Frame Sag - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mseymour · 12-09-2008, 11:26 PM

Hi, new to the site, was hoping someone could help with my problem. 72 blazer 99% resored, and didnt notice when i had the frame off it was weak. anyway it sags in the middle like alot of the older trucks where the bed rubs the cab, I have had to spacer up the inner body mounts to close the doors etc. I had a buddy with same truck, same problem, and he had steel plate welded under the body center to add rigidity. I know I could weld the frame boxed, but its all been powdercoated.
heres a few pics along the way

BLUE THUNDER · 12-10-2008, 12:09 AM

Dude, nice rig and welcome from San Antonio. These problems are to be expected with a 36 year old truck. Are you planning to put a top on it? I don't think it really matter at this point, but shimming the body mounts is your best option. Don't ruin the powder coating on the frame. Looks awesome the way it is. What are some of the specs on your ride?

bouncytruck · 12-10-2008, 01:17 AM

Welcome to the board from Seattle. That's a nice looking rig ya built.

I would suspect the issue is more in the body mounts/frame shims than sagging in the frame.

Are you're rocker/torsion boxes solid?

vtblazer · 12-10-2008, 07:18 AM

Body issue, not frame...common problem with body off resto's.

Great looking ride, welcome to the board

Chevyman63 · 12-10-2008, 07:26 AM

Quote:

Originally Posted by bouncytruck

Welcome to the board from Seattle. That's a nice looking rig ya built.

I would suspect the issue is more in the body mounts/frame shims than sagging in the frame.

Are you're rocker/torsion boxes solid?

Quote:

Originally Posted by vtblazer

Body issue, not frame...common problem with body off resto's.

Great looking ride, welcome to the board

X2

And

from Michigan...nice rig!

1956cameo · 12-10-2008, 08:03 AM

Welcome from the other side of Houston. I too would assume the problem to be with the body and not frame. The truck still looks great!

**Yukon Jack** · 12-10-2008, 03:04 PM

Welcome - sweet K5!

mseymour · 12-10-2008, 03:53 PM

Thanks for the input, similar to what I thought, anyone have a very clean cure? The inside of the body was shot with rhino liner and the underside was bead blasted and painted, so welding is out. I thought about a cage or roll bar that could be modified for support. Some of the specs, full off frame resto, down to the last grade 8 bolt, every piece of metal other than the body was blasted and powdercoated, both axles completely rebuilt, went with 411 posi front/rear, new hubs drive shafts, gas tank, SS fuel and brake lines, rebuilt tranny and transfer case, went with GM HO330 deluxe, all new dash, inst cluster, tilt column, new interior etc.etc.
would like to fix the frame, go efi and drive it more, it has 1600 miles on the odo since the rebuild 7 years ago
I kind of have an itch to start messing with it again
Thanks for all compliments and welcomes
here is a pic near completion
BTW I am the original owner

Big J · 12-10-2008, 04:10 PM

Welcome to the board. You've got a nice ride. I too don't believe its your frame. Just one of those things when doing a frame off with a blazer. You might have to use a couple extra shims here and there to get it to line up right. No big deal. Theres really not enough distance in between front and rear springs to sag. What are some specs on lift, wheels/tires? Any inside pics? I'm going to rubber line the inside and under side of my tub.

vtblazer · 12-10-2008, 04:11 PM

Quote:

Originally Posted by mseymour

fix the frame

It's not the frame.

Shim the body correctly and you'll be all set.

mseymour · 12-10-2008, 04:40 PM

i think its a combination of both, i have @1.5 inches of shim in the middle mostly under front of the bed, when i put the truck on the lift the flex goes the opposite way. have tried alot of things, so far only the shims work. what bugs me is the flex, the rear tops of the doors rattle and rub the top of the bed
started with 3-4 inch lift but i have removed a spring or two now its @1.5, they are 33's, it handles well, but i have the nitro shocks which are too stiff, gonna go to the hydro's so if any one is looking for nitros i will sell all 4 cheap

vtblazer · 12-10-2008, 05:44 PM

Quote:

Originally Posted by mseymour

i think its a combination of both, i have @1.5 inches of shim in the middle mostly under front of the bed, when i put the truck on the lift the flex goes the opposite way. have tried alot of things, so far only the shims work. what bugs me is the flex, the rear tops of the doors rattle and rub the top of the bed
started with 3-4 inch lift but i have removed a spring or two now its @1.5, they are 33's, it handles well, but i have the nitro shocks which are too stiff, gonna go to the hydro's so if any one is looking for nitros i will sell all 4 cheap

Are your torsion boxes intact?

