Chevy Express Rear Differential Info

[Cammalu]

I consider lovers to be a great idea for anyone who wants to get a little further back--and out again. 

REALLY BOB!!!! oh that sentence might just get you another badge!!!!!

Oh My God!

 

[tx2sturgis]

And Bob, remember Rule Number ONE:

No editing after 14 minutes and 59 seconds!

 

[tx2sturgis]

I very much disagree with this idea. I consider [lockers] to be a great idea for anyone who wants to get a little further back--and out again. 

By far the majority of 4x4 folks I've known agree that a locker is a great choice for a van.

I agree, a little further back, yes.

But not full-on two-track on muddy or swampy wet muck, and with no help around, it could be a problem.

As Matt pointed out, common sense is the primary tool to bring along when 'wheeling, OR vanning.

 

[akrvbob]

I had automatically assumed I had a 14 bolt GM rear end on my 2015 2500 GMC Savanah, but this thread scared me!

So I just counted the bolts on my differential and the bottom half has 7, so I think it's safe to assume it is the 14 bolt GM--one of the best rear-ends available!

So when the drivetrain warranty runs out on my van, I'll get a True Trac put in. There is no question in my mind as to their value and how far into the backcountry it will get me.

My first 2 years of boondocking I was in a 4x4 F150 with a home-built camper. I went ANYWHERE I wanted, often in 4x4 LOW!! Never once got stuck!!

The last 7 years I've been in a van, been stuck probably a dozen times. I expect the locker to solve that problem.

 

[cortttt]

I had automatically assumed I had a 14 bolt GM rear end on my 2015 2500 GMC Savanah, but this thread scared  me!

So I just counted the bolts on my differential and the bottom half has 7, so I think it's safe to assume it is the 14 bolt GM--one of the best rear-ends available!

So when the drivetrain warranty runs out on my van, I'll get a True Trac put in. There is no question in my mind as to their value and how far into the backcountry it will get me.

My first 2 years of boondocking I was in a 4x4 F150 with a home-built camper. I went ANYWHERE I wanted, often in 4x4 LOW!! Never once got stuck!!

The last 7 years I've been in a van, been stuck probably a dozen times. I expect the locker to solve that problem.

More on the GM 14-bolt 10.5"  rear end

[font=open-sans, arial, sans-serif]When it comes to strength, value, and vast availability, the full-float 14-bolt rear axle from General Motors is about as good as it gets. Fitted with an impressive 10½-inch ring gear, three pinion bearings, and backed by a strong array of aftermarket support, the [/font][font=open-sans, arial, sans-serif]GM 14-bolt[/font][font=open-sans, arial, sans-serif] can easily handle up-to 44-inch tires in most applications. In case you're not familiar with the 14-bolt, the axle gets its name from the 14 bolts that secure the differential cover. First appearing in 1973, the 14-bolt is one of the most used rear axles in the General Motors stable.[/font]

[font=open-sans, arial, sans-serif][font=open-sans, arial, sans-serif]Although there are a few versions, the full-float, 8-lug 14-bolts are the most desirable for those looking to build an off-road rig or upgrade their pickups light-duty rear axle. [/font]
[/font]
http://www.fourwheeler.com/how-to/t...olt-basics-inside-the-ultimate-junkyard-axle/

[font=open-sans, arial, sans-serif]Enthusiasts love the full-floating eight-lug 14-bolt because it features a massive 10.5-inch ring gear, and a very strong pinion design that incorporates support bearings on each side of the pinion's teeth-awesome for minimizing pinion deflection under high torque applications.[/font]

That's referring to the 10.5" full-floating axle. Chevy's put quite a few different axles on their vans - the Dana 60, 70- super 35 and Dana 80 - 35,37 splines; GM 9.5, GM 10.5 In some years all of these - 6 different differentials - were put on Chevy/GMC one-tons! (I wonder if they were running out of differentials?)

9.5" 14 Bolt Differential

If I'm reading the bolt pattern right (https://www.ringpinion.com/b2c/Diff...&MakeID=3&ModelID=465&Side=Rear&DriveType=RWD) my van (2010 one-ton) has the 9.5" 14 bolt semi-floating axle.

Chevy/GMC also put the 10.5" full floating on their 1-ton vans from 2010-2014 and honestly it seems like a better fit for the one-tons...

