My Front Frame Solution

[vin63]

I started boxing my frame awhile back - had mentioned in another thread how I had my paper patterns laser cut out of cold rolled plate. Anyway, I've been dealing with the issue of the front of the frame and access to the fasteners of the front crossmember. I didn't want to lose access, but also wanted to stiffen the front of the frame. So, I decided to run forward struts from the firewall to the frame. I fabricated plates at the firewall and frame that will allow me to bolt and unbolt the forward strut bars - similar to some of the front clip kits for the early Nova/Chevy IIs. I used existing bolts on the firewall for the mount plates, to keep things as simple as possible. I bent the 1 3/4", 0.120 wall tubing to try and follow the downward break on the inner fender so it didn't stand out too much. Here a couple of final mock ups before I start welding the tubing to the plates. These are prototypes for another set that I'll build for my friend, who wanted a set after seeing what I was doing.

[jason65]

Looks tuff. Got ant more pics?

[vin63]

What would you like to see?

[502tripower]

Looks good. Kind of reminds me of the old Chris Alston Chassis.

[scotts62]

Very cool looks good

[vin63]

Thanks, guys. Yep, I got the idea from my Nova/Chevy II buddies and noticing all of the TCI, Chassisworks, S&W front clip kits and how much of a difference the bolt-in forward struts stiffen their chassis - then it dawned on me last weekend at one of our gatherings that I could do something similar - duh. I just finished welding them and now onto cutting out the driver side rocker to weld in a repair...ugh, what a mess.

[jason65]

Originally Posted by vin63

What would you like to see?

All of it would be very cool.

[joe231]

that is cool!!
but, i don't see how much it would stiffen the frame, considering it is attached to the fire wall sheet metal....
guess maybe attached to and right next to the inner fender has some support, eh? forms a big box with triangulation
i'm not knocking it, just curious, and trying to understand it

[scotts62]

I need to do something like that only from the cab to radiator support for more stability since there isn't any inner fenders.

[vin63]

Originally Posted by jason65

All of it would be very cool.

That's all of it really...two left over roll bar tubing that I bent, four plates and then TIG welded. I can take a couple of photos tomorrow since I just finished welding everything.

Originally Posted by joe231

that is cool!!
but, i don't see how much it would stiffen the frame, considering it is attached to the fire wall sheet metal....
guess maybe attached to and right next to the inner fender has some support, eh? forms a big box with triangulation
i'm not knocking it, just curious, and trying to understand it

Yes, the upper mounts bolt to the reinforced structure that the inner fender bolts to. My main goal was to help reduce some of the twisting motion that the torque of my engine creates on the front of the frame forward of the front cab mounts. Now, I can run a front motor plate to the forward struts tubes to tie everything together.

[rickf]

Originally Posted by joe231

that is cool!!
but, i don't see how much it would stiffen the frame, considering it is attached to the fire wall sheet metal....
guess maybe attached to and right next to the inner fender has some support, eh? forms a big box with triangulation
i'm not knocking it, just curious, and trying to understand it

It looks cool, but I doubt its functionality. The Nova/etc cited are unibody, no frames, right? So such reinforcements are being applied to something that is supposed to already be solid and stiff. The truck cab is mounted on rubber pads on the frame, right? That's built in movement, slight perhaps, but it is there. The firewall to frame is not a solid relationship as it is in the Nova.

So if the frame really does twist under your torque, the bars will push the cab,the cab will move slightly on the rubber mounts. The firewall sheetmetal is the weak link, so it will act like a hinge. Eventually it will work harden and likely will crack.

[vin63]

Originally Posted by rickf

It looks cool, but I doubt its functionality. The Nova/etc cited are unibody, no frames, right? So such reinforcements are being applied to something that is supposed to already be solid and stiff. The truck cab is mounted on rubber pads on the frame, right? That's built in movement, slight perhaps, but it is there. The firewall to frame is not a solid relationship as it is in the Nova.

So if the frame really does twist under your torque, the bars will push the cab,the cab will move slightly on the rubber mounts. The firewall sheetmetal is the weak link, so it will act like a hinge. Eventually it will work harden and likely will crack.

Unibody - solid and stiff? I've put many unibody cars on chassis jigs and solid and stiff is not exactly how I would refer to those chassises. Every unibody car I've put on the chassis jig, the front sub-frames droop, some more than a couple of inches at the radiator support area. Remember, the cab structure is bolted to frame, too.

For our trucks, there isn't much structure at the front of the frame to keep it from twisitng - mainly because the inner fenders and radiator support are sheet metal. I don't think our ladder frames were meant to deal with a lot of torque. After the install of the forward struts, it doesn't twist as much and I'm sure it will twist even less when I use a front motor plate. I've been building drag cars (from backhalves to funny car chassis with pro certifications) for many years and any triangular structure you can ad to the chassis will help stiffen the C-channel frame.

[rickf]

Originally Posted by vin63

Unibody - solid and stiff? I've put many unibody cars on chassis jigs and solid and stiff is not exactly how I would refer to those chassises. Every unibody car I've put on the chassis jig, the front sub-frames droop, some more than a couple of inches at the radiator support area. Remember, the cab structure is bolted to frame, too.

Yeah, I know, that's why I wrote "supposed to be".
They are monocoque construction, with the intention of it being rigid by virtue of all the little tabs and ridges and whatnot. It works okay within the intended load ranges.

Adding the support tubes to the monocoque assembly is just further stiffening something that is already supposed to be stiff. It is all one piece.

The truck cab is bolted to the frame, yes, but it is on rubber pads. It is not intended to be a rigid assembly, just "pretty stiff".

I'm not saying don't do it. Clearly you already did and are not going to undo it. I'm just saying it's not likely to be one of the things that is still working 40 years form now.

[vin63]

Originally Posted by rickf

I'm just saying it's not likely to be one of the things that is still working 40 years form now.

I'll be pushing 100 years old by then. I just need it to add a little rigidity - about the same amount that the boxed portion of the frame I did will provide. I was able to box the frame up to just after the front cab mounts.

[1Bad62Pro/Street]

Looks good Bud!
Can't wait to see some more pictures!
I have to do the same thing to my 62. I have a Mustang II IFS clip in the front of mine.

Did not see below.... Do you have a front clip on your Chemmy?
http://67-72chevytrucks.com/vboard/s...d.php?t=285142

[vin63]

Originally Posted by 1Bad62Pro/Street

Looks good Bud!
Can't wait to see some more pictures!
I have to do the same thing to my 62. I have a Mustang II IFS clip in the front of mine.

Did not see below.... Do you have a front clip on your Chemmy?
http://67-72chevytrucks.com/vboard/s...d.php?t=285142

Gotcha...I would definitely add some structure to your frame clip since it looks like you removed a lot of the inner fender structure.

I kept the stock frame, but I noticed that the front of the frame flexed a lot just aft of where I boxed the frame, I figured if I boxed the frame all the way up to the radiator support, it would probably add the rigidity, but I would lose access the crossmember fasteners. So, I used some left over roll bar tubing I had laying around instead.