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M/T vs. A/T Driveshaft in '69

27K views 35 replies 9 participants last post by  1969XR7Vert 
#1 ·
Anyone know off the top ot their heads if the driveshaft (itself) is the same between manual trans (SB toploader) and auto trans (FMX) on '69? I know the slip yoke is different but hoping the shaft itself is the same. Anyone?

I am fixing to compare the bellhousing/MT length to the FMX length for an answer but figured one of our members may already know.

Thanks in advance,

Bob
 
#2 ·
Think that they are different Bob.
I have a casting numbers book that lists two different drive shaft lengths for a 1969 Mustang with 351. FMX is about 10 inches longer than the manual transmission length. Slip yokes are different as you mentioned.
It looks like the yoke for a C4 is the same as for M3 and M4.

I have a 1968 Cougar with a factory 3 speed trans and the transmission on that one is a 2 piece shaft. Has a rubber section to it. Hard to explain. Not even sure that I still have it. Going to cut down a 1969 one piece drive shaft from an FMX to fit with the T5 and C4 yoke.
 
#3 ·
I believe they're different. Most manual trans shafts are two sections spliced with a rubber shock coupler. My 4 speed Torino is that way. I'm not positive about a Cougar.
 
#4 ·
CougarCJ said:
Think that they are different Bob.
I have a casting numbers book that lists two different drive shaft lengths for a 1969 Mustang with 351. FMX is about 10 inches longer than the manual transmission length.
10", that much? Just from memory, I didn't think they were that far off, will have to make the measurements I alluded to... I can't compare dirveshafts side by side as I swapped a 8 3/4" Mopar rear into my original MT car ('70 HT) and the driveshaft was custom made for that.

CougarCJ said:
I have a 1968 Cougar with a factory 3 speed trans and the transmission on that one is a 2 piece shaft. Has a rubber section to it. Hard to explain. Not even sure that I still have it. Going to cut down a 1969 one piece drive shaft from an FMX to fit with the T5 and C4 yoke.
That's funny, my "Bronx Cat" parts car ('69 XR7 HT) has the same deal, it's a sleeve in a sleeve arrangement with rubber in between the sleeves, kind of like the slip hub on a boat propeller or the rubber in a harmonic balancer. Anyone have insight into these beauties? Don't want to use that for performance and spin it! Strange how 2 '69's I have w/FMX have two different driveshafts.

I am going by gut here, but I really don't recall anywhere near 10" of a difference, if anything I would say by eye they are too close to call. Will investigate further. Thanks for the input though!!

Bob
 
#5 ·
My 1969 428CJ with 4 speed is a one piece drive shaft from factory.
Wonder if it was a vibration problem with 3 speed and 8 inch?
 
#6 · (Edited)
Mercougar67 said:
I believe they're different. Most manual trans shafts are two sections spliced with a rubber shock coupler. My 4 speed Torino is that way. I'm not positive about a Cougar.
Interesting about the rubber, but not in my experience (small sample size though!). My '70 HT w/3 speed MT had a one piece and a '69 HT w/FMX I currently have has the rubber deal! But then, you and CJ both have same to report. No clear pattern there so far (with my parts car in the mix). It doesn't sound like it is confined to MT cars only...

As for shaft length, you both say they're different :-( Guess a driveshaft shop visit is in my future (or a romp in a junk yard at least).

Thanks!

Bob
 
#7 ·
The MPC for 1969 Cougars lists 5 different driveshafts.
C9WY - A 53 9/16" 351 w/ FMX
C9WY - B 53 1/4" 351 w/ M/T
C8WY - B 49 41/64" 390/428 w/ C6
C7WY - B 53 1/32" 390 & B302 w/ MT
C8WY - A 53" 428 w/ MT
 
#8 ·
70B302Cat said:
The MPC for 1969 Cougars lists 5 different driveshafts.
C9WY - A 53 9/16" 351 w/ FMX
C9WY - B 53 1/4" 351 w/ M/T
C8WY - B 49 41/64" 390/428 w/ C6
C7WY - B 53 1/32" 390 & B302 w/ MT
C8WY - A 53" 428 w/ MT
Thanks Dave, I thought they were close. Good news is the AT is longer of the two and I may be able to get away with it, or have it shortened if need be. Thanks again!

Bob
 
#9 ·
Some thoughts:

Yes, MT is a little shorter. You might want to inquire about cost difference between shortening an existing shaft or having one fabricated. By the time they cut, weld, replace u-joints and balance, you're getting close to a new one. I believe I paid $30-$40 more for new one than having the old one fixed - plus you get that spanking new look....

