subframe connectors and stock class Q

Tom keedle · 02-28-2009, 08:02 AM

as some of you know, i'm looking at building a 67 american for stock and as there isn't any (to my knowlege) "bolt in" connectors made.
are weld in's acceptable?
what's legal, what ain't?

Myron Piatek · 02-28-2009, 08:21 AM

In my opinion, the most structurally sound way to install frame connectors is to connect the front and rear subframes with the connectors welded INTO the floor where clearances above and below allow. It basically requires a snug channel where the 2x2 or 2x3 tubing would pass through the floor and would be welded along the length. Some higher floor sections may not need a floor cut. Then an 8 pt. roll bar would include 2 legs from the sides of the main hoop, behind the seats, being welded into the top of those connectors. "Triangulation" is the key to a stiff frame/chassis.

But a simpler way would be to fit a 2x2 below the floor or pushed slightly up into it and welded at all contact points, including the roll bar legs. I believe .083" is a popular thickness but have heard as thin as .065" being used.

henrys57wagon · 02-28-2009, 10:13 AM

Both our Camaro and Nova had weld in frame connectors, never had any questions about them from any tech guys, Henry. (old 1608 from the 80-90's)

Robert Swartz · 02-28-2009, 10:40 AM

Looking at both "2008" rulebooks, I don't have newer ones yet. NHRA calls for a maximum of 2 x 3 x .125. IHRA calls for a maximum 2 x 3 x .120 mild steel. I'll leave it to others more experienced than I to advise you on the minimal allowances.

I agree with the triangulation. My 66 Chevy II bracket car doesn't have this. I intend to rectify that before we return it to the track. Our crate motor Firebird will have alot more thought put into the chassis before we begin construction.

Good luck with your build,

Robert Swartz

Jeff Lee · 02-28-2009, 11:08 AM

Welded is acceptable. You can also use round tube and chromoly is acceptable also.

Tom keedle · 03-01-2009, 09:37 AM

thanks guys, i wasn't sure if it was legal to run them thru the floor if nessassary
(obviously welded in)...
i've been told that in late 68 americans and all 69's that amc added them in oem.
i know my 69 has 'em but the 67 don't...

2X3 X .125" ok? (nhra book says so) or would you suggest a thinner wall tube?

Dwight Southerland · 03-01-2009, 02:50 PM

Sub frame connectors are only legal when used with a roll bar or cage.

Tom keedle · 03-01-2009, 03:47 PM

Quote:

Originally Posted by Dwight Southerland

Sub frame connectors are only legal when used with a roll bar or cage.

i'm ok with that...as i'm figuring on a cage.
need the weight

Myron Piatek · 03-01-2009, 05:22 PM

Quote:

Originally Posted by tomslik

2X3 X .125" ok? (nhra book says so) or would you suggest a thinner wall tube?

Again, just my opinion, but 2x3 and .125" seems like overkill on strength and weight, not to mention possible clearance issues above and below the floor. Having it welded into/through the floor with the inner roll bar legs should make 2"x2"x.083" plenty strong. Then you can add any extra weight where you want to and where it will do the most good.

Mark Yacavone · 03-01-2009, 05:31 PM

Quote:

Originally Posted by Dwight Southerland

Sub frame connectors are only legal when used with a roll bar or cage.

??? That's news to me.

02-28-2009, 08:02 AM	#1
Tom keedle Senior Member Join Date: Dec 2008 Location: Berthoud, Coloraduh Posts: 695 Likes: 13 Liked 7 Times in 6 Posts	subframe connectors and stock class Q as some of you know, i'm looking at building a 67 american for stock and as there isn't any (to my knowlege) "bolt in" connectors made. are weld in's acceptable? what's legal, what ain't?

02-28-2009, 08:21 AM	#2
Myron Piatek VIP Member Join Date: Nov 2001 Location: Florida Posts: 1,538 Likes: 34 Liked 132 Times in 48 Posts	Re: subframe connectors and stock class Q In my opinion, the most structurally sound way to install frame connectors is to connect the front and rear subframes with the connectors welded INTO the floor where clearances above and below allow. It basically requires a snug channel where the 2x2 or 2x3 tubing would pass through the floor and would be welded along the length. Some higher floor sections may not need a floor cut. Then an 8 pt. roll bar would include 2 legs from the sides of the main hoop, behind the seats, being welded into the top of those connectors. "Triangulation" is the key to a stiff frame/chassis. But a simpler way would be to fit a 2x2 below the floor or pushed slightly up into it and welded at all contact points, including the roll bar legs. I believe .083" is a popular thickness but have heard as thin as .065" being used. __________________ LOCOMOTION Racing

02-28-2009, 10:13 AM	#3
henrys57wagon Member Join Date: Jan 2009 Location: Carleton Place, On. Canada Posts: 107 Likes: 5 Liked 0 Times in 0 Posts	Re: subframe connectors and stock class Q Both our Camaro and Nova had weld in frame connectors, never had any questions about them from any tech guys, Henry. (old 1608 from the 80-90's)

02-28-2009, 10:40 AM	#4
Robert Swartz Senior Member Join Date: Aug 2008 Location: Nineveh, Indiana Posts: 512 Likes: 0 Liked 3 Times in 3 Posts	Re: subframe connectors and stock class Q Looking at both "2008" rulebooks, I don't have newer ones yet. NHRA calls for a maximum of 2 x 3 x .125. IHRA calls for a maximum 2 x 3 x .120 mild steel. I'll leave it to others more experienced than I to advise you on the minimal allowances. I agree with the triangulation. My 66 Chevy II bracket car doesn't have this. I intend to rectify that before we return it to the track. Our crate motor Firebird will have alot more thought put into the chassis before we begin construction. Good luck with your build, Robert Swartz __________________ Robert Swartz - Swartz & Lane 66 Chevy II Pro 95 Achieva EF/SA, 78 Mustang II U/SA (work in progress) #354 stock

02-28-2009, 11:08 AM	#5
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 2 Times in 2 Posts	Re: subframe connectors and stock class Q Welded is acceptable. You can also use round tube and chromoly is acceptable also. __________________ Jeff Lee 7494 D/S '70 AMX

03-01-2009, 09:37 AM	#6
Tom keedle Senior Member Join Date: Dec 2008 Location: Berthoud, Coloraduh Posts: 695 Likes: 13 Liked 7 Times in 6 Posts	Re: subframe connectors and stock class Q thanks guys, i wasn't sure if it was legal to run them thru the floor if nessassary (obviously welded in)... i've been told that in late 68 americans and all 69's that amc added them in oem. i know my 69 has 'em but the 67 don't... 2X3 X .125" ok? (nhra book says so) or would you suggest a thinner wall tube?

03-01-2009, 02:50 PM	#7
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,981 Likes: 53 Liked 724 Times in 177 Posts	Re: subframe connectors and stock class Q Sub frame connectors are only legal when used with a roll bar or cage.