I am finally ready to box my frame. I had posted a thread before asking questions and got the answers I was looking for. But now me and my dad have different opinions about how far back to go. He says that if the frame is boxed all the way back to the rear axle there won't be enough flex and if you are uneven ground you might have a wheel that isn't touching the ground.

After giving him the "are you stupid" look, I explained that frames that are made today are boxed all the way back. And even if you do box it, it will still be able to flex when driven. But I'm not very knowledgeable about them and could have just been feeding him something that sounds good.

I just want to ensure that there is enough support on the frame to hold up against 330hp and not bend. He says that going back to the tranny crossmember will be sufficient enough to handle the torque and anything over is just making the frame too strong. Who's right???

 

Dad's right!

Frames that are tubular (completely boxed) have the cross members in places and are attached in ways to be flexible with that type of frame. These trucks are not.

At a minimum, you want to box back to the firewall, but to the tranny mount (or maybe a foot farther back to elliminate all those stresses being focussed at that one point) sounds like good advice.

MIND YOUR FATHER ! (Darn kids anyway)

Tee hee

Julie!

 

The frames were originally designed to "flex" under certain circumstances because most were used for "work", not pleasure. Today, many people want the later IFS and some the IRS suspensions and for them to work properly you need a stiff frame. I don't think you will lift any wheels off the ground unless you are planning an off road expedition.

 

I guess I should have mentioned that. I did put the Mustang II IFS on the front and have an 8.8 off of an explorer I am putting on the back, so it's not stock. It won't be IRS though. Just putting lowering springs on. So Julie, does that still mean that he is right??? If so, I guess I'll go over tomorrow and try to find some way to admit that I wasn't right.

 

Hmmm, well now you are throwing variables into this. Correct me if I'm wrong, but I think you should have already boxed the front with the IFS unless you have the Chassis Engineering Bolt on cross member. That 8.8 in the back (or in the case of my truck a 9 3/8") won't really make a difference.

I have the stock front end and a Lincoln 9 3/8 rear...Haven't boxed anything (yet) I can't use the TCI weld in Mustang II because the shock towers interfere with my out of frame headers. Withthe Bolt on I'll have problems wihtthe big block motor mounts. So until I figure out a fron tend swap that works, I'm stuck with stock front end. At our last Dr.s appt, that 390Pi rated at 412hp. I HAVE snapped an aftermarket tubular motor mount, but, I'm not worried about the frame at this point. (I do have extra/heavy cross member braces up front though and a stronger tranny mont for the C6)

It wouldn't hurt anything to box it all the way back. But, if you thought he ride was rough with the stock running gear before, with a full lenght box it would have beaten you to death. Also, full box is going to require you to reeingineer your bed restoration...Bed support bolts are inside the channel.

If you used the bolt in IFS and didn't box at all, (and you are using their engine mounts welded to the cross member) you may not need to box - I'd call them. But if you used the TCI weld in cross member, then I'm not sure how you did it if you didn't box - at least to the cross member anyway.

If you are leaving the stock suspension in the back, I'd still just go from where you stopped when you put in your IFS to 1 inch past the tranny cross member.

Sorry, I'm still with Dad on this one.

J!

PS. Don't admit you were wrong and CERTAINLY don't tell him you heard it from "some girl" on the internet. You'll never live THAT DOWN. Just tell him you want to wait to do it all the way back to make it easier to do the bed. He may snicker, but he'll forget pretty soon. Most parents of problem children have memory problems - tee hee!

 

Sorry to confuse you Julie. I should have known to put the variables in there because I have read posts before saying that you shouldn't box at all if you're staying stock. The front is already boxed in with what TCI threw in with their kit. I had Pete & Jakes (side note here....they were referred to me by a guy on here and they do outstanding work at very reasonable prices!!!) do the front end with engine and tranny mounts. I'll try inserting pics so you can see what was done.







I think I am going to have to cut out the cross member by the tranny mount though. I was wanting to leave it in there for more support, but with the brake setup that I got from TCI, they want you to remove it. Do you think that the cross section that Pete & Jakes added will be enough, or should I find some way to add another?

