Subframe connectors

[MRGTX]

Cutting them out of square tubing is pretty easy. The only tools I used to do it was a grinder, a chop saw and my MIG welder. And you don't need the chop saw, a grinder with a cut off wheel will suffice. The level of precision isn't bad either, I mean, if everything ends up within a 1/4" you're fine.
....

Again, you make it sound easy!

Some of us are coming from different worlds...I do have a grinder but otherwise, I have just basic tools and an only "slightly better than high school shop class" level of mechanical inclination. A MIG welder is not even in my future. Most of the vaguely unusual tools that I have in my garage were bought only out of necessity in doing my engine swap. I'm actually in the process of getting rid of my engine hoist right now.

So the braces that you cut appear to be similar to the designs of the Mopar (etc) bolt-in connectors. Do you agree that they don't help with torsional stiffness?

Are there other kinds of bracing that could supplement bolt-in style bars?

 

[MRGTX]

Here is a few pictures of a out of the box subframe connector install.. the connectors run inside the the rear stub back to the spring boxes. At the front they line up with the edge of the torsion bar socket and are welded to the side to give the socket extra support.
...

First, is that a 2010 GT500 in the background? I recognize that wheel!

Second, which out of the box connector is this in your pictures? Are you happy with them?

 

[grimreaper]

Ihave a set of US Cartools connectors in my 64 Barracuda and I buit a set from rectangular tubing for my buddies 64 Barracuda. The both effectively stiffened the cars. I think if you rode in both cars blindfolded you could not tell the difference. The US Cartools have the advantage in that once in place they look like something the factory might have done.

 

[75slant6]

Again, you make it sound easy!

Some of us are coming from different worlds...I do have a grinder but otherwise, I have just basic tools and an only "slightly better than high school shop class" level of mechanical inclination. A MIG welder is not even in my future. Most of the vaguely unusual tools that I have in my garage were bought only out of necessity in doing my engine swap. I'm actually in the process of getting rid of my engine hoist right now.

So the braces that you cut appear to be similar to the designs of the Mopar (etc) bolt-in connectors. Do you agree that they don't help with torsional stiffness?

Are there other kinds of bracing that could supplement bolt-in style bars?

if you don't have a welder, you could buy the tubing and plate from a fab shop the cut everything out and get it mocked up in the car then take the pieces back to the fab shop and have them weld the tubing to the plates then you could drill holes and bolt them in until you can get to a shop where they can weld them in and take the bolts back out.

 

[67autocross]

First, is that a 2010 GT500 in the background? I recognize that wheel!

Second, which out of the box connector is this in your pictures? Are you happy with them?

The wheels are off a GT 500 but are on my girl friends 2012 5.0 Mustang

The subframe connectors are just square tubing that was purchased at a local metal supply shop, I posted the pictures just as an alternative to running then over the rear subframe which is the normal installation method.

 

[MRGTX]

if you don't have a welder, you could buy the tubing and plate from a fab shop the cut everything out and get it mocked up in the car then take the pieces back to the fab shop and have them weld the tubing to the plates then you could drill holes and bolt them in until you can get to a shop where they can weld them in and take the bolts back out.

You're absolutely right...it's hard to imagine the materials, labor and time (my own) being much of a bargain over buying and modding US Car Tool pieces though.

 

[MRGTX]

The wheels are off a GT 500 but are on my girl friends 2012 5.0 Mustang

The subframe connectors are just square tubing that was purchased at a local metal supply shop, I posted the pictures just as an alternative to running then over the rear subframe which is the normal installation method.

Thanks...

BTW, your friend has good taste with the Mustang there! I have a 2011 GT in my garage too. I wanted those GT500 forged wheels in the worst way but ended up with RTR wheels. I like that car almost as much as the Dart!

 

[75slant6]

Thanks...

BTW, your friend has good taste with the Mustang there! I have a 2011 GT in my garage too. I wanted those GT500 forged wheels in the worst way but ended up with RTR wheels. I like that car almost as much as the Dart!

View attachment 1715051192

Blasphemy!!!

 

[67autocross]

Thanks...

