55.2-59 '59 4x4 Build

[PuzzleTruck]

My first post here. Backstory: I've been building and modifying cars for many years and saw this truck for sale locally and it's something I've always wanted to build. The PO of the seller disassembled the truck. The seller painted the frame and put the running gear under it, so what I bought was a giant puzzle in pieces. I didn't realize there was so much missing from the puzzle, but I will figure out how to make it all work.

My first dilemma is the location of the drivetrain. The only clue is the front drive shaft to the transfer case is a given length. I was told the drivetrain and running gear were from a '73 Blazer. I've done a ton of measuring to determine where the engine should sit and I think I know pretty close to where it needs to be, but I needed to locate the transfer case first to be sure.

The photos below show the clearance between the tail shaft and the rear cross member. I may have to notch the cross member to raise the T-case a bit. The floor will allow 2-3" more. What gets me is how low the whole thing sits below the frame. It looks like I'll need 4" spacers to mount the transmission cross member. Or maybe there's a different one that drops down? Someone must have run into this issue before, so I'm hoping they will see this and chime in. Thanks.

Toby

[PuzzleTruck]

Here's a couple more pics for clarity. The front of the T-case can come up a couple inches, but that will change the driveline angle, since the tail end has to clear the rear cross member. I tried to get the rotational position correct so the lower two holes are parallel to the trans cross member as seen in previous post. That will be about 4" below the holes when installed.

Toby

[dsraven]

Google 55-59 Chevrolet truck assembly manual and pick the tri5 site for a free downloadable assembly manual with frame drawings etc. It will show you how the whole truck was supposed to be assembled at the factory including where the spot welds are located in case you need to do any patch panels.

[dsraven]

Was the truck ever running as the blazer 4x4 swap or are you the guy who will figure all that out?
I would say get the engine, trans, transfer case mocked up where you want it so you have clearance for oil pan, exhaust, steering column, rad and fan, floor etc. Then make motor mounts to keep it there, and then get your driveline angle figured out and block the trans at that angle, then fab up the transfer case Mount from scratch or modify something you have. The middle of the truck is the high center spot on a 4x4 so try to keep that high if you can. Lots of guys doing engine swaps in a 2wd need to cut the floor or firewall so you may need to consider this too, or a body lift. Then figure out the axle pinion angle to match what you have and install wedge axle mount shims as needed to get that right. if the driveshaft fits after, good but, if not look for another or have one made up or have yours modified or retubed. In my opinion it would be better to fit the shaft to the truck once you get the driveline right than build the truck to fit a certain driveshaft.
Not my truck so you build it how you like it, just some possibly useless info for you. Lol.

[dsraven]

One other thing to keep in mind for the front axle pinion angle is that the caster and steering angles are built on a solid axle front end. If you need to change that the axle tube ends can be clocked to match your needs but it will not be cheap most likely.

[Getter-Done]

I am in for the Build.

Looking good

[dsraven]

here is a link with some frame dimensions from the blazer. the thread is talking about converting a 4x4 to a 2wd but one member posted frame drawings for both. maybe that will give you an idea of where to install the driveline. you can see the blazer had quite a drop in the frame behind the firewall area and the 55-59 trucks are basically flat frames. a large drop in the cross member would be needed, like you show in your pics. personally, I would fab a new cross member once you get the engine/trans/transfer case location figured out. remember that the driveshaft will need some room to expand or contract in length as the suspension travels up and down over bumps. I know some 4x4 guys that have lost a driveshaft due to that when the slip joint expands past it's limits-lifted trucks, gettin air.
hope the link helps. maybe a private message to the poster would get results. if you click on the name of the poster another box will come up with options to choose from. pick private message and go from there.the thread is from 2014 so he may have moved on but he may also still have the info.

http://67-72chevytrucks.com/vboard/s...d.php?t=619850

[dsraven]

and another possibly helpful frame dimension site

https://www.chuckschevytruckpages.com/framespecs.html

[dsraven]

a thread with some balzer frame pics that show the auto trans and transfer case in place. dunno if it will help but you can decide that. from 2008 but pics are still up.

http://67-72chevytrucks.com/vboard/s...d.php?t=293250

[dsraven]

maybe if you consult and cross referencethe pics thread and the frame drawings thread you can see where the engine mount crossmember went and follow through with where the trans cross member needs to go along with the required depth of each member?

