1959 GMC Bus - 4x4 Build

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Baipin

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Thanks for the kind words about the build everyone.

Running into one of my first hurdles here...

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I am trying to keep the existing spring hanger (orange) because for lack of a better word it's skookum as hell... and also because I could not fit one for 3" wide springs (note the downward curve in the red frame section.

Basically:
- The spring hanger is made for 2" springs
- I need to use 3" springs with the Dana 60 (or I could somehow adapt 2" wide springs to 3" wide perches on the axle).
- The center-to-center distance between OEM bus springs is 32.75"-33" approx with the 2" springs. The D60 center-to-center distance is 32". Therefore if I bend one shackle 1 inch outwards, and keep the other straight, it will both fit a 3" spring and fit within the OEM 2" spring hanger (see pic above.
- The issue I foresee is that the hanger center is 1/2" outwards of the spring center, which would exert a bending moment upon the bent S-shaped shackle on the left as the spring compresses. Maybe it's negligible?
- To fix this, I could add a plate between the shackles and weld them together into a single rigid member.
however, if both shackles act together as a single rigid member, that would still transfer load to the inward bushing more than it would the outer I suspect. Though I'm thinking the effect there may be negligible and at worst I need to replace bushings more often. So what.
- Are bushings that might wear out earlier the worst problem here? Or is there some bigger issue I'm missing that makes my design potentially unsafe?

Would appreciate some input here!
 
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GLOCKer

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Thanks for the kind words about the build everyone.

Running into one of my first hurdles here...

View attachment 206739

View attachment 206740

View attachment 206741

I am trying to keep the existing spring hanger (orange) because for lack of a better word it's skookum as hell... and also because I could not fit one for 3" wide springs (note the downward curve in the red frame section.

Basically:
- The spring hanger is made for 2" springs
- I need to use 3" springs with the Dana 60 (or I could somehow adapt 2" wide springs to 3" wide perches on the axle).
- The center-to-center distance between OEM bus springs is 32.75"-33" approx with the 2" springs. The D60 center-to-center distance is 32". Therefore if I bend one shackle 1 inch outwards, and keep the other straight, it will both fit a 3" spring and fit within the OEM 2" spring hanger (see pic above.
- The issue I foresee is that the hanger center is 1/2" outwards of the spring center, which would exert a bending moment upon the bent S-shaped shackle on the left as the spring compresses. Maybe it's negligible?
- To fix this, I could add a plate between the shackles and weld them together into a single rigid member.
however, if both shackles act together as a single rigid member, that would still transfer load to the inward bushing more than it would the outer I suspect. Though I'm thinking the effect there may be negligible and at worst I need to replace bushings more often. So what.
- Are bushings that might wear out earlier the worst problem here? Or is there some bigger issue I'm missing that makes my design potentially unsafe?

Would appreciate some input here!
Hmmmmm. this looks exactly like my Ranger's shackle! The thing is, off the top of my mind, it doesn't kick out 1 inch, which seems kind of far. Can you kick out each side 1/2" and allow it to center better?
 

Baipin

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Hmmmmm. this looks exactly like my Ranger's shackle! The thing is, off the top of my mind, it doesn't kick out 1 inch, which seems kind of far. Can you kick out each side 1/2" and allow it to center better?
Ah cool! That makes two like this I've seen then; the Ranger shackle and a Nissan one... so I guess there's nothing inherently wrong with the design. Moving the spring centers inward 1/2" on each side allows it to mate up with the spring hangers that are 1/2" outward of the Dana 60 spring center-line on each side. I'm not sure if I explained that well but I think you know what I mean? Current springs are at 33" apart, D60 ones are at 32".

The alternative (bending both shackles outwards and keeping the spring center in line with the shackle center, will mean I have to fit 32" center-to-center springs in 33" center-to-center hangers currently on the truck. I'm not sure if that's better or worse than what I'm proposing with the "asymmetrical" shackle design above? For what it's worth; I can easily remove the rearward hanger for the front axle springs and fab up something custom for the new 3" springs. So that can at least be 32" center to center.
 