As for the ride, I never got to ride in it with the stock suspension. It didn't have a front end on it when I got it.

So should I just take out the cross member, and then box a little past where they put the tranny mount?

A little history on it....I had told my dad that I wanted to fix up a 55 or 56. I was in Afghanistan and he told me that he found one. So I sent him a check and he went and got it. I got home and it was a 50. So I waited 6 years and here recently decided to fix her up. I asked if we could do it for around $4000 and he said we definitely could. I'm at $9000 right now and still a long way off. Boy was he wrong on that. So if I were wrong on this (which it looks like I was), it wouldn't have cost me an extra $5000+. But, for the sake of sanity, I'll take your advice and not tell him I was wrong.

 

$4000 in what-1950 dollars? You'll have $15K to $20K EASY doing a nice frame off.

I wonder why TCI wants the old Tranny support cross member out? Maybe master cylinder placement. I'd leave it in if you can or as much as you can, then just box back to the front of that. If not, then there's not much you can do with the tranny cross member being bolted in.

I'm also noticing your new tranny mount is bolted in. And it looks like it is bolted under the frame. It looks fine, but I might be tempted to try and position it on top of the lower frame rail. If you need to pull it out you can always slide it back away from the tranny then tilt it up and out.

It all looks like a great job and plenty strong

J!

 

Maybe he was thinking 1950 dollars. Every time I tell him how much I spent on something he say "Man, it was only $10 back when I was a kid." My goal was just to get the thing running. I don't need a fancy schmancy paint job on it right now. I just want to be able to drive an old truck. The look good stuff will come later when i become rich (and if that don't happen, when i eat ramen noodles long enough to save up for body work and paint).

I haven't been down to look at it to see why they want it cut out. Looking at the kit itself, as long as it is the same size as the stock one, i could probably just drill new holes in the cross member and install it there. Time will tell.

Why would you put it on top of the frame? Just so it has more support for the tranny? That would make sense to me so the tranny isn't held up by 4 bolts. They did all the measuring and mounted the mach stuff, would moving that up to the top throw off their measurements? I wouldn't think that a quarter inch max would mess it up too much, but i've been wrong before (referring to boxing all the way back)?

 

Derek, That looks like a 1st class install from here, I would think that if more was
required, it would have been recommended at the time.Your going to want some flex in the frame to help smooth out the bumps...the stiffer and more rigid the frame..the more the suspension works( and the more frequent suspension component replacement..balljoints,bushings,shocks,springs etc) and usually..the harsher the ride.
The drag race guys want no flex,...none. Everytime a chassis flex;s the chassis reacts differently, which affects their elapsed time, everytime it twists, energy that "could" go directly to the rear wheels as roll inertia , is absorbed. Everytime the lites change in front of them...while as a driver they are doing the exact same thing, their chassis does not,so the e.t is different...how can you win a bracket race like that?
The driving world is another matter, you want it to go and to stop.You want to get in it anytime and it starts,handles well, is comfortable and safe. If you want to make a little noise and smoke the rear tires, depress the accel pedal a little further..LoL!
This old truck hobby is chock full of compromise's and your frame upgrade is a very good one and looks to be well done and professional, if you think you need to add more steel to carry further under the cab ,so be it, it may help some, may look better, but let's not loose sight of " the need justifing the end".
Whatever you do, keep your Dad "involved", that will pay off 10 fold down the road for both of you,that's quality time! Just my $.02, and by the way, thanks for your service!

 

You're welcome for the service cmoritz. "The need" of what I am wanting is a sturdy frame that I'm not going to have to worry about bending. I'm not putting a powerhouse in, but it will be a 302 pushing 330 hp. I look at the frame and think "man, that is some thin metal." But that could be because I am used to up armored trucks that have doors that are a few inches thick. If it will work like it is now, great. It'll be more money and time I can use somewhere else. But I have it stripped all the way down to the frame right now. I want to make sure that everything is done right while it's easy to get to.

