# Frame Question (Boxing frame+)



## Fred007 (Jul 23, 2008)

For my '65 project, I did the following to the frame.
1. Had frame "bent" back to reference by a local shop with a laser table
2. Welded plates between frame flanges (boxed?)
3. Sandblasted
4. Primed
5. 2 coats of black ceramic chassis paint

I am getting ready to mount the engine/tranny and have one last opportunity to do anything else to the frame I might need to. Here are some pics on what I think "boxing" the frame means (based on reading numerous posts). Any comments are welcome and would be appreciated. (frame is a little dusty right now)
















Picture of front portion of frame, opening is left for transmission cross member mount. Since I left this open, my plans for the cross member changed a bit and I think I will be able to close up a bit more of this area.


----------



## 66tempestGT (Nov 28, 2009)

nice looking. have you actually put the crossmember in it. my guess is it wont go.


----------



## 1966 GTO (Nov 18, 2010)

How much horsepower do you plan to have? You will have to make custom brake and fuel lines now.


----------



## Fred007 (Jul 23, 2008)

No cross member yet, will be doing that next. It turns out I am going to use a smaller tubular cross member and hope to fit that in the next week or so. I can then box in the rest of the areas currently open. I left open the portion I thought I would need based on the original cross member and the holes in the frame. However, I am putting in a 4L65 so have no real reference for where the transmission mount will end up. But, got the engine last week and have the motor and transmission mounts so will hopefully be able to fit that very soon.

The engine I have dynoed at 610. And, yes I am planning on all new brake and fuel lines. The lines you see in this picture are the air and electric lines for the front suspension.

Besides welding the frame closed like shown, is there anything else I should be doing to the frame? Also, I did not box the frame in the rear (below trunk), figured it was not necessary but would like to double check that thinking.

Thanks for the help/pointers. Great to have the feedback!


----------



## BearGFR (Aug 25, 2008)

Fred007 said:


> However, I am putting in a 4L65 so have no real reference for where the transmission mount will end up. But, got the engine last week and have the motor and transmission mounts so will hopefully be able to fit that very soon.
> 
> The engine I have dynoed at 610. And, yes I am planning on all new brake and fuel lines. The lines you see in this picture are the air and electric lines for the front suspension.
> 
> Besides welding the frame closed like shown, is there anything else I should be doing to the frame?


Carrying that much power, be sure you also install a set of control arm mount braces/stiffeners on the rear. These connect the front mounts of the upper and lower control arms together to make those points stronger and stiffer.

Hopefully you're also installing adjustable upper rear control arms at least, so you'll be able to properly set the pinion angle - which is sure to need adjusting with the new trans and trans crossmember.

Bear


----------



## Fred007 (Jul 23, 2008)

I was primarily focused on the frame for this post, but I also have a Street Challenge suspension and Currie 9+ rear installed already.
The rear looks like this currently.








And the front like this.









Have not done anything on the drive shaft yet, planning on ordering one once I get everything set. Will know the pinion angle at that point. I have a fair amount of experience with this (both good and bad) with my Jeep. Is there a target angle for driveshaft? This will be a bit interesting as I will have basically two angles, one at full compression and one at full extension.


----------



## BearGFR (Aug 25, 2008)

Fred007 said:


> I have a fair amount of experience with this (both good and bad) with my Jeep. Is there a target angle for driveshaft? This will be a bit interesting as I will have basically two angles, one at full compression and one at full extension.


Sorry about the Jeep (I have one my son drives that I go a few rounds with from time to time).

Nice looking setup!

The important thing about what is somewhat deceptively called "pinion angle" is making sure that the pinion centerline runs exactly parallel to the crank/transmission centerline, otherwise you're very likely to get vibrations in the drive-line. Depending on the types of bushings being used, how much power you're carrying, and how much general "slack" there might be in the rear suspension, under heavy load as the pinion tries to climb the ring gear it will force the housing to rotate a little. For best results drag racing you want to make sure the pinion centerline is parallel to the crank while this load is applied which usually means setting the pinion "a degree or 2 or 3" "down" from the crank centerline. For street driving, best results are usually acheived by setting the pinion and crank/tranny to be parallel with the car at rest, sitting at normal ride height with the weight on the suspension.

