55.2-59 Replacing Cab Supports

[59c10]

Hey Guys, Im looking for some advice or tips when replacing the cab supports on the cab. I have tried to find a how too DIY video but can't seem to find one.

I need to replace the front two and im re-doing the front of the floor while I do this. Previous job was not done well.
Also what is everyone doing to replace the rear cab support brackets (under the cab)?

Any help would be great, this is my first big project so im pretty green when it comes to these trucks.

[mr48chev]

Welcome to the group. If you don't have the "factory assembly manual" I'd suggest investing in one. It isn't gospel but on the cab it answers most of the how does this go together, how far should these be apart and what goes on first questions.

The truck trinket vendors sell them or you can get them off Amazon or Ebay https://www.amazon.com/1955-1959-Che.../dp/B006YBPSM4

When the TF guys log on you should be able to get some answers.

[dsraven]

hello and welcome.
for the floor and front cab mount replacements I really recommend first ensuring the door hinges are in good shape and the door is also not cracked in the hinge mount areas etc. then fir the doors to the cab, don't worry about how the doors fit against the fenders as that is another step past the doors fitting the cab. this is important because the front cab supports are tied into the forward door pillars and the step. if you replace the cab supports and don't have the doors supported and fitting well then you are really asking for trouble when it comes time for door fitment. not sure if you have any history with the task force trucks but the common issue with them is that the grille in front of the windshield is common to the cowl and side venting systems on the cab. the cowl lets air into the vents by your feet but it also lets water in there as well. the water will normally drain out the bottom of the side cowls but the hole it has there is pretty small so any leaves, pine needles, mouse house supplies etc will plug the vent. then when water gets in the cowl there is nowhere for the water to go except evaporate, if it is a small amount, or, for the deluge rains or snow build up, the excess run off build up inside the side cowls until it reaches the height of the vent doors and then it runs out onto the cab floor. eventually this leads to the floor rusting along with the step well and the forward door hinge pillar. since the door hinge pillar is also connected to the step, the fender rear lower mount AND the cab mounts you can see how this all works together for a disaster if you simply cut out the old rusty stuff and weld in some new parts. on my old 57 gmc I found the front hinge pillars were toast along with that whole corner of the cab, floor, steps, rockers, fender mount, pillars, firewall etc. it was bad enough so the floor actually had a low spot under the pedals because the cab mounts were soft and non supportive anymore and so the weight of the front of the cab/firewall, doors etc was enough to make the floor sag. if you check all that stuf out and there is no other issue other than the cab supports and and floor work then that is great. I would go ahead and fit the doors, then with the doors on and closed, weld in some cross bracing in the door openings and then across the cab from side to side at the front of the door openings. do it in such a way that you can still do the work without too much trouble. then when it is all done fit the doors back on and remove the bracing. this should ensure the cab can't move out of square when you remove the doors that are sort of holding things together. below is a link to the factory assembly manual pdf that someone was good enough to post. I would download it and save a copy for future reference.
https://www.trifive.com/d1/55-59Assy.pdf

here is another link to a site with some good info
http://chevy.oldcarmanualproject.com...esto/index.htm


here are some pics of how I braced mine except for the door fore to aft bracing. I haven't found that pic yet. when I did that part I made a horizontal brace high enough off the floor so I could slip a couple of 2x4's under it, on edge for strength, and I was able to "hang" the cab from those by placing the 2x4's on sawhorses. this allowed me to work under the cab floor without anything in the way. I also cut my firewall out because it was pretty rusty where it met the floor and I wanted to fab a new one to fit around the LS engine and trans. there is also a pic of the front hinge pillar from the front side with it all taken apart and taken off the frame. it shows the crushing and consequential sagging problem. the pillar gets soft and crushes under the weight of the front section of the cab. there is a pic of the front of the cab with the main cowl part removed. it is hard to see but there is spot welds drilled out and there is a gap between the inner and outer section where air is supposed to flow down to the vents. below the section with the surface rust. you can also see the inner cowls are rusted out where the front fenders mount at the top rear of the fender. that is also really common where I come from anyway.

