Chevy Express Rear Differential Info

Disclaimer: I do not know the full Express history.  The information below applies to the current Express models and possibly the whole generation:

A requirement of mine is to get off the pavement and down some forest service roads and such.  Nothing too rough, but I'd like to do some dispersed camping and not get stuck!  Especially alone.  I figured I'd get an Express and have an Eaton Tru Trac rear locker installed.  However, I recently learned the Chevy Express has an odd ball rear differential and Eaton does NOT make a True Trac locker for this differential.  Eaton makes one for the Dana 60 and the Dana 80 (as well as a host of others).  However, Eaton does not make a Tru Trac locker for the Dana 70 which the current Chevy Express utilizes.  From my research, it looks like if you want two wheels spinning in the the rear your stuck (no pun intended) with GM's G80 limited slip differential.  And that's if your particular van has it?  A retrofit could get pretty expensive.  G80 is a pretty rare feature where I live.  However, if you want a leather wrapped steering wheel that's a different story.  Most have it :dodgy:

I'm sharing this in case some of you might not be aware.  I have not seen this discussed here before.   It could have been a very expensive mistake for me. 

I got my information from a very reputable differential shop and they did not try to sell me something else.  I'm not sure what to make of that.  Does that mean no other locker is available?  I don't know, but I've moved on to a 4x4 pickup w/camper.


Just sharing,

Matt

Matt, have you looked here?

http://www.drivetrain.com/parts_catalog/positraction/


http://www.drivetrain.com/parts_catalog/positraction/detroit_locker_eaton_limited_slip.html#Dana70

tx2sturgis,

Looking at the 1st link I just see an overview. Kind of a locker 101, but I did not dig any deeper. The 2nd link does show lockers available for the Dana 70 but not in the gear ratio of the Dana 70 in the Chevy Express (3.42) unless 4.10 and down works. I don't know. I'm just going by what I was told.

hangtownmatt said:

tx2sturgis,

Looking at the 1st link I just see an overview.  Kind of a locker 101, but I did not dig any deeper.  The 2nd link does show lockers available for the Dana 70 but not in the gear ratio of the Dana 70 in the Chevy Express (3.42) unless 4.10 and down works.  I don't know.  I'm just going by what I was told.

Click to expand...

Yes, but the pages have several links...

Do you think you would really need a locking diff? Many of the GM and Ford vans come with limited slip, or posi-trac, and unless you plan to crawl over loose rocks, they work pretty well.

My van has the limited slip rear, and it works quite well most of the time.

Of course a 4x4 with limited slip or lockers is the very best for getting 50 feet further down the trail, high-centering, and then you get to deploy the winch.

Been there, done that!

Matt,  I did alot of research on this last year with virtually no prior experience.  One of the best youtube videos that I've seen is this one:



It explains very well the different types and how they work that are out there.  But like you found out,  some vehicles don't have offerings.  I have a 2012 gmc savana 2500 12 seat passenger van that I am converting to camper/tow vehicle.  Last year I put an ARB air locker in mine.  After much research I wanted an electric locker but couldn't find one for my vehicle.   The hardest part of the whole process was finding out exactly which rear end was in my van.  There was no tag on rear end.  I did find a part # on the diff cover which led my to the rear end being a 920 series AAM rear end.  Oh let me back up some I bought my 5 year old van from a dealership.  I asked them what it would cost to put a limited diff in and they said approx $5k.  I laughed and walked away.  I knew I didn't want a limited,  didn't seem to be an electric. (I like the idea of going from open diff to positraction with a flip of a switch)  So I decided on air locker (same idea, positraction with a flip of a switch)

Well I put the air locker in myself but took research and learning new things which I like to do.  I later found out easier ways to find your rear end specs.

I only have the original tires and this van is so light it can barely traverse wet grass on level ground but when I'm finished with my build I will expect that to change.

Even 4x4's are not true 4x4 without lockers.  Looked at lunchbox lockers like Falcon put in his.  It's the easiest and cheapest but didn't want the extra noise.

gapper2


Oh after I was into the project,  I found that gm offered an electric model for the hummer but same rear end.  Very hard to find one though.  Offered on Rockauto for awhile.






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Oh, My rear end is a gm 14 bolt,  9.5 inch ring gear,  3.42 gear ratio (lower is better for fuel mpg)  33 spline count on rear drive shafts.  All the info needed for locker research.  Varies by vehicle so get that info first.

I would rather have a Detroit Locker. they are cheaper, super strong, and very simple. an ARB Air Locker or an Eaton Electric Locker are very nice but expensive. highdesertranger

Limited slip rear ends are not the same as locking rear ends.  The factory installed limited slips are all based on clutch packs, which wear.  By the time you hit 80,000 to 100,000 miles, they've worn so much they no longer have any real effect, and you're back to running an open diff.

The Detroit TruTrac is a limited slip that doesn't use clutches and never wears out.