 

Hi Tiger,

Yep I think Mertz has just about wrapped it up in a nutshell. Especially the time with Dad......... do the thing with your dad....Some day he won't be around and this time is priceless.

WRT putting the tranny member on top of the channel: That 1/4 inch isn't going to hurt anything. I like to sit mine on top because that transferes some of the torquing and bouncing to the frame and not just to the four bolts - spreads out the streese over the entire end length of the cross member and not just on the bolt holes/bolt heads.

Also, I always have this vision of the bolts coming loose or failing on one side. If it does, it will stay in place in all three dimensions if it's sitting on top. And that's much better than than dragging your output shaft housing and drive shaft on the ground and possibly torque busting something up in the motor mounting system as well. On top about the only thing you will do is make a lot of slapping noise. I may be a little overcautious but with no disadvantage and only advantage, I think it's a good safety valve. Remember, I've broken one of those "Indestructable" motor mounts. Safety valve kept $5000 woth of engine in th etruck and off the pavement or worse, my axel/tie rod).

Echo Mertz: Really nice set up, outstanding workmanship, and I think it's good as is but I would bring the boxing back just the tad more I expressed earlier so the boxing end is not co located with the front cross member (or the rear one either). Safety valves......

Happy Veterans Day!

J!

 

Hi Derek,
I think you will be fine as is, most of your weight is up front so unless you do some re-engineering...your will never get enough traction to hurt anything, you'll just smoke tires forever...LoL! Keep after it, that is a great foundation. As a side note, some have installed tubular k-members to stiffin things up with an incorporated trans mount, Walton Engineering in Ca. , comes to mind...just something to compare and look at if you think you want to go stronger.You could add crossmembers along the way, adding a driveshaft safety hoop for example, then boxing only that portion of the frame where the crossmember mounts. Many a Hotrod/custom frame starts and ends with what you have. Good Luck!...

 

Yes the whole thing got started because I wanted to spend what time with him I could. The doctors gave him 2 years to live 3 years ago. And he's still going strong. He has his bad days, but he has more good ones. I enjoy the time...and learning, even though sometimes I wonder if he knows what he's talking about. But thanks for setting me straight Julie. I'll have to trust him for now on. Haha.

So I will definitely move the tranny mount to the top. I like your reasoning on that. What are safety valves though???

 

Stiffer the better in my opinion. The suspension does the work not the frame. Uni body vehicles are a good example of this. The only real flex they could have is in the door openings, and you probably won't see any paint chipping off them. Frame designers strive for stiffness. Call some aftermarket companies and get their opinions. Always ask the experts. Peter

 

Ok, lets pull thi sone back into perspective. Please re read the quote Mertz posted earlier.

Sometimes on this site all th eguys who know all the race car jargon and stuff seem to get a little scope locked. Mertz is right and I eluded to ride as well. there is no reason in the world to PETRIFY this frame - none, unless you are going to race it.

The advice I was offering was done for completely different and more important reasons, and that is drive train torquing. The big engine withthe added weight and horsepower is going to introduce twisting and torquing moments on the fron of the frame that are going to translate to different parts of it to be relieved. If you don't box at all, chances are you will eventually twist the front frame. And Mertz is right about how professional and good a job has been done. Butm there is a certain amount of strength you want to add over a given distance to distribute that torque. And normally a full box to the firewall is a good generic measure. One reason I mentioned not going to the transmission mount or a foot past is to avoid the colocation of multi directional torquing points. In other words, the end of your box is your first point that the frame is a little weaker than the boxed part. It goes from stiff to flexible right at that point. If you have that where the transmission mount is affixed, it's going to be a double whammy to that one spot. So spread them out, if you are worried about strength. You have nothing to worry about with the set up as is though.

Safety valves are common sense measures that provide added safety in the event of a failure or a redundant back up for something. That mount is a perfect example: why not move it on top. It's completely irrelevent from a functional standpoint, but makes complete sense in the event of a bolt failure. So why not do the smarter thing. The drive shaft loop that someone mentioned is another.

J!