Ford 9 Inch Rear Swap

[Sweet 85 C10]

Coupele questions, what are some of your Ford 9 inch rear swappers doing with the drive shaft length and connection at the yoke. I have my original drive shaft and was wondering would I have to change the drive shaft joints for the connections at the rear end. Since its going fro my T400 to the ford 9inch rear will my orginal driveshaft work? Can someone help me out?

[Tagg33]

I'm not sure if this picture will help but I have the exact setup you described. My spare universal joint my dad bought me when he picked up my new drive shaft is a 2-3011HD. If this didn't help, I'm sure someone else will chime in that knows way more about it. This board is an amazing resource.

[Sweet 85 C10]

Thanks for the reply what I need to know is if I can use my original chevy Drivesaft with this Ford 9inch or is there somewhere I might need to purchase a different drive shaft?

[chevy_mike]

There are too many variables to say for sure. You have different pinion flange types (1310, 1330, 1350, widths, etc.) and I think the housing/flange is longer on the 9" over the Chevy rear end.

The only way to know for sure is to see if your u-joint matches the 9" you have and after the 9" is installed, measure the tranny output yoke and rear end.

You might get lucky, you might not.

[Skirkpat]

Just wondering why you would put a 9 inch in when a 9.5 inch 12 bolt was probably already there? Ease of gear swaps?

[grinch4om]

there's no comparison of 12 bolt to a 9". 12 bolts pinion have 2 bearings supporting the pinion. The 9" has a 3 bearings on the pinion,2 in front, one on the teeth end...much stronger. also, no C clips on the axles. I have a 10 bolt in mine and am putting in a 9". why would I search for an inferior axle? If I had a 12 bolt, I'd use it but since I have to swap, why not get a rear that is stronger and more versatile?.

[chevy_mike]

The truck 12 bolt rear end is just about as strong as a Ford 9" as the gear is 8.75". Eliminating the C-clips is fine, espeically if racing but good aftermarket axles (harder then stock) would be fine as well. Normal road use, you don't see that many C clips break.

The biggest advantage to the 9" is the ease to swap third members, so you can change gears at a drop of the hat.

Downside of the 9" is that it takes more HP to turn, typically 3-5% more then a GM rear end.

[Skirkpat]

Originally Posted by grinch4om

there's no comparison of 12 bolt to a 9". 12 bolts pinion have 2 bearings supporting the pinion. The 9" has a 3 bearings on the pinion,2 in front, one on the teeth end...much stronger. also, no C clips on the axles. I have a 10 bolt in mine and am putting in a 9". why would I search for an inferior axle? If I had a 12 bolt, I'd use it but since I have to swap, why not get a rear that is stronger and more versatile?.

Actually a stock 12 bolt is superior to a stock 9 inch, as far as not being comparable when built , I believe you are wrong, very marginal difference and to get where your 9 inch will compare you will need to step up to the nodular housing (assuming you do not have one already), upgrade your posi, and step up from the weaker 28 spline axles...I understand the change if you want gear selection, but to discount a 12 bolt on reliabilty or strength is not accurate. For the money needed to modify and be in the same league as the 12 bolt, I think I would just use C-Clip eliminators, and build the lighter and more efficient GM rear that bolts in. This is just my opinion, and either rear is a great choice, one is not far superior to the other though as I see it.
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[SCOTI]

12bolt truck rear housings & 12-bolt car housings are 2 different animals. The 12bolt car housing in perf trim is equal to the 9". The 12bolt truck housing has a smaller diameter pinion vs. the 12bolt car & 9" rears which ultimately equals failure before the other units in similar circumstances.

That being said, a truck driven on the street most likely won't have to worry about it. Slicks, a sticky track, & the right launch RPM.... that's when the concern escalates.

[Sweet 85 C10]

Wassup Guys! Thanks for all the feedback but my question wasnt answered. Do you think that my original stock drive shaft will fit this Ford 9 Inch? I will be trying to see if it does this week but im not sure also would you guys reccomend a slipe yoke drive shaft for a bagged truck application?

[SCOTI]

Originally Posted by Sweet 85 C10

Wassup Guys! Thanks for all the feedback but my question wasnt answered. Do you think that my original stock drive shaft will fit this Ford 9 Inch? I will be trying to see if it does this week but im not sure also would you guys reccomend a slipe yoke drive shaft for a bagged truck application?

If it was going into a completely stock set-up, I would say no, it will need to be changed as the 3rd member/pinion yoke are different lengths (from what I remember).

But.... I'm guessing your truck isn't stock sice your asking about the 9" swap. If the wheel base and/or engine placement was altered any, it may help or it could hinder the fit so only you can correctly answer your question.

[Sweet 85 C10]

Thanks for the feedback, and makes sense in what your saying but heres a little more info of what I got going on.

Raised Cross member
Small Block Chevy w/400T Trans
Ford 9inch Rear 58inches Long 31 Spline
Stock Driveshaft Chevy

I havent yet set up the transmission and engine in place just yet. Do you guys suggest that I wait until then to get whats needed for this? The truck is already bagged and setup was just curious to know from those that have done this conversion did you re-use the stock drive shaft or did a custom one get built?

[SCOTI]

Originally Posted by Sweet 85 C10

Thanks for the feedback, and makes sense in what your saying but heres a little more info of what I got going on.

Raised Cross member
Small Block Chevy w/400T Trans
Ford 9inch Rear 58inches Long 31 Spline
Stock Driveshaft Chevy

I havent yet set up the transmission and engine in place just yet. Do you guys suggest that I wait until then to get whats needed for this? The truck is already bagged and setup was just curious to know from those that have done this conversion did you re-use the stock drive shaft or did a custom one get built?

The raised c.member (SD's correct?) IIRC moves engine placement slightly forward. Did you center the 'new' rear suspension where it was originally located (rear axle tube center-line)?

I would recommend waiting until the parts are assembled within the frame before committing to a drive-shaft length. Make sense? It would suck to have to spend money twice because of too many unknowns.

[PBFAB.COM]

As SCOTI stated, the driveshaft should be measured/built/purchased after the drive-train (motor/trans/rear diff.) is installed. This will allow you to make an accurate measurement.

[Sweet 85 C10]

Hey Guys thanks for the replys and yes it all makes sense now. I will keep everyone updated on what I come up with.

So far I have tryed my stock shaft and it actually works on my differential as far as fitment. But as far as length etc I dont know yet.

[xtremedurb00]

Just came across this if anyone was interested. Havent looked into this much. I think I'm just going to rebuild and beef up my 12 bolt.
http://www.speedwaymotors.com/Bolt-I...cks,80935.html

[blazer2007]

They do make 2 different length pinion yolks for the 9 inch,that might come in handi.I,m swapping one in my blazer and with the longer pinion yolk it looks bang on so far.There seems to be lots of u joints to adapt different driveshafts with yolks.