Ford 9" questions

[1994rcsbLS]

Hello everyone!
So i've looked through the threads and i may have missed it so sorry if this is a repeat question.

94 C1500 I have a worked 6.0. Purchased the truck with a quick performance ford 9" with 4.11 gears. rears a pretty stout build.
Anyways, the tabs weren't welded in. Does anyone have measurements of where i can weld in the spring perches to get to the closest pinion angle possible?. truck has an axle flip as well. Im just trying to get some insight before I start crawling under the truck and pulling it apart during the summer.

 

[Schurkey]

Does anyone have measurements of where i can weld in the spring perches to get to the closest pinion angle possible?

Wild Guess: You're going to have to mock-up the suspension in order to discover where the perches need to be positioned. There's far too many variables, ESPECIALLY with a modified truck to give you a "canned" answer.

IF you were to find an OEM axle, position it so the pinion gear shaft was perfectly level, (Front edge of the pinion yoke at a 90 degree angle) and then measure the angle of the perches, you'd MAYBE be in-the-ballpark; but a modified truck could need something significantly different from the OEM angles.

 

[1994rcsbLS]

Wild Guess: You're going to have to mock-up the suspension in order to discover where the perches need to be positioned. There's far too many variables, ESPECIALLY with a modified truck to give you a "canned" answer.

IF you were to find an OEM axle, position it so the pinion gear shaft was perfectly level, (Front edge of the pinion yoke at a 90 degree angle) and then measure the angle of the perches, you'd MAYBE be in-the-ballpark; but a modified truck could need something significantly different from the OEM angles.

Fair enough, yeah i was trying to get somewhere in the ball park. and then adjust as needed from there. with no lift or garage its kind of rough lol.

 

[Javlin42]

Can you post more pictures of your truck. I'm about to order a qp 9" for my truck but would like to get it a couple inches more narrow

 

[1994rcsbLS]

Can you post more pictures of your truck. I'm about to order a qp 9" for my truck but would like to get it a couple inches more narrow

what exactly are you trying to see? just so i could help yah out better. If i was you id probably call QP and talk to them. theyre extremely helpful over the phone, website kinda outdated if you ask me..

 

[Schurkey]

I don't understand the romance of the Ford Nine Inch.

They're a strength upgrade from a GM "Ten Bolt", either the 8.2" or 8.5"; and they don't use C-clips to hold the axles. They're great for "gear changes" in that a person sets-up some carriers with a variety of ratios, and then (2WD) ya' just swap carriers, and maybe bleed brakes.

They're not as strong as a 9.5" GM/AAM semi-float. C-clips are not a problem if the axle is kept in good condition--it's the worn-out ones that the C-clips fail or fall out and the axle goes Bye-Bye.

I see lots of Ford Nines in drag cars, absorbing tremendous shock loads. I've seen lots of Ford Nines in ordinary passenger cars, with wiped-out bearings, wiped-out side/spider gears, wiped-out ring and pinion gears. They take shock-loads very well. Not so fabulous for ordinary high-mileage wear.

Overall, they're just more trouble than they're worth UNLESS the exceptional range of gear ratios is an advantage for you at the racetrack. Not such an advantage on the street, and no advantage at all in a 4WD.

Well...at least they don't have the curse of the 254mm leading/trailing drum brakes.

 

[1994rcsbLS]

I don't understand the romance of the Ford Nine Inch.

They're a strength upgrade from a GM "Ten Bolt", either the 8.2" or 8.5"; and they don't use C-clips to hold the axles. They're great for "gear changes" in that a person sets-up some carriers with a variety of ratios, and then (2WD) ya' just swap carriers, and maybe bleed brakes.

They're not as strong as a 9.5" GM/AAM semi-float. C-clips are not a problem if the axle is kept in good condition--it's the worn-out ones that the C-clips fail or fall out and the axle goes Bye-Bye.

I see lots of Ford Nines in drag cars, absorbing tremendous shock loads. I've seen lots of Ford Nines in ordinary passenger cars, with wiped-out bearings, wiped-out side/spider gears, wiped-out ring and pinion gears. They take shock-loads very well. Not so fabulous for ordinary high-mileage wear.

Overall, they're just more trouble than they're worth UNLESS the exceptional range of gear ratios is an advantage for you at the racetrack. Not such an advantage on the street, and no advantage at all in a 4WD.

Well...at least they don't have the curse of the 254mm leading/trailing drum brakes.

i'm not 4wd, and this truck is being slowly built out for track and a little street use. not my everyday truck lol I got my rear with 35 spline axles and has disk brake setup. And last time this truck jumped off the line on 2 step the axle was waved goodbye to on the other "10" bolt lol

 

[Erik the Awful]

I don't understand the romance of the Ford Nine Inch... They're not as strong as a 9.5" GM/AAM semi-float.

The 9" has an additional bearing on the back side of the pinion that makes it stronger than the 14-bolt. It also has a dropped pinion that allows it to handle loading better. The downside is that dropped pinion robs a bit of horsepower.

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[Schurkey]

The straddle-mounted pinion is a neat design. The 10.5" AAM also has the straddle-mount. Lil' pinion bearing of my K2500 10.5" visible in this photo from my Truetrac installation.

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You're correct, the 9.5" AAM axle has an overhung pinion (no third bearing). But it works well enough. It's not like that two-bearing design hasn't been thoroughly tested.

The lower-mounted pinion may be one reason that the Nine handles shock-loads well, but doesn't seem to handle regular high-mileage all that great. Lower-mounted pinion also increases gear lube temperature, and has more tendency to push the differential case out the back--added stress on the differential side-bearings and bearing caps.

As for gear contact area being greater on the lower-mounted pinion, this is true if everything else is equal. But everything may or may not be equal. Wider pinion/wider ring gear would also increase contact area. I don't know how the Nine Inch ring and pinion gear width compare to the 9.5" semi-float. I haven't had a Nine Inch differential apart since I was in Trade School, other than to replace pinion seals, axle bearings, and gear lube. I've never done "real" differential work on one.

Jim Allen, and Randy Lyman (of Randy's Ring And Pinion) (RIP) published a book--Differentials Identification, Restoration and Repair, ISBN 978-1-4243-2661-7--detailing general service procedures, and the history and various specs for a heap of different differentials.
www.themotorbookstore.com/differentials-identification-restoration-repair-manual.html

Differentials: Identification, Restoration, Repair 2nd Edition

Differential repair tips, tricks and performance mods. All 1960-on American axles. By Jim Allen and Randy Lyman. Ring & Pinion Services, 26617. Free Shipping.

www.themotorbookstore.com

They've got a "strength" rating for each axle design, based--I guess--on how big of a tire the axle should be able to cope with. Larger-diameter tire = more strength. This seems to me to be more 4WD, off-road strength than drag race, but it's all I've got. The Ford Nine in 33-spline variety is "rated" for a 33" tire. The Nine in the stronger 35-spline version is "rated" for a 35" tire.

By comparison, a Mopar 8 3/4 is "rated" for 35" tires, the 9.5" AAM is "rated" for a 37" tire. A Dana 60 is rated for 38" tires.

Maybe that doesn't mean much for drag-race use, but it seems appropriate for axles crammed under normal-use pickup trucks.

The biggest advantage of the Nine Inch is the enormous aftermarket support.

 

[Erik the Awful]

Maybe that doesn't mean much for drag-race use, but it seems appropriate for axles crammed under normal-use pickup trucks.

Yup. Back in the day when guys were snapping 12-bolts in their Chevelles, the 9" rears weren't breaking.

Out of curiosity, what do they rate the strength of my Dana 70 in Roscoe?