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Subframe connector options and opinions #1161168
01/20/12 02:44 AM
01/20/12 02:44 AM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline OP
Striving for excellence
Kern Dog  Offline OP
Striving for excellence

Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Being the frugal guy that I have been for years, the last 2 sets of subframe connectors that I have installed have been homemade using 3x3 .120 stock cut to fit. I welded both sets in, both were A body cars. Now I am ready to do this in the Charger. When I painted the car in 2003, I sprayed the underside to match the topside. This means that when I weld whatever connectors into place, My welds will need to be cleaned up and everything will get painted body color.
I have seen all sorts of different types of connectors in Mopars. The 2x3 bolt in type seem to be the least effective but offer the most ground clearance. In theory, I like the look of the XV contour fit units, but they appear to be only 3 sided. How effective can that be? I'll guess that they intend the edges to be welded to the floorpans? I'd bet that their units are thicker than the guage of the floorpans, so what would you recomend as far as welding two sections of metal of different thicknesses?
I spent $44 for 3x3 plus cutting & grinding discs to make the A body connectors. They are welded on 3 sides at the T-bar crossmember and 3 sides at the rear frame rail. My thinking is that being boxed rather that 3 sided, these should be stronger.
I'm interested in seeing pictures and reading about other members connectors. It may help me decide which way to go. Thanks.

7027684-DSCN1035.JPG (389 downloads)
Re: Subframe connector options and opinions [Re: Kern Dog] #1161169
01/20/12 04:40 AM
01/20/12 04:40 AM
Joined: Jan 2011
Posts: 4,785
Utah and Alaska
astjp2 Offline
master
astjp2  Offline
master

Joined: Jan 2011
Posts: 4,785
Utah and Alaska
The floor pan boxes in the weld in XV style, they remain rigid if they cant flex. Not a big deal. Tim

Re: Subframe connector options and opinions [Re: Kern Dog] #1161170
01/20/12 11:29 AM
01/20/12 11:29 AM
Joined: Dec 2003
Posts: 22,732
Bitopia
J
jcc Offline
If you can't dazzle em with diamonds..
jcc  Offline
If you can't dazzle em with diamonds..
J

Joined: Dec 2003
Posts: 22,732
Bitopia
The first question should be IMO, could someone describe and BACK UP at least, with sound reasoning, what actual forces sub frame connectors resist? I am not questioning many many positive reports of thier improvements in ride etc. So are they resisting compression as the rear leafs push forward upon acceleration, are they resisting twist individually, if just under tension we can just use a steel cable, are they preventing a bending moment as front of leaf pushes up upon acceleration with a bending moment provided by the front mass of the car, ie engine, etc, are they just straightening out the force path thru 4 right? angle turns from the front hanger to the doorsills back to the TB crossmember, etc?.

If we knew what they are resisting, it would be a lot easier to design a solution. I suspect they are doing all the above, but some more then others, but which one? Say if twist was the main force, a large dia tube would be first choice, if bending moment, a tall I beam, yaw? bending, an I beam on its side, etc. My understanding is it needs to be the smallest and lightest shape/size that gets the job done. Anyone can oversize a solution, only a smart designer knows just how much is needed, if you way oversize, you look.....?

Years back member AAR? (patent attorney) had a lengthly thread on Subframe connectors, and main conclusion was the larger the crossection of the subframe, the stiffer, wall thickness provides a lot less stiffness then crossection increase gives. The installation advantages are numerous with the contour cut-out connectors, and installation ease IMO is thier only advantage. Performance wise, compared to a full tube they leave a lot on the table.


Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
Re: Subframe connector options and opinions [Re: jcc] #1161171
01/20/12 11:36 AM
01/20/12 11:36 AM
Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
dangina Offline
pro stock
dangina  Offline
pro stock

Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
Brads70 from protouring mopar offered this idea from his ride which I'll be doing myself - its 1x2" 0.90 tubing with tubes added for strength:


Last edited by dangina; 01/20/12 11:37 AM.
Re: Subframe connector options and opinions [Re: Kern Dog] #1161172
01/20/12 02:51 PM
01/20/12 02:51 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline
EL Master
domingo  Offline
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
way i do em

7028233-023.JPG (516 downloads)
Re: Subframe connector options and opinions [Re: domingo] #1161173
01/20/12 02:53 PM
01/20/12 02:53 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline
EL Master
domingo  Offline
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
2" x 2" sqare tube 3mm tick wall.

i dont go rectangular because it prtrudes too much into the pass compartment, rectangular is for a race car only IMO.

On an e body I will only cut the rear floor pans to the point that the portion that prtrudes into the pass compartment can be hidden with padding on the sides and then carpet on.