John Bishop

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It’s likely there’s more to this than I’m seeing, but I would be inclined to use spacers on both sides of the hanger and keep the shackle plates straight.
 

GLOCKer

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Ah cool! That makes two like this I've seen then; the Ranger shackle and a Nissan one... so I guess there's nothing inherently wrong with the design. Moving the spring centers inward 1/2" on each side allows it to mate up with the spring hangers that are 1/2" outward of the Dana 60 spring center-line on each side. I'm not sure if I explained that well but I think you know what I mean? Current springs are at 33" apart, D60 ones are at 32".

The alternative (bending both shackles outwards and keeping the spring center in line with the shackle center, will mean I have to fit 32" center-to-center springs in 33" center-to-center hangers currently on the truck. I'm not sure if that's better or worse than what I'm proposing with the "asymmetrical" shackle design above? For what it's worth; I can easily remove the rearward hanger for the front axle springs and fab up something custom for the new 3" springs. So that can at least be 32" center to center.
Oh yeah. that makes sense. I didn't think about the geometry of what you had vs. what you were trying to mate it to being different.
 
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Baipin

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It’s likely there’s more to this than I’m seeing, but I would be inclined to use spacers on both sides of the hanger and keep the shackle plates straight.
Yeah, that'd be the easiest. I worry about shear forces bending the bolt through the shackle though, since it isn't pressed up against the hanger. I might be overthinking this though... I figure I could just give it a shot and see what happens.
 

Baipin

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Well, much has happened but not the kind of stuff that's worth photographing - just picking up parts, and moving the bus to its storage location for me to have a bit of space to work on the axles, trans, and such. I'll be able to fully enclose the thing with a tent or pole barn if need be - so that'll be nice!

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Absolutely love the curves on this thing.

The current plan is to jack this thing up onto some wood cribbing I have, use the cherrypicker to remove the front cowl, and that'll give me ample room to clean up the engine + do the front axle swap...

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The ring gear says 41-9 - I assume that means 4.56 gears? That matches the tag on the axle. The seller said that the yoke nut was loosened and it'll need a new crush washer - there is slop along the yoke's axis of rotation, so this makes sense. I've heard the D60 fronts do not have crush washers, only spacers? I've also heard the opposite - so I'm not sure what to believe until I tear it down. That aside, the axle seems good - just needs some bushings replaced.

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Tore into the NP205 recently too - everything looks pretty good, will just need a new rear output needle bearing, which I have on the way, seals and gaskets, a new 4WD/2WD indicator (are there any aftermarket ones that'll fit - or should I solder on new tabs and pot it in epoxy?) and a new plastic speedometer gear. If anyone has one to sell, please let me know! They aren't easy nor cheap to find up here in Canada.

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Tore apart the floor as well - kept the stripper's pole though... :grin: Only a handful of rust holes to patch up, which is nice!

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Baipin

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Alright guys, could use some help here...

So, the front axle's springs this bus came with are 44" long and the shackles are on the front. I'm guessing front shackles + short springs will make for one helluva rough ride? The current plan is to run 47" chevy springs, Dead simple to install; I just need to fab up new rear spring hangers and use the existing front shackle hangers with DIY shackles. The issues with this are, I've only got a slightly longer spring, the shackle is still in the front, and the tire is going to sit back 2" in the wheel well.

However, I'm also considering using even longer springs; 54" or whatever else I can find. Because things can't ever be easy with builds like these, if I do this I've got to work with either oddly-curved frame sections or rusted out, massacred, swiss cheese of a frame, on the front:

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The tape measure is zeroed at where the axle should sit. As you can see, the new 47" springs (23.5" front eye to pin) would need a shackle at a steep ~45 deg. angle to bring the center of the new axle in line with the original axle's position. Otherwise, the tire will sit about 2.5" behind the original location if I bolt the Dana 60 up with these 47" springs with 5" shackles at a more reasonable angle .

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Top arc is the original spring, bottom arc is the 47" chevy spring.

