1989-91 R/V3500 Series

[V30 mongo]

My little ditty about "work trucks" has made points about Ford and Dodge as being built for heavy use. This is a forum on Chevy/Gmc trucks. True, the newer model trucks will carry more and pull larger trailers than there older counterparts, but that is all they will do. Wrecker trucks, dump tucks, salt spreaders, etc. all require one thing to operate at capacity properly, a power take off. This device, attached to transmission or transfer case must be able to supply at least 25 horse power to operate attached equipment. All newer trucks do not have PTO capabilities on ther 4x4 transfer cases and only some automatic transmissions will accept a PTO unit and then only a special "hot shift" type that is only capable to run a hydraulic pump that will supply only about 10 GPH. They will not take the mechanical shift type PTO units and reversable PTO's are impossible. This will run a small dump body, but to use it for a wrecker or salt spreader, it will not operate it at any speed to be usefull. Also, the rear frames on most of the newer trucks is nice and flat and this is good for the mounting of vocational bodies, but the location of fuel tanks and exhaust systems make it a nightmare to fit PTO drive shafts and there driven equipment. There is a lot more to just how much a truck will carry or pull to make it a true "work truck".

[meatwagon83]

Originally Posted by Keith Seymore

I was being a little bit silly and playing off the brevity of your original response -

K

yeah i caught that! ive always considered the 6.2 a slug and have seen quite a few pulled in favor of a 454

[Desert1957]

Originally Posted by Keith Seymore

...Because it will run on french fry grease...

I'm a huge fan of diesels because of the opportunity to run alternate/bio fuels. K

I make a living on fixing Diesel engines that run on 20% Bio, ONLY older mechanical injected Diesel engine can pass it through their old nasty injectors. NEW electronic engines have much more sensitive injectors that cannot pass any trash at all.

Keith PM me for more info on this topic , If you want.

Desert

[Keith Seymore]

Originally Posted by V30 mongo

My little ditty about "work trucks" has made points about Ford and Dodge as being built for heavy use. This is a forum on Chevy/Gmc trucks. True, the newer model trucks will carry more and pull larger trailers than there older counterparts, but that is all they will do. Wrecker trucks, dump tucks, salt spreaders, etc. all require one thing to operate at capacity properly, a power take off. This device, attached to transmission or transfer case must be able to supply at least 25 horse power to operate attached equipment. All newer trucks do not have PTO capabilities on ther 4x4 transfer cases and only some automatic transmissions will accept a PTO unit and then only a special "hot shift" type that is only capable to run a hydraulic pump that will supply only about 10 GPH. They will not take the mechanical shift type PTO units and reversable PTO's are impossible. This will run a small dump body, but to use it for a wrecker or salt spreader, it will not operate it at any speed to be usefull. Also, the rear frames on most of the newer trucks is nice and flat and this is good for the mounting of vocational bodies, but the location of fuel tanks and exhaust systems make it a nightmare to fit PTO drive shafts and there driven equipment. There is a lot more to just how much a truck will carry or pull to make it a true "work truck".

I asked our Transfer Case subject expert about this; his reply is as follows:

"We made a conscious decision back in the start of the GMT800 to move the PTO from the Tcase to the transmission. This was partially done because the existing technology was to put the Tcase gear on the reduction carrier which ran at a reduced ratio of 2.72:1 to the tcase input. So the Tcase input had to spin fairly fast to get the pitch line velocity needed to power many devices. This made devices powered on slow moving vehicles ineffective. It was better to run on a gear that was close to the front end of the transmission to provide consistent speed over an extended driving speed range. When the PTO is operated in a stationery vehicle, the Tcase pump on the output is not spinning, and there is also thus lubrication issues to resolve for the PTO.

"There has been no discussion to move the PTO back to the Tcase in the last decade. I believe the PTO is still available on the Allison. It would take considerable effort to add the PTO back to the Tcase. I imagine it would be a difficult business case to make, however I am open to discussing it further if there is a significant need."

So (my interpretation) - it sounds like the original design was not effective for many users and was detrimental to Tcase durability (for stationary use) - and - that there hasn't been much pull from our customer data to go back to the previous strategy.

FWIW.

K

[Keith Seymore]

Originally Posted by Desert1957

I make a living on fixing Diesel engines that run on 20% Bio, ONLY older mechanical injected Diesel engine can pass it through their old nasty injectors. NEW electronic engines have much more sensitive injectors that cannot pass any trash at all.

Keith PM me for more info on this topic , If you want.

Desert

Thank you; I am always interested in learning more but am not in a position to do anything practical with it at this point....

K

[oltronj]

Ok so I am a little confused. I had a 91 crew cab so is it an r/v series truck?
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[GM72K10]

Yes
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