear to the bottom of the fill holes when the diff's are hot.


Blue Max,


Thanks for the tip. Sounds easy enough. I'll check them both this weekend (I need to change the oil in my wife's car anyway, so I'll be dirty).


If they're low, what brand/weight of oil is the best for this? And is it okay to just top them off, or should I drain and refill completely with the new lube?


~Terel

I have mixed brands before and nothing has blown up or failed. I usally run my new trucks no more than 5000 miles on the factory fills and change them to get the junk out. A lot of guys run Mobile 75W-90 synthetic and I have used that before but I decided to try some Royal Purple 75W-140 this time and it seems to be working out very well and the rear end runs cool, but then I have a Mag-Hytec with 8 quarts of oil in it. http://www.dieselplace.com/forum/smileys/Big Smile.gif Edited by: Blue Max

I have mixed brands before and nothing has blown up or failed. I usally run my new trucks no more than 5000 miles on the factory fills and change them to get the junk out. A lot of guys run Mobile 75W-90 synthetic and I have used that before but I decided to try some Royal Purple 75W-140 this time and it seems to be working out very well and the rear end runs cool, but then I have a Mag-Hytec with 8 quarts of oil in it. http://www.dieselplace.com/forum/smileys/Big Smile.gif





Thanks, Blue Max. I'll probably do it this weekend.


Take care,


Terel