X Member Design and Frame Bracing- '66 C10

[theastronaut]

A cage would make the frame much stiffer but it's just going to be a driver and not an all out track car. I'd like to eventually upgrade the suspension and occasionally autocross it but that'll be later down the road. I want to do the frame mods while the body is off now, so the later upgrades will have a good foundation.

[vin63]

Originally Posted by vin63

I didn't box my frame for vertical load bearing, but to resist some torsional flex/movement. I transferred my plate patterns to a water jet mill and cutting the patterns from 0.1875 1018 steel plate. The plates fit snuggly inside the C-channel frame (which is not heat treated) and I TIG welded them in an inch at a time rotating locations (both front to back and top and bottom). This, in addition to the strength of the OE sheetmetal structures helped to reduce some of the torsional flex in my case without having to go the full roll cage route.

Originally Posted by tubbedII

Is the goal you are trying to reach just to improve the flex with just crossmembers? I only ask because wouldn't a roll cage stop this type of flex much more?

Yep, previous post above...since these will be street driven, a roll cage is not a good option.

[kieth]

Thanks a lot for the information and I feel like I have learned a lot by participating in the discussion. Lots of really good information on this site and there are a lot of knowledgeable people as well. That is why I come here to lurk, learn, and discuss. Great ideas on how to increase the strenth of the frame and the X brace design is great........Kieth

[bcutt]

Here is one that Nate from Porterbuilt did.

http://67-72chevytrucks.com/vboard/s...358687&page=13

[aggie91]

Thanks, bcutt. That is the one I remembered and could not find.

[bcutt]

I thought that had to be it. As far as I know PB sells this as a partial kit with all the tubing pre bent, along with the crossmember and mounting plates. It would still take some cutting and fitting but the hard work would be done.
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[65Custom]

Originally Posted by kieth

Thanks a lot for the information and I feel like I have learned a lot by participating in the discussion. Lots of really good information on this site and there are a lot of knowledgeable people as well. That is why I come here to lurk, learn, and discuss. Great ideas on how to increase the strenth of the frame and the X brace design is great........Kieth

I second this

[theastronaut]

I have this week off so I was able to start making some progress. I decided to use 1"x2" 14g rectangle tubing for the X members, and it should be here tomorrow. I got the frame stripped down and temporary braces welded in, then flipped the trailing arm crossmember and temporarily reinstalled it and the the trailing arms/axle. I laid out the rear X member with string to check for trailing arm and driveshaft clearance at full drop and lift. I've decided to use a T56 trans and have a friend that's going to let me borrow his to mock up the engine/trans so I can build the front X member around it. Here's the pics of the rear, let me know what you think before I start welding in tubing!


Flipped T/A crossmember.




Full drop, string represents bed floor.




Upper and lower X's, will have triangulated braces tying the top and bottom together.








Bottom tubes will be bent for trailing arm/driveshaft clearance. I have a tubing roller to do this with.

[theastronaut]

I've got the upper tubes cut, shaped, welded, and clamped in place. It's amazing how much stiffer the rear half of the frame is with just the upper X clamped in place!!



I tapered down the ends of the tubing up front to make sure they cleared the cab when it goes back on.







Slight bend to clear the bed floor braces.





Driveshaft clearance at full drop.





Finished up, ready to be welded in place.









Bed floor rail clearance.







Trailing arm clearance at full drop.

[gofastnut]

My poor little pea brain is bursting at the seams with all the info....

[gringoloco]

Astro: Nice work! Looks awesome- don't know how I missed this before- any more progress?

[theastronaut]

Originally Posted by gofastnut

My poor little pea brain is bursting at the seams with all the info....

I know what you mean, this is all new to me!

Originally Posted by gringoloco

Astro: Nice work! Looks awesome- don't know how I missed this before- any more progress?

Thanks!! I'm hoping to get back on it and make the real lower brace soon. I've fit to find a way to bend the lower tubes first though.
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[jmlcolorado]

Originally Posted by theastronaut

I know what you mean, this is all new to me!




Thanks!! I'm hoping to get back on it and make the real lower brace soon. I've fit to find a way to bend the lower tubes first though.
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Are you going to make a lower brace matching the top, then add 'struts' in between to lock them together?
That would make 1 heck of a stiff rear end
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[bcutt]

I like it, Hotchkis did a similar setup on one of their sponsored trucks, here are a couple pics in case you haven't seen them.
Brandon

[theastronaut]

Originally Posted by jmlcolorado

Are you going to make a lower brace matching the top, then add 'struts' in between to lock them together?
That would make 1 heck of a stiff rear end
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That's the plan, make a matching lower brace and tie the two together. The lower brace will have to have bends in the tubing to clear the driveshaft and trailing arms. I'll build another pair of braces to go ahead of the trailing arm crossmember as well.