BTW, your friend has good taste with the Mustang there! I have a 2011 GT in my garage too. I wanted those GT500 forged wheels in the worst way but ended up with RTR wheels. I like that car almost as much as the Dart!

View attachment 1715051192

I got the wheels and tires off my friend who sent his GT500 to Shelby for super snake treatment.
I originally bought the Stang for me but she started driving it about 3 years ago after her car was wrecked and never give it back .... they are a really amazing performing car for the money.

 

[72bluNblu]

Again, you make it sound easy!

Some of us are coming from different worlds...I do have a grinder but otherwise, I have just basic tools and an only "slightly better than high school shop class" level of mechanical inclination. A MIG welder is not even in my future. Most of the vaguely unusual tools that I have in my garage were bought only out of necessity in doing my engine swap. I'm actually in the process of getting rid of my engine hoist right now.

So the braces that you cut appear to be similar to the designs of the Mopar (etc) bolt-in connectors. Do you agree that they don't help with torsional stiffness?

Are there other kinds of bracing that could supplement bolt-in style bars?

Without turning this into yet another "which subframe connector is better" thread I'll say that I obviously disagree with the idea that tubular style subframe connectors don't help with torsional stiffness. Obviously there are some differences, and there are a lot of different ways you can construct the tubular connectors. The MP bolt in connectors are probably the flimsiest, even when welded in. I'm not even sure they're 1.5x1.5". Mine are 1.5"x3", which means no floor mods. I've seen tubular connectors all the way up to 3x3" on A-bodies. Anything 2x3" or up has to go through at least part of the floor. The 1.5"x3" connectors I use stay in contact with the floor all the way across the rear footwells, so, you could seam weld them to the floor if you wanted. Mine aren't right now. Thickness of the tubes and the size of the landing plates/overlap on the frame make a difference too.

I can tell you anecdotally that the connectors I installed made a BIG difference in the torsional stiffness of my Duster. Felt completely different on the road, even with 225/60/15's. And I can give you a pretty impressive list of road handling cars that use tubular connectors- the Hotchkis Challenger, the Hotchkis Taxi ('70 Satellite), the Green Brick (autorust), the Red Brick (partially floor welded, custom? @lilcuda ), @autoxcuda 's barracuda (hotchkis), @tomswheels '67 Valiant (hotchkis), and possibly Peter Bergman @GMachineDartGT (not positive, he just said he had an "old" set on his car). I mean, if they didn't work, why do the possibly the most successful Mopar handling machines use them?

Like I said, I think the weld to floor connectors have their place. Which is why I just installed the US Cartool connectors on my EL5 GT. But comparing the resulting chassis stiffness without actual testing is a non-starter. I don't think there's enough of a difference that you'll notice on the road personally. Adding bracing to that section of the chassis can only do so much, regardless of how it's done. It's only one piece of a large, complex, 3 dimensional puzzle. Past a certain point increasing the stiffness of the subframe connector won't change the whole picture.

 

[oi81b4uu812b4]

I've actually tested chassis torsional stiffness on a chassis table at work. You can gain some stiffness with bolt in connectors. The best ones will have some sort of a "mid-section" cross brace to tie them back into the floor. This could be as simple as a perpendicular bar that picks up the front seat mounts.

I have seen a greater increase in torsional stiffness with stiffener's that weld to the contour of the floor pan. Double that of bolt in connectors. This depends on the car and thickness of the metal in the floor pan.

With a load applied to a corner of a uni-body car say we see 2" of flex on the "kitty-corner". Installing sub frame connectors can usually knock that down quite a bit. Well below 1" some times.

It's important to know that on uni-body cars your floor pan is a major frame component. Dimples and layers of pinch welds like around the wheel tubs are all there to create stiffness. If your stuff is clapped out, rusty or poorly repaired. Installing sub frame connectors are just a band-aid then and you probably aren't gaining anything over the original structure.

The issue with weld-in ones that follow the pan contour is getting 40+ year old undercoating off the floor pan to weld them up. And applying a flame to it doesn't always soften it.

