1959 GMC Adventure Bus Build

baipin

Active member
Rear axle clean up is coming along nicely. Waiting on new seals, a 1550 yoke, and brake stuff in the mail...

vfIcE3r.jpeg


In the meantime, thinking about the rear suspension.

I currently have 52" leaves back there. I was surprised to find they're only rated for 4350lbs ea. if I am reading this right, in spite of the massive 15,000lb two-speed axle back there currently. Seems to be something specific to school bus models:
firefox_2023-04-17_20-53-34.png

My options, as I see it, are to...

1. Keep the current 52" 4350lb ea. leaf springs.
2. Air assist with current leaf springs. Is this feasible? What would it look like - similar to a typical Firestone "airbag assist" kit, like the Kelderman 2-stage class 6/7 kit which uses existing leaves?
3. Keep current hangers, replace with new leaf springs. Isuzu NPR springs would fit with minor work, which gives a modern off-the-shelf option. A custom option is possible, too.
4. Longer leaf springs. If ride quality would be significantly better, I could replace these springs with F53 motorhome springs that are 64" long - 1 ft. more than current, or 23% longer. If going with longer springs, they must be 60"+. There is a pressed bump in the frame, around the current fixed-end spring hanger, that makes it impossible to mount anything overlapping the current location.
5. Full air ride. Could do either a Freightliner FAS-II system, or 4-link, but the latter is prohibitively expensive and I fundamentally do not want my bus riding on rubber airbags that are prone to failure, puncture, dry rot, etc. Not doing this option.

Ride quality is important insomuch as I don't vibrate my interior build apart. Reliability, redundancy, and simplicity are my main considerations. Passenger and driver seats will be air ride, plus the front axle has airbag stabilizers (modeled after Donvel's system).
 

baipin

Active member
Im not sure how I'm twice you age, and ended up with 1/8th of your skills and knowledge, but good job! Im jealous of both....and your project!

I'm not sure either. A lot of teaching myself what I wanted to learn and procrastinating on what I "should" have been learning, was a big part of it throughout my teens and 20's I think. Haha!

--

I've been going back and forth on what to do with the front axle. Very close to buying a Jana 76 kit for it. However, I recently found a NoSpin for this 19060S rear axle for $740 which far as I can tell is a pretty good price. That's about the same cost as the Jana 76 kit + a loadbolt (Canadian dollars).

Adding the NoSpin for the rear and a Jantz loadbolt for the front would keep me within what I've budgeted for axle stuff.

Think that's a more practical option, instead of bigger 70 gears up front and an open rear? I expect around 34F/66R to 40F/60R weight distribution, FYI.
 

baipin

Active member
Rear axle is done and cleaned up nicely. Got a Detroit NoSpin for it, for cheap too - got lucky there!

Bh5OTL6.png


Also considering dualling up the rears with basic 11R22.5's:

Photoshop_2023-05-11_19-56-40.png


I'd like to aim for a 40/60 split in weight distribution, front to rear. However, I'd like to limit weight on the front to no greater than 6,500lb, with a 16,000lb overall target weight. A 37/63 split offers 5,900lb front and 10,100lb rear. I know for some, that's the difference between getting stuck or not, though I'm not sure if running duals would help or hurt in that respect...

Regarding surplus military XZL's and G177's; I assume the consensus is that running 10 year old tires, just isn't a safe or wise move for a vehicle like this?
 

baipin

Active member
Consider the tire situation solved. I just found the hen's teeth of beadlock wheels:

nc_ohc-sxlr6fmluqkax9dhaoo-_nc_ht-scontent-fykz1-2-jpg.701411


8IIPNx8.png


Yes, these are 22.5" beadlocks!

The story is that they're off of an AM General humvee replacement prototype; the NXT360. The seller who owns the junkyard I got them from has a brother who works for AM General, they had his junkyard destroy the prototype trucks after testing, but they were allowed to keep the wheels, tires and a few other things that could be purchased on the civilian market. Only 8 other wheels exist that I know of; 4 at Eastern Surplus in a narrower size, and 4 in the hands of a couple in Minnesota with a Ram 4500 camper. Apparently they run them on 385/65R22.5's, even though they're a 10.5" wheel. That will be my long-term plan as these tires have 95% tread but are from 2009.

yxrlqv4-jpg.702354


I think they look pretty good.

My plans for adapting them to the axles is by using hubcentric laser cut adapter plates. The 1" thick aluminum wheel would be bored out beyond the exiting bolt pattern. Front example:

sketchup_2023-06-09_02-22-24-png.702337


The steel plate, either 3/8" or 1/2" thick, is held on with 12 bolts, weight is carried by the bolts in tension, in a slip critical joint. It is hubcentric for the 8x6.5 bolt circle, but the wheel/plate interface is centered by the 12 bolthole tolerances. There won't be much runout, maybe 1 or 2mm so I'd assume it's fine this way.

