1959 GMC Bus - 4x4 Build

[Baipin]

Really not much to say beyond the title... I've got a 1959 GMC bus, and I've got every intention of converting it to 4x4. :) The Axles have to go anyways. The hubs would be prohibitively expensive to modify, have an odd bolt pattern with hard-to-find wheels, and I'd rather not use Firestone RH5 "widowmakers" anyways. Always wanted a 4x4 short bus anyways, and this seems to be a great, simple, platform to work off of: About 23 ft long bumper to bumper, 17 ft. interior length. About 8,000lbs curb, likely under 11,00lbs fully built, 14,000 GVWR. 283 gasser, SM420, frame and body are in fabulous shape - especially for a bus here in Canada!



The plan is to put a divorced NP205 behind the SM420, or marry it to a SM465/6BT combo. Since it's relatively lightweight for a bus, I'm thinking this should work. I've seen NP205's on Fusos, after all... Probably a Dana S110 or 80 for the rear and Dana 60 or 70 up front. The 283 does run well so I'd consider a diesel swap later down the road. Right now, I'd just like to get it on the road and do the 4x4 bits.

Right now, I'm wondering what the best front axle would be for this? I can find plenty of RAM D60's but they're all set up for coils. Would it not be worth the work to cut off that junk and weld on leaf spring seats? Am I better off finding a Chevy axle already set up for leafs? The spring to spring dimensions on the bus match up very closely with RAM and Chevy axles. One issue is that these springs are 2" wide whereas the newer Chevy and dodge are 2.5" I believe?:



I suppose there's always the option of a new chassis for the old bus body. 4x4 manual medium duty chassis aren't the easiest things to find though... let alone something old enough to be dead simple - without a single computer onboard. Some thoughts on the pros and cons of each way to take this build would be much appreciated.

 

[MazeVX]

Consider getting custom axles built, for example Fusion 4x4. The axle will be built to your specifications. In the end it's not more expensive than buying a used 1ton modify it and replacing everything and you have a brand new axle.

And other than that, absolutely great project!
I wish you good luck with the build!

 

[Cypress]

Cool bus.

I have a 56 Ford I considered adding 4x4 to but decided it was just too big. My future plan is to drop it on an F53 motorhome chassis.

 

[GLOCKer]

Well holy crap. Consider this my sub! I have images in my mind of this thing looking like a vintage safari beast!

 

[Baipin]

Consider getting custom axles built, for example Fusion 4x4. The axle will be built to your specifications. In the end it's not more expensive than buying a used 1ton modify it and replacing everything and you have a brand new axle.

And other than that, absolutely great project!
I wish you good luck with the build!

Thanks for the well wishes and the tip - hadn't even considered this! Have any Canadians here on OB used Fusion 4x4 before? I feel like shipping might be prohibitively expensive, but this is a very interesting option nonetheless...

Cool bus.

I have a 56 Ford I considered adding 4x4 to but decided it was just too big. My future plan is to drop it on an F53 motorhome chassis.

Great looking bus! I think you have the same body as mine, plus one or two windows - is it a Ward? Someone else is doing a very nice job with a Superior over here: 1959 ford f-500 superior 4 window - School Bus Conversion Resources

Well holy crap. Consider this my sub! I have images in my mind of this thing looking like a vintage safari beast!

Hah - you've got good taste then! "Vintage safari beast" is more or less the kind of rig I'm after.

 

[MazeVX]

Maybe you can get them shipped to someone close to the border and pick them up if it's not too far, but I'm familiar with the shipping problem, living in Europe makes shipping from US quite expensive for me ;-)

 

[Billiebob]

Go to vintage Marmon Herrington web sites. They build front axles altho you'd still have the rim bolt pattern dilemna,
Building a plate to mate the 2.5" saddle to the 2.0" leaf should be pretty simple.

283 is a real light engine compared to any diesel. And rpm vs gearing might be an issue with a diesel, depending on the rest of the package like tire diameter.

 

[Baipin]

Well guys, one step closer to getting started on this build... Loaded up and on it's way from Saskatchewan!







If you're wondering why there's only one tire on the wheel, well... the Firestone split rims (RH5's I believe) did what they do best. I'll be glad to get those deathtraps off. I believe the wheels are 10x7.5 bolt pattern, 19.5" diameter. The rear end should be rated at 11,000 GAWR according to the GM literature. It's also a vacuum-operated two speed. I believe it's 6.17:1 which is too high for what I want (4.88 or therebouts would be better if I go the 6BT route, and I imagine it'd be okay with the gasser - I have no intentions of getting anywhere quickly, I won't have a full load of students, and I won't be stopping/driving all the time, like a bus would). Would anyone be able to identify this rear end? I believe it's an Eaton. I've been told HO72 before, but that doesn't seem right for a 1.5-2 ton truck. Not to mention, GAWR is off...

All in all, the frame and body seem to be in fantastic condition. Only two spots of through-rust near the front and rear doors. Typical for any bus. For something 60 years old, I'm very pleased - looks better than many 10 year old buses here in Ontario!