Still betting it's not the frame flexing, it's the mounts letting things move due to the tub being in sub-par condition.

mseymour · 12-10-2008, 05:56 PM

help me out, what are torsion boxes?

vtblazer · 12-10-2008, 06:32 PM

Quote:

Originally Posted by mseymour

help me out, what are torsion boxes?

Passenger side looking towards the front...

mseymour · 12-10-2008, 06:35 PM

how do i know i they are bad?

RED72blazer · 12-10-2008, 07:26 PM

Quote:

Originally Posted by mseymour

how do i know i they are bad?

rust.

mseymour · 12-10-2008, 07:37 PM

no they look good, and the the sag is really more in the door area

mseymour · 12-10-2008, 07:41 PM

put it this way, there is @ a 1.5inch (the amount of spacer) dip in the frame right below the doors, if i put it on the lift or put a jack under the frame, it goes away. the door area is the weak point of the body, as there is no lateral support there

**jaros44sr** · 12-10-2008, 07:44 PM

Quote:

Originally Posted by mseymour

no they look good, and the the sag is really more in the door area

Yeah, but....they control the sag in the door area w/o the top on

mseymour · 12-10-2008, 07:51 PM

I see that they run forward past the doors, but they are in good (solid) shape. what is allowing the sag? again I have to use 1-1.5 inches of spacers in the middle mounts to get the doors to close, other wise the body buckles in the middle

**jaros44sr** · 12-10-2008, 08:10 PM

Hinges are in good shape right? Are we talking with the top off it sags...Spacers aren't always a bad thing

mseymour · 12-10-2008, 08:18 PM

dont have a top, if it was a little more rigid it would be ok, but the flex causes the doors to rub against the bed, rattles and has chipped the paint, I may end up doing some bracing underneath, if i can ever engineer it. I will probably try and find a roll bar for it first and see if I can connect everything

**jaros44sr** · 12-10-2008, 08:24 PM

Do you have those little chrome rub blocks mounted in the top of the doors, the doors shouldn't rattle

mseymour · 12-10-2008, 08:31 PM

yep, and the latches are adjusted tight, it squeeks and rattles as the frame & body flexes

bouncytruck · 12-10-2008, 08:38 PM

Did you replace the body mounts when you did the resto? Is there a possibility you got the body mounts in wrong or the body mounts?

As you can tell, most of us don't think it's the frame. These trucks have a tendency to flex in the middle when the body mounts are shot. My 72 rubs on the top of the doors just like you are describing. It didn't happen until pulled the top for the first time. I know I need to replace the body mounts to solve the issue.

Since you're the original owner, you'd know if the truck was abuse or wrecked to the extent that the frame is bent. Since you clearly appreciate the truck and spent a lot of time, money and energy restoring it, I'm going to guess it hasn't been abused.

12-09-2008, 11:26 PM	#1
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Frame Sag Hi, new to the site, was hoping someone could help with my problem. 72 blazer 99% resored, and didnt notice when i had the frame off it was weak. anyway it sags in the middle like alot of the older trucks where the bed rubs the cab, I have had to spacer up the inner body mounts to close the doors etc. I had a buddy with same truck, same problem, and he had steel plate welded under the body center to add rigidity. I know I could weld the frame boxed, but its all been powdercoated. heres a few pics along the way Attached Images

12-10-2008, 12:09 AM	#2
BLUE THUNDER Registered User Join Date: May 2007 Location: San Antonio Posts: 993	Re: Frame Sag Dude, nice rig and welcome from San Antonio. These problems are to be expected with a 36 year old truck. Are you planning to put a top on it? I don't think it really matter at this point, but shimming the body mounts is your best option. Don't ruin the powder coating on the frame. Looks awesome the way it is. What are some of the specs on your ride?

12-10-2008, 01:17 AM	#3
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,049	Re: Frame Sag Welcome to the board from Seattle. That's a nice looking rig ya built. I would suspect the issue is more in the body mounts/frame shims than sagging in the frame. Are you're rocker/torsion boxes solid? __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

12-10-2008, 07:18 AM	#4
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,538	Re: Frame Sag Body issue, not frame...common problem with body off resto's. Great looking ride, welcome to the board

12-10-2008, 08:03 AM	#6
1956cameo Registered User Join Date: Apr 2008 Location: Angleton, TX Posts: 2,219	Re: Frame Sag Welcome from the other side of Houston. I too would assume the problem to be with the body and not frame. The truck still looks great!

