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

Gary,
Talk about enough stuff to mull over. Overwhelmed is an understatment. I have already bought what I thought was the perfect platform to convert 3 times, lol. First one was a school bus, then an MCI 102A3 tour bus, then another better school bus, and now I am set on the HDT. I just gotta make sure I start with the right one. Buying and selling this things is a royal PITA!! lol

....the 3.58:1 with a 10 speed overdrive is the best of 2 worlds for me....final ratio is .73.....tires are another issue....I'd like 24.5's but I have 22.5's now and would change them out but they are new 3 years ago and some still have the rubber tits in spots....so I will stay with the 22.5's till 2012....then I will go to 24.5's if still available...I have to have steel rims also since I hate aluminum rims....I still whack a curb now and them while backing....steels cost me $25 each sand blasted...I repaint black after a cost of steel primer[Porter 296 red and 2 coats of Rust-o-leum 7777 Black satin top coat ] I'd like the tallest 24'5 on the market but....who knows what will be available then....there are some 3:21's available but it isn't worth the effort now to change them out I drive less than 20,000 a year....It is hard to justify anything with that kind of mileage-even at 5 mpg!....I get 8.6 loaded down and 10+ empty running at 70+.....geofkaye

Geof what is your weighted down weight and what do you have for a truck?

'98 Volvo 610 / N-14 @ 500 hp/ super 10 /with 3:58's tractor is 23,000# loaded and trailer is 11,000# loaded....."loaded" means everything the girlz[4] can think of to take at the last minute with 125 gallons of water....no gray or black water as I have an Incinolet and I ground dump clear water.....food is MRE's - we eat out as much as possible.....geofkaye

Geof, have you purchased the truck yet for your conversion. I am a new member to this blog site and could recommend a few changes. I am the Volvo Trucks salesman that specializes in RV/Motorcoach chassi specs. I currently work with 14 of the nations top manufacturers in the RV industry. The original pricing of a VNL780 is incorrect and the cost difference between new and used is not that significant. Feel free to send me and e-mail at jtackett@stykemain.com
Good Luck

....BIGT:...I'm on my 7th conversion[personally] and now have a tractor just for me-that I won's sell or give away....or trade for anyone's old lady/dirt bike/4 wheeler /coon hound. My tractors come from Freightliner here in Cincinnati Ohio....World Wide and Arrow are not interested in doing business with me as I only spend a $110k a year on 4 tractors....at the most. That nets me the big fat [1] in sales and conversions, upgrades and custom stuff....I'm a little little fish is a big empty lake....in this economy I have to follow the buck and step in buck poop to give me something to do in my spare time....Have you called on Waylon Long in Texas-he makes high line conversions-for the horse crowd....there is none better than 2L's master pieces....There is a federal law against allowing me to drive one -It makes me look too ugly-they are so unique-say "hey" to Waylon - he is a good ol' boy from Texas....geofkaye

Big T,
What is the approx cost of a new Volvo chassis from the factory set up for motorcoach use? I (and everyone here) would be curious to know because if a new chassis that is already lengthened and factory built for a coach build is a reasonable price, the difference in cost from a used HDT would probably be offset by the extra cost it takes to lengthen the HDT, the warranty of the new truck, etc. I know there are many options, but if you could give us a general cost of a new chassis that would be great. Thanks.