One thing to consider: take the actual measurement. If the third member was ever replaced, the pinion yoke might be a little longer/shorter - depending on what the member was pulled from.

If you plan on using a console, the auto consoles work just fine. There is a difference between factory 4sp and auto consoles, but I haven't had a problem with either one of mine, and they were switched out long ago...People have claimed you need the 4sp console, but I haven't found that to be the case, either factory shifter or Hurst Comp +.

David Kee (I believe www.davidkee.com) is an excellent vendor for tranny parts, such as yokes.

I've converted two 4speeds from FMX's. It's relatively easy - with the two hardest pieces being aligning the hole (and drilling/cutting) the firewall for the clutch rod and getting the right mounting bracket for the shifter - it's that easy - if you have the parts.

Hope this helps! And have fun!

Rod
 
#10 · (Edited)
Elroy said:
Some thoughts:

Yes, MT is a little shorter. You might want to inquire about cost difference between shortening an existing shaft or having one fabricated. By the time they cut, weld, replace u-joints and balance, you're getting close to a new one. I believe I paid $30-$40 more for new one than having the old one fixed - plus you get that spanking new look....
The shop I have used in the past quote: $275 for a new one, $40 to change an end, $40 to balance, cheaper to fix up a used one in the case of this shop anyway.

Elroy said:
One thing to consider: take the actual measurement. If the third member was ever replaced, the pinion yoke might be a little longer/shorter - depending on what the member was pulled from.
Original differential, changing center section but believe yoke is the same size, so MT shaft should be correct. BTW, amazing that there were 4 driveshaft lengths in 69 Cougar, all within a 9/16" range of length. Then there are thr rubber coupled versions which (as of yet) are not differentiated from the solid ones. Will check fit before doing anything. Original FMX driveshaft will be starting point for MT since my original MT driveshaft was modified to sit in front of a 8 3/4" Mopar rear.

Elroy said:
If you plan on using a console, the auto consoles work just fine. There is a difference between factory 4sp and auto consoles, but I haven't had a problem with either one of mine, and they were switched out long ago...People have claimed you need the 4sp console, but I haven't found that to be the case, either factory shifter or Hurst Comp +.
Yep, using AT console, actually insert is the only thing different, but not different enough to bother getting a MT one (unless the chrome on mine is too rough).

Elroy said:
David Kee (I believe www.davidkee.com) is an excellent vendor for tranny parts, such as yokes.
http://www.4speedtoploaders.com/ is the correct link. There are two 28 spline yokes, a 1310 and a 1330, maybe this the OD of the yoke? Have an email into Dave on this.

Elroy said:
I've converted two 4speeds from FMX's. It's relatively easy - with the two hardest pieces being aligning the hole (and drilling/cutting) the firewall for the clutch rod and getting the right mounting bracket for the shifter - it's that easy - if you have the parts.
What did you do about driveshafts in the ones you did?

I found the firewall actually has a dimple for the clutch rod punch out, so that should be relatively simple, hope to find and use a greenlee chassis punch to get that done, better than using a unibit or what have you.

On the shifter, have a complete comp+ setup w/brackets, should be all set. Wouldn't think of using an original, too sloppy (originality not a great concern with this resto). Have all the parts from a previous car.

One more question (since we've gotten into the nuts and bolts of the changeover here). I have not verified this for sure yet, but it appears that the threads (5/16" rivnuts?) for the chassis side Z Bar pivot may not be there on this AT car. Haven't gotten a good look yet (dirt, grease and engine still in), but thought I saw an empty hex hole in the frame rail. Hope I am wrong and this was something else (not the pivot bolts holes). If I am not wrong, anyone know of a source for correct 5/16" threaded frame fasteners? If not, I am looking at some sort of weld a nut in and grind down to flush...

Thanks Rod.

Bob
 
#11 ·
1969XR7Vert said:
http://www.4speedtoploaders.com/ is the correct link. There are two 28 spline yokes, a 1310 and a 1330, maybe this the OD of the yoke? Have an email into Dave on this. I belive it's the width of the cradle that's the difference and how the u-joint is mounted.



What did you do about driveshafts in the ones you did?


One more question (since we've gotten into the nuts and bolts of the changeover here).

Bob
I believe I just paid $120 for a new one. I supplied the two cradle end caps - maybe that was the difference.

The difference in yokes is the cradle size and how the u-joints are mounted. Measuring old one will help here - or measure the cradle end cap.

Driveshafts: One I believe came from an original M/T, and the other was fabricated.

