1958 GMC Front Clip Question

[angelobackwards]

Hello all, I'm new to the whole restoring and customizing addiction as well as this site, and am looking for a little help/advice. My father and I are restoring a 58 GMC. The truck has a 72 Monte Carlo front clip installed by the previous owner who knows how many years ago. Anyways I have been putting the front sheet metal on and noticed the that the two radiator mounting tabs that are supposed to bolt down on the frame to help mount the clip are not sitting on the frame. The driver side side tab sits on the frame but the passenger side is about 2-3' away from the frame. Does this mean the frame is installed crooked or is it simply because the clip is wider that the original frame rails? I can get pictures tomorrow if it'll help to show what I am talking about. Thanks for any advice. I also enjoy reading all the builds they give me some great ideas that I never thought of, now im just working on getting the tools to do them =/. Anyways thanks again for any advice and help.

[tmoble]

pics will be needed to understand properly. are you using the 58 core support?

[SCHRUMGMC]

I have a '59 Gmc 100

Yes, post photos of yours

[angelobackwards]

Originally Posted by tmoble

pics will be needed to understand properly. are you using the 58 core support?

Yes I am using the 58 core support. The pictures below are somewhat hard to make out but the support bracket sitting on the frame is on the driver side and the support bracket hanging off the frame 2-3 inches is the passenger side.
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[angelobackwards]

Originally Posted by angelobackwards

Yes I am using the 58 core support. The pictures below are somewhat hard to make out but the support bracket sitting on the frame is on the driver side and the support bracket hanging off the frame 2-3 inches is the passenger side.
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[_Ogre]

it could be many things.
clip welded on crooked or the cab on crooked are the 2 that come to mind immediately
has the body ever been on the modified frame before?

[angelobackwards]

Originally Posted by _Ogre

it could be many things.
clip welded on crooked or the cab on crooked are the 2 that come to mind immediately
has the body ever been on the modified frame before?

Yes when my dad purchased the truck X amount of years ago it was on this frame with the clip already installed. To make sure the frame is on straight would we just measure back from a set point to the cab to make sure they're same distance? Thanks for all the help I appreciate it.
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[OrrieG]

To check for clip to frame squareness you need to diagonally measure from known points on the orginal frame that align (front cab mount rivets) to center of spindle axis on opposite side. If the measurements are the same spindles are square to the original frame. If they are not the same the clip is rotated or offset to one side relative to the orignal frame. I found the attached document that shows the frame is symettrical side to side, so something is off. As Orge said it might be the cab was not centered on the frame. There is enough movement in the mounts that if it got rotated just a little it could translate to the inches at the radiator support. measure from the same point at the outside of the step to the frame, it should be the same. When I put on my clip I had to loosen the cab bolts and jockey it around to get the fenders and hood gaps close. Worse case is the original fabricator did not brace the frame and it got pulled out of square too when welded. They are designed to move and flex. Mine was 1" out of square but pulled back into place with a come-along.

[_Ogre]

don't ignore advise given; you have 2 choices... pay attention or scrap the frame

as orierg says () measure diagonal from the center of the x-member to each cab support to see if the clip is straight
measuring from the cab means nothing

the cab on the frame .5'' out of square would have the core support 1.5 inches off
the core support 3'' off one side and right on on the other means your 1.5'' off center
loosen the cab mount bolts and twist the cab until the core support lines up

easy peasy

[angelobackwards]

Thank you both for the info. I'm back to work for the next few days but know what I'll be doing on my days off. Hopefully it's good news. Thanks for the help and advice. Maybe once I get this squared away I can start a thread at turtle speed =\.
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[ChuckDriver]

The mounts look to be Chevy not GMC, as the GMC core support was secured with to bolts centered below the radiator.

[angelobackwards]

Originally Posted by ChuckDriver

The mounts look to be Chevy not GMC, as the GMC core support was secured with to bolts centered below the radiator.

Yeah I believe the front sheet metal is Chevy. The cab is a GMC cab sorry about that.
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[angelobackwards]

Hey all thanks for the advice with the core support issue. I'm currently working on checking the frame squareness and adjusting the cab. Do you happen to know if there is a spec to tighten the cab mounting bolts down to? I don't want it so tight to distort the bushings a whole lot but don't want it loose where the cab may be unstable. Thanks for the help.
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[OrrieG]

Tight enough to compress the lock washer. That is what I used.

[angelobackwards]

Got it. Hopefully my last questions at least for a few days =\. Would any of you happen to have or know the measurements from the cab mounts to the core support mounts. Maybe this way I can fab something up for my core supports to start getting the front sheet metal in place. Thanks you guys have been of great help!
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[angelobackwards]

Hello all, could any of you possibly give me the length from the center of the front cab mount hole to the core support bolt hole? And also how much of the core support actually sits on the frame? I have a picture of the frame dimensions but with the sub that is on I am having a hard time finding matching points to measure from.

What I'm planning on doing is measuring the whole frame length and then cutting the front x amount of inches and using a jig and weld up a filler piece at the normal 40" width to get the core supports to sit on. Thanks

[tmoble]

I cut my Camaro sub off at the front of the steering box, plated it over. made a couple simple right angle brackets, made new core support mounts on the front of the core support. Stock core support mount came down right on top of the steering box, dang.

Hmpf, looks like I don't have any good pics of that part of the install. See what I can do tomorrow.

[angelobackwards]

Originally Posted by tmoble

I cut my Camaro sub off at the front of the steering box, plated it over. made a couple simple right angle brackets, made new core support mounts on the front of the core support. Stock core support mount came down right on top of the steering box, dang.

Hmpf, looks like I don't have any good pics of that part of the install. See what I can do tomorrow.

That would be great thank you!
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