9" vs 12 bolt.

tommy d · 04-15-2023, 11:15 AM

Could switching from a 12 bolt with a light spool to the Ford be 6-8 slower?

Alan Roehrich · 04-15-2023, 10:57 PM

Apples to apples, the Ford stuff is heavier, and the Ford has a less efficient hypoid angle, so it absorbs more power there as well. There could be a multitude of other differences, in component weight, bearing drag, etc. Is it possible for it to be 0.06 in the quarter? I suppose. Depending upon the rest of the combination. There's definitely a reason Mark Williams and other companies make really expensive stuff to run a 12 bolt Chevy in a 9" housing.

tommy d · 04-15-2023, 11:08 PM

I read 30lbs heavier and 3% h.p. loss due to increased friction. Figured you guys would know for sure. Thanks for the response.

Tom Goldman · 04-17-2023, 09:08 PM

Many years ago my uncle owned one of the Defrank and Cohen Hemi 'Cudas. we would always put the 12 bolt axle under it for class ,heads up or record runs . I seem to remember .05-.08 difference .
Both were light weight in their day.

Jim Caughlin · 04-18-2023, 12:45 PM

I don't think that Strange developed the 12 bolt drop out center section that fits into a 9" housing for the fun of it.

SSDiv6 · 04-18-2023, 05:00 PM

Quote:

Originally Posted by Jim Caughlin

I don't think that Strange developed the 12 bolt drop out center section that fits into a 9" housing for the fun of it.

At one time, there was also a Ford 8.8" dropout to use on the 9" housing made by Chris Alston ChassisWorks. The 8.8" has the same load and drag characteristics as a 12-Bolt.

Ralph A Powell · 04-18-2023, 06:05 PM

Quote:

Originally Posted by Jim Caughlin

I don't think that Strange developed the 12 bolt drop out center section that fits into a 9" housing for the fun of it.

Yes Strange did develop the 12 bolt drop out. The did it for Ford racing as Ford wanted to run it on the restrictor plate tracks. Ford tested it on the cup cars but NASCAR wouldn’t approve it. Strange was building all the 9 inch’s Nodular case’s for Ford. Ford did not have a source to pour nodular after they shut down the Flat Rock Casting Foundry in late 1981. Strange also made the High Strength Steel Case that Ford was using in NASCAR up to the end of the 2021.

richie 2 · 04-19-2023, 01:39 PM

is it popular today in SS? strange 12blt case/9'' housing...

Dirk Olson · 04-19-2023, 01:49 PM

Quote:

Originally Posted by tommy d

Could switching from a 12 bolt with a light spool to the Ford be 6-8 slower?

Better gear selection with the 9 bolt. and using a dewco center section with a 9.5 ring gear starts to level the playing field. Given the ease of gear change out, gear selection, it would hard to go to the 12 bolt unless class dictates it.

FED 387 · 04-19-2023, 02:28 PM

DEWCO is great stuff only problem is Don the DEWCO owner has/had serious health problems might have a problem getting product---FED 387

04-15-2023, 11:15 AM	#1
tommy d Senior Member Join Date: Oct 2010 Location: Indiana Posts: 830 Likes: 1,609 Liked 359 Times in 135 Posts	9" vs 12 bolt. Could switching from a 12 bolt with a light spool to the Ford be 6-8 slower? __________________ Who owns this car, with the peace sign,mag wheels, and four on the floor?

04-15-2023, 10:57 PM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,110 Likes: 1,570 Liked 1,807 Times in 411 Posts	Re: 9" vs 12 bolt. Apples to apples, the Ford stuff is heavier, and the Ford has a less efficient hypoid angle, so it absorbs more power there as well. There could be a multitude of other differences, in component weight, bearing drag, etc. Is it possible for it to be 0.06 in the quarter? I suppose. Depending upon the rest of the combination. There's definitely a reason Mark Williams and other companies make really expensive stuff to run a 12 bolt Chevy in a 9" housing. __________________ Alan Roehrich 212A G/S

04-15-2023, 11:08 PM	#3
tommy d Senior Member Join Date: Oct 2010 Location: Indiana Posts: 830 Likes: 1,609 Liked 359 Times in 135 Posts	Re: 9" vs 12 bolt. I read 30lbs heavier and 3% h.p. loss due to increased friction. Figured you guys would know for sure. Thanks for the response. __________________ Who owns this car, with the peace sign,mag wheels, and four on the floor?

04-17-2023, 09:08 PM	#4
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,475 Likes: 887 Liked 865 Times in 235 Posts	Re: 9" vs 12 bolt. Many years ago my uncle owned one of the Defrank and Cohen Hemi 'Cudas. we would always put the 12 bolt axle under it for class ,heads up or record runs . I seem to remember .05-.08 difference . Both were light weight in their day. __________________ Tom Goldman 1500 SG , 1506 STK

04-18-2023, 12:45 PM	#5
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 685 Likes: 82 Liked 805 Times in 245 Posts	Re: 9" vs 12 bolt. I don't think that Strange developed the 12 bolt drop out center section that fits into a 9" housing for the fun of it.

04-19-2023, 01:39 PM	#8
richie 2 Senior Member Join Date: Feb 2009 Posts: 971 Likes: 425 Liked 205 Times in 93 Posts	Re: 9" vs 12 bolt. is it popular today in SS? strange 12blt case/9'' housing...

04-19-2023, 02:28 PM	#10
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,419 Likes: 528 Liked 332 Times in 180 Posts	Re: 9" vs 12 bolt. DEWCO is great stuff only problem is Don the DEWCO owner has/had serious health problems might have a problem getting product---FED 387