Competition Ford 9" in a sled-puller?

[GO 4LO]

Would a 9" make a good candidate for a rear axle for a sledpuller? If I understand the rules correctly, cusom internals are okay, so 40-spline axles and spools would be available for a 9", and it would save a lot of weight over a D80. I've heard differing opinions on strength of the r&p - the Ford 9's pinion gear is bigger and thicker, and the ring is thicker, but the ring is smaller in dia. than the D80, and the pinion shaft may also be smaller dia. than the D80 (anyone know for sure?).

Shaft strength will go to the 9", as the biggest Dana80 shafts are 37-spline. The housings will be heavily trussed either way, so no big difference between the two there.

So which r&p are stronger - the Ford 9's or the Dana 80's? Thanks in advance, everyone.

Chris

 

[fox]

Actually I believe your are refering to an aftermarket 9" based on the ford design. It may be quite strong but is unproven in this application. I bet it gets broken!

The pinion is lowered on the ring gear by design which weakens it a lot.

The stock 9" is actually weaker than the stock Dana 60.

Ford guys will argue this!

 

[GO 4LO]

Yeah, I'm talking built-to-the-hilt axles. I realize the pinion is lower on the 9" but am not sure how this weakens the axle - can you explain?

Stock D60's came in 35-spline configs (SF, though), but I believe 31-spline was the largest stock 9". But with spools and shafts available up to 46 or 49 spline, it would seem that as long as the r&p can hold up, a 9" would be stronger than the D80. The 9" has been used in desert race trucks and rockcrawling applications for years and held up pretty well.

Oh, and while we're at it, throw the GM 14B into the mix - a friend just told me that 46-spline spools and shafts are out for this axle as well. Big $$, though, just like the big 9" stuff.

So is there a particular reason no one uses the 9" - is there a particular weakness with the r&p, or is it a cost issue?

Chris

 

[Sled Puller]

They are too weak.



"custom internals" means in the OEM Dodge drivetrain.



A Ford 9" in a Dodge would be a custom EXTERNAL.

 

[GO 4LO]

Originally posted by Sled Puller

They are too weak.



"custom internals" means in the OEM Dodge drivetrain.



A Ford 9" in a Dodge would be a custom EXTERNAL.

Does this mean you can't run them? I know it says 'non-oem rearends prohibited' in the rule book for the Street and Pro-street classes, but not the Mod class, so this leaves two questions:



1. For the Street and Pro-street classes, what is allowed?

a. bone-stock axle

b. stock axle with different R&P

c. stock axle with lockers and/or custom shafts

d. any axle that came stock on a one-ton or smaller pickup



2. For the Modified class, is there any limit as to what axle you can run?



Thanks, Gene.

Chris

 

[Hornball]

I bet u it breaks. Spline Count isn't everything. Shaft diameter has to be looked at too. But not sure what diameter shafts u are looking at for the 9.

 

[fox]

I think it has more to do with the quality of the material used for the gears and axles, as far as strength.

Many years ago there was a comparison done with the ford 9", Dana 60, and GM 12 bolt. This was for the drag cars.

The chevy took the least hp to turn then the dana .

The Dana took the strength over the 9".

Some of the pulling guys have discussed the GM 14 and a guy said he has tried several and they break quicker than the Dana 80.

 

[Sled Puller]

The mod class is open to axle changes. At this time, no limits.



The other two classes, have to have OEM externals. Whatever Dodge, Ford, Cheby sent from the factory.

Custom internals are allowed,ie: Moser axles, Detroit Locker, ARB Lockers, etc.



I forsee no change in that rule, as noone wants to pull covers and check for a factory LS unit.



To put this in perspective as far as strength goes, Mark at Greensburg Machine runs a Dana 60 in his 440(HOT) gasser puller.

He builds them strong, but mostly does it for the weight savings.

Most gasser guys, think the Dana 70 is indestructible, where as the Cummins will twist the yoke off pretty quick, unless you are lucky.

 

[GO 4LO]

Originally posted by Hornball

I bet u it breaks. Spline Count isn't everything. Shaft diameter has to be looked at too. But not sure what diameter shafts u are looking at for the 9.

Spline count and axle diameter both are available much larger with the 9" than the D80. However, the pinion shaft diameter is a lot smaller.



Are most of the failures in pulling at the shaft or at the r&p or the locker or what?



fox, what part of the 14B was your buddy having trouble with?



Thanks, everyone!



Chris

 

[fox]

The guys I was refering to aren't close friends. They posted this topic someplace, try a search, TDR, DTR or Diesel -central.