Drive Shaft Tunnel Construction

mginnett · 01-21-2011, 03:44 AM

Race car construction question;
in a tube chassis car I read the IHRA drive shaft tunnel cover material requirement as .120 steel (2011 rule book). Cars I have seen have aluminum tunnel covers.
This is a low slung four link / strut front round tube car, the drive shaft passes next to your right leg / hip. Looking for input on this matter.

Thank you
Michael Ginnett
567 IHRA
Anchorage, Alaska

63corvette · 01-21-2011, 11:28 AM

I think you are looking at the drive shaft loop not the tunnel.
The loop can be mild steel at .120 or chrome molly at a lesser thickness that should also be quoted in the specs. The location is also dictated by the rule book.
The tunnel spec should be the same as the firewall spec.
Hope this helps.
Rick Cates

Tom Goldman · 01-21-2011, 01:20 PM

Applied Racing Technology in Florida makes a very nice kit for the driveshaft enclosure.
saves a lot of fab time.
I've never liked sitting next to the driveshaft.
I've been constructing all my and my customers cars with a 1/8" steel tunnel on the drivers side for years,and started using the SFI enclosure recently.
Saw a guy loose an arm a few years back on a brand new car when the shaft broke when coming out of the water!
made me think a whole lot about the flimsy loops that NHRA required .

Dave Steltz · 01-21-2011, 06:32 PM

Tom , when you say "drivers side", its a half side of the tunnel ?? I've been known to have a driveshaft chase me around the car (in my old camaro, it almost went out the back window)...so with an aluminum tunnel already in there, could this be an added piece, from underneath ? Do you bend it to match the contour of the tunnel...questions, questions...post a pic if you have one....

I thought I read somewhere that this is gonna be a rule soon , or is one already for some cars...

Tom Goldman · 01-21-2011, 07:20 PM

Dave , My roadster has the rear part of the tunnel over the driveshaft made out of .125" CM plate and it covers 180 degrees on the top. ..It takes the place of the tin.
I had S&W bend it to my specs as my bender won't handle that heavy a gauge steel.
I tabbed the frame rails and the "x" bar to attach it to.
Previously I had only been doing the top and drivers side in 1/8" ,but have since changed.
If you have the room ,or are starting with a clean sheet of paper,the SFI tube is the way to go.
I've been lucky and have never broken a yoke or joint, but I've repaired a few cars that had failures,and I can tell you the drivers were lucky to have escaped injury.
The cars had devastating damage to the frames ,tin and sometimes even the bodies!

mginnett · 01-21-2011, 09:49 PM

Thank you very much for the commentary, most appreciated. I think I may end up with a .120 steel tunnel, with 2 each 1" x .065 x 180 degree loops over the outsides well as the passage through the main rollcage hoop.
With the 360 degree setups I have seen, how much of a pain in the arse is it to pull the drive shaft / change the transmission?
This is a 66 Nova super gas style car, eventually will end up running mid to low eights.

01-21-2011, 03:44 AM	#1
mginnett Junior Member Join Date: Nov 2007 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Drive Shaft Tunnel Construction Race car construction question; in a tube chassis car I read the IHRA drive shaft tunnel cover material requirement as .120 steel (2011 rule book). Cars I have seen have aluminum tunnel covers. This is a low slung four link / strut front round tube car, the drive shaft passes next to your right leg / hip. Looking for input on this matter. Thank you Michael Ginnett 567 IHRA Anchorage, Alaska

01-21-2011, 11:28 AM	#2
63corvette Senior Member Join Date: Mar 2007 Location: Canyon, Tx Posts: 539 Likes: 122 Liked 299 Times in 91 Posts	Re: Drive Shaft Tunnel Construction I think you are looking at the drive shaft loop not the tunnel. The loop can be mild steel at .120 or chrome molly at a lesser thickness that should also be quoted in the specs. The location is also dictated by the rule book. The tunnel spec should be the same as the firewall spec. Hope this helps. Rick Cates

01-21-2011, 01:20 PM	#3
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,438 Likes: 786 Liked 703 Times in 206 Posts	Re: Drive Shaft Tunnel Construction Applied Racing Technology in Florida makes a very nice kit for the driveshaft enclosure. saves a lot of fab time. I've never liked sitting next to the driveshaft. I've been constructing all my and my customers cars with a 1/8" steel tunnel on the drivers side for years,and started using the SFI enclosure recently. Saw a guy loose an arm a few years back on a brand new car when the shaft broke when coming out of the water! made me think a whole lot about the flimsy loops that NHRA required . __________________ Tom Goldman 1500 SG , 1506 STK

01-21-2011, 06:32 PM	#4
Dave Steltz Member Join Date: Nov 2003 Posts: 323 Likes: 0 Liked 0 Times in 0 Posts	Re: Drive Shaft Tunnel Construction Tom , when you say "drivers side", its a half side of the tunnel ?? I've been known to have a driveshaft chase me around the car (in my old camaro, it almost went out the back window)...so with an aluminum tunnel already in there, could this be an added piece, from underneath ? Do you bend it to match the contour of the tunnel...questions, questions...post a pic if you have one.... I thought I read somewhere that this is gonna be a rule soon , or is one already for some cars... __________________ Dave Steltz 135G SG/SP/SST BIAECH Racing Team

01-21-2011, 07:20 PM	#5
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,438 Likes: 786 Liked 703 Times in 206 Posts	Re: Drive Shaft Tunnel Construction Dave , My roadster has the rear part of the tunnel over the driveshaft made out of .125" CM plate and it covers 180 degrees on the top. ..It takes the place of the tin. I had S&W bend it to my specs as my bender won't handle that heavy a gauge steel. I tabbed the frame rails and the "x" bar to attach it to. Previously I had only been doing the top and drivers side in 1/8" ,but have since changed. If you have the room ,or are starting with a clean sheet of paper,the SFI tube is the way to go. I've been lucky and have never broken a yoke or joint, but I've repaired a few cars that had failures,and I can tell you the drivers were lucky to have escaped injury. The cars had devastating damage to the frames ,tin and sometimes even the bodies! __________________ Tom Goldman 1500 SG , 1506 STK

01-21-2011, 09:49 PM	#6
mginnett Junior Member Join Date: Nov 2007 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Drive Shaft Tunnel Construction Thank you very much for the commentary, most appreciated. I think I may end up with a .120 steel tunnel, with 2 each 1" x .065 x 180 degree loops over the outsides well as the passage through the main rollcage hoop. With the 360 degree setups I have seen, how much of a pain in the arse is it to pull the drive shaft / change the transmission? This is a 66 Nova super gas style car, eventually will end up running mid to low eights.