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67MercCat 10-18-2011 07:43 PM

Ford 9 inch swap questions
I have a 65 Thunderbird 9 inch rear end that I want to drop into my cougar. The width is fine (inch longer than my 8 inch) and I'm already familiar with the fact that I have to cut off and reweld the spring perches. My next question is this...

1. Should I have grabbed the driveshaft too, so the u-joints match? (my current driveshaft u joint housing proves to be too small and too long)
2. Where do I find a compatible yoke for my T-5 to 9 inch driveshaft (aftermarket or pick a part) ?
Thanks guys

327NUT 10-18-2011 08:14 PM

Whomever builds your new driveshaft will be able to furnish the needed parts to adapt the T5 to the 9"

67MercCat 10-18-2011 08:23 PM

oh I see, I wasn't familiar with how that's done. So the driveline company I use will be responsible for all that. It's my first time doing this so that type of info is greatly I appreciated.

speedydeedy 10-18-2011 08:48 PM

Having a drive shaft made as stated is the best way,but if you have one the right length NAPA sells cross over ujoints that will let you use your shaft with a different yoke.I have done this many times when putting a Ford 9" in a Chevy.

67MercCat 10-19-2011 09:50 AM

cross over U joints? wouldn't that cause a balance issue?

327NUT 10-19-2011 11:00 AM

You're worrying way too much about these things, call a good driveline company and tell them your application and they will build you a properly balanced driveshaft that will mateup to your 9" and T5.

techinspector1 10-19-2011 11:22 AM

You may not have what you think you have. According to what I read, the diff you have is a 9 3/8", not a 9". They were a heavier duty diff used in the largest, most powerful Ford cars. I have come across them before in hot rodding. There are no aftermarket parts available for them like there are for the 9".

copied and pasted from ....
'63-77 Lincoln, LTD, and Thunderbirds had 9 3/8 inch centers, housings were cut away at the gasket surface for ring gear clearance, one curved rib at the front top portion of differential, strong but poor selection of axle ratios.

copied and pasted from ....
It also has a different pinion support, with a C8AW-B casting number.

copied and pasted from
1 - 3.00:1
4 - 3.25:1
5 - 3.50:1
6 - 2.80:1
A - 3.00:1 Equa Lock
D - 3.25:1 Equa Lock
E - 3.50:1
F - 2.80:1

cobalt327 10-19-2011 01:04 PM

Below is a photo of the Ford 9-3/8" rear end. The '65 T-Bird is said to have either the 9" or the 9-3/8" diff depending on the source, so it would be well worth your trouble to make sure before getting too far into it.

speedydeedy 10-21-2011 05:48 AM

No,the cross over joints do not cause a balance problem.They are correct about the 9 3/8" diff. I would do like tech and cobalt says and make sure you have a 9" because like it was stated there is no aftermarket support for the other one,only the 9". Hope this helps.

67MercCat 10-25-2011 10:16 PM

thx for the heads up guys but its a 9 inch. the case doesn't look like that one with the curved rib and plug...its has straight ribs and big spring perches (which I cut off today) whats the next step? buying new perches?

harleypc 10-26-2011 06:41 AM

Ford 9 inch
The 9 inch is the way to go, but be careful welding on the axle tubes, don't get them too hot and make sure the housing is square with the front wheels. There is nothing uglier than a nice looking car "dog tracking" down the highway..............pc

67MercCat 10-26-2011 08:07 PM

yeah man thats so lame, I always wonder what caused the car to look like its drive crooked haha. I'm going to use the leaf springs as a guide (for straightness) and I'm going to remove the current rear end and place the 9 inch rear end housing on the plates, adjust the pinion angle using an adjustable jack stand and tack weld them to the housing.

As far as the welding, I've been told to weld 1 inch at a time and switch from side to side in intervals to get around the heat issue.

I went to the driveline company today and they told me to bring in my current shaft and they'll shorten it to go from my T5

harleypc 10-27-2011 03:37 PM

Ford 9 inch
Hey, I would say you got it going on. We have done a bunch of those conversions and finally learned not to mess around with drive lines, its cheaper to pay somebody that has the proper equipment...good luck..pc

67MercCat 10-29-2011 10:37 PM

Any suggestions for a 4X4 supply where I can buy some perches for a good price? I've been searching and haven't come up with anything reasonable....

timothale 10-30-2011 08:22 AM

speedway ?
look in your speedway catalog or go to a trailer supply Co, The bigger ones have a lot of parts handy for fabbing rods , or a good steel supply co that has parts to build wrought iron fences, brackets drilled plates etc.

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