Rear diff issues - PlowSite.com™

My bowtie · #1 04-12-2012, 07:29 PM

It seems GM is underfilling thier differentials. My 2011 3500 1 ton about lost the passenger duals yesterday...dealer called and told me the diff was underfilled at the facyory, and its trashed..Ordered a complete rear axle along with a caliper, rotor, and a rim.(rim was rubbing against the caliper). I've read about this underfilling issue for a few yrs, and cant figure out why this is still a issue. Gonna be without my truck for at least a week....

2006Sierra1500 · #2 04-12-2012, 08:23 PM

Should check my 2011 1500 then...its been going for 8000 miles with no issues.

BlizzardBeater · #3 04-13-2012, 08:19 AM

Went through it on my newest Kubota as well, front diff underfilled from factory. I never take anything for granted on a new machine. All fluids get an initial check as well as after 5 hrs/500 miles, 10 hrs/1000miles, and 50 hrs/5000-7500 miles. I've discovered things on many occasions that may have been detrimental to the machine or vehicle. It does take time that I sometimes dont have but I just dont trust manufacturers/dealers to do as thourough a job as I do.

My bowtie · #4 04-13-2012, 09:55 AM

I agree with ya, but no reason for GM to have this issue for a few yrs. Its a simple fix...No reason for this to happen. I also put some blame on the dealer. Its a known issue, check the diff's durring prep.

Plowtoy · #5 04-13-2012, 03:24 PM

Quote:

Originally Posted by My bowtie

I agree with ya, but no reason for GM to have this issue for a few yrs. Its a simple fix...No reason for this to happen. I also put some blame on the dealer. Its a known issue, check the diff's durring prep.

Back in the early 2000s when i was a tech at a GMC dealer, it was a part of a new car prep, but most techs are too lazy to take the 5 seconds to actually check them. They just assume that they are fully filled and what could go wrong at the factory.

On a different note, I was told by my trans guy, that most GM transmissions are ran at the min spec also from the factory. My trans guy suggest to run at least 2 qrts overfull in GM trans missions (that is about an inch above the full hot mark on the dipstick). He suspects that it is done for two reasons, 1 fuel mileage to meet EPA regulations, and 2 cost savings to the manufacture. Just think of all the cars/trucks that the manufactures build, multiply 1-2 quarts of fluid per vehicle and oil ranging 2.50 to $14 a qrt for synthetic= a substantial savings.

My bowtie · #6 04-13-2012, 03:52 PM

Quote:

Originally Posted by Plowtoy

Back in the early 2000s when i was a tech at a GMC dealer, it was a part of a new car prep, but most techs are too lazy to take the 5 seconds to actually check them. They just assume that they are fully filled and what could go wrong at the factory.

On a different note, I was told by my trans guy, that most GM transmissions are ran at the min spec also from the factory. My trans guy suggest to run at least 2 qrts overfull in GM trans missions (that is about an inch above the full hot mark on the dipstick). He suspects that it is done for two reasons, 1 fuel mileage to meet EPA regulations, and 2 cost savings to the manufacture. Just think of all the cars/trucks that the manufactures build, multiply 1-2 quarts of fluid per vehicle and oil ranging 2.50 to $14 a qrt for synthetic= a substantial savings.

I agree on the cost savings, but this is costing GM alot of $$ in parts,labor, and a rental. Plus the fact that it COULD sway someone to a different brand...

NICHOLS LANDSCA · #7 04-13-2012, 08:50 PM

Quote:

Originally Posted by Plowtoy

Back in the early 2000s when i was a tech at a GMC dealer, it was a part of a new car prep, but most techs are too lazy to take the 5 seconds to actually check them. They just assume that they are fully filled and what could go wrong at the factory.

On a different note, I was told by my trans guy, that most GM transmissions are ran at the min spec also from the factory. My trans guy suggest to run at least 2 qrts overfull in GM trans missions (that is about an inch above the full hot mark on the dipstick). He suspects that it is done for two reasons, 1 fuel mileage to meet EPA regulations, and 2 cost savings to the manufacture. Just think of all the cars/trucks that the manufactures build, multiply 1-2 quarts of fluid per vehicle and oil ranging 2.50 to $14 a qrt for synthetic= a substantial savings.

Not sure about your tranny guy but 2 qts over full is too much. With a 4l60 it's a good idea to run it a pint over and transaxles usually live a happier life with an extra splash in them. 2 qts over is too much, it will probably puke some out on it's own. Never run an Allison over full, best to run it below the FULL mark or it will run warm. Someone will probably argue but whatever

Plowtoy · #8 04-16-2012, 08:31 AM

Quote:

Originally Posted by NICHOLS LANDSCA

Not sure about your tranny guy but 2 qts over full is too much. With a 4l60 it's a good idea to run it a pint over and transaxles usually live a happier life with an extra splash in them. 2 qts over is too much, it will probably puke some out on it's own. Never run an Allison over full, best to run it below the FULL mark or it will run warm. Someone will probably argue but whatever

I have been running both my 4L60 in my Yukon overfull and also the 4T60 in my wifes Impala overfull for at least 2 years now. I found this out when I brought the Impala to him shortly after I bought it. 3rd gear was/still is slipping and it had a tcc code. He put in a partial shift kit and told me then that GM purposely under filled them and a 4T60 will cavitate/slip on parking lot speed turns because the fluid can move away from the pickup. By overfilling it (by about one inch on the dipstick) it will take care of that. So far, I haven't had any leaks by overfilling them

My bowtie · #9 04-20-2012, 11:02 AM

Speaking of trannys...Just got a call from dealer, and when the rear diff let loose, it took out first gear

...So now i'll have a rebuilt tranny in a new truck...

70monte · #10 04-20-2012, 11:59 PM

Back in 1998 when I bought my K1500 Z71 new, when I checked the rear diff fluid when I brought it home, it was low. Some of my other fluids were low and one of the components had too much in it. Needless to say when I received my satisfaction card from the dealer, they got low marks on this aspect and they were not happy. They said I should have contacted them first to make it right. I told them they should have done the pre-inspection job right in the first place. I was never impressed with their service department later on down the road on other things.

Wayne