1980 GMC 42' Class A

rexwalker · Oct 16, 2016

I am looking for any and all info I can find on a motorhome I just bought. Its 42'-6" long, the title says 1980 GMC. It has a Detroit Turbo Deseil engine at the back.
I have search high and low and can't find anything on it. It has air brakes and 1 slide out that may have been added.
Bed is in back. Shower is in front of bedroom with a closet opposite the shower.
entry door is at the very front and the passenger seats are behind the driver.

I am looking in particular for wiring, battery arrangement, info on generator, water/utility tank sizes. I have been told the propane is a 100 gallon. what size fuel tank would help also.

Thanks

Gary RV_Wizard · Oct 17, 2016

GMC did not build motorhomes that size, so what you undoubtedly have is a conversion of a GMC bus (motorcoach). Somewhere on the body there should be some other name besides GMC, to indicate who made the conversion (unless it was a privately done custom conversion).

Finding any info on it is likely to be impossible, but bus conversion owners often share info and ideas. In addition to the Bus Conversion board on this site, you may find help at sites like these:
Bus Conversion Magazine: https://www.busconversions.com/
Bus Nuts Yahoo Group: https://groups.yahoo.com/neo/groups/all-bus-nuts/info

Frizlefrak · Oct 18, 2016

Got a pic of it? I'd love to see it.

Utclmjmpr · Oct 18, 2016

Look in the compartment under the drivers seat for the model number,, they did not have VIN numbers,,it will be stamped on the frame.. If it is turbo'ed the engine will be an 8V92 or a 6V92 two stroke detroit..>>>Dan

rexwalker · Oct 19, 2016

Here are some pictures.

Utclmjmpr · Oct 19, 2016

That is a Inter City coach with the 6V92TA engine, probably set up to 350 horsepower. The main problem is the city gearing is too low for over the highway travel and NO storage underneath the bus,,,They are the sleekest/sharpest looking of all the bus models
GM made.. Higher gears are next to impossible to find and with the standard gears your mileage will be terrible for hwy use.

Go to Bus Conversion Magazine bulletin board and talk to Geoff,, He has one and is a Detroit/GM specialist..>>>Dan

rexwalker · Oct 19, 2016

Thanks a lot.
it only has 8,020 original miles on it.

Utclmjmpr · Oct 19, 2016

+ The general model description (in that world) for that bus is an RTS.>>>Dan

grashley · Oct 19, 2016

THIS FORUM IS AMAZING!!!!

Post a picture of an unknown model motorhome, and within a day, somebody here tells you all about it, including where to get specific model help!! I have seen it before, and I am still amazed!!

kdbgoat · Oct 19, 2016

This site is amazing most of the time. Now if someone can help Muddy with his slide leak problem. ...

Utclmjmpr · Oct 19, 2016

I would not take that mileage to the bank,,an RTS was only purchased by cities for inner city transport,, after reaching its useful life in that regard they are normally auctioned off and eventually reach the public domain or the scrappers. Many were used by the military and did not get into high mileages , but never that low.>>>Dan

Utclmjmpr · Oct 19, 2016

Rex,, your Detroit engine is a V6 552CID two cycle with a turbocharged and aftercooled induction system,,it uses ONLY straight weight oil, (Delo 100 straight 40 weight).. Any modern multi grade oil will cause (over time) an increase in oil consumtion..
You may be challenged to find a straight weight oil when you need it so stock up when you do. That engine does NOT like to be "lugged", so when you feel it struggling up a grade gear down and let the engine spin, DO NOT OVERHEAT THIS ENGINE,,,it will get expensive quickly.. When overheated they will crack the heads quicker than you realize..>>>Dan

rexwalker · Oct 20, 2016

ok, I need help on this. The guy I bought from had a contraction that went on the batteries, but he got from a guy that drove it from MO to TX and they put it on electrical hookup.
It appeared to be a item that connect batteries in series for 24 volt. But as we looked at it, it was solid in the middle which would have been a dead short. He put two 12 volt batteries in parallel.

Does anyone know if those two batteries are series or parallel? 12volt or 24 volt. I assume those are the house batteries, the other (1) 12v battery seems to be the one that cranks it.

There is a (2) gauges on the dash one appears to be 12V system showing greenbar between 12-16 the other a 24v system showing green between 24 and 30.http://www.rvforum.net/SMF_forum/index.php?action=dlattach;topic=99670.0;attach=107756;image

Utclmjmpr · Oct 20, 2016

That unit was standard with a 24 volt system,,more than likely the "house" side has been wired for 12 volts to make the RV type off the shelf items commonly used in RVs, work ... The starter and probably the bus heating system, and things like dash lights, headlights, and various "bus" systems was left 24 (and there may be little left to worry about) You are going to have to work out the systems with a VOM to determine how it was done, (there is no "standard" way,it depends on how and what the converter wanted at the time). At no point should these two systems "come together" Vary seldom have I seen a converted coach sold with any schematics or plumbing data included. Your coach (from the pictures) looks like a pro conversion and nicely done, BUT,, it will be a learning curve for you..>>>Dan ( The starter is easy to access, so look it over to determine if it has been replaced with a 12 volt starter..You will also need at least two group 31 batteries to start that engine, particularly when cold..

rexwalker · Oct 20, 2016

Thanks

Utclmjmpr · Oct 20, 2016

REX,, go to this link....https://beta.groups.yahoo.com/neo/groups/RTS-bus-nuts/info >>>Dan

edjunior · Oct 20, 2016

Holy crap Dan. You are the man. I think you have made a serious new friend with Rex! Great job.

Very cool looking coach by the way. Can you post some innie pics? That is quite a unique piece of RV.

Back2PA · Oct 20, 2016

edjunior said:
Very cool looking coach by the way. Can you post some innie pics? That is quite a unique piece of RV.

X2. Very cool

rexwalker · Oct 21, 2016

Some interiors. The center piece in the bedroom comes out for a skylight.

rexwalker · Oct 21, 2016

Thanks for all the help and great advice.

1980 GMC 42' Class A

Member

Site Team

Well-known member

Well-known member

Member

Attachments

Well-known member

Member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Member

Attachments

Well-known member

Member

Well-known member

Well-known member

Well-known member

Member

Attachments

Member

Attachments

Forum statistics