Checking Frame Straightness/Alignment - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue85 · 02-20-2006, 07:42 PM

Is there a way to check frame straightness at home?

jku72 · 02-20-2006, 10:23 PM

There is a quick way I use, and that is to drive on to a flat surface, smooth concrete is best. With a very accurate tape measure measure identical points on each side down to the ground. You must have same size and same inflated tires. If the numbers all match side to side, there is a low likely hood of a bent frame. If your numbers don't match, your frame still might not be bent, but there is still the chance. Putting the truck then on jack stands and remeasureing can help determine if spring sag is an issue.
Usually, in my expirience anyway, bent frames are often only bent at the front and rear horns, from a collision. Cabs frequently sag, and the rubber bushings under the radiator support fall out giving the appearance of a lean, or bent frame. Dont put the jackstands at the frame horns, put them under the cab or under the engine cross member.

The official way is to get the factory frame measurement specification and do the full line of checks, but I'm way too busy to do that.

*Billla* · 02-20-2006, 10:44 PM

If the frame is bare you can get the "crash sheets" which have all the dimensions. Then all you need is a pretty darn dead level floor...which is usually the challenge.

4x4Poet · 02-21-2006, 02:24 AM

Its in the Service Manual. Look in Frame chapter for a fig. "Frame Horizontal Checking -Typical".

TravisH · 02-22-2006, 10:57 PM

If its a bare frame:
- do a corner to corner measure to determine if the frames square.
- lay a 4' level on the sections that should be straight to see any waves.
- run a stringline down the center of your crossmembers and take measurements to your frame rails to see if theres been any tweaking on the curved areas

If it passes the first step your frame is good, do the second two to pinpoint any damage if its out by more than 1/8".

02-20-2006, 07:42 PM	#1
Blue85 Oilfield Trash Join Date: Sep 2003 Location: Raymore, Sk, Canada, Earth Posts: 3,170	Checking Frame Straightness/Alignment Is there a way to check frame straightness at home? __________________ 14 Dodge 3500 Mega Cab 08 Dodge 3500 Mega Cab 87 Chev 3+3 4x4 80 GMC K10 High Sierra bone stock 70 Chevelle 350SS long term project 68 GMC 3ton Grain Truck/Garbage wagon 50 Pontiac 2 Door Coupe Project "I've got a shotgun rifle and a 4 wheel drive and a country boy can survive" Hank Jr.

02-20-2006, 10:23 PM	#2
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	Re: Checking Frame Straightness/Alignment There is a quick way I use, and that is to drive on to a flat surface, smooth concrete is best. With a very accurate tape measure measure identical points on each side down to the ground. You must have same size and same inflated tires. If the numbers all match side to side, there is a low likely hood of a bent frame. If your numbers don't match, your frame still might not be bent, but there is still the chance. Putting the truck then on jack stands and remeasureing can help determine if spring sag is an issue. Usually, in my expirience anyway, bent frames are often only bent at the front and rear horns, from a collision. Cabs frequently sag, and the rubber bushings under the radiator support fall out giving the appearance of a lean, or bent frame. Dont put the jackstands at the frame horns, put them under the cab or under the engine cross member. The official way is to get the factory frame measurement specification and do the full line of checks, but I'm way too busy to do that. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

02-20-2006, 10:44 PM	#3
Billla Account Suspended Join Date: Sep 2005 Location: Monroe, WA Posts: 3,814	Re: Checking Frame Straightness/Alignment If the frame is bare you can get the "crash sheets" which have all the dimensions. Then all you need is a pretty darn dead level floor...which is usually the challenge.

02-21-2006, 02:24 AM	#4
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	Re: Checking Frame Straightness/Alignment Its in the Service Manual. Look in Frame chapter for a fig. "Frame Horizontal Checking -Typical". __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup. Last edited by 4x4Poet; 02-21-2006 at 02:25 AM.

02-22-2006, 10:57 PM	#5
TravisH Registered User Join Date: Mar 2005 Location: Alberta Posts: 316	Re: Checking Frame Straightness/Alignment If its a bare frame: - do a corner to corner measure to determine if the frames square. - lay a 4' level on the sections that should be straight to see any waves. - run a stringline down the center of your crossmembers and take measurements to your frame rails to see if theres been any tweaking on the curved areas If it passes the first step your frame is good, do the second two to pinpoint any damage if its out by more than 1/8".



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.