Ford 9 inch or 9.5 SF???

[twoslo4five0]

i got a 9 inch 31 spline out of a van...never broke an axle up to 4os...when i went to 44 i broke one..couldnt find a replacment axle in time for a bog so ditched it for a 14 bff...i sill have it a 44 a broken locker and about 3 3rd members waiting for a buyer...

 

[MaxPF]

9 inch

Pros: Huge aftermarket support, non c clip axles, maybe find one with a limited slip. Availability, low cost
Cons: 5 lug, stock axles are usually 28 spline, and it's a Ford. No idea what kinds of gears would come stock for most fords. My guess would be a 3.50.

No idea on the WMS to WMS on fullsize fords, but I'd guess it's close enough.

9.5 SF

Pros: GM made, six lug possible with stock parts, 33 spline probably easy to find with 3.73's or 4.10's
Cons: c-clip axle, aftermarket support, expensive lockers??? could find one with a gov-lock. Availability?? Cost???

What would you run?

Easy answer: 14bsf. 33 spline vs. 31 spline = no brainer. Yes, you can get em in 6 lug (I did ). 6 lug axles aren't as common as 8 lug, and it will be found under a NBS truck so you will have to move spring perches and shock mounts. As for cost, I paid $140 for mine. Aftermarket support? Lockers? Well, you can get axles from Superior, and available lockers include the Detroit, ARB, Eaton E-locker, Powertrax's Lock-Rite and No-slip, and of course posi's from Eaton and Auburn. The lockers aren't any more expensive than the ones for, say, D60s and other similar sized diffs.

C-clips... yup, it uses C-clips. BFD. People consider it inferior to externally retained axles, but that's not really the case. Let me explain: I have seen externally-retained axles (i.e. 9 inch, D44) break, and while the axle doesn't slide out the vehicle is NOT driveable. The broken axle flops around inside the tube, and as a result the tire wobbles and the axle makes a racket. The axle ends up cocking the axle in the bearing which is something the bearings definitely aren't built for and won't tolerate for long. You can simply put disk brakes on a c-clip axle and it will be retained if the axle breaks. It will still do all of the bad things that the externally-retained axle will - that's just a limitation of SF axles. If you want to be able to drive on it after you break an axle, get a full floater. C-clip axles do have one distinct advantage oner externally-retained axles - the axle bearings have a higher capacity for a given tube size. This is because the C-clip axle uses the shaft itself for the inner race, which means it can be a larger diameter and the rollers can be bigger.

Here's some food for thought: The smallest diameter on a 14bsf shaft is 1.400", just behind the splines. The splines are 1.420", and about midway the axle necks up to 1.700". According to Pirate 4x4 (http://www.pirate4x4.com/tech/billavista/14b_bible/index.html, scroll down about 1/3 of the way) teh operating diameter of a 14b full floater shaft is 1.351". This means that, assuming the shafts are made of the same material (which they are), the sf shaft should be capable of handling as much torque as the ff. Some will make the argument that the ff shaft doesn't have to support the weight of the vehicle (which is true),, but they forget that the part of a sf shaft that supports the vehicle is 1.700" in diameter. You can look at this as being a 1.700" .150" wall tube supporting the vehicle with a 1.400" shaft transmitting torque through the middle, i.e. there is enough extra meat that loading capacity isn't a problem. This will be heresy on this site, but I bet the sf shaft can handle as much torque as a ff. The difference, of course, is that if you do manage to break the shaft you can still drive the ff

OK, long winded. Well, I'm going on a hunting trip in the morning, so I won't see any replies to my heresy for a week. Feel free to flame

 

[u2slow]

Let me explain: I have seen externally-retained axles (i.e. 9 inch, D44) break, and while the axle doesn't slide out the vehicle is NOT driveable.

If the bearing goes south on you and separates you CAN lose your axle on a 9". Nevermind that you can sustain a break outboard of the bearing.

That aside, the whole idea of using the shaft surface as a race on a c-clip axle seems really cheaped-out. It turns the shaft into a consumable item.

 

[MaxPF]

If the bearing goes south on you and separates you CAN lose your axle on a 9". Nevermind that you can sustain a break outboard of the bearing.

That aside, the whole idea of using the shaft surface as a race on a c-clip axle seems really cheaped-out. It turns the shaft into a consumable item.

Not really. My 14bsf came out of a well used 93 work truck. I have no idea how many miles the truck had on it, but it looked as used as a dockside tart on payday. I'm sure the fluid was also never changed, and yet the bearing surface on the axles were perfect. Remember, since the axle acts as an inner race the bearing can effectively have more surface area to run on. In the case of the 14bsf, the bearing is BIG:

If a bearing with an inner race were used instead you would either have to use a smaller diameter shaft (to retain the same size rollers) or use smaller rollers (to accomodate a larger inner race that can fit a 1.700" shaft). In the first case you weaken the shaft and in the second you have a bearing with less load capacity. Since they seem to run forever (unless you run your diff out of oil), I don't really see a problem with it considering the strength advantages

 

[Bubba Ray Boudreaux]

Easy answer: 14bsf. 33 spline vs. 31 spline = no brainer. Yes, you can get em in 6 lug (I did ). 6 lug axles aren't as common as 8 lug, and it will be found under a NBS truck so you will have to move spring perches and shock mounts. As for cost, I paid $140 for mine. Aftermarket support? Lockers? Well, you can get axles from Superior, and available lockers include the Detroit, ARB, Eaton E-locker, Powertrax's Lock-Rite and No-slip, and of course posi's from Eaton and Auburn. The lockers aren't any more expensive than the ones for, say, D60s and other similar sized diffs.