While the 12 bolts shouldn't be in shear, because the connection is supposed to be slip critical, I could machine a lip into the adapter plate, so it registers perfectly concentric, with the bore of the Hutchinson wheels. The advantage here would be zero runout and if some nuts/bolts got loose, the adapter plate would be riding on the lip, rather than shearing the bolts. Like usual, I may be overthinking this... heh

Another option would be to bore out the hubs to a 10x11.25 pattern, native to the rear axle, then adapt with a plate to the front axle's 8x6.5 pattern. That is quite a bit more costly because it would require three machining operations (center bore, bolt pattern bore, fly cutting rear surface) and I don't see any advantage to it.

p7kug9t-png.702356


ssxab7i-jpg.702355
 

Deleted Member 183

Well-known member
Wow! Fantastic project! I can't believe I have not seen this before... Oh wait, your original posting was during the period I was banned here,

Can you share with us what your new rear axle came out of? I'm curious as to why the rear axle is offset the the left. Does this align with your transfer case?
 

baipin

Active member
Any updates?

Yes! I forgot about my ExPo thread, I post everything on Irate4x4 now.

First off, the engine bay, firewall, etc. metalwork has been finished, as well as all the patch panels needed:

1704836752685.jpeg

1704836822288.jpeg

Everything here was hand-formed with a couple hammers and MDF forms. Been years since I did anything like this, back in art school... Very happy with the end result.

1704836130385.jpeg

1704836145937.jpeg

1704836162798.jpeg

1704836187749.jpeg

1704836215372.jpeg
This floor section was rotted, thanks to a leaky heater, but I figured I'd make the most of the "opportunity" it gave me and make a sunken box for the LiFePO4 batteries:

1704836299272.jpeg

Will be able to fit 13kWh there, plus some other electrical bits.

I also got those wheels machined, finally. Added a gasket to the interior so nothing leaks between the wheel and the new center plates (the center of the aluminum wheel steps down about 2mm).

1704836405190.jpeg

And of course, with the new centers. These were laser cut then finished by drilling and reaming the holes to spec.



1704836441096.jpeg

Painted them with VHT roll bar paint, and then POR15 + tractor paint + hardener over the rad support. I've found the POR15 + tractor paint + hardener to be a very durable, wear-resistant, and UV-resistant finish that can be done on the "cheap" - just wait for TSC to put the gallon tractor paint and hardener on sale... Used this combo on my subaru, and not a spot of rust in 6+ years.



Wow! Fantastic project! I can't believe I have not seen this before... Oh wait, your original posting was during the period I was banned here,

Can you share with us what your new rear axle came out of? I'm curious as to why the rear axle is offset the the left. Does this align with your transfer case?

Funny enough, the rear axle is actually centered. The offset of the bowl makes up for the offset of the carrier, so the pinion is actually dead-center in the axle. That came out of a 2007 IH 4700. It's a Dana Spicer 19060S. The other common one is the 17060s. 19k and 17k lb GAWR, respectively. The transfer case has a large drop and the front and rear outputs are on the same plane, though slightly to the passenger side, but it's minor enough that angles work out nicely for both my front and rear driveshafts. You could flip the entire housing, the carrier fits, but the amount of fab work and bolthole drilling for the carrier just wouldn't be worth the effort for - in my case - no significant gain. With a shorter wheelbase and a significantly offset t-case, it'd make sense though.
 

baipin

Active member
Those wheels are also attached to a new axle.

1704837059296.jpeg

I caved in, ditched putting lipstick on the pig that is the D60, and went with a D70 instead. Got it for free, in a trade of stuff I just wanted to get rid of... Not a popular axle because it's of closed knuckle design and has ~31 deg. steering angle. Though, with the size of my tires, the width of the axle, and the location of the draglink, I could only get 1 deg. more steering than what the closed knuckle axle offers. So, not an issue for me. I see the closed knuckle design as beneficial given the amount of salt and snow we get up here.

For anyone familiar with these axles, their major weak point is spindle retention: They use bolts rater than studs, and fine thread in cast too. Not a great mix. However, the knuckle is notably thicker than Dana 60 stuff, and the spindle is essentially the same. So, to fix this weak point...

1704837268745.png

I tapped 3 new holes per knuckle.

1704837309095.png


I then drilled out the existing threaded holes, added bosses, and installed drive-in studs similar to the Dana 60 ones.

1704837354652.png

With 8 thread-in and drive-in studs, this should be plenty strong.

1704837413706.jpeg

Also trussed the housing

1704837442376.jpeg

The biggest change was with the brakes. Not wanting to use the original drums, obviously, and not wanted to adapt tiny D60 brakes, I opted for International Durastar brakes to pair with the rear axle's brakes. This should also make buying replacements easier in the future, given the common platform. The rotors are from a F650, which offered the required shallow "hat" to make these work:
1704837602540.jpeg
As you can see in the photos above and below; the larger ring is press fit over the existing rotor flange on the D60 hub. The smaller 4-bolt ring then slips over the existing lip on the hub, to form a new, concentric lip for the new rotor to register against. This is important since the outer circumference of the hub's spoke-like flange is not machined for concentricity. By tapping the larger ring slightly below the existing machined rotor surface, then bolting the new rotor to it, the ring should be drawn upwards against the new rotor, which at the same time is being pulled "into" the machined surface. At that point, I can then weld the ring in place. I'm not sure if that makes sense. If it does, good. Needless to say I ended up with between 0.015" +-0.005" runout at the edge of the rotor, which is within spec (0.025" as I recall).

