F1 Front drive shaft yoke

[B_man_Al]

Does anyone have a picture of an F1 driveshaft inserted into a 3 speed transmission?

I had a drive shaft made for my F1, and the machined portion of the front yoke spline sticks out from the end of the transmission by about 2 1/2 in with the differential connected.

The total length of the splined portion is about 3 1/2 in. They left a 1" slip allowance.

When fully bottomed, the yoke sticks out about 1 1/2 in. The output shaft on the transmission extends about 1 " beyond the end of the transmission, so the total engagement is about 2". Does this seem right?.. it seems to stick out a long way past the transmission ( 2 1/2")?

Is a 2" engagement enough to keep the drive shaft running true on the splines?

Thanks Al

[jimvette59]

Are you replacing the original drive shaft or did you have a special one made ? What did you give the drive shaft shop for measurements. Remember the rear needs to travel. I would like to see another half inch in the transmission but your setup should work. IMHO

[B_man_Al]

jimvette59 ... I asked for a driveshaft that was 61 7/8" long (ceter of u joint to center of u joint, with 3/4 " of slip. It came out closer to 61 5/8", with about 1" of slip.

I had it made because there was no power train in the truck when I got it, but it is "stock" setup with an 8Ba and a 3 speed top loader.

[4t8v8]

My stock shaft had 1/2 - 3/4 inches of slip when sitting on the tires unloaded. When I installed my T5 had the new shaft built with the same slip. Yours should work ok if you don't have too much wear on the inside of the yoke. With no more spline contact than you have it could vibrate. Not guessing - experience. Thought I'd never find the vibration.

[Barry-ct]

Ford part number was 21C 4841 for the slip yoke.
Overall length of the shaft, minus the yoke should be 64-7/16 inches. THat's from outside to outside, not center to center of the u-joint like nowadays.
THe yoke measures from center of u-joint to end of splined end 5-1/8 inch. Spline should be full length of inside length of yoke.
Yoke is 1-1/2 OD . From snap ring to snap ring groove is 3-15/32", 16 splines, U-joint cap is 1-1/16 " OD. Spline ID is 1-1/32 and OD is 1=11/64" . Spline has 1/8 " spacing.
All this info is for an F-1 with a LD 3 speed trans. THere were some with the HD 3 speed, which had a different yoke.
Hope this helps

[RMR&C]

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It should work fine, I had the same setup in mine. Those 3 speeds have a short output shaft and yoke.

[Ross F-1]

This is where mine sits. The arrow points to the point it travelled to in normal driving (not fully loaded). Over an inch of travel available.

[B_man_Al]

Ross F-1 ... I will post a picture of mine tomorrow. Yours looks to be about an inch further in than mine. That is what I was concerned about.

I took it for its first ride today (no cab, or front clip etc) . It seems to work OK, don't see any wobble, but I'm not going fast enough to create any vibration.

The front yoke is what the TX shop found, based on my output shaft and oil seal dimensions so I don't know if it is a Ford part , or something else .... but it fits in the hole OK.

As I said earlier, the "shiney" part on the yoke is about 3 1/2" long, and about 2 1/2" is showing when it is connected to the differential.

As an aside, there is a lot of movement in and out as you accelerate, and decelerate of the yoke. .... probably an inch in total.

[Ross F-1]

Believe it or not, certain powerglide yokes are the same spline and OD, and about an inch longer. http://www.dennysdriveshaft.com/c75_general_motors.html
That is how MTFlat adapted a 9" to his F-1.

[B_man_Al]

Ross, Barry ...
Here is my setup without a cab or front clip. As you can see it is about and inch further out than yours. Barry ... the slip yoke I have is about 4 1/2 in from center of U joint to end of splines.

[Fibber Mcgee]

Wow,that looks awful long to me....

[Ross F-1]

Yep, I wouldn't drive it like that! If the end of the splines gets past the seal, you'll be in a world of hurt, and it looks like that could happen. I'm afraid adding an inch or so the the DS is going to be expensive, too, I needed that and was told the only right way was a new tube.

[mtflat]

Originally Posted by Ross F-1

Believe it or not, certain powerglide yokes are the same spline and OD, and about an inch longer. http://www.dennysdriveshaft.com/c75_general_motors.html
That is how MTFlat adapted a 9" to his F-1.

Mine was sorta like that.

I have the 3 spd HD trans which uses a driveshaft like the F2/3. The output shaft has the U-joint bolted to it which puts the slip joint on the front of the driveshaft. This makes adapting rear ends infinitely easier than what you guys have to go thru.

I picked up a longer slip joint/yoke at a local driveline specialty shop and it was made there I believe.

[Ross F-1]

Sorry Tim, I didn't realize that. Maybe I'm thinking of someone else? As I recall the Powerglide yoke is 6" long. That's still not an ideal solution because of the overhang on the output shaft.