7028238-001.JPG (403 downloads)
Re: Subframe connector options and opinions [Re: domingo] #1161174
01/20/12 02:55 PM
01/20/12 02:55 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline
EL Master
domingo  Offline
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
I go thru the trans cross memeber and weld to the front frame rails...much better than what anybody else offers you out there.

7028239-026.JPG (477 downloads)
Re: Subframe connector options and opinions [Re: domingo] #1161175
01/20/12 02:56 PM
01/20/12 02:56 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline
EL Master
domingo  Offline
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
I also use torque boxes on all 4 corners. You can get them thrugh the link in my signature.

7028243-028.JPG (395 downloads)
Re: Subframe connector options and opinions [Re: domingo] #1161176
01/20/12 02:59 PM
01/20/12 02:59 PM
Joined: Jan 2007
Posts: 780
Woodinville, WA
Viol8r Offline
super stock
Viol8r  Offline
super stock

Joined: Jan 2007
Posts: 780
Woodinville, WA
Save up and buy the Hotchkis connectors. Takes about 2 hours to install and you don't to hassle with modifying the floor, interior or even your e-brake cable.


1968 Pro-Touring Dodge Charger
*2011 Optima Ultimate Street Car Challenge Invitee
http://www.popularhotrodding.com/features/1203phr_1968_dodge_charger/index.html
Re: Subframe connector options and opinions [Re: domingo] #1161177
01/20/12 10:07 PM
01/20/12 10:07 PM
Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
dangina Offline
pro stock
dangina  Offline
pro stock

Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
Quote:

I go thru the trans cross memeber and weld to the front frame rails...much better than what anybody else offers you out there.




looks great is it bad to cut through you tranny crossmember? would it be better to run the subframe brace to the transmission crossmember on one side, and then to the frame rail on the other side?

Re: Subframe connector options and opinions [Re: dangina] #1161178
01/20/12 10:17 PM
01/20/12 10:17 PM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline OP
Striving for excellence
Kern Dog  Offline OP
Striving for excellence

Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Quote:

Quote:

I go thru the trans cross memeber and weld to the front frame rails...much better than what anybody else offers you out there.




looks great is it bad to cut through you tranny crossmember? would it be better to run the subframe brace to the transmission crossmember on one side, and then to the frame rail on the other side?




I was thinking the same thing. Maybe if the car is a bare shell, cutting through the T bar crossmember may not pose a problem. I like the way it looks though.

Re: Subframe connector options and opinions [Re: Kern Dog] #1161179
01/20/12 10:32 PM
01/20/12 10:32 PM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline OP
Striving for excellence
Kern Dog  Offline OP
Striving for excellence

Joined: Feb 2010
Posts: 18,493
Granite Bay CA
I was also interested in seeing photos of factory or custom torque boxes installed in the car. I understand that they were factory instelled on Hemi and convertible cars, but until now I never paid much attention to them.

Re: Subframe connector options and opinions [Re: dangina] #1161180
01/21/12 12:09 AM
01/21/12 12:09 AM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline
EL Master
domingo  Offline
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
Quote:

Quote:

I go thru the trans cross memeber and weld to the front frame rails...much better than what anybody else offers you out there.




looks great is it bad to cut through you tranny crossmember? would it be better to run the subframe brace to the transmission crossmember on one side, and then to the frame rail on the other side?




Its MIG welded all around, how could it possibly be weaker??? You can do it either way really, it doesnt matter. as long as you cut and then weld everything, its as strong or stronger than before because now the crossmember has a bigger area (the connector) to spread the forces the torsion bar inflicts on it. Either way you see it is stronger all the way.

Re: Subframe connector options and opinions [Re: domingo] #1161181
01/21/12 12:22 AM
01/21/12 12:22 AM
Joined: Jun 2008
Posts: 186
Middleton, ID
C
curleysracecars Offline
member
curleysracecars  Offline
member
C

Joined: Jun 2008
Posts: 186
Middleton, ID
No worries welding two different thicknesses of metal...they wont be much different anyways. The 3 sided units are probably comparable to a 4 sided tube, but you will pay for them obviously. I REALLY like the idea of going through the Tbar crossmember and tieing them back into the frame rails. I have been thinking about building some as a production product...maybe I can make an option that goes through the crossmember.
By the way, where in Granite Bay are you? Small town...we cant be too far away. LOL.


Kyle Curley
Re: Subframe connector options and opinions [Re: curleysracecars] #1161182
01/21/12 01:52 AM
01/21/12 01:52 AM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline OP
Striving for excellence
Kern Dog  Offline OP
Striving for excellence

Joined: Feb 2010
Posts: 18,493
Granite Bay CA
I'm near Folsom Lake, not too far from the dam.
PM me if you want. I'm a member of the Capital City Mopars car club. We always welcome visitors as well as new members!