[font=open-sans, arial, sans-serif]However, most people are not aware of the less common six-lug, semi-floating version of the 14-bolt axle. GM called it the "9.5" 14-bolt (after its ring-gear diameter) and offered it exclusively in light-duty 3/4-ton pickups built between 1986 and '93. While not as strong as its eight-lug cousin, the semi-floating 14-bolt rearend does sport some noteworthy attributes. [/font]

[font=open-sans, arial, sans-serif][size=medium][font=open-sans, arial, sans-serif]For instance, the all-important width measurement from wheel mounting surface to wheel mounting surface is 67 inches-perfect for most 1/2-ton pickups. Generally, you wouldn't even need to change mounting brackets to bolt this housing right into the rear of a 1/2-ton GM pickup because the leaf spring architecture is identical. [/font][/font][/size]

[font=open-sans, arial, sans-serif][size=medium][font=open-sans, arial, sans-serif]We like the fact that the ring gear measures out at a healthy 9 1/2-inch diameter, and the 33-spline axleshafts have a 1.370-inch diameter-a sure improvement in strength over the typical 1/2-ton shafts. This less grown-up version of the 14-bolt may not have the extra pinion support bearing of its eight-lug cousin, but it's rated to handle 5,000 lb-ft of torque, so it's no lightweight either. Moreover, aftermarket suppliers such as Randy's Ring and Pinion offer all the upgrade goodies you need to make this rear end survive with up to 37-inch-tall rubber.

http://www.fourwheeler.com/how-to/t...-14-bolt-axle-gears-and-locker/[/font][/SIZE][/font]

[font=open-sans, arial, sans-serif]More information on the 9.5"[/font]

The GM 9-1/2" semi-float rear axle was introduced in 1981 for 3/4 ton trucks as a lower cost replacement for the full floating 10-1/2" 14 Bolt axle used on 1973-1980 3/4 ton models. Starting in 1988, the 9-1/2" axle is also used on 1/2 ton heavy-duty models. The GM and AAM 9-1/2" axles are the same. The name difference is due to GM selling it's axle group to a group of investors who named the new company American Axle Manufacturing. The 9-12" axle design has remained pretty much unchanged over the years with the exception of seal changes and brakes.

[font=Lato, sans-serif]http://www.quad4x4.com/catalog/category/gm9.5r[/font]

Some reviews of the 9.5" axle

[font=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]Pretty standard Semi-Float 14 bolt, 9.5" ring gear (33 spline) rear GM axle of that era. Pretty solid axle that can take quite a bit of abuse.[/font]

[font=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif][font=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]Like was said, the 9.5" is a great axle for what it is (far better/stronger than the 8.5" 10-bolt used in ½-tons, and is sought after by some of their owners). The 10.5" was made for heavier-duty service (is also used in 1-ton C/K-30 / 3500 trucks), it's a larger axle w/full-float hubs (also identifiable by the 8 axle bolts that attach the axle shafts to the wheel hubs)[/font][/font]

According to this site - https://www.provenforce.com/positraction/gm_truck_c30_3500_rear_positraction.html -  the following 

[size=small][font=Verdana, Arial, Helvetica, sans-serif] Eaton Detroit Locker, Detroit TrueTrac, Eaton Positractions and electric ELocker positraction units are available for [/font][font=Verdana, Arial, Helvetica, sans-serif]GM 14 Bolt 9.5"[/font][font=Verdana, Arial, Helvetica, sans-serif], [/font][/size]

 

[Stanvan]

Thank you, Cortttt, for bumping this thread. I've joined up here after this thread, and is totally relevant to what I'm currently dealing with. I am sadly surprised at Chevy for not using a locking diff in a vehicle known for towing. My last van was an AWD Astro, and going from that to ONE wheel drive is frustrating, at best. I got mine this past July, and we got our first snow(one lousy inch) last week, and I couldn't get out of the driveway in my back yard. I hate to think what could happen at a slimy boat ramp, trying to pull a boat out. I've seen Youtube's about that, and it's hilarious, unless it's happening to you.

I haven't decided as exactly to what I'll install. It's either a Detroit Locker, or a Powertrax Lock Right. I have to crawl under and find the numbers because I've seen discrepancies between some of the websites with pictures of the different covers and which ones are which. As a former parts guy, I know the numbers don't lie.

I'd be interested in what the OP did.

 

[cortttt]

Thank you, Cortttt, for bumping this thread.  I've joined up here after this thread, and is totally relevant to what I'm currently dealing with.  I am sadly surprised at Chevy for not using a locking diff in a vehicle known for towing. My last van was an AWD Astro, and going from that to ONE wheel drive is frustrating, at best. I got mine this past July, and we got our first snow(one lousy inch) last week, and I couldn't get out of the driveway in my back yard.  I hate to think what could happen at a slimy boat ramp, trying to pull a boat out. I've seen Youtube's about that, and it's hilarious, unless it's happening to you.

I haven't decided as exactly to what I'll install. It's either a Detroit Locker, or a Powertrax Lock Right.  I have to crawl under and find the numbers because I've seen discrepancies between some of the websites with pictures of the different covers and which ones are which.  As a former parts guy, I know the numbers don't lie.

I'd be interested in what the OP did.

Very frustrating. I get stuck about 2 or 3 times a year. Had to be towed out of one - about $500 when all was said and done...Much better not to get stuck in the first place. 

The folks a 4x4 van conversions recommended a Detroit TrueTrac  - limited slip differential - for this axle... I was hoping for an manually engageable rear locker .