 

[jbc426]

You guys do some nice work. I'll add a few things that popped in my head when I read these posts.

A good muffler shop guy could easily weld in your connectors once fitted and temporarily bolted or screwed into place, and there are a lot of those types of shops around.

I stated I stich welded my connectors in place, but they are still fully welded along all contact points. As 72bluNblu said, this makes them much stronger.

I also installed the entire chassis stiffening kit from US Cartool in my car. The shock towers are also fully welded to the inner fenders. This requires repainting the engine compartment, but it is very much worth it, as this dramatically reduces cowl shake especially on washboard style road defects.

Be very careful about removing the undercoating. It is actually some very toxic stuff once loose. I had a friend use the heat and scrape method on a hot sweaty day and he ended up with a horrible rash that lasted for several weeks all over his arms and shoulders.

 

[lilcuda]

I can tell you anecdotally that the connectors I installed made a BIG difference in the torsional stiffness of my Duster. Felt completely different on the road, even with 225/60/15's. And I can give you a pretty impressive list of road handling cars that use tubular connectors- the Hotchkis Challenger, the Hotchkis Taxi ('70 Satellite), the Green Brick (autorust), the Red Brick (partially floor welded, custom? @lilcuda ), @autoxcuda 's barracuda (hotchkis), @tomswheels '67 Valiant (hotchkis), and possibly Peter Bergman @GMachineDartGT (not positive, he just said he had an "old" set on his car). I mean, if they didn't work, why do the possibly the most successful Mopar handling machines use them?

FYI - I sold the Red Brick last fall and now the guy I sold it to has recently sold it to another owner here on FABO. I never actually got under the car to see what the subframe connectors were like. I pretty much just drove it and did maintenance and fixed an oil leak.

I'm sure you'll be hearing more about the car once the new owner gets his hands on it.

 

[72bluNblu]

I've actually tested chassis torsional stiffness on a chassis table at work. You can gain some stiffness with bolt in connectors. The best ones will have some sort of a "mid-section" cross brace to tie them back into the floor. This could be as simple as a perpendicular bar that picks up the front seat mounts.

I have seen a greater increase in torsional stiffness with stiffener's that weld to the contour of the floor pan. Double that of bolt in connectors. This depends on the car and thickness of the metal in the floor pan.

With a load applied to a corner of a uni-body car say we see 2" of flex on the "kitty-corner". Installing sub frame connectors can usually knock that down quite a bit. Well below 1" some times.

It's important to know that on uni-body cars your floor pan is a major frame component. Dimples and layers of pinch welds like around the wheel tubs are all there to create stiffness. If your stuff is clapped out, rusty or poorly repaired. Installing sub frame connectors are just a band-aid then and you probably aren't gaining anything over the original structure.

The issue with weld-in ones that follow the pan contour is getting 40+ year old undercoating off the floor pan to weld them up. And applying a flame to it doesn't always soften it.

I think it's pretty obvious any kind of weld in connector will outperform a bolt in connector.

When you did your testing how did you constrain the chassis to the table? Did you measure the size of the load you were applying? Did you repeat each loading situation multiple times? Were the chassis' tested the same wheelbase? How many different chassis' did you test? Do you have a table or spreadsheet for the data you obtained showing the location of the applied load, the size of the applied load, and the resulting deflections?

Again, I think everyone is aware that the floor pan is a structural member in the chassis of these cars. But that doesn't necessarily mean that the weld to floor connectors are the only way to stiffen the chassis significantly, and it doesn't mean that strengthening the floor pan doesn't have limits for stiffening the entire chassis.

FYI - I sold the Red Brick last fall and now the guy I sold it to has recently sold it to another owner here on FABO. I never actually got under the car to see what the subframe connectors were like. I pretty much just drove it and did maintenance and fixed an oil leak.

I'm sure you'll be hearing more about the car once the new owner gets his hands on it.

Sorry, I knew you had sold the car but you were the last owner that I remembered that was a member here that I could easily tag. Thanks for chiming in! Tomswheels sold his car last year too, the new owner is a member here as well.