The existing shackle hanger is located in a spot I can't move it: it's also an integral part of what gives the front crossmember rigidity. It's a big, forged hunk of steel that helps keep a few things together and wraps around under the frame. I won't be removing it. To get around this issue + the swiss cheese frame pictured above, I'm considering building a crossmember/spring hanger and welding it to the 3" section of sloped (but not curved) part of frame. In the above pic, there's a bit of red paint there. The design would be something like this (red parts are existing frame):

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or this:

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Is it worth all the fab work to get springs longer than 47" and swap the shackle to the rear? I'm also on a budget, so if the investment in time, materials, and money would be better spent elsewhere on this bus, that's helpful to know. For what it's worth mentioning; the bus will have air ride driver and passenger seats. I'm considering 4 link air ride or at the very least, air assist, in the rear.

As a bonus; here's a video of her running - the carb rebuild made an incredible difference! It's even temporarily straight-piped ;) Had to re-route the exhaust for the cribbing to support the bus.

NP205 was rebuilt, twin-sticked, and painted too! Whipped up some rod end adapters - only had 1/4" 7018 stick on hand, hence the ugly welds:
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Dilldog

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So my two cents on this. Move the shackles to the rear and run the longer spring. With a front shackle you will get a terrible ride and less effective spring function. To put it simply, when you hit a bump the shackle is effectively moving toward the bump, rather than away from it. Moving away from the bump is a more natural movement and allows the spring to work much better. Next the longer spring, will allow for more movement in the front end further improving ride but also improving articulation, also if both sets of springs are GMs the 57s will have a higher load rating. As far as re configuring the mounts, I would cut off the rusted frame sections and build an extension, this will also provide plenty of room for a winch without the need for a huge bumper that will more negatively impact approach angles.
 

Baipin

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So my two cents on this. Move the shackles to the rear and run the longer spring. With a front shackle you will get a terrible ride and less effective spring function. To put it simply, when you hit a bump the shackle is effectively moving toward the bump, rather than away from it. Moving away from the bump is a more natural movement and allows the spring to work much better. Next the longer spring, will allow for more movement in the front end further improving ride but also improving articulation, also if both sets of springs are GMs the 57s will have a higher load rating. As far as re configuring the mounts, I would cut off the rusted frame sections and build an extension, this will also provide plenty of room for a winch without the need for a huge bumper that will more negatively impact approach angles.
Thank you for all the input. The axle physics you mention make sense... I think I'll head down to the bus tomorrow, cut off the rusted part, and see what I have to work with. My main worries about welding on new hangers there is that the hangers and the crossmember won't necessarily be under the existing frame; i.e. a lot of the new metal that'll be welded on will be loaded in shear. In my drawings above, only 1/2 to 1/4 of the new hangers can fit under the tiny section of sloped, but not curved, frame. I worry about cyclic loading on the weld - even with fish plates - which is fully in shear and carrying a 1/4 of the vehicle's weight. In any case, I'll weld on a crossmember there - even if it's just for a future winch. I really like the front on the bus and how it'll fit a winch snugly, slightly recessed, in the middle!

If I swap the shackles front to rear, must I also replace the existing steering box with one on the opposite side of the axle, as it currently sits? I've heard that the steering box should always be on the fixed side of the leaf.

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This is how everything sat prior to the axle being swapped out (wheel is cranked hard right).
 
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Smileyshaun

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As far as being concerned about the shackle offset , there’s a lot of offset in the kits used to sas swap a 99+ Chevy so I think you should be fine as far as bushing wear goes . 9C75CC79-001C-4AF7-8BF9-29DCE29DBA79.png
 
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Baipin

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Made a couple of the offset shackles; same 3/8" thickness as the originals, but 1.5" wide instead of the original 1.125".

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I'll head down to the bus today and see how they look.

Fun tip: Railroad track cut in half makes for an excellent press punch!
 
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Dilldog

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For the frame modification research a Z channel cut. When I was helping with building old school hot rods we did this to a few 'Mercs. Short story is you cut the frame in a Z shape so when you weld in the new sections the joint is not in shear. The other option is to sleeve the frame. When I did the 4 link on my old Wagoneer and turned it into a truggy I chopped the frame and used some rectangular steel that slid over the existing frame, welded the seams and did a few plug welds as well, again, no shear loading on the weld. As far as the steering box goes, here I must admit ignorance, though what you say makes sense. However I would say with the added stress of a larger axle/ tire and some off road I would go to a crossover steering set up. This will also lessen the load on the frame section you plan on modifying. Just grab a 2wd square body chevy pickup steering box so the pitman arm goes the right way.
 
