flexing Front Crossmember/Stiffener 81 c10

[Manriquez]

Hi Guys

my brother's 81 c10 front stiffener is flexing like crazy and is driving me nut.
the manuals normally call this part "Front Cross Member" but for me that is the big one in the front wheels Center Line so decided to add a photo so we all understand the same (see attached picture).

the factory rivets are very soft so have changed them in all the trucks we owned before.

after changing the stiffener noticed the chassis still flex when turning the  steering wheel
even with a light movement with the engine not running and light pressure after the steering wheel play the stiffener compressed/elongate a total 5/16" which I guess will be enough for a terrible ride

before re installation cleaned the stiffener to bare metal and painted so I'm positive it isn't cracked
thew frame doesn't seems to be cracked neither.

now I'm coming to the conclusion this lighter design is probably causing the problem (my 75 Scottsdale use one without the big holes in the middle )

what you think?

regards
Pedro

[zieg85]

Is the flexing seen with the front bumper on and tight?

[Manriquez]

yes, the front bumper was replaced and all the brackets are installed and properly tightened.

front bumper and all their brackets are crucial for frame rigidity

[Captkaos]

How big of tires are you running?  How much is it flexing?  And is anything else flexing.  What does the area behind the steering box look like? 

Chris Lucas
73-87chevytrucks.com
squarebody.biz

[VileZambonie]

This is extremely common. What happens is the rivets loosen up just like the hood hinges do on the 73-80 trucks which results in the sprung hood. While these frames will flex because that is how they are, the excessive amount of movement in the front can be minimized by running a bead weld at the points in which they intersect. If you choose to do this just make sure the wheel is centered and one side isn't loaded more than the other. I'll see if I can take a picture to demonstrate.

[Manriquez]

How big of tires are you running?  How much is it flexing?  And is anything else flexing.  What does the area behind the steering box look like? 

the tires aren't too big in my opinion:  235/70/15

the stiffener on the picture flex along with that part of the frame

not sure on the last question but I guess you want to know
1.- if the area is cracked: and no, it isn't cracked nor damaged.
2.-and if the frame have a reinforcement: no it doesn't have any

regards

[Captkaos]

That tire size is fine.

Chris Lucas
73-87chevytrucks.com
squarebody.biz

[Manriquez]

This is extremely common. What happens is the rivets loosen up just like the hood hinges do on the 73-80 trucks which results in the sprung hood. While these frames will flex because that is how they are, the excessive amount of movement in the front can be minimized by running a bead weld at the points in which they intersect. If you choose to do this just make sure the wheel is centered and one side isn't loaded more than the other. I'll see if I can take a picture to demonstrate.

oh, yes! factory rivets (in that area) needed to be changed on every c10 I ever had.
particularly in this truck before the change you could see the frame "eating" 3/8" of the stiffener when turning the steering wheel

I have seen them welded, frame to stiffener, but we believe here that creates a crack right after the welding ends.
I rather remove the rivets with a pneumatic chisel (or a mallet and a chisel like in this case) and get them replaced with good grade bolts.
as per the perfect combination of paranoia and mania I used 7/16" x 1" studs in my own 75 (this 81 belongs to my brother) so the part without threads gets fill completely the holes.

but that picture will be really welcome, and guess I need to upload mine


regards
Pedro

[VileZambonie]

I have seen them welded, frame to stiffener, but we believe here that creates a crack right after the welding ends.

I have never seen this result in cracking and don't see why it would unless there is already another underlying issue. The first one of these I welded was over 20 years ago now and it's still strong with no issue. Nuts and bolts will eventually lead to the same issue regardless of the grade fastener you use but it's better than just leaving it.

[Manriquez]

I have seen them welded, frame to stiffener, but we believe here that creates a crack right after the welding ends.

I have never seen this result in cracking and don't see why it would unless there is already another underlying issue. The first one of these I welded was over 20 years ago now and it's still strong with no issue. Nuts and bolts will eventually lead to the same issue regardless of the grade fastener you use but it's better than just leaving it.

Please don't take my comment as a criticism because is not. just see the way I wrote it:"we believe here that..."
I'm positive the people saying "weld end up crack" had tons of another issues, these trucks were really ABUSED here.

but learned years ago to replace the rivets with bolts and worked fine for me so far.

now the stiffener is driving me mad: I may ending up replacing it with the old one (73-78?) that seems to be a better design. adding a strut or who knows

[Captkaos]

They get loose at the rivets so the 73-80 style won't prevent that.

Chris Lucas
73-87chevytrucks.com
squarebody.biz