9" vs 12 bolt.
 

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

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.

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.

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.

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.

Re: 9" vs 12 bolt.
 

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.

Re: 9" vs 12 bolt.
 

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.

Re: 9" vs 12 bolt.
 

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

Re: 9" vs 12 bolt.
 

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.

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

Re: 9" vs 12 bolt.
 

lots of them

Re: 9" vs 12 bolt.
 

I changed from a 9 inch to 9.5 inch Gleason set up. These were pretty common pro stock set ups years ago before they moved on to bigger stuff. Much more efficient than the standard 9 inch

Re: 9" vs 12 bolt.
 

A buddy used one of those 12-bolt drop out pieces many moons ago in a SS application.
He used up gears like crazy, that lead me to believe the performance advantage aspect somewhat disappeared, it was a heavy car
and the Aluminum 3'd member maybe was flexing?

Re: 9" vs 12 bolt.
 

A good test would be to a loss test on the 9” nodular vs the High strength steel that Strange manufactures for Ford NASCAR program the HS case is 3 lbs lighter that nodular and about 30 % stiffer. According to Bob Stange so it hold everything in place. I don’t believe an aluminum case is as strong as the Ford nodular with the modified tail bearing, the Daytona pinion support and a load bolt to support the ring gear.