[B_man_Al]

Maybe I asked the wrong question at the beginning of this thread. What I should have asked is if anyone knows how deep the slip yoke can go into the back of the transmission before it bottoms out. Mine appears to be only about 2 inchs or so. Unless I have something internally interferring with it, when fully bottomed I have 1 1/2" of slip yoke visible protruding beyond the seal. The output shaft extends beyond the seal by about 1". So at best there is only about 3 in of engagement with no slip allowance.

After making allowance for say 1" of slip, that makes the minimum engagement only about 2" ... not very much as you have indicated. The end of the yoke is very close to coming out of the seal, and the only thing left is the portion of the output shaft that extends beyong the seal.

[Ross F-1]

I'd swear mine goes in until the yoke hits the seal face. I wonder if your speedo drive gear has come loose? There's a snap ring that holds it in place, as well as the rear mainshaft bearing. It came out of the groove on mine, let the speedo gear slide back 1/2" or so.

[B_man_Al]

OK .... maybe that's it. I'll check it tomorow. Gonna be some pissed off if I intentionally bought a "short" drive shaft.


Thanks
Al

[Mike B]

I went and measured a F1 shaft I have, weld to weld on the tube is 60 inches...I had cut it off at the front weld, so can't measure U-Joints to U joint...but yours appears to be shorter than factory shaft.

[B_man_Al]

Ross ....

I think we are on the right track now. I looked back at some measurements I made on the output shaft when I was re-doing the transmission. From the back of the C clip to the end of the splines is about 3.3 in. Therefore if nothing is stopping it, the yoke shoud go in 3.3 in. not the 2" I'm getting. Either there is something in the transmission stopping it , or the yoke I have only has 2" of splines ........ The plot thickens!!

[DD931]

When I traded a four speed for a regular 3 speed in my avatar '48 F-1 I had to change the mount, u-joint, yoke and driveshaft. When I went looking for the driveshaft I consulted the Ford truck parts manual which also showed the length I needed (I'd look it up but the books aren't available to me right now). I found what I wanted leaning against a barn in rural Maine - you have to keep your eyes open in this hobby! I strongly recommend that you consult the Ford truck parts book(s). It all went together fine and does not show the long length of machined surface that yours does.

[Ross F-1]

Here's a pic that should clarify... plenty of shaft there

[B_man_Al]

Ross .... After all of this, I'm coming to the conclusion that its the way Henry wanted it. Ross from your picture, the visible length of spline should be 3.35 or so. I confirmed by taking off the drive shaft and then inserting a fine long screwdriver into the end until it hit the C clip. The distance was 3 3/8.

When the mount is installed on the back, there is only 1 " of shaft visible . So from the time the yoke meets the seal, there is only another 2 .3 left before it bottoms. It seems then that my yoke must be longer than yours or an original.

Based on this I get a nominal overlap between the yoke and the output shaft of about 2.25, going up to 3.25 if it bottoms.

At the other extreme, if the yoke moves out by .75”, there will still be about 1.5” of engagement, but will be very close to coming out of the seal . Don’t like it but the only way to correct is to reduce the slip allowance

The yoke moves inwards on acceleration, and outwards on deceleration, or in reverse.

[Ross F-1]

I can't really measure now, but here's what mine looks like assembled. Looks a little more than an inch, not much tho.

[B_man_Al]

Ross ..... Yes it is over an inch. I just noticed my 1 in measurement is because my rear seal is not fully bottomed! See my pic on this thread . Guess I forgot to replace it with a new one when I did the rebuild and just left the old one in there loose. Dam .... this makes it even worse for the possibility of it coming out on deceleration!!!!

[Ross F-1]

There is a different seal, from a C4 maybe? that has a rubber boot over the exposed part of the splines, and a flange that sets it right at the back of the housing, that can be used. A friend got it based on measurements at a Carquest shop, but he doesn't have the number. I think I will try to find it next time I need one. Not sure it would help you as the actual seal is still about flush with the face of the housing.

[RMR&C]

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Hi Ross, that was me that used the Powerglide yoke. I used it to take up the slack from the 9" install. Seemed to work fine with no vibes till I put the T-5 in. Pic below of PG and stock yokes...

[B_man_Al]

RMR&C .... You wouldn't happen to have any measurements of these 2 yoke lengths?

I think I can come pretty close from the pics, assuming the joints are 1310's. A 1310 yoke measures about 3 1/2 OS to OS, and 2 3/8 IS-IS in width at the joint.

[Ross F-1]

http://www.summitracing.com/parts/str-u1661

Not sure if this is the exact one.

[RMR&C]

Originally Posted by B_man_Al

RMR&C .... You wouldn't happen to have any measurements of these 2 yoke lengths?

I think I can come pretty close from the pics, assuming the joints are 1310's. A 1310 yoke measures about 3 1/2 OS to OS, and 2 3/8 IS-IS in width at the joint.

Pretty sure the PG yoke required a conversion u-joint, inside clips on it? Will have to check.