[dsraven]

curious also, what will you use for a steering box? the frame mounted box from the blazer is forward of the axle on the outside of the frame, but the frame is narrower ahead of the firewall on the blazer I think, so the tire may rub and you will have less turning radius if you bolt that to the 55-59 frame. guys with these trucks have done that for 2wd trucks and found they work well but not if you have a right hand turn to make, lol.

[dsraven]

just spitballing here on the cross member thing but, if you find the location you need, you could block the transfer case at that height and then use some flat plate bolted to the outside of the frame web on each side and hang it down to the height needed to bolt the original blazer cross member to. then bend it to be horizontal at that height so the cross member will bolt onto it. when done reinforce it with some flat bar welded to the edge of it below the truck frame height to simulate a C channel shape. make it longer, fore to aft, than the cross member is for added strength, sort of like a triangle that is upside down. you can use cardboard or poster board for a template just to mock things up and see if you like it first. I suppose you could do the same idea with a length of C channel bolted to the outside of the frame web but then you might as well just fab a new cross member from channel and/or square tube, it might look better.

[PuzzleTruck]

Thanks DSRaven, for the extensive and detailed info. Yes, I'm the guy who will be figuring everything out. New spring perches were bolted to the frame so it rolls, and everything else was disassembled. That's why it's the PuzzleTruck. I'm using a power steering box (presumably from the same 73 Blazer) on an adapter outside of the frame and don't see any likelihood of interference with the tire on right turns with suspension compressed. I think the PO gave up when he was faced with the difficult task of locating the engine, trans and T-case without the body on, or any reference. I don't have a rear driveshaft, so I will have one made, or modified from a salvaged part. I used the front shaft as a reference because the length is likely to stay the same and has a double Cardan joint at the top. I lined up the slip joint grease seal with the wear marks from where it was originally, to keep the splines in the middle of their travel during suspension movement. I have rotatable bolt-on spring perches on the rear axle to dial in the pinion angle and will weld on permanent perches when the angle is matched to the drive train. Then I'll measure and cut the driveshaft accordingly.

What you're telling me about the drop in the Blazer mid-frame and needing to fab some drops for my cross member is what I was expecting, but wanted to hear it from someone else. Being the only mount, other than the two forward mounts on the engine, I certainly want to make it strong. I prefer to do as much myself as possible, but when I need heavy equipment to make it right, I check in with a friend who has a fab shop nearby. I'll probably cut the cross member to keep the middle section and make angled drops on the sides, with plates on the frame as you described. Enough typing - back to work!

[PuzzleTruck]

Several more times measuring and working from the cab location to locate the rear of the engine brought me to a conclusion. The front driveshaft will need to be cut about 3" to work. I think I have the drive line angle set pretty well with the T-case as high as it can go without cutting a frame cross member. The TransDapt motor mounts I have will sit up under the upper frame rail. I had to remove the parking brake pivot bracket from the left frame rail. Below is a picture of the mounts mocked up before drilling holes.

After DSRaven mentioned steering interference, I lifted the front and moved the steering to full right lock just to double check. The tire almost rubs on the steering arm, so I may switch to a crossover steering setup if it becomes a problem. I've heard they reduce bump steer anyway, so that may also be a factor in deciding.

[dsraven]

I believe there was a torque brace on the old blazers as well that bolted to the side of the transfer case somehow. it was to keep the engine from rolling out of the engine mounts under hard loads etc
did some quick google work and found this thread from this site. it shows the torque mount and how it is mounted. its an old thread but still available. have you seen something like this in your box of goodies?
http://67-72chevytrucks.com/vboard/s...d.php?t=220183

[dsraven]

nice pics.
after you get things figured out I would suggest to brace up the frame portion of the engine mounts you have. something to connect the upper frame flange with the frame web or the lower frame flange.

