Body-Builders?

[phantomjock]

No - not a membership to the local Fitness Club.

While I've been chasing a few wires for mods, I've been all over the inter-web looking for good, accurate, readable, useful wiring diagrams for my 2008 Chevy 2500.

Other folks have asked previously about the '07, and other years and models. I may have found the (GM) Gold Mine!
{i couldn't find reference to in in my searches - so this posting}

General Motors created a site/repository for those folks using the GM platform (like Roadtrek - back in the day) to help do the job right. Now, you can get your own copy at this link:
https://www.gmupfitter.com/body-builder-manuals/

Pretty picture from site:

Happy hunting!

Cheers - Jim

[phantomjock]

I am sharing my effort validating the "lineage" of relationship(s) between the Chevrolet G/H Vans produced in the late 1990s and the Chevy Express Vans used in many Class B's. I maybe off on my guestimates, and look forward to the "greybeards" in the RT community to help.

In the Chevrolet Forum, the best one-liner I could find is; "The "G" series vans were made up until 1995. 1996-now are the Express series vans..." and that was posted in 2010. No specific reference was posted. https://chevroletforum.com/forum/exp...-g-vans-37517/

The reason I'm asking, as there are very specific guides provided by GM to Upfitters to ensure the vans remain secure and sound as they underwent conversions. These guides are very useful for mechanical and electrical reference, and IF the GM G/H vans are the same vehicle as the Chevy Express Van - VERY useful. These are also referred to by GM as "Body Builder Manuals- GM Upfitter." https://www.gmupfitter.com/body-builder-manuals/ Light Duty - Full Size Vans (Full Body/Cut-away). Prior to 2013, you can find 16 pdfs, many of which are listed as "G/H and Chevrolet Express & GMC Savana." Seems a bit closer than just "kissin' cousins."

Another reference to the differences between the Chevy 1500, 2500, and 3500 I came across is at: https://tworoamingsouls.com/whats-th...and-3500-vans/
In that article, they add;

The Chevy Express and GMC Savana are General Motors’ full-size vans that have been in production since 1995. They replaced the Chevrolet Van and GMC Vandura which were based on a unibody design. But beginning with the Express and Savana, they switched to a body-on-frame design that’s borrowed from their trucks.

Regarding build differences, they point out;

So the 2500’s and 3500’s are built with more robust suspension, brakes, etc. They may also have larger engines, better transmissions, and higher output alternator.

Useful information, but no pointing to the "truck" chassis GM used. Were these actually the former G/H chassis? I suspect so, as I found a GM Upfitter Manual for the 2008 G/H and have used it as a guide for a number of my modifications. And clearly both the Express Vans and the G/H are chassis-based, not unibody.

Thoughts or comments are appreciated.

Cheers - Jim

[booster]

I can't speak to any changes that were made at the 1995ish name change point, but there was a redesign in the Express version in 2003/2004 timeframe.


AFAIK, most of the changes had to do with going to LS series engine from the old Gen I small block, big block engines, and diesels. It appears that is also when the smaller Dana Super 60 semifloating axle appeared in the heavier weight vans, with a Dana Super 70 full floating option available in the trailer towing package. The Dana axles replaced the very nice GM "corporate" full floating axles of the previous generation.


As far as body and frame changes go many were also related to the engine changes.


The engine compartment and doghouse got smaller/narrower as no big blocks or diesels are used. The front stub of the frame also got narrower across between the frame rails to match the narrower compartment. This allowed them to use longer upper and lower control arms to improve geometry and that would improve handling somewhat. Longer springs could also be used allowing more usable travel and lower progression for better ride and bump handling.


I think they also decided to put the van on a diet also as there appear to be some changes in the front frame stub based on the fact that the center jack lift point in the center of the front frame crossmember was taken off the recommended lift points. How much else in the front frame was weakened I have no idea.


There did appear to be a change to power steering in about 2007 when it changed from the basic GM system for recirculating ball to one that adds an assembly to the steering shaft end of the steering gear to give them the more modern feel springy centering return. Drive by wire appeared at about the same time replacing the throttle cable.


In 2010 the 6.0 engines got the 6L90 six speed transmission which also is programmed differently than the 4 speed and eliminated overheated transmission issues of the 4 speeds. There is an extra bump up on the floor between the seats to clear the 6 speed.



Variable valve time also appeared about 2010 and over the year tweaks to intake manifolds and such increased hp and torque and generally raised the rpm power curve somewhat which probably matches the 6 speed better.


I am sure that other stuff happened also, and some might entail cost reductions as GM was not doing well in the 2007 time period.

[phantomjock]

booster-
I was pretty certain you'd have a good grasp on this topic.

There is a LOT of good detail in the various Body-Builders pdfs, mechanical and electrical. This info might help others on the forum if searching for Express Van-specific torque values (useful in suspension mods!), and electrical mods or troubleshooting.

The documents detail the difference in torques for fasteners in several locations based on model 1500/2500/3500, not so much detail on mounting positions for engine - that I've noted (so far).

Cheers - Jim