1692930350278-jpeg.735903


For this, I had to design my own caliper mounting (for the safety-conscious, I performed a FEA on the weldements and bolted connections. I confirmed everything I was doing with an actual engineer, not someone like me who is LARPing as one) :D:

1696651351235-jpeg.754592


1696913902167-jpeg.756021
1697335973664-jpeg.758471
 

baipin

Active member
...and the final product:

1704838266191.jpeg

1704838331722.jpeg


1704838323143.jpeg

Now all that's left to do is put the tires back on, put the axles under, and a bit of work with the engine then she's driveable. I have some other work regarding that which I have not photographed. I can barely be bothered to post progress online on one site, let alone 2 or 3...

Progress has been a bit slower than I'd of hoped, but ironically, because I've been working on other people's buses. Someone saw my project on Instagram, had to check it out in person, and hired me on the spot. Over the last few months I've done a bit of a career pivot and now do general fabrication/welding/electrical for buses being repurposed for commercial uses or as "skoolies". Best decision I've made in a while.
 

Deleted Member 183

Well-known member
Too bad you are not closer to the Central Coast of California! I will be putting this Meritor/ Rockwell FDS 75 up for sale in the next 4 or 5 months.

casa_newmotor2.jpg
 

baipin

Active member
Too bad you are not closer to the Central Coast of California! I will be putting this Meritor/ Rockwell FDS 75 up for sale in the next 4 or 5 months.

View attachment 814393

Are you the same guy that asked about the brakes on Skoolie.net recently? Seems like I've seen this before ;) FDS75 is a great axle and they were the "next step up" from my Dana 70 when those axles were used under a number of Dodge and International medium duty platforms around the 70's. What are you replacing it with? I can't imagine it's a weak link - are you going with a different ratio than what the FDS75 allows?
 

Moyshe Kapoyer

Active member
Rear axle clean up is coming along nicely. Waiting on new seals, a 1550 yoke, and brake stuff in the mail...

vfIcE3r.jpeg


In the meantime, thinking about the rear suspension.

I currently have 52" leaves back there. I was surprised to find they're only rated for 4350lbs ea. if I am reading this right, in spite of the massive 15,000lb two-speed axle back there currently. Seems to be something specific to school bus models:
View attachment 774549

My options, as I see it, are to...

1. Keep the current 52" 4350lb ea. leaf springs.
2. Air assist with current leaf springs. Is this feasible? What would it look like - similar to a typical Firestone "airbag assist" kit, like the Kelderman 2-stage class 6/7 kit which uses existing leaves?
3. Keep current hangers, replace with new leaf springs. Isuzu NPR springs would fit with minor work, which gives a modern off-the-shelf option. A custom option is possible, too.
4. Longer leaf springs. If ride quality would be significantly better, I could replace these springs with F53 motorhome springs that are 64" long - 1 ft. more than current, or 23% longer. If going with longer springs, they must be 60"+. There is a pressed bump in the frame, around the current fixed-end spring hanger, that makes it impossible to mount anything overlapping the current location.
5. Full air ride. Could do either a Freightliner FAS-II system, or 4-link, but the latter is prohibitively expensive and I fundamentally do not want my bus riding on rubber airbags that are prone to failure, puncture, dry rot, etc. Not doing this option.

Ride quality is important insomuch as I don't vibrate my interior build apart. Reliability, redundancy, and simplicity are my main considerations. Passenger and driver seats will be air ride, plus the front axle has airbag stabilizers (modeled after Donvel's system).
If it was me, I'd go with option 4. It's simple, affordable, and replacement parts shouldn't be a problem.
 

Deleted Member 183

Well-known member
Are you the same guy that asked about the brakes on Skoolie.net recently? Seems like I've seen this before ;) FDS75 is a great axle and they were the "next step up" from my Dana 70 when those axles were used under a number of Dodge and International medium duty platforms around the 70's. What are you replacing it with? I can't imagine it's a weak link - are you going with a different ratio than what the FDS75 allows?
My apologies for now replying earlier! I am SLAMMED with a project that has gotten more complicated and on the verge of "out of control" (yeah, what else in new... Kinda the story of my life).

Yes that is me on Skoolie! However I will no longer be posting there because of them not permitting a contributing member to edit or delete their posts... Is essentially stealing a members intellectual properties! "F" that monkey business!!!!

I am replacing the FDS75 that is under Casa with this FDS90 that I'll swap the 4.63:1 ratio third member from the current axle in to while adding a Detroit "no-spin". You will notice that there is another machined top pivot spindle sitting on the right spring perch, that will replace the non-machined right top pivot to receive the steering assist ram that I'll be adding as well.

IMG_1514.JPG
 

Forum statistics

Threads
186,274
Messages
2,883,978
Members
226,151
Latest member
Dgollman
Top