The big question: clean up a little grease/dirt on top of the frame rail and you will find the welding in nuts in the frame rail just below and to the rear of the gearbox. Frame was made to be generic and it had them in case it came down the line with 4speed intentions..

As you found out, the two hardest pieces I mentioned were not that hard at all - which makes this job an easy one for all...they weren't that hard for me, just the two where I had to scratch my head a little. The wrong mounting plate can throw off the angle of the shifter just enought to bust knuckles on the dash when throwing into third...

Glad you have all the pieces. Some of the zbar linkage components are starting to dry up...

The auto reverse light wires will hook up just fine also. You probably will have to change the speedo cable too - the M/T are about 5" longer and the extra length is needed.....

One thing you didn't mention, but will cover: the best gearing, IMHO, is the 3:50 for this setup. I tried 3:91's, but pulled them right back out because they were not a travelling gear, too much loud whine going 60...

Again, glad this is working out for you!

Rod
 
#12 ·
http://www.4speedtoploaders.com/ is the correct link. There are two 28 spline yokes, a 1310 and a 1330, maybe this the OD of the yoke? Have an email into Dave on this.
The 1310 series joint is your standard Ford/Chevy external lock joint that came on 85% (+/-) of the Cougars

A 1330 joint came on CJ cars and is slightly larger than the 1310.

BTW, you can get a long or short pinion yoke to jockey the length + or - an inch.

I used a 27" toploader on my 68, was able to use a stock length 68 Mustang CJ shaft with a short 1330 pinion yoke.

If you're replacing a C-6 with a long (27") toploader you can keep your same driveshaft.
 
#13 ·
Elroy said:
I believe I just paid $120 for a new one. I supplied the two cradle end caps - maybe that was the difference.

The difference in yokes is the cradle size and how the u-joints are mounted. Measuring old one will help here - or measure the cradle end cap.
Right you are, David Kee called me earlier about this. BTW, his prices are very good.

Elroy said:
Driveshafts: One I believe came from an original M/T, and the other was fabricated.
Maybe a silly question, but do you happen to know the length of either or both of these?

Elroy said:
The big question: clean up a little grease/dirt on top of the frame rail and you will find the welding in nuts in the frame rail just below and to the rear of the gearbox. Frame was made to be generic and it had them in case it came down the line with 4speed intentions..
That is good to hear, I kind of thought the same thing, but when I saw a hex hole in the frame rail in that area, I became worried. Hopefully those fears will be unfounded. Engine coming out tonight and should be easy to see then.

Elroy said:
As you found out, the two hardest pieces I mentioned were not that hard at all - which makes this job an easy one for all...they weren't that hard for me, just the two where I had to scratch my head a little. The wrong mounting plate can throw off the angle of the shifter just enought to bust knuckles on the dash when throwing into third...

Glad you have all the pieces. Some of the zbar linkage components are starting to dry up...
Actually, I seem to recall a knuckle incident somewhere in the past. Will have to watch for this. I plan on perhaps changing the shifter arm angle (or using a different mechanism as I mentioned). As for Z bar stuff, it's all been broken and fixed/reinforced from past trouble resulting from a monster springed Long style clutch. Bought a diaphragm and am expecting great things...

Elroy said:
The auto reverse light wires will hook up just fine also. You probably will have to change the speedo cable too - the M/T are about 5" longer and the extra length is needed.....
Have a Hurst unit at the ready and a MT speedo cable, MT port is on passenger side, how to properly dress the cable?

Elroy said:
One thing you didn't mention, but will cover: the best gearing, IMHO, is the 3:50 for this setup. I tried 3:91's, but pulled them right back out because they were not a travelling gear, too much loud whine going 60...
Guess what the new pumpkin I have ready to go has in it? 3.50. I used to run 3.23 (too high), then 4.10 (too low), hoping 3.50 will be "just right"! BTW, what speedo cable gear you using? Purple as I recall is the right one, but going from memory, forget the # of T, I will be running larger tires though, so who knows...

You the man Rod! Thanks so much for the detailed info.

Regards,

Bob
 
#14 ·
Art said:
The 1310 series joint is your standard Ford/Chevy external lock joint that came on 85% (+/-) of the Cougars

A 1330 joint came on CJ cars and is slightly larger than the 1310.
Thanks Art, yes, David Kee: 1310: 3 3/32" cap to cap, 1330: 3 5/8" cap to cap. I expect I have the 1310.

Art said:
BTW, you can get a long or short pinion yoke to jockey the length + or - an inch.
Godo info, thanks!

Art said:
I used a 27" toploader on my 68, was able to use a stock length 68 Mustang CJ shaft with a short 1330 pinion yoke.
My small block toploader is 25" flange to end of output shaft.