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Baipin

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For the frame modification research a Z channel cut. When I was helping with building old school hot rods we did this to a few 'Mercs. Short story is you cut the frame in a Z shape so when you weld in the new sections the joint is not in shear. The other option is to sleeve the frame. When I did the 4 link on my old Wagoneer and turned it into a truggy I chopped the frame and used some rectangular steel that slid over the existing frame, welded the seams and did a few plug welds as well, again, no shear loading on the weld. As far as the steering box goes, here I must admit ignorance, though what you say makes sense. However I would say with the added stress of a larger axle/ tire and some off road I would go to a crossover steering set up. This will also lessen the load on the frame section you plan on modifying. Just grab a 2wd square body chevy pickup steering box so the pitman arm goes the right way.
Ah yeah, good idea with the frame notching to keep it out of complete shear loading. That's giving me some ideas... Sleeving just won't be possible (with my skills and tools anyways) for the oddball curves on the front of the frame. But, I think something like this would work nicely:



Everything forward of the red line will be cut off. I have no idea why it was butchered like it was, but jeeze... awful weld beads on the inside corner of the frame, and it was run so hot there are holes melted all the way through! :laughing: Since drawing the above, I'm thinking I'll extend the yellow 3x3x34" crossmember inwards towards the red hose, and double its width to 3x6x34", so it rests in compression under more of the frame. Basically, extending it right up to where the frame slopes upwards sharply. That'll allow the front hangers to rest completely in compression relative to the remaining frame section. Finally, I'll add fish plates to the side of the new crossmember and up the frame. This will make for an excellent winch mounting point too.

Far as winches go, I'd like some input on that one. I will have a 48V 14kWh battery bank. Anyone know of any 48V winches? Alternatively, I could run a 48V hydraulic pump, or a pump off of the NP205 or SM465's PTO.
 

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Ah yeah, good idea with the frame notching to keep it out of complete shear loading. That's giving me some ideas... Sleeving just won't be possible (with my skills and tools anyways) for the oddball curves on the front of the frame. But, I think something like this would work nicely:



Everything forward of the red line will be cut off. I have no idea why it was butchered like it was, but jeeze... awful weld beads on the inside corner of the frame, and it was run so hot there are holes melted all the way through! :laughing: Since drawing the above, I'm thinking I'll extend the yellow 3x3x34" crossmember inwards towards the red hose, and double its width to 3x6x34", so it rests in compression under more of the frame. Basically, extending it right up to where the frame slopes upwards sharply. That'll allow the front hangers to rest completely in compression relative to the remaining frame section. Finally, I'll add fish plates to the side of the new crossmember and up the frame. This will make for an excellent winch mounting point too.

Far as winches go, I'd like some input on that one. I will have a 48V 14kWh battery bank. Anyone know of any 48V winches? Alternatively, I could run a 48V hydraulic pump, or a pump off of the NP205 or SM465's PTO.
In case of the 48V, you can normally split out 24V for the winch, should be quite easy.
 

shortbus4x4

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Dana 60s don't have crush sleeves. They use shims to set pinion depth and bearing preload. Have you tried looking for a Dana 70 dually rearend from a Chevy dually? That's what would have been the rearend most likely that came behind your front axle your using. Be aware they came in different widths depending on if it's a cab and chassis or pickup bed.

Cool build, looking forward to it.
 
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Dilldog

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Good call on the Dana 70, however having been around 70s and the 14bolt GM axles I would still run a 14bolt. The axle all together is stronger, 3 pinion supports, fully enclosed carrier, thicker axle tubes, 4 spider gears. Also they are cheaper and easier to work on (separate pinion housing and threaded carrier side bearing caps). The dana 70 is a similar weight rating, but doesnt have as stout a center section. Its not until you get into the Dana70U or Dana80s that you get a "stronger" axle, but my money would still be on the old school 14bolt.
 
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