Front Crossmember

[firebane]

I'm looking for valid reasons for why the front cross member on my K10 4x4 is important.

The truck already has a engine crossmember which would do the same thing as the front crossmember since they are so close. Also the front crossmember doesn't even touch the frame so it seams its only purpose is to attach the prop valve for the brakes and the sway bar to it.

I know that if GM put it there that it must have a reason for it to be there but I'm honestly curious of what its purpose is.

 

[MadOgre]

For one it keeps the frame rails from pulling apart seeing as that's where the front spring hangers are located. And 2 that engine cross member has been known to crack and break many times. If you removed the front cross member, then the engine cross member would break in half in very short order. So 2 is way better than 1. Also when you look at a bare frame, It almost looks inadequate that there is only 2 little tiny cross members up front. 3rd that front cross member also supports the steering box!

So if your thinking that removing that front cross member is a good idea. DO NOT DO IT! Its a bad idea and your frame rails will still be bent. They wont magically straighten out just cause you remove the cross members. If the cross members are bent so are the rails.

If you pulled the cross member out you could straighten it pretty easily with a big hammer. but don't leave it out. That is a very important frame item.

 

[Keith Seymore]

Also the front crossmember doesn't even touch the frame ...

This doesn't sound right. Can you post a pic?

I may be thinking of the 2wd version but the 2wd definitely touches the rails.

Also - the frame rails were received in the vehicle assembly as loose parts (just rails) and were riveted together on a "pedestal" (a moving fixture). The front crossmember also provides some stability while the bare frame is being built and squared up.

K

 

[firebane]

This doesn't sound right. Can you post a pic?

I may be thinking of the 2wd version but the 2wd definitely touches the rails.

Also - the frame rails were received in the vehicle assembly as loose parts (just rails) and were riveted together on a "pedestal" (a moving fixture). The front crossmember also provides some stability while the bare frame is being built and squared up.

K

This is the left side:

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This is the right side:

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[Keith Seymore]

Ok - so it does "touch the frame" - it's just attached to the upper and lower flange of the rail rather than the vertical portion. There is some clearance provided there to accomodate build variation.

K

 

[firebane]

Ok - so it does "touch the frame" - it's just attached to the upper and lower flange of the rail rather than the vertical portion. There is some clearance provided there to accomodate build variation.

K

Is it true that there was never any real "tolerances" when these frames were built and that the older frames could have issues?

I'd read a bunch of different articles about how frames come from the factory not straight and having issues.

 

[Keith Seymore]

Is it true that there was never any real "tolerances" when these frames were built and that the older frames could have issues?

I'd read a bunch of different articles about how frames come from the factory not straight and having issues.

No; that would not be true.

I don't know what the tolerances are offhand but every part that is designed as a tolerance on it, either a specific tolerance based on the performance criteria or at a minimum a standard tolerance applied to all parts.

However, that doesn't prevent them coming from the factory not straight and having issues.

K

 

[Georgeb]

This is a continuation of the bent frame thread. I noticed in one of Keith's other posts on a different thread about how they would slide the core support around to align the panels and such. Perhaps that nugget of info could be helpful in getting this whole thing figured out.....

 

[highdesertrange]

just a little side note here, your front bumper is considered your front cross member. do not run without a front bumper. highdesertranger

 

[firebane]

just a little side note here, your front bumper is considered your front cross member. do not run without a front bumper. highdesertranger

If that is the case then what is the one behind that? Because that would make that a front crossmember than the engine crossmember..

I currently have my bush guard bolted to the frame rails right now without a bumper.

 

[highdesertrange]

I don't know exactly what your asking about which cross member is what number, but your front bumper is your front cross member you must have it on. also the side arms that bolt to the outside of the bumper to the frame are as important as the bumper. these must be on to. if you run without the side arms and or the bumper your frame will start getting loose walking back and forth when you steer, especially under stress. highdesertranger

 

[firebane]

I don't know exactly what your asking about which cross member is what number, but your front bumper is your front cross member you must have it on. also the side arms that bolt to the outside of the bumper to the frame are as important as the bumper. these must be on to. if you run without the side arms and or the bumper your frame will start getting loose walking back and forth when you steer, especially under stress. highdesertranger

This cross member ... Is this not the front cross member? And god I hope I don't need all those brackets... Nothing lines up at all and will require a ton of fab work :\

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[highdesertrange]

well call it what you want but your front bumper is a cross member and because of those out board kicker brackets it is the most important one. those two brackets form triangles on the cross member an give it strength against the frame walk. triangles are the strongest structure man has come up with. don't run without a complete front bumper and if you go with a home built or after market bumper make sure you have the kickers. highdesertranger

 

[bucket]

I've seen a lot of trucks run without the front bumper and no harm done. BUT, the triangulation part of it does make a lot of sense. A farm truck or something would be fine missing the bumper or crossmember, but for anything that sees a lot of use, I'd want all the parts there.

 

[firebane]

I've seen a lot of trucks run without the front bumper and no harm done. BUT, the triangulation part of it does make a lot of sense. A farm truck or something would be fine missing the bumper or crossmember, but for anything that sees a lot of use, I'd want all the parts there.

Well even after market bumpers don't take into account the angle brackets and only rely on straight bolting to the frame.

If the bumper brackets are thick enough I don't think the side brackets would be necessary.