In the meantime, I have this NP205 lined up. It's a 10-spline passenger drop and will mate up perfectly with the SM465 + figure-8 adapter I have lined up as well. Passenger drop t-cases seem impossible to find in this country, but I figure that's the way to go: a Chevy or RAM pass. drop axle will match up very nicely with the current spring hangers on the front, at 32.8" center-to-center. Have seen a Chevy Viking 2-ton 4x4 conversion that used a Chevy axle with little work needed to make it fit, so figure I can't go wrong there. Ford driver-drop axles are a dime a dozen here but I just can't imagine any way I could get them to fit; 37" center-to-center.

Couple questions for those of you more experienced at this than myself:
- Is a Dana 60 large enough? Dana 70's seem scarce; only one I could find was out of a Ram and had coil junk on it. Not sure if I could weld on new spring seats at the correct distance, without biting into the diff housing. Any benefit to trussing a Dana 60?
- I hear the slip yoke on the NP205 rear output is undesirable. Is it worth it to adapt the existing bus' driveshaft (including its slip yoke) to fit a fixed output on the NP205?
- I'm thinking an 8x6.5" bolt pattern would be easiest to work with, given new Chevy or Dodge axles. I've also thought about 10x225 "big truck" wheels. Swapping the rear end for something with the correct hubs out of a medium duty truck, might be feasible. 8x6.5 seems easiest though. Any thoughts on that?

As for the interior, it'll look something like this:

 

[joemerchant26]

This is going to be an interesting build.

 

[John Bishop]

Cool build! Don’t scrap the split rims; they make great fire rings! …Although that’s probably not something you would want to pack in your camping kit…

 

[Baipin]

Cool build! Don’t scrap the split rims; they make great fire rings! …Although that’s probably not something you would want to pack in your camping kit…

Hah, great idea! I know someone who was looking for a fire ring anyways...

 

[GLOCKer]

I'm really looking forward to seeing this shape out!

 

[Baipin]

Took delivery of the bus a few days ago...





Didn't want to start it before I had a look over the engine. Good thing, considering the carb wanted to leak fuel and drip it down near the generator! Ha!

But I got it to run...

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Picked this up too! Not 100% sure what I'll do for the rear... Kodiak/Topkick axle perhaps? Has a GMC T-170 2-speed currently under the bus.

 

[Dilldog]

Super awesome build!
For the rear axle, depending on overall weight and HP you could probably run a GM 10.5" 14 bolt. They ran that axle in 15 passenger vans as well as in pickups. They are stout, cheap, and have plenty of parts availability.

 

[GLOCKer]

Just a thought, but I am wondering if that bus body would fit on the heavy duty chassis of something like a 4x4 ambulance or dump truck!?! It'd probably be cost prohibitive but could up the reliability factor.

 

[Baipin]

Picked this up too! Not 100% sure what I'll do for the rear... Kodiak/Topkick axle perhaps? Has a GMC T-170 2-speed currently under the bus

Just a thought, but I am wondering if that bus body would fit on the heavy duty chassis of something like a 4x4 ambulance or dump truck!?! It'd probably be cost prohibitive but could up the reliability factor.

Oh yeah, it definitely would. That was my initial plan actually! 4x4 ambulances and dump trucks are unicorns around here though. I've found 2 4x4 IH 4300 salt trucks in Quebec, but being what they are, the frames are absolutely trashed, rusty messes. I was very close to buying a whole salt truck for 10k - Fabco front and rear with a Fabco t-case too - but decided against it when there looked to be some dodgy paint work over untreated rust scale. The 60 year old bus frame is many times better than that one, not to mention, better than about half of the IC CE and Thomas C2 buses around here, less than 10 years old!

I'm thinking the ideal platform would, IMO, be a factory 4x4 Kodiak with a D70 front and whatever big Eaton they put on the rear. However, I've only ever seen 2 in Central/East Canada, and they were all mint condition ($$$). The way I see it, the Dana 60 is more than good enough for my needs. Literature on these buses/chassis is dodgy, but the front I-beam axle would be rated at approx. 4,800lbs give or take a few hundred depending on exact chassis model. The D60 is what, 6,000 to 6,500 lbs GAWR?

Super awesome build!
For the rear axle, depending on overall weight and HP you could probably run a GM 10.5" 14 bolt. They ran that axle in 15 passenger vans as well as in pickups. They are stout, cheap, and have plenty of parts availability.

Yeah, I've had my eye on the 14-bolt. Way easier to find than the D80! I'm concerned about GAWR though. I believe my current axle is a GM T150 with a GAWR of 15,000lbs. (Two speed vacuum operated, Detroit No-Slip, probably 7.17, but it could be 5.57, 5.83, or 6.50). Granted, this becoming 4x4 I want more equal weight distribution, so a rear and front closer in GAWR are probably fine, right?