Re: Subframe connector options and opinions [Re: Kern Dog] #1161183
01/21/12 04:03 AM
01/21/12 04:03 AM
Joined: Jan 2003
Posts: 1,376
NORTHERN CA
HUSTLESTUFF Offline
pro stock
HUSTLESTUFF  Offline
pro stock

Joined: Jan 2003
Posts: 1,376
NORTHERN CA
I like the hotchkis style as it kinda does away with the need for torque boxes. It in reality, transfers the "load" from the rear end to the front of the car. It also ends up at the front frame rail vs off to the side. I just made a set for my 74 Petty Clone. I used 1 1/2 x 1 and welded two together so I have 1 1.2 x 2. Probably $35 in materials. Franky, Come on up to Orland if you want to build a set. Mike


"Were in it to win it. Anything less will end up being..... A whole lot of fun doing!!" UNLAWFL
RIP UN
Re: Subframe connector options and opinions [Re: HUSTLESTUFF] #1161184
01/21/12 04:22 AM
01/21/12 04:22 AM
Joined: Jan 2003
Posts: 42,714
Spokane Washington
ScottSmith_Harms Offline
Mr Wizzard
ScottSmith_Harms  Offline
Mr Wizzard

Joined: Jan 2003
Posts: 42,714
Spokane Washington
Orland! I went to high school in Willows!

Re: Subframe connector options and opinions [Re: ScottSmith_Harms] #1161185
01/21/12 07:44 AM
01/21/12 07:44 AM
Joined: Jan 2005
Posts: 4,862
the frozen wastes...
Pale_Roader Offline
Swears too much
Pale_Roader  Offline
Swears too much

Joined: Jan 2005
Posts: 4,862
the frozen wastes...

Domingo definitely has the aesthetic vote... looks like the factory built it. That was one ov my options.

The other option was the contoured cut-out, weld to floor version. I would think that keeping the stronger 2x3 piece intact and cutting through the weaker floor sheetmetal would be stronger though. I'd also like a lower profile connector than both ov these ideas... my exhaust is going out the side T/A style.

Hmmm...

Re: Subframe connector options and opinions [Re: jcc] #1161186
01/21/12 11:38 AM
01/21/12 11:38 AM

A
Anonymous
Unregistered
Anonymous
Unregistered
A



Quote:

The first question should be IMO, could someone describe and BACK UP at least, with sound reasoning, what actual forces sub frame connectors resist? I am not questioning many many positive reports of thier improvements in ride etc. So are they resisting compression as the rear leafs push forward upon acceleration, are they resisting twist individually, if just under tension we can just use a steel cable, are they preventing a bending moment as front of leaf pushes up upon acceleration with a bending moment provided by the front mass of the car, ie engine, etc, are they just straightening out the force path thru 4 right? angle turns from the front hanger to the doorsills back to the TB crossmember, etc?.

If we knew what they are resisting, it would be a lot easier to design a solution. I suspect they are doing all the above, but some more then others, but which one? Say if twist was the main force, a large dia tube would be first choice, if bending moment, a tall I beam, yaw? bending, an I beam on its side, etc. My understanding is it needs to be the smallest and lightest shape/size that gets the job done. Anyone can oversize a solution, only a smart designer knows just how much is needed, if you way oversize, you look.....?

Years back member AAR? (patent attorney) had a lengthly thread on Subframe connectors, and main conclusion was the larger the crossection of the subframe, the stiffer, wall thickness provides a lot less stiffness then crossection increase gives. The installation advantages are numerous with the contour cut-out connectors, and installation ease IMO is thier only advantage. Performance wise, compared to a full tube they leave a lot on the table.




Aren't the factory rockers in effect thick gauge sorta-square tubes connecting the front and rear subframes? If so, what do aftermarket subrame connectors do that they don't? Just add strength to the connection because you now have four subrame connectors instead of two? Perform some other function?

And although it might present clearance issues for driveshaft and/or exhaust, wouldn't an X-shaped subframe connector be much more rigid than two straight tubes?

Re: Subframe connector options and opinions [Re: domingo] #1161187
01/21/12 11:42 AM
01/21/12 11:42 AM
Joined: Dec 2003
Posts: 22,732
Bitopia
J
jcc Offline
If you can't dazzle em with diamonds..
jcc  Offline
If you can't dazzle em with diamonds..
J

Joined: Dec 2003
Posts: 22,732
Bitopia
Quote:

I go thru the trans cross memeber and weld to the front frame rails...much better than what anybody else offers you out there.




yes, I like that, simple, clean, direct path for load transfer, no goofy add on's, reinforces TB load point


Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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