[dsraven]

originally in these trucks there was a transmission cross member that went under the bellhousing and the bellhousing sat on rubber mounts that bolted directly to that cross member. I see yours has been cut out to accomodate the new driveline set up. something to think about is that the cross member held the frame rails at a given width where the cab mount brackets are. some guys have had problems when that cross member is removed and there is a long distance between the remaining cross members in that area. too much frame flex there can affect the cab mounts and cause the cab to crack and/or cause the body to fit poorly. door to fender contact and/or door misalignment usually. a lot of guys like to get the door to fender gaps narrow, these old trucks weren't built that way but will work that way if there is enough support to keep things from moving. with a 4x4 I would assume there will be more frame flex than a road driven low rider. just a thought for you to consider. for body alignment youtube check out "old man fixing stuff" 55 chevy truck build, going over fixing the gaps" or somethng like that

[dsraven]

looking at your steering box set up and wondering if a different angle on the pitman arm would allow the hard right without tire rub. if it was clocked just a bit more at full right the tire may miss. that or recess the box into the frame. the blazer frame was narrower so the box would be closer to the frame centerline

[PuzzleTruck]

Originally Posted by dsraven

looking at your steering box set up and wondering if a different angle on the pitman arm would allow the hard right without tire rub. if it was clocked just a bit more at full right the tire may miss. that or recess the box into the frame. the blazer frame was narrower so the box would be closer to the frame centerline

Interesting. That's pretty low on my list right now, but when the time comes I'll look into the possible solutions. I'll most likely go with a crossover steering system.

[PuzzleTruck]

Here's another problem I tackled last week. The drivers side rocker had a nice hole in it and some knucklehead just patched in a replacement rocker over the old one, essentially making a rust sandwich. I stripped off the bad repair job and proceeded to remove the original rusted rocker and welded in the replacement. After tacking the corners, I grabbed the door and hung it by one upper and one lower bolt and checked the fit. Then I went ahead and welded it in.

[PuzzleTruck]

2 More pics of finished step/rocker. When I get better at welding I won't have to grind as much. LOL! It won't come apart though.

[PuzzleTruck]

Originally Posted by dsraven

I believe there was a torque brace on the old blazers as well that bolted to the side of the transfer case somehow. it was to keep the engine from rolling out of the engine mounts under hard loads etc
did some quick google work and found this thread from this site. it shows the torque mount and how it is mounted. its an old thread but still available. have you seen something like this in your box of goodies?
http://67-72chevytrucks.com/vboard/s...d.php?t=220183

dsraven, thanks for that link, I just took a look at it. Those are some good pics showing the setup. Now, where to find a T-case bracket? If I can't find one, I can fab one. I'll also need to stiffen up the frame so I don't get the flex you mentioned. I still have the old cross member from under the transmission, so maybe that will come in handy.

[dsraven]

hey, no problem. glad something I did made a differnce.
you could easily fab something up using some energy suspension urethane mounts or something similar.it should be dampened for both directions of torque. it should take some of the strain off the engine mounts.

[PuzzleTruck]

I recently bought an LS 6.0 and 4L60E transmission. I got a pretty good deal and wasn't thrilled about rebuilding the old 350 and having a TH350 3spd auto. It will need some parts that were removed, and the trans is for a 2WD so I ordered a 4x4 adapter and tailshaft. I won't document the process, since I found a very good video online that I can't top. https://www.youtube.com/watch?v=4IDfs0UMne0 I'll be using this video as a guide to make sure I get it right.

[PuzzleTruck]

Well, I finally got the engine and trans completed. The wiring harness is 98% figured out. I won't know if it's 100% until I have it in the truck. I mounted the engine, trans and t-case in the frame and measured from the cab mounts to the engine to make sure I clear the cab by at least an inch. Then I measured the drop needed for the rear support. Turned out to be 4", as I expected. I cut the cross member, made drop plates and welded them in. Looks like it should work fine. The front driveshaft will be used as-is and the rear will be 44" long. Right now I'm working on fabricating a torque mount for the transfer case. Pics to follow.