As it turns out, "stock length" is a nebulous term! See Dave's post on the driveshaft lengths.

Art said:
If you're replacing a C-6 with a long (27") toploader you can keep your same driveshaft.
Nope, but do have hopes of keeping the same FMX driveshaft. We'll see...

Very enlightening, thanks once again guys.

Bob
 
#15 ·
Bob -

To answer two of your questions:

I just wire-tied the speedo cable and reverse light wires together and looped them over the top of the bell on the right side, away from any linkage.

Driven gear: I'm glad you said "purple" as that's what it was. I think purple is a 19, but I can definitely confirm purple....I actually bought a couple different ones from Ford and tried. I wasn't too succesful with the formula. I figured a $7 investment for each a 17,18, and 20 was worth it - then I had them - which, BTW, you can still get from Ford. If I remember, the difference from one to the other was about 3 mph's, roughly.

The third question: I could measure the driveshaft lengths for you (along with pinion shaft length) if it would help. I'll be under the Coupe tonight putting in headers.

If I were "the man", I would know how to split up "quotes" like you do....

Us 69XR7Verts need to stick together....

Rod
 
#16 · (Edited)
Here is a good upgrade to the stock clutch shaft bushings. It is a wider bushing that replaces those stock ones on all brake equalizer brackets. Even Cougars and Mustangs with the automatic have bushings installed for a manual transmission application.

These come with two bushings, snap rings to hold and the bushing sleeves.
These wider bushings allow more contact space on the clutch shaft.
It is a Scott Drake part, I sourced mine through the SoCal Cougar Connection. Brian had the best prices. Call him at (760) 233-2277.

There is also a needle bearing bushing kit offered, but it costs a buck twenty or more. With shipping this one was under $25 in 2004.
 
#17 ·
CougarCJ said:
There is also a needle bearing bushing kit offered, but it costs a buck twenty or more. With shipping this one was under $25 in 2004.
Actually, the needle bearing kit w/shaft is only $49.95 (C5ZZ2478RBMK) and $34.95 (C5ZZ2478RB) w/o the shaft, both from MU. I bought and installed one in the pedal bracket already, works super!

How do these prices compare to Brian's? Just curious.

Thanks,

Bob
 
#18 ·
1969XR7Vert said:
Actually, the needle bearing kit w/shaft is only $49.95 (C5ZZ2478RBMK) and $34.95 (C5ZZ2478RB) w/o the shaft, both from MU. I bought and installed one in the pedal bracket already, works super!

How do these prices compare to Brian's? Just curious.

Thanks,

Bob
I did not know that these were available other than from the original source. That is good to know. I guess that I will have to wait 40 more years to get that set up when these wear down, but then I will not likely be driving. Brian's pricing is much better than other sources because he has such little overhead.
 
#19 ·
Elroy said:
The third question: I could measure the driveshaft lengths for you (along with pinion shaft length) if it would help. I'll be under the Coupe tonight putting in headers.
That'd be great if you have a chance. I'll be yanking the old 351W in prep for major body surgery (inner rockers/cowl transplant).

Elroy said:
If I were "the man", I would know how to split up "quotes" like you do....
That's easy Rod. What you do is when you hit "Quote" to reply, look for the {quote=XXXXX} and {/quote} html tags and copy and paste them around each thing you want to quote (The "{" and "}" are actually "[" and "]" and the XXXX is the name of who you are quoting). The posting starts out as just one set of the bracketed html thingies on the whole thing you are quoting. Each pair of these tags you add makes a separate quote and you put your comments after a {/quote} but before the next {quote=XXXX} Hope that makes sense.

Elroy said:
Us 69XR7Verts need to stick together....
I'm in, I'm in!!

Bob
 
#20 ·
Rubber Isolated Driveshafts

As an aside or in a related question:

Anyone have any knowledge on these rubber isolated driveshafts? Some cars come with a tube in a tube driveshaft which has a rubber isolator bonded in between.

It has been suggested to me that these driveshafts are for MT cars only and they are required, something about dampening the direct coupling between the engine, trans and rear on a MT car (besides the springs in the clutch disk hub).

While this makes sense to me on some level, two of the three examples I have to draw from do not support the notion:

- The '70 HT w/factory 3 speed MT had a solid driveshaft

- One of the two FMX '69's I have has the rubber isolated shaft while the other does not.

I plan on running a solid driveshaft, but could theoretically run either. The driveshaft place I may end up needing to use suggests that regardless of what they were intended for, do not use one, they (as I suspected) separate, just as a harmonic balancer slips or a boat prop spins its hub.

