How to tell if a frame is bent? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Patrick Sullivan · 10-27-2002, 01:33 AM

My bed leans to the passenger side at the rear, but it's flat(ter) in the front. It really started bothering me lately, so I figured I'd take the bed off and remount it. Looking underneath it.. all the bolts were tight, nothing loose or missing. The only reason I thought bed bolts was that it also felt very "loose".. the bed feels like it's hopping when you go over a bump.

So now I have no clue why it leans to one side. The bed itself is straight, as far as I can tell. The rear end of the trailing arms both sit the same distance from the ground. The coils measure within 1/4" of each other. The fact still remains that, measuring from the outside lip of the rear wheel well to the ground, the passenger side sits at 33 3/4", and the driver's side sits at 35".

So, I guess the only thing left is for the frame to be bent, huh? Is there anyway I can check for this? The frame isn't visibly tweaked/bent/wrinkled at any certain point, to my untrained eye anyway.

yellowgmc · 10-27-2002, 02:20 AM

you could hang a plumb bob from each frame corner and measure. you'd have to have the same psi in all your tire to get an accurate measurment so i'm not sur how well that'd work. that's my only idea. hope it helps.

Hutch · 10-27-2002, 11:30 AM

Maybe the mounting pads (rubber)or bed frame stands (on the frame rails are crushed.
For a test put some spacers under the bed mounts on one side.

neonlarry · 10-27-2002, 04:48 PM

I talked to someone that remembered their dad buying a brand new 69 GMC, and the first thing he did when he brought it home was put 1/2 inch spacers under the bed on one side so it would sit level. I am not sure, but maybe some of them were just made crooked?

mikep · 10-27-2002, 05:22 PM

When I bought my truck it leaned to one side like that. Couldnt figure out why. It had a receiver hitch that was welded to the frame along with the step bumper that was on the truck. When I cut the bumper and hitch away from the frame to put the new bumper on it made a loud noise. After that it sat level. I figure the receiver hitch was welded on while it was on a lift and it loaded the frame to sit high on one side. Might have been like that for 20 years or more.

Patrick Sullivan · 10-27-2002, 07:08 PM

Quote:

When I bought my truck it leaned to one side like that. Couldnt figure out why. It had a receiver hitch that was welded to the frame along with the step bumper that was on the truck. When I cut the bumper and hitch away from the frame to put the new bumper on it made a loud noise. After that it sat level. I figure the receiver hitch was welded on while it was on a lift and it loaded the frame to sit high on one side. Might have been like that for 20 years or more.

Hahah, mine is welded the same exact way. Maybe I'll grind the hitch and bumper off (been meaning to anyway) and see if it gets me anywhere. If not.. I guess I can shim the bed around a bit. Thanks guys.

crazy longhorn · 10-27-2002, 07:59 PM

It could be the same guy welded both hitches

. you might also try swappin the springs side for side, & see if that makes a difference. Some times a measure at the frame rails can be deceiving, as that is roughly a 3' span, & to measure the wheel lips you are workin with more like a 6' span.......if a spring is weak it will lay one side over, & the other side may be up a bit. if you had the box off, &6' layed a straight edge across the frame, it would be very clear that the distances would change from the center point to either end.....more drastically the farther you measure out........crazy AL

sbrban · 10-27-2002, 09:17 PM

To measure your frame you would need to take the susp. out of the measurement.Put floor jacks at 4 corners of the frame- all of same height-2 under frame at front cab mounts and 2 at rear of cab(or a little farther) in same spots.let susp. hang then measure side to side to see any major differences-there's gonna be a little,after all it is 30 years old. If its close there then you've eliminated the frame.

10-27-2002, 01:33 AM	#1
Patrick Sullivan Transcendental Trucker Join Date: Dec 2001 Location: Rockaway Beach, OR Posts: 374	How to tell if a frame is bent? My bed leans to the passenger side at the rear, but it's flat(ter) in the front. It really started bothering me lately, so I figured I'd take the bed off and remount it. Looking underneath it.. all the bolts were tight, nothing loose or missing. The only reason I thought bed bolts was that it also felt very "loose".. the bed feels like it's hopping when you go over a bump. So now I have no clue why it leans to one side. The bed itself is straight, as far as I can tell. The rear end of the trailing arms both sit the same distance from the ground. The coils measure within 1/4" of each other. The fact still remains that, measuring from the outside lip of the rear wheel well to the ground, the passenger side sits at 33 3/4", and the driver's side sits at 35". So, I guess the only thing left is for the frame to be bent, huh? Is there anyway I can check for this? The frame isn't visibly tweaked/bent/wrinkled at any certain point, to my untrained eye anyway. __________________ Patrick Sullivan \| sullivan@oregoncoast.com Rockaway Beach, Oregon 1972 Chevy Cheyenne C-20 1998 Dodge Dakota 4x4 So, fill to me the parting glass And drink a health whate'er befalls... Then gently rise and softly call Goodnight and joy be to you all!

10-27-2002, 02:20 AM	#2
yellowgmc Getting cabin fever?!?!?! Join Date: Oct 2002 Location: chisholm, mn Posts: 1,679	you could hang a plumb bob from each frame corner and measure. you'd have to have the same psi in all your tire to get an accurate measurment so i'm not sur how well that'd work. that's my only idea. hope it helps. __________________ Member of the Discs Up Front Club 1972 GMC 1500 1994 F-150 XL 4x4 Tact is for people not whitty enough to be sarcastic

10-27-2002, 11:30 AM	#3
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	Maybe the mounting pads (rubber)or bed frame stands (on the frame rails are crushed. For a test put some spacers under the bed mounts on one side. __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

10-27-2002, 04:48 PM	#4
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	I talked to someone that remembered their dad buying a brand new 69 GMC, and the first thing he did when he brought it home was put 1/2 inch spacers under the bed on one side so it would sit level. I am not sure, but maybe some of them were just made crooked? __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

10-27-2002, 05:22 PM	#5
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	When I bought my truck it leaned to one side like that. Couldnt figure out why. It had a receiver hitch that was welded to the frame along with the step bumper that was on the truck. When I cut the bumper and hitch away from the frame to put the new bumper on it made a loud noise. After that it sat level. I figure the receiver hitch was welded on while it was on a lift and it loaded the frame to sit high on one side. Might have been like that for 20 years or more. __________________ No truck :-(

10-27-2002, 07:59 PM	#7
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	It could be the same guy welded both hitches . you might also try swappin the springs side for side, & see if that makes a difference. Some times a measure at the frame rails can be deceiving, as that is roughly a 3' span, & to measure the wheel lips you are workin with more like a 6' span.......if a spring is weak it will lay one side over, & the other side may be up a bit. if you had the box off, &6' layed a straight edge across the frame, it would be very clear that the distances would change from the center point to either end.....more drastically the farther you measure out........crazy AL

10-27-2002, 09:17 PM	#8
sbrban Registered User Join Date: Sep 2002 Location: Iowa Posts: 236	To measure your frame you would need to take the susp. out of the measurement.Put floor jacks at 4 corners of the frame- all of same height-2 under frame at front cab mounts and 2 at rear of cab(or a little farther) in same spots.let susp. hang then measure side to side to see any major differences-there's gonna be a little,after all it is 30 years old. If its close there then you've eliminated the frame. __________________ you never have too many suburbans....



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