 

[moparmat2000]

Made my own as well. 2x3 box. 1/8". Heres pix prior to welding in. I rerouted my parking brake cable to run inboard alongside the subframe connector instead of passing over or thru it. The cable will clear the zee bar for stick shift too. I drilled new holes in the crossmember with a rotary cutter (rotabroach) for it to pass thru, but it looks stock, and routes straight and even with the subframe connector right to the rear floorpan fairlead. Everything is being mocked up. Green primer is epoxy etch primer.

 

[lilcuda]

Sorry, I knew you had sold the car but you were the last owner that I remembered that was a member here that I could easily tag. Thanks for chiming in! Tomswheels sold his car last year too, the new owner is a member here as well.

No need to apologize, just stating the facts. Yeah, I know Joe, the guy with Tomswheels car. Haven't heard from him in a while, though.

 

[ratvon]

what about toque boxes? should the be added with the frame connectors? or did I miss that somewhere in this thread?

 

[moparmat2000]

He wasnt asking about torque boxes, but they perform 2 different functions compared to the subframe connectors.

 

[ratvon]

He wasnt asking about torque boxes, but they perform 2 different functions compared to the subframe connectors.

Ok enlighten me

 

[moparmat2000]

Rear torque boxes are for preventing front leaf spring mounts from pushing forward under hard acceleration. Thats why big block and 4 speed cars have them.

Forward torque boxes tie front framerails to the rockers to lessen or prevent front framerail flex in the cowl area.

Both front and rear torque boxes are to stiffen the rockers at both ends as those are essentially the cars original framerails.

 

[moparmat2000]

Blasphemy!!!

I disagree. I love my 2007 mustang GT. I wish the Coyote 5.0 was available that year.

 

[belmateo]

Rear torque boxes are for preventing front leaf spring mounts from pushing forward under hard acceleration. Thats why big block and 4 speed cars have them.

Forward torque boxes tie front framerails to the rockers to lessen or prevent front framerail flex in the cowl area.

Both front and rear torque boxes are to stiffen the rockers at both ends as those are essentially the cars original framerails.

You will also find torque boxes on all convertible cars

 

[72bluNblu]

The torque boxes do a lot to increase torsional stiffness too, they basically box the corners of the frame rails and the rockers. By strengthening the corners it improves the stiffness of the whole chassis, which is why 'verts and the higher horsepower cars had them. Just like gusseting a corner, same idea. Helps to make up for the lack of a roof on the 'verts and deal with the extra twist on the higher horsepower cars. They were the factory's answer to stiffening the chassis.

And you can add them with subframe connectors, I have them on my Duster and my Dart now and both have subframe connectors. The rear boxes may need a little modification where they overlap your frame connectors, depending on how you did them. If the subframe connectors are flush close to it (like the .120" overlap on mine) with the rear rails on the bottom then there's no changes, if the subframe connectors hang down any from the rear rails you'll have to notch the rear torque boxes.

I already posted this one, but you can see the torque box overlapping the frame connector

Better view from my Dart. US Cartool boxes and connectors. Also improves the strength of the subframe connector to rear frame rail joint.

 

[RogerRamRod]

Seems like every place I went to buy metal for projects wanted a fortune, and all the scrap places are no longer dealing pieces to the public. They just want to deal with large recycling accounts. It seemed cheaper to just order a ready made product......unfortunately.

 

[autoxcuda]

FYI - I sold the Red Brick last fall and now the guy I sold it to has recently sold it to another owner here on FABO. I never actually got under the car to see what the subframe connectors were like. I pretty much just drove it and did maintenance and fixed an oil leak.

I'm sure you'll be hearing more about the car once the new owner gets his hands on it.

The red brick has a full roll cage in it.

I know Bob Reed with the red 68 Baracuda that was in Hot Rod with just frame connectors (pictured above), drove the red brick at willow springs years ago.

He said the difference from just frame connectors to the roll cage in the red brick was huge with a stiff sprung high effort handling/track type build. The roll cage really tied everything together.

Here's Bob's old barracuda: 1968 Plymouth Barracuda S340 - Featured Vehicles - Car Craft Magazine