QuestionWell after living with a whiner since50k it finally blew--my rear that is. Precursor was a spline seal @90k replaced with brakes.
Bit of an oddball van Autoform conversion
5.7L OD ABS. If I'm not mistaken 700R4 trans.
Mechanic finds 1 from junkyard as he says rebuild over $1000 due to parts. $400 for rear $250 install OK price. Work done:test drive NG worse whine than before and now other"mystery" noise like rub rub rub.He says maybe oiler ring damaged
Junkyard willing to send replacement rear.What can be put in there? Want to keep highway gearing,dont
know if its a 2.73 or not.Stronger,quieter,gas milage is how I want to go.Any suggestions on how to proceed as many people have mentioned the weakness of chevy rears.
AnswerCharlie - All I can tell you is what I would do in your case.
First, in order to keep that rear end in there, and stay there, I would suggest going with a full synthetic gear oil. This is now factory fill in all GM truck rear ends now. Then change that oil, once a year if you are towing, and otherwise, every two years. I am not sure, but it sure seems to have worked for myself and my customers.
The whining, may not be faulty parts. I mean, what is an "oiler ring"? Unless it is a misnomer, there is no such thing. You may want to get a second opinion on the work that has to be done, which means it'll cost you a bit of labor, some oil, and some RTV. Remember Reagan? Trust, but verify.
Then, do some research. Either get your VIN decoded at the parts dept. at the GM dealership, or look for a white sheet about 6"x8" with a whole bunch of three digit codes on it. Usually in the glove box. This will tell you what the van came with for an axle ratio. I would be surprised to find out that it came with a 2.73 ratio. Not impossible, just unlikely. Here are the codes to look for: (and I can't remember the 2.73 code!)
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42
GT4 - 3.73
G80 - Rear Locking Differential
Once you have verified what you had, I would suggest checking out jobber gear sets. They can be had for quite a bit less than OEM. If you are going to keep the van, it may be worthwhile. Again, this is something you will have to decide. I give you different things to look at, you make the final decision.
If you still want to go reclcyled parts, there is a three digit code on the right hand axle tube of the diff that will tell you what is inside. Take this to the parts dept and they can decode. Or count the teeth in your ring and pinion. For instance, 36 on one and 11 on the other = 3.27.
Gas mileage should not be affected that much. Going from one gearset to another, only changes your engine rpm's by about 200 rpm at any given speed. So, if you had 3.42, and went to 3.73's, you would go from about 1750 to about 1950 rpm at 63 mph. With a van, you have so much frontal area to push and weight, that you may not see a difference. Again, this is what I would do, knowing what I know.
Myself, I wouldn't be scared to put in anything from the 2.73 to 3.42 or even 3.73's in a pinch. Remember that with the OD transmission, that whatever you put in for a rear diff, the ratio is lowered by about 25% with the OD gear. So, a 3.73 in OD gives an actual ratio of 2.80:1. If you only have a three speed auto (again, unlikely), then the 2.73 is the more likely one to have. The only thing you may have to deal with is speedo gears to get the correct readings.
If you do a bit of checking beforehand, then that should give you some more options to deal with, rather than being at the mercy of only one thing. And it sounds like there are some options available to you!
If you have any other questions, please drop me a line.
Have A Great Weekend!
Automotively yours,
Dean
