I looked over the info I found on a site while looking for truck blueprints and saw the spec sheet and price for a new 07 Volvo VNL64T780. Base of $129,944 and total of $161,128 with options (500HP Engine and misc other upgrades)! This is only with the standard 12mo/100,000 mile/3250hr warranty. It would cost even more with the upgraded warranty!
Now a used model for $25,000 - $35,000 doesn't sound so bad :-)Stretch the frame, build a custom coach body and BAM! I have one heck of a truck for allot less money :-) Now to find that money.......hmmmmm :-)

Don't forget: stretch the driveline, air lines, exhaust, wiring harness, beef up the frame, add extra x-members, increase the ft axle & suspension weight capacity, & change the rear end ratios.

Bob,
Tell me more about preferred rear-end ratios. Many of the OTR trucks come setup pretty well for RV use from what I can tell but I would like to hear more.
Thanks,
Rad

Bob,
All of the frame changes you mentioned would be included with stretching the frame. The rear end ratio from the stock truck shouldn't need to be changed as long as the truck doesn't have an off the wall setup.Same for the front end...it should be rated for 12,500 stock. The airlines and wiring are easy to lengthen, and I would change it to a "weedburner" side dump exhaust. The driveshaft lengthening can also be handled by the frame shop. The biggest expense would be building and outfitting the coach body in both time and money. Thats why I want to use an HDT instead of an MDT. The HDT is already beefy enough to use with minimal modifications (the ones you mentioned) unlike an MDT, which requires allot more care in planning and placement of everything as well as potentially more upgrades needed. Thanks for the feedback.

A lot of the chassis mods would depend on the length of the conversion, rear axle placement & GVW.
If you build a 40+ foot conversion with rear axles placed towards the rear, you should consider a double frame. You may also need to increase the ft axle weigh capacity to 15 or 16K lbs as the load ratio would be forward biased.
Rear end ratios for an over-the-road truck are setup for hauling a nominal 80K lbs. Unless you're going to be hauling a 40K pound trailer, chances are you would benifit from a higher ratio, considering fuel mileage, engine wear, etc.
I would agree most of this wouldn't be absolutely necessary however,...as compared to building a house, the "foundation" needs to be correct before starting on anything else.

Thanks Bob. I agree. I want to spend the time needed to research and plan this project to address all the things you mentioned plus a ton of other concerns/questions. Having everything planned and engineered correctly before starting will make the project go much smoother and quicker and result in a safe, quality built rig. Thanks for all your input.

.....3:58 seems to be the winner for me....might go higher but can't just now.....too busy with a update/rebuilt house to do.....others are starving and I'm too busy to take a vacation.....something is wrong here!......goefkaye

.....3:58 seems to be the winner for me....might go higher but can't just now.....too busy with a update/rebuilt house to do.....others are starving and I'm too busy to take a vacation.....something is wrong here!......geofkaye

GeofKaye, is the 3.58 rearend ratio that you like in a direct or over drive tanny and 22.5 or 24.5 wheels?

Hey Notstock,

A lot of the trucks I see have about 3.73:1 gears in them, and they always have 9- or 10-speed trannies with overdrive in them. Without overdrive you would probably need 3.17 gears just to have the same final ratio as with 3.73's AND overdrive. Having said that, 3.58 gears and an O/D trans would "relax" the engine a bit pulling the lighter load you'd have with your conversion. Without the O/D trans, you might look at about a 3.08 gear to get the same final ratio. Now, with ALL that said, I've heard of guys using a 3.08 gear WITH an O/D trans. Talk about long legs! Anyway, I hope this gave you enough stuff to mull over about your future rig! (kinda fun, huh?)

Gary