My 2WD 4Runner had a manually engageable "limited slip differential" which made hardly any difference at all in traction. It was so poor that I wonder if it was a true LSD....I hope it wasn't!

 

[brooksto]

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 i am interested in details of what rear axle is in your van. I have a 2013 chevy express 2500 with a 14 bolt rear end, that i assumed was a gm 9.5 14 bolt. So i thought that would take the eaton truetrac part njmber 914a538. Now after reading your post i am worried it wont work. Can you give any more details on the rearend in your van? Pics markings etc?

 

[Stanvan]

Do not assume anything in regards to this issue (or most anything in life!!). There doesn't seem to be any rhyme or reason in what diff you might have. I found this link to be helpful;

http://www.gearheaddiva.com/7314/differential-identification/

Take a picture of your diff to compare it with the link. Scroll down the page for comparison pics. There also should be a tag or sticker on your diff with the pertinent info on it. My '16 sticker was not readable, but a friend's '06 was.

 

[cortttt]

Matt i am interested in details of what rear axle is in your van. I have a 2013 chevy express 2500 with a 14 bolt rear end, that i assumed was a gm 9.5 14 bolt. So i thought that would take the eaton truetrac part njmber 914a538. Now after reading your post i am worried it wont work. Can you give any more details on the rearend in your van? Pics markings etc?

I sourced mine using this link from highdesertranger - http://www.differentials.com/technical-help-2/differential-identification/ I had a 9.5" GM 14 bolt and just got a Detroit Truetrac put in yesterday. 

You can also take the last 8 of the VIN to the dealer and find out that way

 

[Chuck1]

A full locked rear end with someone who can drive and the right tires can go almost anywhere a 4x4 can go.

Offroad racing as been dominated by two wheel drive trucks and race cars, you should see some of the stuff they get through with no problem.

Just put a spool in it

 

[Stanvan]

Cortt, I'm curious why you went with a TrueTrac instead of a Locker.

 

[cortttt]

Cortt, I'm curious why you went with a TrueTrac instead of a Locker.

I went to several shops and everyone recommended a TrueTrac. I was a bit surprised. In fact not one mentioned a locker. It may have been because of price. One shop told me a e-locker is a lot more expensive. 

The same shop told me there's very little "slip" in the LSD - it catches on really quickly and every shop said the TrueTrac was really robust. The prices I got ranged from about $950 to $1300. (Good to shop around!)

The other reason is that while I'm not in snow alot, the LSD is apparently a lot better in snow. 

Nothing's better than a locker, though, for getting out of a tough spot on the trail.

 

[Stanvan]

I hope that includes labor. Detroit Lockers go from $400.00 to $500.00 before labor. It is said that they're fairly easy to install. I won't tackle the job myself, but my labor costs will probably be beer and BBQ. And before someone says it, I trust these guys with a few beers in them over most sober mechanics.

I just gotta figure out which diff I have. The shape of the cover says GM 8.6(25), except that it is a 14 bolt, and the 8.6(25) is a 10 bolt. And at two years old, there's no ink on the sticker with any ID numbers.

 

[highdesertranger]

a note, Detroit Lockers are very harsh when locking and unlocking. this is the biggest compliant against them, to the point were most people don't like them. I run a Detroit Locker in my truck, is it harsh? yes. but it's a small price to pay for the toughest, simplest locker on the market. highdesertranger

 

[John61CT]

Could you explain what "harsh" means, and what actual disadvantages that would entail?

 

[highdesertranger]

lets see, when I say harsh I mean when it locks or unlocks it's very hard. if you ever drag raced and popped the clutch, it's kinda like that. if you aren't aware of this and don't dive accordingly you could loose control of your vehicle. on a lighter weight vehicle it could cause it to change direction. this is especially true when cornering and even truer when going down hill into a curve and hitting your brakes. you MUST drive according to the locker. when coasting downhill into a curve downshift instead of hitting the brakes. to me the advantages far outweigh the disadvantages. I have been driving vehicles with Detroit Lockers since the 70's I wouldn't even consider another type, in fact the Locker I have in my current truck I bought in the early 90's it's been in 3 of my trucks since and still works fine. highdesertranger

 

[John61CT]

I've never heard of a "drag race", had to look it up, never mind done it. Thought maybe an LGBTQ thing

Sounds like if I go that way I maybe should invest in some specialized driving lessons.

 

[Stanvan]

While I don't have any personal experience driving with a locker(yet), the way it's been described to me is not quite as harsh as Highdesertranger describes. I've been told that it can be heard and felt in normal driving. Certainly not something that deserves a driving class. If you race through the streets, not in a straight line(drag racing) yes you could get in to trouble.

 

[highdesertranger]

or coasting downhill into a sharp curve at 65mph and you suddenly realize you are going to fast for the curve and hit your brakes while in a sharp curve. bad driving habits are amplified with a locker. a lot people, especially those with automatics have bad driving habits in the mountains. highdesertranger