Originally Posted by bcutt

I like it, Hotchkis did a similar setup on one of their sponsored trucks, here are a couple pics in case you haven't seen them.
Brandon

Thanks for posting those! I have seen that build and it's awesome!! I had been debating whether or not to box the frame since I was thinking that my bracing would be plenty effective on its on, and seeing that they didn't box their frame helped me with that decision.
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[truckzilla]

I know it's an old thread, but how did the final bracing turn out?
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[theastronaut]

Originally Posted by truckzilla

I know it's an old thread, but how did the final bracing turn out?
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I haven't finished it. I decided to swap in a LS/T56 instead of the originally-planned 250 L6/T56 so I had to wait to get my engine/trans mocked up. I have a 5.3 and T56 in it now to check for clearances around the cab floor, crossmember, and frame rails. Once I get my engine mounts and trans crossmember built then I'll have a sleeve made to go around the T56 and start back with the 1"x2" bracing up front.


There is enough clearance around the T56 to build a sleeve for the center of the X braces.

[truckzilla]

I was going to go with a T56 with my LS conversion in my '77, but decided it was harder to shift gears while holding an adult beverage between my legs so I opted for a 6L80 that I can paddle shift.

I'm waiting to see how you finish crossbracing Goldy so I can get an idea of how to do the same. Guys like you that have talent is what keeps guys like me with none, enthused about the little we attempt.

[jc70chevy]

Any up dates

[Walkersan]

I am also working on some frame reinforcement. Any progress on this?

[truckzilla]

Maybe he is just swamped with other stuff and giving Goldy the summer off.

[theastronaut]

Haven't done anything else, we're slammed at work with three restoration jobs and more lined up after they leave. My daily driver has been needing some attention for awhile so I'm currently sorting through making some suspension/wheel/tire changes on it in my spare time; might be at Goodguys Charlotte autocross with it later this year. I also bought a few cars to flip for more Goldilocks bucks and I still need to sell those. I will post back here once I start back on it.

[TowwDogg]

Originally Posted by kieth

I see all of the bracing and the addition of a flat piece of steel welded onto the flange of the frame (boxing) in a lot of hot rods. I think it looks great but do not know how much true strength that it adds to the frame of the vehicle.
When trying to make a big truck frame stronger and sometimes longer we keep these simple rules in mind.

1. do not weld on a truck frame .......reinforce and bolt it in.

2. if you cut and weld a frame do it on a angle (45 degrees) so it will not break when loaded (90 degree butt weld).....if we do butt weld, then we line the frame with another frame section, bolt it into place (inner glove) and make sure it goes well past the butt weld. (this spreads the load out away from the butt weld)

3. If you want to add ridigity to the frame make a frame section like the original (out of harder and thicker material if possible)-----do not weld on the frame

4. Only drill a hole in the web of the frame not the top or bottom flange...drilling a hole in the flange weakens the frame and if done the hole must be filled with a very tight fitting bolt or rivet so it helps keep the strength of the flange in tact....

5. Section modulus X material yield strength = RBM resistance to bend moment.

5a. 6" + 2.5 + 2.5 = 11" X 55000psi yield strength = 605,000 rbm

5b. boxing------------- 11" + 6" box X55,000 + 935,000 rbm (less the strength we took away welding it in....

5c. double framing 11" + 11" X 55000psi= 1,210,000 rbm


So here is what we are doing when we box a frame:

a. we make it prettier

b. we make it weaker by welding it in and loosing the heat treating of the frame where we weld it. this means if it is loaded heavily it will start to break at that weak point where it lost its strength.


If we really want to have a stronger frame adding full U shaped sections of frame material will add strength to the frame, these U sections can be welded together before they are installed and bolted into place. when we add U sections we are getting the benefit of the full length of the frame web and the frame flange.......this adds much more rigidity than boxing the frame and does not weaken the existing frame by removing the heat treating.....

Again not trying to start a war just trying to inform.......I do not build pickups for a living but I do build larger trucks (class 8 road trucks) and have been modifying them for 30 years...... Kieth

ps I think robnolimit has added some comments and techniques for adding rigidity to our truck frames, he did use tubing to reenforce where the loads get quite high during turning but he did say to use full channel U sections to reinforce the weak points in our truck frames. JMO Kieth

Great info. Thanks ...

[chevyc10lover]

great tread!

[Dan@Hotchkis]

Here is an album of what we did to stiffen up the C-10 we built in house...
https://www.facebook.com/media/set/?...1375072&type=3