I put these braces on my car.

And here's how they look installed.









I've put a Moser 9" in mine.

Bear

Bear


----------



## 66tempestGT (Nov 28, 2009)

what i am getting at about the x-member is that the original is much wider than the narrowest part of the frame. so, you have to put it at a pretty severe angle to get it to fit between the rails, then slide it into place perpendicular to the rails. if you just try and lay it in there you will see what i mean. boxed frames use a narrower x-member and have brackets welded to the inside of the boxed portion of the frame. all that is no big deal especially if you are making your own x-member anyway. just looks like maybe you havent run into this yet.


----------



## Fred007 (Jul 23, 2008)

Got it, didn't catch your meaning at first. Will check that out tonight. As I mentioned, I was planning on using the original x-member, but ended up getting a transmission mount and cross member from Muscle Rods. Their kit has a smaller tubular x-member. Will have to see if I've left enough room to slide it in. (knowing my luck...)


----------



## Eric Animal (Oct 28, 2007)

Fred, Lookin' good! You can weld "shelves" onto the boxed portion of the chassis and mount a convertible x-member to them .......just another option. Eric:cheers


----------



## Fred007 (Jul 23, 2008)

Got it roughed out today, had to remove my welds on the forward portion of the frame. Here is a shot of the cross member just sitting there giving me an idea of where it had to go. You can see the pieces I welded in that had to go.








Here is what it looked like after I removed those sections.








So, my question now is... Once I get everything mounted, I can box that section of the frame in again, but would have to remove the welds if I ever wanted to remove/adjust the cross member.

My current thinking is that I will weld back in those sections, once I get everything mounted and triple checked. Figure that I should not have to move the cross member any time soon and want the extra strength.

Thoughts?


----------



## 66tempestGT (Nov 28, 2009)

if it was mine i would just run it like it is. what you have is only semi boxed anyway. theres no way i would weld it up so that it has to be cut out later. the way you have it boxed it still has weak spots anyway.


----------



## BearGFR (Aug 25, 2008)

Fred007 said:


> So, my question now is... Once I get everything mounted, I can box that section of the frame in again, but would have to remove the welds if I ever wanted to remove/adjust the cross member.
> Thoughts?


Well, what if "down the road" you need to pull the transmission after the car has been assembled? Do you really want to sign up for having to cut welds on an assembled car just to remove the trans? It doesn't look like you're talking about "all that much" boxing in that spot to begin with, so unless your motor's going to be making enough torque to tilt the planet on its axis it's doubtful that the difference in leaving that section open would ever show up on a time slip. If you're solid bolting the cross member to the frame rails as opposed to the original factory rubber mounts, that alone will significantly improve rigidity in that area anyway - even more so if you added some metal to the crossmember so that it bolted to both the lower and upper part of the frame channel and ties them together.

On my car, I nuked the rubber mounts and welded extra metal to the factory crossmember to widen it, then hard bolted it to the frame. Of course that lowered the tail of the tranny "just a tad" which would have upset the driveshaft operating angle. However, I also added a driveshaft safety loop that mounts between the trans and the mount, so that just about put everything back at the original height.










Bear


----------



## 66tempestGT (Nov 28, 2009)

you will find pics of a boxed frame and how the x member mounts here El Camino Frame-Off Restoration! - Chevelle Tech


----------



## 66tempestGT (Nov 28, 2009)

i think i would bend that loop down about 1/4" to make sure it never touches the body.


----------



## BearGFR (Aug 25, 2008)

66tempestGT said:


> i think i would bend that loop down about 1/4" to make sure it never touches the body.