The GVWR stamped on this bus is 13,000lbs (just to add to the confusion, the literature says it should be 14,000lbs - I'm assuming the bodybuilder Wayne-Welles derated for some reason). I was expecting the curb weight to be around 7,000lbs, and the camper conversion to bring it up around 9.5k to 10k, but the driver bringing it from out west said it made his truck sag more than a tractor that weighed 9k - outright said the seller lied about vehicle weight - so I don't know what's up there. I'll be moving the bus to a different location to do engine and axle work since I don't really have room in the driveway. I think I'll take it over the scales then...

 

[GLOCKer]

Picked this up too! Not 100% sure what I'll do for the rear... Kodiak/Topkick axle perhaps? Has a GMC T-170 2-speed currently under the bus


Oh yeah, it definitely would. That was my initial plan actually! 4x4 ambulances and dump trucks are unicorns around here though. I've found 2 4x4 IH 4300 salt trucks in Quebec, but being what they are, the frames are absolutely trashed, rusty messes. I was very close to buying a whole salt truck for 10k - Fabco front and rear with a Fabco t-case too - but decided against it when there looked to be some dodgy paint work over untreated rust scale. The 60 year old bus frame is many times better than that one, not to mention, better than about half of the IC CE and Thomas C2 buses around here, less than 10 years old!

I'm thinking the ideal platform would, IMO, be a factory 4x4 Kodiak with a D70 front and whatever big Eaton they put on the rear. However, I've only ever seen 2 in Central/East Canada, and they were all mint condition ($$$). The way I see it, the Dana 60 is more than good enough for my needs. Literature on these buses/chassis is dodgy, but the front I-beam axle would be rated at approx. 4,800lbs give or take a few hundred depending on exact chassis model. The D60 is what, 6,000 to 6,500 lbs GAWR?

The only thing I can suggest is to keep an eye out for trucks south of your border. Maybe an old medium duty dump truck or something. It could be a PITA though! I'm just wondering how much it would save you in engineering that frame into a 4WD versus dropping the body on something already rigged for the fight. Either way, it's still going to be pretty damn cool to see your progress with it!

 

[Baipin]

The only thing I can suggest is to keep an eye out for trucks south of your border. Maybe an old medium duty dump truck or something. It could be a PITA though! I'm just wondering how much it would save you in engineering that frame into a 4WD versus dropping the body on something already rigged for the fight. Either way, it's still going to be pretty damn cool to see your progress with it!

I'll keep an eye out - thanks! Not sure what bringing vehicles cross border is like nowadays though.

As for converting to 4x4, am I right that it basically involves the following:

Find axles with same ratios, correct GAWR. Remove front axle and springs. Fab new 3" spring hangers (it has 2" wide spring currently - I'm assuming I'd want 3" wide springs for this Chevy D60 front). Remove old hangers, add new ones. Mate up pitman arm with knuckle (the drag link this D60 comes with should mate up with minimal fab work). Drop driveshaft, bolt up SM465 adapter + NP205. Take measurements for new NP205 crossmember and fab it up. Attach crossmember. Add shifter for NP205 in cabin. Remove rear axle. Get new rear axle. Relocate spring pads as needed to account for bus' frame width. (Rear currently has 2.5" springs - any reason why I shouldn't stick with existing spring hangers)? Have new driveshafts for front and rear made. Complete braking system.

Anything glaringly obvious that I'm missing?

The NP205 has a slip yoke on the rear. The current driveshaft has its own slip yoke. Is there a preference on which one I should keep, when I get that driveshaft shortened? I understand the GM NP205 slip yoke is undesirable for some reason - does that reason apply here? I'm not going to be wheeling a 23ft bus hard haha, and driveline angles/space underneath are less of a concern with something that long.

 

[jcx03]

I love this - I'm very interested in getting a short bus with 4x4 later down the road.

 

[GLOCKer]

I'll keep an eye out - thanks! Not sure what bringing vehicles cross border is like nowadays though.

As for converting to 4x4, am I right that it basically involves the following:

Find axles with same ratios, correct GAWR. Remove front axle and springs. Fab new 3" spring hangers (it has 2" wide spring currently - I'm assuming I'd want 3" wide springs for this Chevy D60 front). Remove old hangers, add new ones. Mate up pitman arm with knuckle (the drag link this D60 comes with should mate up with minimal fab work). Drop driveshaft, bolt up SM465 adapter + NP205. Take measurements for new NP205 crossmember and fab it up. Attach crossmember. Add shifter for NP205 in cabin. Remove rear axle. Get new rear axle. Relocate spring pads as needed to account for bus' frame width. (Rear currently has 2.5" springs - any reason why I shouldn't stick with existing spring hangers)? Have new driveshafts for front and rear made. Complete braking system.

Anything glaringly obvious that I'm missing?

The NP205 has a slip yoke on the rear. The current driveshaft has its own slip yoke. Is there a preference on which one I should keep, when I get that driveshaft shortened? I understand the GM NP205 slip yoke is undesirable for some reason - does that reason apply here? I'm not going to be wheeling a 23ft bus hard haha, and driveline angles/space underneath are less of a concern with something that long.

HA! I think it sounds like you've thought this out pretty well. And on second thoughts, mounting a bus of odd dimensions onto an ambulance or dump truck frame will probably give you fits adapting the bus to the frame measurements.