C-clips... yup, it uses C-clips. BFD. People consider it inferior to externally retained axles, but that's not really the case. Let me explain: I have seen externally-retained axles (i.e. 9 inch, D44) break, and while the axle doesn't slide out the vehicle is NOT driveable. The broken axle flops around inside the tube, and as a result the tire wobbles and the axle makes a racket. The axle ends up cocking the axle in the bearing which is something the bearings definitely aren't built for and won't tolerate for long. You can simply put disk brakes on a c-clip axle and it will be retained if the axle breaks. It will still do all of the bad things that the externally-retained axle will - that's just a limitation of SF axles. If you want to be able to drive on it after you break an axle, get a full floater. C-clip axles do have one distinct advantage oner externally-retained axles - the axle bearings have a higher capacity for a given tube size. This is because the C-clip axle uses the shaft itself for the inner race, which means it can be a larger diameter and the rollers can be bigger.

Here's some food for thought: The smallest diameter on a 14bsf shaft is 1.400", just behind the splines. The splines are 1.420", and about midway the axle necks up to 1.700". According to Pirate 4x4 (http://www.pirate4x4.com/tech/billavista/14b_bible/index.html, scroll down about 1/3 of the way) teh operating diameter of a 14b full floater shaft is 1.351". This means that, assuming the shafts are made of the same material (which they are), the sf shaft should be capable of handling as much torque as the ff. Some will make the argument that the ff shaft doesn't have to support the weight of the vehicle (which is true),, but they forget that the part of a sf shaft that supports the vehicle is 1.700" in diameter. You can look at this as being a 1.700" .150" wall tube supporting the vehicle with a 1.400" shaft transmitting torque through the middle, i.e. there is enough extra meat that loading capacity isn't a problem. This will be heresy on this site, but I bet the sf shaft can handle as much torque as a ff. The difference, of course, is that if you do manage to break the shaft you can still drive the ff

OK, long winded. Well, I'm going on a hunting trip in the morning, so I won't see any replies to my heresy for a week. Feel free to flame

IIRC, the 31 spline 9" shafts are just a hair, and I do mean just a hair smaller than a 14FF shaft

 

[blazinzuk]

More clearance with the 9" huge aftermarket support. If its out of a later full size truck its going to be a 31 spline super easy to set up gears on. I would go 9" They are a strong axle. The biggest disadvantage I see with a 9" is the low pinion entry. You need to get to know some Ford guys someone will have a 9" sitting around

 

[marv_springer]

9.5 SF

Cons: c-clip axle

Why is a "c-clip" axle a con....

I'd run the 9.5.

Marv

 

[ryan22re]

I dunno, I guess it's a con with the 10 bolts, but now that I have thought about it, not so much.

 

[big dan]

I say if youve got the wheels and parts to make the front 8 lug then grab a 14bff cause at least around here they are cheaper then the 9.5" but if you want to stay 6 lug then go with the 9.5". In the end I guess it really depends on the deal you can find on the axle cause Im sure the semi float could handle 35s with no problem. I think the 9" is out of the question if your looking for something cheap.

 

[Hogback Fabrication]

Here's some food for thought: The smallest diameter on a 14bsf shaft is 1.400", just behind the splines. The splines are 1.420", and about midway the axle necks up to 1.700". According to Pirate 4x4 (http://www.pirate4x4.com/tech/billavista/14b_bible/index.html, scroll down about 1/3 of the way) teh operating diameter of a 14b full floater shaft is 1.351".

I swear I have heard (and read) with no actual proof that FF 14 bolt shafts have some through hardening to them.

It kinda makes sense to me that FF shafts could be made with a different process than SF to achieve the same fatigue strength. Full floating shafts only need to sustain torque and could therefore be made of a different material with the same factor of safety at a smaller size. I believe I read that FF 14 bolt shafts are through hardened from the factory (almost bling) somewhere but I don't have anything to back that up I guess

The bottom line of what am saying is that I think the FF 14 bolt shafts are WAY over designed for what they are. There is a reason that the FF 14 bolt is considered unbreakable (up to 44" tires or so).

Its all pretty off topic but there is a reason that the Sf 14 bolt isn't as revered as the FF 14 bolt. No offense, but you aren't the first one to consider it as a reasonable replacement. It is the right choice for some people and the direction they choose to go with their truck.

 

[MaxPF]

I swear I have heard (and read) with no actual proof that FF 14 bolt shafts have some through hardening to them.

It kinda makes sense to me that FF shafts could be made with a different process than SF to achieve the same fatigue strength. Full floating shafts only need to sustain torque and could therefore be made of a different material with the same factor of safety at a smaller size. I believe I read that FF 14 bolt shafts are through hardened from the factory (almost bling) somewhere but I don't have anything to back that up I guess

The bottom line of what am saying is that I think the FF 14 bolt shafts are WAY over designed for what they are. There is a reason that the FF 14 bolt is considered unbreakable (up to 44" tires or so).

Its all pretty off topic but there is a reason that the Sf 14 bolt isn't as revered as the FF 14 bolt. No offense, but you aren't the first one to consider it as a reasonable replacement. It is the right choice for some people and the direction they choose to go with their truck.

Yeah, I don't really know what material the shafts are made of. OTOH, I also don't know of anyone who has ever broken a 14bsf shaft (granted, not many are in use compared to the ff), and numerous folks have commented that you will break a 1350 u-joint before you break a 14bsf. I don't know if that is true or not, though. Without performing destructive testing on them all we have are educated guesses... Still, I wouldn't be afraid to run 39-40 inch tires on a sf, and it should be essentially unbreakable with 37's.

 

[jonathon]

Are you trying to avoid going 8 lug? You can use a 6 lug 14bsf but the threads are different.. I'd just get a 14 bff with the gears you want and call it good.