I thought about that. The other commonly available loops mount to the body directly in that same location instead of to the trans mount. This one as it sits now is actually wedged into the tunnel there very tightly. I'd be very surprised if it ever rattles. I'm going to start out like it is and see how it goes. That's 1/4" steel so bending it would take a torch and significant effort. The camera angle in that photo makes the loop look "high", but in actuality with the drive shaft intalled it's pretty much centered in the loop. If I were to bend it down, the top of the loop would be pretty close to the top of the driveshaft.

Bear


----------



## Fred007 (Jul 23, 2008)

I'm a little confused on exactly what the term "boxing" the frame means. I thought it was basically welding the inner portion of the frame together. I assumed a couple of gaps would not be a big deal and suspect this was a mistake. To truly give some frame support here, do I need to have the complete (i.e. no gaps) inner portion of the frame welded together? If so, given my current setup with the transmission cross member I have, what about attaching the cross member to the underside of the frame? The difference in height would be minimal and I could rig up a way to have a couple of bolts that hold the cross member to the bottom of the frame.

I also don't want to over engineer something that I really don't need. My engine makes 573 ft/lbs max so if I really don't need this I am good with working on other things.

I read through the El Camino thread referenced but could not find any details on how they worked the frame. (think they might have cut some pages from that post, I could only see 9 pages and someone mentioned 30)

Thanks for all the input, really appreciate the help!


----------



## 66tempestGT (Nov 28, 2009)

BearGFR said:


> I thought about that. The other commonly available loops mount to the body directly in that same location instead of to the trans mount. This one as it sits now is actually wedged into the tunnel there very tightly. I'd be very surprised if it ever rattles. I'm going to start out like it is and see how it goes. That's 1/4" steel so bending it would take a torch and significant effort. The camera angle in that photo makes the loop look "high", but in actuality with the drive shaft intalled it's pretty much centered in the loop. If I were to bend it down, the top of the loop would be pretty close to the top of the driveshaft.
> 
> Bear


if you still have the body mounted with rubber bushings you should make sure that you have clearance. if everything else is metal to metal it wont make any difference. the other loop you are talking about does not attach the body to the transmission. its not rattling that will be a problem its vibration. "transferring harmonics"


----------



## 66tempestGT (Nov 28, 2009)

the frame in that thread is not modified, it is a factory frame. it is twice the size of yours and solid from end to end. IMO unless you plan to compete in some sort of road race/ autocross the setup you have now will serve you well. im not saying yours isnt stronger than factory but its not much stronger. the whole point is to make it more rigid and yours still has lots of places to flex. i have run these cars (a bodies) for long time and more than 1000 drag strip passes and have never had a boxed frame. even my elcamino has a passenger car frame under it. 573 is a lot of torque but are you going to be beating on the car or being nice to it. the thing about the x member with the boxed frame is to use a narrower x member and attatch it to some brackets on the inside of the "box". i guess bolting it to the bottom would work.


----------



## BearGFR (Aug 25, 2008)

66tempestGT said:


> if you still have the body mounted with rubber bushings you should make sure that you have clearance. if everything else is metal to metal it wont make any difference. the other loop you are talking about does not attach the body to the transmission. its not rattling that will be a problem its vibration. "transferring harmonics"


Hmmm.... that's a thought. I am still using rubber body mounts, new ones mind you, but still rubber. I wonder how it would work out if I put some strips of rubber between the loop and the body to allow some give. 

Or, maybe I'll just get the torch out and redo it. That's been an irritation all along on this project: more often than not when an aftermarket vendor uses the phrase "bolt on" in reference to a product, it's a lie. It usually means, "cut, modify, re-engineer, cuss a lot, throw things, THEN bolt on".

Bear


----------



## Eric Animal (Oct 28, 2007)

get a cross member that fits inside the perimiter of the rail ....mount a "shelf on both rails......put the ends of the x-member in rubber isolators...mount to shelves......LIKE GM DID on the convertables.....E


----------

