Body Flex... How much?

[elks]

So I have been running a soft top since I got my Blazer like 5 years ago. Every since I bought the blazer I noticed it has some body flex. Enough to feel the seats shift in twist, Door get stuck when twisted etc.

Does your blazers body flex when twistet upP If so enough to cause a door to stick?

If not why does mine? Frame seems solid and everything. I do have a small crack near power steering box, but other than that it all seems solid? It almost feel like the flex in a unibody Cherokee(not quite as bad)..

If my body is flexing will it cause hard top issues or will the hard top help fix the issue?

[SeventyOne]

It's all normal - but will make getting a hardtop back on and all the bolts in place a PITA.

Your body mounts will have a lot to do with the flex while driving w/o a top.

Are they original? Rotting away?

Also I know the rocker boxes underneath the Blazer play a role in structural support with the top off. Make sure yours are in tact.

[Erik V]

In the door jamb, up high in 71/72 I believe, are these little chrome/stainless striker plates. Those are supposed to help with doors getting bound up. My Jimmy has them, but last week when I was out playing in the snow, I parked a couple times all crooked/crawly style and only once did the driver door fail to open. But without a top thats no big deal, just meant I looked rediculous setting the pictures up.

Erik

[elks]

Thanks guys. I was just curious, I did not want to throw a hard top on and have the body flex stress and crack it. I rode last night in a buddies really sweat blazer with the hard top on and it felt the same when flexed.

Body mounts are solid, no rust anywhere, and I am guessing just normal flex. I do not know if I have the chrome striker plates. Anyone have a pic?

[GMC-YA68]

What actually is flexing on the bodies of these trucks? And the cause is only from not running a hard top?

[fxdxharley]

they flex between the a and b pillars, aka the door opening. the flex is always there top on or off but is greatly increased when the top is off because there is no roof to tie the a and b pillers together at the top like on a truck cab. the added torsion boxes help limit the flex. there is no way to eliminate it.

[theastronaut]

The open C-chanel frame rails with riveted crossmember joints are the cause of the flex. I can flex my bare frame by hand, it's that weak. The rivets loosen up over time, and an open C-channel isn't good a good design to resist torsional flex.

This is my frame with one rear air bag pumped up, you can see the flex pretty clearly- the front crossmember is level.

[GMC-YA68]

what is to keep someone from putting a type of subframe connector/brace under the body like the f-body cars all do? They use them all the time to get the cars from twisting due to drag racing. I knew of a few T-top cars that ran around town a few times and couldn't get them back in...There are all different types obviously, but they worked wonders compared to a stock set up.

[skorpioskorpio]

This is to connect front and rear subframes on a unibody vehicle, the Blazer is a rubber mounted body on frame vehicle so I'm not sure how this applies. I suppose you could weld body to frame to achive something like this, not sure how that would work out though.

[elks]

I am looking at a full cage that ties into the frame.

I am also looking at what sort things I can do to stiffin the frame up some...

[GMC-YA68]

[QUOTE=theastronaut;5804346]The open C-chanel frame rails with riveted crossmember joints are the cause of the flex. I can flex my bare frame by hand, it's that weak. The rivets loosen up over time, and an open C-channel isn't good a good design to resist torsional flex.

This is my frame with one rear air bag pumped up, you can see the flex pretty clearly- the front crossmember is level.

I see...

So why not weld the cross members down, and weld some beefed up plates on them?

[theastronaut]

Originally Posted by GMC-YA68

I see...

So why not weld the cross members down, and weld some beefed up plates on them?

I eventually will weld in the crossmembers, and add bracing to limit the flex.

I've started building X-members, it'll eventually have a matching lower X, and also a pair in front of the trailing arm crossmember that wrap around the transmission.

[Erik V]

my frame was boxed from the top of the front hump, to the top of the rear hump. Dad was racing it since the time he bought it, and noticed drastically less frame flex after plating the inside of the channels. Aside from that, a full cage connecting front frame heads to rear would ideally be the way you want to go...but thats only going to work well visually for an offroader.

Just went out and took a couple quick pics in the garage:





edit: when did my paint show up this poorly in a picture? blech! As for the plates, I'm going off vague memory here, but I believe it was a 71/72 thing, or maybe it was a CST/Custom thing. I just know the 69 Blazer my family had briefly years ago didnt have them AFAIK. Hopefully somebody smarter than me can remember more about these door jamb pieces.

Erik

[floyd]

A fully boxed frame and and/or welded custom crossmembers would take alot of the flex out.... a cage tied into the frame and body would also add alot of stiffness.

I just put urathane body mount bushings in my 70 2wd blazer project and it seemed to tighten up some of the noticeable body/frame flex I could see when picking it up on my lift.

[rfsnyder]

I too am having lots of body flex on a newly painted, hardtop-less '72. It heartbreaking, for it has chipped my paint down to bare metal in the door jambs and on the kick panels! I have a couple chips now about the size of a quarter!! Very disappointing! First thing I did on this project was replacing the body mounts! Obviously didn't seem to help. I also have the brass striker plates, but had to remove for they were binding so bad.

[elks]

Originally Posted by rfsnyder

I too am having lots of body flex on a newly painted, hardtop-less '72. It heartbreaking, for it has chipped my paint down to bare metal in the door jambs and on the kick panels! I have a couple chips now about the size of a quarter!! Very disappointing! First thing I did on this project was replacing the body mounts! Obviously didn't seem to help. I also have the brass striker plates, but had to remove for they were binding so bad.

Yes my paint is way bad as well. I wonder how much that has to do with the amount of hardener in the paint? Somebody told me that when the blazer is repainted to consider a paint mixture with less hardener. My drivers side has ton chipping and my passenger side is fine? I can almost see a difference on a straight line from where the paint is cracking/chipping and not.

[heyray]

Originally Posted by rfsnyder

I too am having lots of body flex on a newly painted, hardtop-less '72. It heartbreaking, for it has chipped my paint down to bare metal in the door jambs and on the kick panels! I have a couple chips now about the size of a quarter!! Very disappointing! First thing I did on this project was replacing the body mounts! Obviously didn't seem to help. I also have the brass striker plates, but had to remove for they were binding so bad.

If it makes you feel better same thing happend to me. Bummer now Im cutting my doors for a bit more clearance. I should have been more careful when welding in new rockers. I think I welded in some sag???????