Love When Parts Fall Off - Rubber Mounting/Body Supports

[Rich72C10]

The other day I found this rubber bit on the floor of my garage (photo 1). I am pretty sure this is the passenger side lower radiator rubber mounting cushion. Photo 2 is the cab's driver side forward lower rubber mounting cushion and then Photo 3 is the cab's backside lower rubber mounting cushion.

My brain says if you need to replace one, replace them all. Yes?

I'll go with rubber, not polyurethane and I think I'll source the parts from GMC Pauls. I viewed a YouTube from LMC Tucks and seems straight forward for the cab with a helper.

Question:
But when you do one side and jack up the cab - that won't put stress / bend anything on the other side if it isn't loosened?

For the lower radiator, LMC Truck's YouTube isn't for a 72, seems there was a change - the LMC Truck's video is for 60~68.

Question:
Anyone have a steps/tips - how much disassembly is needed to get the old ones off and the new ones in?

Overall it seems the hardware is in pretty good shape all around, though I think I'll get the full kit from GMC Pauls. Which you can get the bed bits too. They sell "Bed Mounting Pads", is this a upgrade? Suggestions on this item?

[LockDoc]

Originally Posted by Rich72C10

The other day I found this rubber bit on the floor of my garage (photo 1). I am pretty sure this is the passenger side lower radiator rubber mounting cushion. Photo 2 is the cab's driver side forward lower rubber mounting cushion and then Photo 3 is the cab's backside lower rubber mounting cushion.

My brain says if you need to replace one, replace them all. Yes?

I'll go with rubber, not polyurethane and I think I'll source the parts from GMC Pauls. I viewed a YouTube from LMC Tucks and seems straight forward for the cab with a helper.

Question:
But when you do one side and jack up the cab - that won't put stress / bend anything on the other side if it isn't loosened?

For the lower radiator, LMC Truck's YouTube isn't for a 72, seems there was a change - the LMC Truck's video is for 60~68.

Question:
Anyone have a steps/tips - how much disassembly is needed to get the old ones off and the new ones in?

Overall it seems the hardware is in pretty good shape all around, though I think I'll get the full kit from GMC Pauls. Which you can get the bed bits too. They sell "Bed Mounting Pads", is this a upgrade? Suggestions on this item?

The back one is in pretty good shape. Replace them all. Be sure you get the kit for your application. 1/2 and 3/4 tons are different. Looks like yours is a 1/2 ton.

Basically you only have to raise the cab enough to slide the upper bushings in and there should be enough give in the mounts for that. I do side to side to replace them, instead of front to back but you can do it either way. Don't go any higher than you need to to get the top bushings in. You may or may not need the metal shims. The rear bolts come out the from the bottom and the front ones come out from the top. The front ones may have a spot weld on the head of the bolt, if so you will have to cut or grind the spot weld off to get the bolt out. The rear bolts have a cage nut on the inside of the cab so they should just unscrew from the bottom.

LockDoc

[Rich72C10]

Hey Leon,

Thank you for that information. I had sent in a question to GMC Paul's, didn't expect a Saturday reply. I do in fact have a C10 1/2 Ton Truck, I believe I'll get the full kit and use what I need from it. I think I'll also get the optional "Rubber Bed Mounting Pads". My brother has offered to help in his shop, just need to find the time to drive up to East Texas.

If anyone has tips for the front/radiator (pictures?) of what it take to do those two - that would be great!

Originally Posted by GMC Pauls via Email

The kit is the same as GM sold them and includes all radiator support 2 upper & 2 lower rubber mounting cushions 2 steel spacer sleeves and required hardware to install.

It also includes all 4 of the cab body support upper and 4 lower rubber mounting cushions, all 4 required steel spacer sleeves, 4-washers, 4-bolts, & 4-nuts needed to install the cushions correctly, plus the 8 bed mounting bolts 8 flat washers 8 lock washers and 8 nuts in the kit to attach either a steel or wood floor bed to the frame.

You are correct the Rubber Bed Mounting Pads that can be added optionally in cart are the same bed pads that are sold separately at the bottom of the same web page.

The only thing not included are body mounting shims as these were a shim as required item and are not always needed and the amount of shimming if required varied from truck to truck and would consist of either 1/16" or 1/8" thick washers.