" The factory installed limited slips are all based on clutch packs, which wear"  That is what I found out and did not go that route.  The ARB does have the added cost of an air compressor.  Very well built.  I was a machinist in a former life.  I believe Detroit did make one for Matt's van not sure about his specs (don't think it was a tru trac though).  I like the idea of open diff 99.5% of the time. YMMV

Optimistic Paranoid said:

Limited slip rear ends are not the same as locking rear ends.  The factory installed limited slips are all based on clutch packs, which wear.  By the time you hit 80,000 to 100,000 miles, they've worn so much they no longer have any real effect, and you're back to running an open diff.

The Detroit TruTrac is a limited slip that doesn't use clutches and never wears out.

Click to expand...

This is what I learned also.  I wanted an Eaton Detroit Tru Trac.  My local differential shop told me it was not available for the current Chevy Express.  They did not try to steer me towards another locker either.  Their suggestion was to not buy a Chevy Express and get something with a real differential.  There words not mine.  Don't shoot the messenger.

Matt

I'm considering ordering a new 2500 Express Cargo, in part to get the differential option, which in the build page on their site Chevy refers to as "Heavy-duty locking rear differential-$325". And that's list price of course. Often things are a matter of terminology, but at $325 it made me wonder how much it would cost to service it down the road if need be. I called a well respected diff shop where I live and he said he wouldn't service/rebuild it but would rather replace it with an aftermarket unit, $1200-1500. He then asked me how I would be using the vehicle, and I told him it would be occasional Forest Service roads and other dirt/rough roads, etc, but nothing crazy and that I knew the difference between this and a 4-wheel drive vehicle . With that he said the standard Eaton G-80 would be fine for what I want to do, and also pointed out that the life of the unit will depend a lot on how the vehicle is driven on a day to day basis-I'm a pretty mellow driver. He explained how it operates, that it's not a true locking diff, which I understood all along. Interesting Chevy calls it locking instead of lim-slip.

Thanks, interesting thread!

I too agree an interesting thread Dave06,

   I thank Falcon's build thread for giving me the courage to research such a project!  Actually his research into lunchbox lockers are not far from a Detroit locker.  The lunchbox locker looked to be a very inexpensive, relatively easy for the novice.  No removal of the Carrier unit in the diff (which adds a little complexity to the project)  but not much in my case. And for a few hundred dollars it is a true locking differential.  No clutches to replace or adjust.  It would be nice to get an update from Falcon on what he now thinks of that project.  I do realize most peeps will never need such equipment.  But actual experience is invaluable.

gapper2

Yeah, I've been trying to figure out what's on my '07 Express 2500HD with 8-lug wheels. From the looks of the diff it's a Dana something-or-other. My off-roading mechanic buddy said it's a 60. I found one online listing saying it's a Super 60. A couple of others said it was some GM diff, so online info is iffy. I hadn't heard of a Dana 70 so I looked it up. Wikipedia said there's a 70 cast into the diff housing. So I crawled under the van. I didn't see a 70 but the part ID sticker said it has a standard diff (which I knew), a 3.73 ratio and a model number 60S. So, is that a Super 60 or something else?

this might help ID axles for those that need help.

http://www.differentials.com/technical-help-2/differential-identification/

highdesertranger

Take the VIN to a GM dealer and they can give you a build sheet of EVERYTHING your van had installed when it was built.  That may be too easy though.

Matt I remembered something else that happened while I was doing my research for a locker.  After I looked through all the locker manf. sites.  I was still guessing at what size ring gear I had.  I contacted ARB tech support and told the agent which vehicle I had and he thought the ARB RD197 kit would fit.
I then called the local ARB dealership in Atlanta and asked if he had a kit to fit my van and wanted to know the installation cost.  The dealer in Atlanta told me that he didn't have a kit to fit.  I told him I had just talked to tech support.  So he took my phone # and called ARB and then called me back and said that I was correct,  they did have a kit.  Evidently they don't get many "nuts" who just want to get off the beaten path in a van.  

Mr. Noodly,
  I had a hard time finding which rear end was in my van.  I don't think the auto dealership with a vin number works because that just tells about the gear ratio.  I think if one wants to get the quickest info about your rear end is to stop by an installer and ask what kind of locker they have for your van.  They can look at it tell you probably.  Once you have the rear end manf, gear ratio, ring gear size, and drive shaft spline count you can do your own research.

 A word of caution about ARB installation manuals.  MUCH incorrect install instructions.  Had to research lots and couldn't even get the rear drive shafts out until happening on a youtube video.  ARB manual didn't have C clip info not to mention the ABS sensors have to be pulled to get the shafts out.  Thank you youtube!

What do you guys link of Torsen-style diffs like the Detroit Trutrac?

Mr. Noodly,

   I am a real rookie at this stuff but that youtube video I linked to talked about the pros and cons of torsen if you have the bandwidth.

gapper2 said:

Evidently they don't get many "nuts" who just want to get off the beaten path in a van.  

Click to expand...

Too funny.  I resemble that remark :shy:

Matt

gapper2 said:

...that youtube video I linked to talked about the pros and cons of torsen...

Click to expand...

Thanks. Since I'm not a Jeep trails or snow-plowing kind of guy, the locker options would be overkill for me, and I wouldn't want to deal with upkeep on a LSD. If the military uses Torsens then that's enough of a recommendation for me. No special servicing, no buttons or levers to use, no clunking... Now I just need to come up with the money.