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Discussion Starter · #1 ·
Hi all.
I know many will disapprove of the mod however i now have to ask.
As you will be aware i have asked a similar question on posi conversion to the rear of "Alice".
Many a member has answered my questions on a posi conversion in "Alice" and i have received many a great response to what needs to be done.
As i am on the other side of the world and the $$ for this conversion is becoming a huge issue, with freight, posi carier, crown wheel and pinion set, bearing set and new axles i would be all in at about 2.5k for the build.
My question now comes as i can procure a 9" ( a Freebie in working order ) out of a Aussie build 72 f100 bronco. With this the housing comes with all req parts for the conversion. Housing, pumpkin,axles brakes etc.
I know i will have to shorten the housing (ford 61.25 axle flange to axle flange and the Chev is 60"). The spring perches will have to be changed and pinion angle corrected.Other than the obvious stud pattern change to chev , i have a few questions i have been unable to answer on all the conversions i have read up on.
On the + side i can procure as a freebie and a cost of 1000 for the housing mods
1) What if any mods would need to be done to the drive shaft?
2) Would i have to go down the path again on my universal saga i had with the front yoke?
3) Can i retain the disc conversion i procured and fitted to suit the chev housing or will i have to use the ford stuff.
4) Can i shorten the housing as needed and fit the chev tube ends and use the std 57 bearings?
5) If #4 can be done can a set of axles be made to suit thus retaining my new chev conversion?
6) Due to the larger size of the pumpkin will i run into issues with the 1 1/2 lowered rear end and shock bar?
Any and all advise will be noted and taken into consideration before i proceed with any changes.
Just to refresh "Alice" is at this time a mild 350 coupled to a TH350 with stg 2 shift kit and 2000-2500 stall converter. This config may change at a later stage to a blown 383 stroker ( This will be a long term improvement as i build my engine over a few years. one can only dream at the moment on that one :) )
Thanks in advance David
 

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Hey Mouse, in regards to question #4, you will have to make sure that the housing is 100% straight, and as being out of 72 F100 it is more than likely that she has had a hard life and has began to fatigue ( remembering she is 41 years old ). To do this it needs to go to a diff guy and put in his jig and inspected.

I recently went through the same thing with a disc brake 9 inch out of a Falcon. In the end I got a housing made from scratch to my desired length with billet 32 splined axles - Chev pattern. The spring purchases were fully welded on while it was in the jig to stop warping of the housing. If you want to use the 57 bearings, that can be accommodated when fabricating the housing and your current rotors can be drilled out to the Chev pattern.

Not something you want to think about, but if you are going to a blown 383 in the future you want to have piece of mind that you are not going to tear out the rear end when you step on the fast pedal. Hope this helps.
 

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Discussion Starter · #3 ·
Bump btt
 

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Hey Mouse,
There's so many options...
However, depending on application and end aim it can be simple or complicated.

At the minimum cost end, one idea... At 61.25" across the wheel mounting surfaces you can get rims with an offset that would allow it to bolt in (after welding on spring perches). Not ideal or highest torque capacity but fairly simple depending on your goal. I'm not familiar with the brakes on these but would guess it might be possible to get wheel cylinders that are compatible with a power front disc system. As for the Ford pattern, an option would be to leave as is. Get an old dual pattern wheel from a swapmeet and you've got a spare that'll do both ends.

Just a thought after reviewing your post: If this is one of the equal axle length F100 assemblies ignore my typing above. The tailshaft would be off centre and the large stud pattern would make getting rims a hassle.

Of course it can be modified in any number of ways to make width, stud pattern, torque capacity and brake type more ideal, just need to balance the cost vs the goal and intended use.
 

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the other thing

That needs to be accounted for is the pinion must be centered. Fords typically have more offset than a GM so watch this also. If you are going to build a big Horse engine you will want to use 31 spline axles. I believe that would be way larger than your idea of stock axle ends. You would want to keep the larger Ford bearings anyway. Also if building a horse motor you would want to use the High nodular iron case not the standard case and not all case with 2 ribs are strong there is one week one called the WAR case.
 

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That needs to be accounted for is the pinion must be centered. Fords typically have more offset than a GM so watch this also. If you are going to build a big Horse engine you will want to use 31 spline axles. I believe that would be way larger than your idea of stock axle ends. You would want to keep the larger Ford bearings anyway. Also if building a horse motor you would want to use the High nodular iron case not the standard case and not all case with 2 ribs are strong there is one week one called the WAR case.
WAR & WER not good look Like N case, The bearing to use when narrowing is the Olds [aka big Ford] . Olds used this bearing is the early 40s or over ten years prior to Ford, so I refuse to give Henry the credit. Toms Differential has axle ends that use this bearing with Chevelle/Camaro brakes or Impala/light truck brakes.
 

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You may have change the driveshaft length, but hopefully you know a competent shop that can do that and balance it. And there are a variety of “adapter” type u-joints available. My car once used a rear u-joint that connected a 1310 driveshaft yoke to a 1330 pinion yoke.

I just remembered that the early 28-spline axles are tapered, so can't be shortened much, if at all.
 

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Ford 9" axles came with yokes for at least 4 different u-joints. Also there are different lengths of yokes. Different yoke length = different driveshaft length. You can get lucky and not have to change the driveshaft at all. But don't take anybody's word for it on a given combo, there are too many possibilities.
 

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Ford 9" axles came with yokes for at least 4 different u-joints. Also there are different lengths of yokes. Different yoke length = different driveshaft length. You can get lucky and not have to change the driveshaft at all. But don't take anybody's word for it on a given combo, there are too many possibilities.
In the 70s when I was much younger and not so bright I ran a 9 inch in my 67 Camaro with no driveshaft mods, I was lucky because I once had six different style yokes on six different third members.
 
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