[LockDoc]

Originally Posted by Rich72C10

Hey Leon,

Thank you for that information. I had sent in a question to GMC Paul's, didn't expect a Saturday reply. I do in fact have a C10 1/2 Ton Truck, I believe I'll get the full kit and use what I need from it. I think I'll also get the optional "Rubber Bed Mounting Pads". My brother has offered to help in his shop, just need to find the time to drive up to East Texas.

If anyone has tips for the front/radiator (pictures?) of what it take to do those two - that would be great!

The radiator mounts are basically the same as the cab ones. They have a carriage type bolt in them but they have a keeper under the head of the bolt that keeps it from turning while you remove the nut. You may have to have a helper hold down on the head of the bolt while you remove the nut. Sometimes when you get them loosened up a little bit they will want to start turning. Spray the threads & nut underneath with penetrating oil before you start. I can't remember off the top of my head if the radiator needs to be raised up to get the bolts out or not.

LockDoc

[Rich72C10]

Sorry if this is a stupid question...

Should you do the Cab first and then Radiator or doesn't matter?

Just wondering if I could try to tackle the Radiator first one each one at a time? Seeing that one of them mostly fell off the truck!

[RustyPile]

Originally Posted by Rich72C10

Sorry if this is a stupid question...

Should you do the Cab first and then Radiator or doesn't matter?

Just wondering if I could try to tackle the Radiator first one each one at a time? Seeing that one of them mostly fell off the truck!

I recently replaced all 6 (4 under the cab and 2 under core support) on my truck.. Here's how I did it.. Remove the nuts and bolts and all pieces on the bottom of the mounting brackets on one side of the truck (core support and body) and just loosen those on the other side.. Put a 2 foot 4X4 on the lifting foot of a floor jack.. Place the jack under the bottom of the rocker panel on the side where the nuts/bolts were removed.. Place the 4X4 running along the bottom of the rocker panel.. Lift the truck body only about 2 - 3 inches.. This will lift the body, fender, and core support as a unit.. Replace those 3 mounts but don't tighten the nuts/bolts yet..

Go to the other side and remove those nuts and bolts. Place the jack and 4X4 as you did on the previous side and raise the body a couple inches.. Replace the remaining mounts.. Remove the jack and tighten bolts to the recommended torque.


Replacing the mounts side to side instead of front to back maintains the fender/door alignment and nothing gets "buckled" in the process..

[Rich72C10]

Thanks Rusty!

Why can't I find the radiator support mounts in either the Service, Overhaul, or assembly manuals? I can find the Cab's support mounts all over the place... I must be blind I guess.

I assume the torque is the same between the radiator and front cab support mount nuts - 40~55 LBS FT?

Interesting there is a difference in the LBS FT between front and rear support mounts on the cab.

[weq92f]

Originally Posted by RustyPile

I recently replaced all 6 (4 under the cab and 2 under core support) on my truck.. Here's how I did it.. Remove the nuts and bolts and all pieces on the bottom of the mounting brackets on one side of the truck (core support and body) and just loosen those on the other side.. Put a 2 foot 4X4 on the lifting foot of a floor jack.. Place the jack under the bottom of the rocker panel on the side where the nuts/bolts were removed.. Place the 4X4 running along the bottom of the rocker panel.. Lift the truck body only about 2 - 3 inches.. This will lift the body, fender, and core support as a unit.. Replace those 3 mounts but don't tighten the nuts/bolts yet..

Go to the other side and remove those nuts and bolts. Place the jack and 4X4 as you did on the previous side and raise the body a couple inches.. Replace the remaining mounts.. Remove the jack and tighten bolts to the recommended torque.


Replacing the mounts side to side instead of front to back maintains the fender/door alignment and nothing gets "buckled" in the process..

.

This is exactly how I did mine. While there, shimmed the cab to be level/even with the bed. The body lines were off by 3/4 inch on driver side and 1/2 inch on the drinker side.

-klb

[dagnabbitt]

Me too.

Also, the front cab ones are much easier if you have a buddy. And if you are under the truck wear goggles, lol, cause 50 years of dirty is going to fall out and on your face.

[GMCPaul]

Originally Posted by Rich72C10

Thanks Rusty!

Why can't I find the radiator support mounts in either the Service, Overhaul, or assembly manuals? I can find the Cab's support mounts all over the place... I must be blind I guess.

I assume the torque is the same between the radiator and front cab support mount nuts - 40~55 LBS FT?

Interesting there is a difference in the LBS FT between front and rear support mounts on the cab.

67-68 & 69-72 Radiator support mounting kits torque value
35-55ft lbs
Paul Jr @ GMCPauls