12-10-2008, 03:04 PM	#7
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	Re: Frame Sag Welcome - sweet K5! __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

12-10-2008, 03:53 PM	#8
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag Thanks for the input, similar to what I thought, anyone have a very clean cure? The inside of the body was shot with rhino liner and the underside was bead blasted and painted, so welding is out. I thought about a cage or roll bar that could be modified for support. Some of the specs, full off frame resto, down to the last grade 8 bolt, every piece of metal other than the body was blasted and powdercoated, both axles completely rebuilt, went with 411 posi front/rear, new hubs drive shafts, gas tank, SS fuel and brake lines, rebuilt tranny and transfer case, went with GM HO330 deluxe, all new dash, inst cluster, tilt column, new interior etc.etc. would like to fix the frame, go efi and drive it more, it has 1600 miles on the odo since the rebuild 7 years ago I kind of have an itch to start messing with it again Thanks for all compliments and welcomes here is a pic near completion BTW I am the original owner Attached Images

12-10-2008, 04:10 PM	#9
Big J Its lookin' like a Blazer! Join Date: Aug 2003 Location: Gods Country, KY Posts: 1,773	Re: Frame Sag Welcome to the board. You've got a nice ride. I too don't believe its your frame. Just one of those things when doing a frame off with a blazer. You might have to use a couple extra shims here and there to get it to line up right. No big deal. Theres really not enough distance in between front and rear springs to sag. What are some specs on lift, wheels/tires? Any inside pics? I'm going to rubber line the inside and under side of my tub. __________________ BAZINGA! My Build

12-10-2008, 04:40 PM	#11
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag i think its a combination of both, i have @1.5 inches of shim in the middle mostly under front of the bed, when i put the truck on the lift the flex goes the opposite way. have tried alot of things, so far only the shims work. what bugs me is the flex, the rear tops of the doors rattle and rub the top of the bed started with 3-4 inch lift but i have removed a spring or two now its @1.5, they are 33's, it handles well, but i have the nitro shocks which are too stiff, gonna go to the hydro's so if any one is looking for nitros i will sell all 4 cheap

12-10-2008, 05:56 PM	#13
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag help me out, what are torsion boxes?

12-10-2008, 06:35 PM	#15
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag how do i know i they are bad?

12-10-2008, 07:37 PM	#17
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag no they look good, and the the sag is really more in the door area

12-10-2008, 07:41 PM	#18
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag put it this way, there is @ a 1.5inch (the amount of spacer) dip in the frame right below the doors, if i put it on the lift or put a jack under the frame, it goes away. the door area is the weak point of the body, as there is no lateral support there

12-10-2008, 07:51 PM	#20
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag I see that they run forward past the doors, but they are in good (solid) shape. what is allowing the sag? again I have to use 1-1.5 inches of spacers in the middle mounts to get the doors to close, other wise the body buckles in the middle

12-10-2008, 08:10 PM	#21
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,694	Re: Frame Sag Hinges are in good shape right? Are we talking with the top off it sags...Spacers aren't always a bad thing __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim Last edited by jaros44sr; 12-10-2008 at 08:11 PM.



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12-10-2008, 08:18 PM	#22
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag dont have a top, if it was a little more rigid it would be ok, but the flex causes the doors to rub against the bed, rattles and has chipped the paint, I may end up doing some bracing underneath, if i can ever engineer it. I will probably try and find a roll bar for it first and see if I can connect everything

12-10-2008, 08:24 PM	#23
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,694	Re: Frame Sag Do you have those little chrome rub blocks mounted in the top of the doors, the doors shouldn't rattle __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

12-10-2008, 08:31 PM	#24
mseymour Registered User Join Date: Dec 2008 Location: Woodlands TX Posts: 23	Re: Frame Sag yep, and the latches are adjusted tight, it squeeks and rattles as the frame & body flexes

12-10-2008, 08:38 PM	#25
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,049	Re: Frame Sag Did you replace the body mounts when you did the resto? Is there a possibility you got the body mounts in wrong or the body mounts? As you can tell, most of us don't think it's the frame. These trucks have a tendency to flex in the middle when the body mounts are shot. My 72 rubs on the top of the doors just like you are describing. It didn't happen until pulled the top for the first time. I know I need to replace the body mounts to solve the issue. Since you're the original owner, you'd know if the truck was abuse or wrecked to the extent that the frame is bent. Since you clearly appreciate the truck and spent a lot of time, money and energy restoring it, I'm going to guess it hasn't been abused. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

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