[dsraven]

any news over there '59?

[59c10]

dsravenm yes and no. I rebuilt the suspension with all new bushings and ball joints tire rods. added lowing springs and did a rear flip kit.
The cab work has been slow, and stalled for a bit this summer. I will take some pics of the progress so far. I replaced the drivers cab corner and step so far, and working my way around the cab. I bought a set of LS fabrication fire wall and toe board panels for it and will be starting that process soon.

[59c10]

Heres an update, finally uploaded soem pictures from my phone. I will hopefully be updating more progress from now on.

I have stripped all the wiring out of the cab. previous owner spliced in the C10 donar harness, there were connections with electrical tape and or house wiring marettes. I have a full new ez wiring harness to go in later.

Drivers cab corner was my first attempt at welding sheet metal. grinder got a work out. still have to finish some of the grinding but slapped some primer and and paint on it before it started snowing jsut incase. also had to replace the lower b pilar and step. ( in this picture its not welding in yet)

The previous owner scabbed in the C10 brake master/steerin bracket. I removed it and and replicating the drip rail section then using LS fabrication fire wall fillers to smooth the fire wall.

after removing lots of bondo i found what looks to be plasma cut our spot welds. there has been lots of suprises hidden under bondo so far.

Cab supports, both sides have similar rot. I have replacements but was wondering if anyone has advice ora DIY on patching these or replacing them. This truck will be a driver not a show vehicle. but the intenet is to keep it going down the road safely.

[dsraven]

thenassembly manual has dimensions for nearly everything and it is available from the tri5 site for free download. possibly download that and print the page with the dimensions you need to ensure the new cab mounts, floor and firewall patching results in a proper fitting set of doors, fenders and hood. it will also show you how many spot welds hold things together and where they will be located. the cab mounts are a sandwich affair at the step and door pillar end and there are a few parts there at the bottom of the pillar to fill the pillar hole and provide strength and also a bracket to attach the lower front fender bolt. when the cab supports and the floor rust out they get weak and the weight of the firewall and front of cab can make the whole unit sag. you may have noticed the floor seemed to drop down at the front below the pedals and that is part of the sag thing. this is why I always recommend to fit the doors in the cab openings and cross bracw stuff before removing the doors to allow work to be done, so the doors will fit when the repairs are finished. the, remove the old mounts and clean up the area to bare metal, getting rid of any metal that is suspect for thickness due to rust. sandblasting can really help here and will quickly show up thin spots. all the parts for the area are available from the patch panels section of the various parts suppliers. when you are ready mock everything up with cleco fasteners and vice grips after you have punched a few holes where you will be spot welding the parts together, or leave that part untill after you have fir the parts and then mark the weld spots, dissassemble and punch the holes at that point. I like to use a piece of square tube or angle iron vice gripped to the ab mounts t connect them side to side and that keeps them flat and level in relation to each other so the floor will be flat and level. if you don't have some cleco's and the cleco pliers they are relatively cheap on ebay or amazon and really help keep things tight together as well as acting like a third or fourth hand. the c clamp vice grips are also invaluable as is a hole punch that will punch a big enough hole for a good spot weld. a step drill can also be your friend here as they don't chew through the metal like a regular drill bit does so they don't leave a piece of steel on the back side of the sheet metal. I usually buff the parts and spray them with some weld through primer so the parts will have some protection between the layers when done, then either clean and epoxy the area or clean and coat the area with weld through primer, which is high in zinc, so it doesn't start to rust before I get to the epoxy stage. the weld through primer actually comes off fairly easily using laquer thinner but will stick good enough for protection untill the time comes to remove it and sand before the epoxy stage.
anyway, long story short, before you weld ensure the doors are gonna fit the cab otherwise you extend your repair time and your frustration level. they need to fit the cab well, then the fender gets adjusted to fit the front of the door, so don't be too concerned with the front fender. if your door is not original to the truck it may not fit that well either as door swapping, for me, has produced various results with doors from 3 different trucks. these trucks were put together by hand mostly and the fitment was just good enough to allow the door to latch, not really worried about the gaps etc.