Just out of curiousity, anyone have some insight into or the rhyme and/or reason behind the use of theses driveshafts?

Bob
 
#21 ·
Bob -

Here are the measurements from the coupe:

Tranny : 24 1/4"
Shaft : 53 7/8" end of cradle loop to end of cradle loop
Pinion Yoke: 4 3/8"

I didn't take the measurement for the slack in yoke, but guessing right around 1".

The pinion yoke probably isn't original, so length could be reason the shaft is very, very near the measurement of the FMX shaft length...that surprised me.

And to previous post, I haven't experienced any issues with a non rubber split shaft.

Also, seeing that you're from NJ, I certainly hope you are not a Giants fan with all this help! Originally being from NE PA, us Eagle fans look a little leary towards the Giant fans...:beer:
 
#22 · (Edited)
Elroy said:
Pinion Yoke: 4 3/8"

I didn't take the measurement for the slack in yoke, but guessing right around 1".

The pinion yoke probably isn't original, so length could be reason the shaft is very, very near the measurement of the FMX shaft length...that surprised me.
Thanks Rod, will check shaft length against the ones I have. The pinon yoke, what protrudes from the front of the differential carrier right? I am confused by what you mean by slack in that? I take it from your explanation that your pinion yoke would be shorter then resulting in a longer driveshaft (close to or FMX length).

I think the way the lengths are specified are not end to end of the driveshaft (apparently cup center to cup center?), I found mine to be longer than any of the lengths that Dave posted from his MPC.

Elroy said:
And to previous post, I haven't experienced any issues with a non rubber split shaft.
Me neither, I ran solid one for many years without issue.

Elroy said:
Also, seeing that you're from NJ, I certainly hope you are not a Giants fan with all this help! Originally being from NE PA, us Eagle fans look a little leary towards the Giant fans...:beer:
Who are the Giants? For that matter, who are the Eagles? Is that a sports reference? Yes, Rod, you are talking to a bonafide motor head. I honestly do not the have time or inclination to sit around and watch TV almost at all, let alone sports! I would go to a game in person though, haven't done that is while...

Have a great weekend and thank you for your ongoing interest and help.

Bob
 
#23 ·
Bob -

Sorry for the confusion.....yes, the pinion yoke is the piece protruding from the third member. Sometimes these come in different lengths, depending what application the rear came from (only issue is if the third member has been a transplant).

The slack in the yoke that I was referring to is the slack between the driveshaft yoke and the tranny rear. You need the slack so the driveline doesn't bind as the suspension moves (up and down, and when rear rotates a little when you plant the tires...) - part of the yoke sleeve that is showing.

Have a great one!

Rod
 
#24 · (Edited)
Elroy said:
Sorry for the confusion.....yes, the pinion yoke is the piece protruding from the third member. Sometimes these come in different lengths, depending what application the rear came from (only issue is if the third member has been a transplant).
Thanks for the clarification Rod.

Elroy said:
The slack in the yoke that I was referring to is the slack between the driveshaft yoke and the tranny rear. You need the slack so the driveline doesn't bind as the suspension moves (up and down, and when rear rotates a little when you plant the tires...) - part of the yoke sleeve that is showing.
Gotcha, thanks.

Last question (and I think I already know the answer): "end of cradle loop to end of cradle loop" basically means the length of the extremities of the driveshaft, from one extreme to the other, which is the outside edge of one hole that the U-joint cup goes into to the same thing on the other end, correct?

Amazing how hard (at least for you and I) it is to describe the part of the driveshaft we are talking about! There must be a more succinct description, but I don't know what that would be...

Thanks again Rod.

Bob
 
#25 ·
1969XR7Vert said:
Last question (and I think I already know the answer): "end of cradle loop to end of cradle loop" basically means the length of the extremities of the driveshaft, from one extreme to the other, which is the outside edge of one hole that the U-joint cup goes into to the same thing on the other end, correct?
You are correct!

1969XR7Vert said:
Amazing how hard (at least for you and I) it is to describe the part of the driveshaft we are talking about! There must be a more succinct description, but I don't know what that would be...
Next time, maybe pictures......

Rod

Ps - notice that I split up the quotes this time??
 
#26 ·
Alles klar, Herr Kommissar!

Good Job on all Rod (and you learned how to quote in parts, very good!).

I will confirm tonight, but I am pretty sure (going by what you reported) that the FMX driveshaft is the right length (wouldn't that be nice).

You have been a tremendous help. Thank you for your willingness to provide information and the time it took to get and report it, it is very much appreciated.

:beer:

Bob
 
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