[RMR&C]

Originally Posted by Ross F-1

http://www.summitracing.com/parts/str-u1661

Not sure if this is the exact one.

I think that would work, has the right U-joint too...

[Ross F-1]

I'd want to check the OD and spline count, there are a couple of flavors of PG output shafts.

[B_man_Al]

That one is spec'd at 27 splines ... need 16?

[Ross F-1]

This should tell you everything you need to know, not sure it's much longer tho

http://www.dennysdriveshaft.com/p304...line_5_in.html

[B_man_Al]

Ross/RMR&C .. The stock yoke shown on the right works out to about 2.75 in of machined length on the yoke, assuming the OD is 1.5". Ross this would explain why your "stock" yoke will bottom on the back of the transmission.

[F1Resto]

I have my driveshaft out of the truck (49 F1) that I am rebuilding. I have redone the trans already. Have not found a new front yoke, but as folks point out, there is a chevy yoke for the powerglide that can be mod'd to work. I have not found one yet, but did find one with different u-joint. But, if it would help, you can email me at [email protected] and I can send some photos and dimensions of the original shaft and the yoke.

[B_man_Al]

RMR&C ... Do you know if your "stock" yoke allows the output shaft splines to stick out past the U joint end of the yoke?. If not , and the barrel length is around 2 3/4 ( from photo), it can never bottom on C clip inside the transmission. Looks like around 5/8 min spacing. This really makes it very close to the seal, even at nominal without any allowance for slip during deceleration.

[Ross F-1]

There is a dome-shaped plug in the joint end of the stock yoke's splines that seals the splines against dirt. That would prevent the splines from sticking out into the joint, too.

[RMR&C]

Originally Posted by B_man_Al

RMR&C ... Do you know if your "stock" yoke allows the output shaft splines to stick out past the U joint end of the yoke?. If not , and the barrel length is around 2 3/4 ( from photo), it can never bottom on C clip inside the transmission. Looks like around 5/8 min spacing. This really makes it very close to the seal, even at nominal without any allowance for slip during deceleration.

I swapped in a T-5 trans so my old driveshaft and trans are in storage. If I remember....The shaft bottoms in the yoke before it can touch any thing in the trans . When I replaced the seal I didn't drive the seal into the bottom of the housing, I just squared it at the outer edge. That moves it out about 3/4".

The stock yoke has 3" of spline and 2 3/4" seal surface
PG yoke has 4 1/4" of spline and 3 3/4" seal surface

The PG yoke that I have uses a U joint with inside clips.

[B_man_Al]

Here are the details of the yoke shown in my post. It is a SPICER 2-3-1331X.

[Ross F-1]

Do you mean your stock yoke?

[B_man_Al]

No this is not a "stock" yoke. Its the one the TX shop found for me and is shown in post #10. It is very similar to the one you referred to in post #33. Same barrel length, but 1/8 shorter.

[Ross F-1]

I went for a drive in my truck last night, after a monthlong hiatus (out of town). Funny what a fresh perspective does... On a highway with a 55 mph speed limit, as soon as I got above 45 - 50, I could distinctly feel the driveshaft vibrating. Got under there today, I don't see anything wrong. I had the driveshaft balanced < 500 miles ago, all new U-joints. I'll check the pinion and trans angles, that's all I can figure. I measured the as-sitting length of yoke from the face of the seal/trans, it came out at 1-5/8". Yippee, my seal appears to be shot, too...

[B_man_Al]

Hi Ross…. Is that a “good” yippee or a “bad” yippee. Attached is my understanding of how an original yoke and transmission mesh together based on the tech info I received from Steve, Ross ,Scott and others. Thanks all very much. Ross your 1-5/8” visible nominal agrees very well with my 1.7”, as I referenced the back of the casting on the transmission rather than the end of the seal.

[jimvette59]

Originally Posted by B_man_Al

jimvette59 ... I asked for a driveshaft that was 61 7/8" long (ceter of u joint to center of u joint, with 3/4 " of slip. It came out closer to 61 5/8", with about 1" of slip.

I had it made because there was no power train in the truck when I got it, but it is "stock" setup with an 8Ba and a 3 speed top loader.

The drive shaft in my 34 was like that and presented no problems.

[Equipped28]

Did anyone get a definite yoke or one that needs shortening for these that are easily available? As I've just picked up one of these boxes and need one. Thanks Harley

[1948F-1Pickup]

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Originally Posted by Ross F-1

There is a different seal, from a C4 maybe? that has a rubber boot over the exposed part of the splines, and a flange that sets it right at the back of the housing, that can be used. A friend got it based on measurements at a Carquest shop, but he doesn't have the number. I think I will try to find it next time I need one. Not sure it would help you as the actual seal is still about flush with the face of the housing.

Old post, but here's the seal number..... National 7692S
https://www.amazon.com/National-7692.../dp/B004A6V072