9" Aluminum center section...Pros/Cons ?

[TerryD]

Considering using an Aluminum Center Section. Anyone know of any issues with this for street use? The car weighs approximately 3600 lbs. will be running 3.55's and Falken Azenis 335's. Engine puts out 660+ ft lbs, 4L80E Trans.

TIA

[andrewb70]

I see no issue with it. I am guessing you aren't going to do any serious drag racing, right?

Andrew

[TerryD]

Not planning on any drag racing, other than any chance encounters.. lol.
wondering about any potential thermal considerations for street or autocross use.
Getting ready to order another quadralink setup for a new project and weighing the option the options between the 9" and a 12 Bolt. I went with the 9" with a nodular iron 3rd member last time. Looking for unsprung weight savings.
The Pandora's box question.....9" vs 12 Bolt??

[sam 74]

you can get some deflection with an aluminum center, but from what it sounds like you're doing with it you should be ok.

[parsonsj]

If you want a quiet set of rear gears, consider the Ford 8.8. You can still buy new gears from Ford and it has lots of differential choices.

[Ron Sutton]

We don't run aluminum 3rd members or pinion supports on street or track. In my experience, the aluminum 3rd doesn't manage the heat well from extended running & the aluminum pinion supports swell up so much the pinion seal pushes out & leaks. We run the base nodular 3rd member from Strange or Ford SVO (same unit) and the nodular iron Daytona pinion support. The weight difference is minimal & the issues are none. Just my 2¢

:cheers:

[TerryD]

We don't run aluminum 3rd members or pinion supports on street or track. In my experience, the aluminum 3rd doesn't manage the heat well from extended running & the aluminum pinion supports swell up so much the pinion seal pushes out & leaks. We run the base nodular 3rd member from Strange or Ford SVO (same unit) and the nodular iron Daytona pinion support. The weight difference is minimal & the issues are none. Just my 2¢

:cheers:

Thanks for the input Ron. I was thinking that there might be a thermal issue.

What's your 2 cents on the 9" vs a 12 bolt? Other than easier gear changes I recall reading that the 12 bolt is a bit more efficient. Haven't looked into any weight differences.

Thanks again.

[Ron Sutton]

Thanks for the input Ron. I was thinking that there might be a thermal issue.

What's your 2 cents on the 9" vs a 12 bolt? Other than easier gear changes I recall reading that the 12 bolt is a bit more efficient. Haven't looked into any weight differences.

Thanks again.

The Pro & Con of the 9" are from the same detail. The pinion drop (offset downward) of the 9" Ford is 2-1/4" That is huge. So it has more tooth contact surface area with the ring gear. This both makes the pinion gear stronger (load is spread) & also makes it have more friction, which reduces the power output to the wheels a small percentage.

For reference ...
12-Bolt has 1-7/16" pinion drop
Dana 60 has 1-1/8" pinion drop
Mopar 8-3/4" has 1-1/2" has pinion drop

If I was running 200 hp, I'd want a 12-Bolt or even an 8.5" 10-Bolt (and change the outer bearings to something like a Super Set 20). But as we build 400-500+ HP & abuse these cars, the additional strength of the 9" Ford 3rd member is a better choice in my experience. It does cost more to build a 9" correctly, but the benefits are worth it IMHO.

[TerryD]

Thanks again Ron. That makes the decision pretty clear. The engine is producing 640 hp and 668 ftlbs of torque. So the 9" is the clear winner!

Really appreciate all the knowledge you share with all of us!

[Skip Fix]

Ron if pinion drop affects gear strength by spreading the load and the Dana has less why is it considered a stronger rear end-other than easier to get larger axle spline counts?

[Ron Sutton]

Ron if pinion drop affects gear strength by spreading the load and the Dana has less why is it considered a stronger rear end-other than easier to get larger axle spline counts?

The Dana 60 ring & pinion assembly are larger & beefier than the 9" Ford. The Dana 60 ring gear is 9.75" & the pinion is equally larger. The bearings are bigger too. In drag racing, I preferred the Dana 60 over the 9" Ford because it was stronger all around ... as long as you didn't need to change gear ratios quickly. It was great for fast bracket cars, Super/Gas, Super/Comp, etc.

For our drag cars that ran different engines, we still ran the 9" Ford, so we could swap in 3rd members with different gear ratios quickly. All of our Pro Level cars ran the 9" Ford for the lighter weight & better control of the rear end on launches.

[Skip Fix]

Thanks Ron. Got a 9" for my 470/409 Impala project but I've been pondering a Dana for the 65 GTO project as it looks a little more like the stock style than a "pumpkin" rear end. It is getting a RAIV Pontiac 428/440 with a stick 5 speed so I think even the 12 bolt I picked up might grenade.

[Ron Sutton]

Thanks Ron. Got a 9" for my 470/409 Impala project but I've been pondering a Dana for the 65 GTO project as it looks a little more like the stock style than a "pumpkin" rear end. It is getting a RAIV Pontiac 428/440 with a stick 5 speed so I think even the 12 bolt I picked up might grenade.

The Dana could be a good choice there. Heavier of course, but strong as heck.

[Skip Fix]

And with a stick you HAVE to side step the clutch at 5000:)

Tranny is the old Nash/Richmond race version straight cut gears 2.80,2.22,1/77,1/33,1.0.