Jayycobb

This is a pic of my driveshaft yoke, the line is where the yoke sits in the transmission when the suspension is loaded, its 1.5" from the line to the end of the yoke and 1.5" from bottoming in the transmission, does this shaft have to be lengthened? Keep in mind my car is a 71 cutlass with a TH400 transmission (not sure what the driveshaft is out of) and a 68 Buick Gransport Rear axle.

svnt442

If it needed to be longer you'd know it. I sure did. It TORE UP my yoke and I had to get a new one when I had the new shaft made.

Jayycobb

Hmmm, Havent driven the car yet, still building it... I kinda dont want to find out the hard way but also dont want to pay $400 to have the shaft lenghened 1/2" if I dont have to...

Rickman48

That yoke itself looks a little short, to me.
And that grey crap looks like engine oil and water mix - is the rear seal on the trans bad?
I'd look around for a longer yoke -

svnt442

I kinda looks like the yoke was cut down at some point like instead of shortening the shaft they just cut off the end of the yoke.

And I had a completely new shaft built with a replacement yoke for $325.

Jayycobb

Who did yours? Was that including shipping? The setup in this car before was a 1971 cutlass rear axle with a th400, so they prob needed it to be shorter? not sure...

Jayycobb

Where would I be able to find a longer yoke, do you know someone i could speak to on the phone about this? Im guessing I need about a 1/2" longer yoke, arent there stock yokes that are a bit longer?

When you say rear trans seal, did you mean to say rear Main seal, like on the engine? just wondering

507OLDS

There are a wide variety of yoke lengths for the TH400.You also need to see where the splines stop inside.Some are splined to the end,but some don't start the splines until about an inch or so down in the barrel,so you need top make sure you have good spline engagement.
A 68-72 Cutlass/442 2-door,with TH400mand 8.5" 10-bolt rear,will have a driveshaft that is 53 1/4" from center of u-joint,to the center of the other u-joint.If you have the BOP 8.2" rear,then your driveshaft should be 53 3/4" center to center.

What does your existing driveshaft measure right now?

Jayycobb

I will measure it tonight, if I had to guess its prob the 53 3/4" since the rear that was in it with no shaft problems, noises/ engagement issues was an 8.2" 10 bolt BOP... Who can I order yokes from? Just brainstorming here, doesnt the shape of the u joint side of the yoke determine "more" or "less" engagement in the trans? It would have to be closer to a "Y" than a "U" to get the U-joint to act like the shaft is longer... Do you know what I mean? Because There is only so much the yoke can go into the trans before it hits a wall. Man, this stuff sounds pretty funny, shafts, holes, being too long to fit before hitting walls inside, ok getting back to the subject at hand, is this correct?

Run to Rund

Get another GM yoke, there are thousands out there on good and bad/dented driveshafts in the junkyards. The stock yoke should be 4" or longer in the smooth area that the seal rides on. Ideally there will be 1" to 1.5" travel from where it is in the trans at ride height to where it bottoms in the trans. It should bottom in the trans where the seal surface ends near the u-joint. since you are probably going to replace the u-joints anyway, changing the yoke won't be a big deal. Keep the old one to plug the trans while replacing it, so ATF won't drool out.

oldcutlass

That is the yoke for a T400 trans, you need to push the yoke in all the way. Then pull it out 3/4 of an inch, and measure from the center of the front ujoint area to flat center of the rear ujoint area. I just had a brand new steel driveshaft fab'd for my cutlass for $220. Mine was 59" long for a 1967.

Rocketbrian

I happen to be cleaning up and painting the driveshaft from my 71 442 with a TH400. I have taken a few pictures of it's all original shaft complete with original U-joints. Yours should be the same, except for the difference necessitated by having a 68 Buick rear end. I have the corporate 8.5" 10 bolt.
The overal length is 61 5/8". The actual length of the entire yoke is 7 & 1/2", while the smooth section for the tranny is 4 & 9/16", which is a fair bit longer than yours. Maybe size does matter! Hope this helps.

507OLDS

RocketBrian,
What are you getting from the center of the rear u-joint to the center of the front u-joint.The yoke looks like the one from my 71.Is yours splined up to the top,or is there a bare smooth section before the splines start.
I am guessing jaycobb's yoke looked like yours originally,before it was cut.

oldcutlass

Is that 61 5/8 center to center on your ujoints.

507OLDS

No,I think he hooked the tape on the end of the joint ear,to get an overall length,tip to tip. Yes?

Rocketbrian

The measurement from the middle of the front Ujoint cap to middle of the rear Ujoint cap is approx. 54 1/4. Yes, inside the yoke there is a smooth section of 1 & 7/8" before you hit the splines.
The overall length from the rear ujoint ear to edge of yoke is the 61 & 5/8".

Jayycobb

I think the yoke was definitely cut and then the edges sanded/grinded down... So I went on Ebay typed in "GM YOKE" and found 329 yokes, ranging anywhere from 4" to 8" long! 31 spline, 32 spline... from $50-$150, outside clips/inside clips, cap sizes, theres so much to be done just to get the right yoke??? (it beats paying 400bux for a driveshaft)

Im assuming I need the 32 Spline since that is the only spline count ive seen on the T400 yokes, I still have not had a chance to get to my car this week to take ANY other measurements, so pissed...

Ive noticed that there is also a seal surface diameter measurement? I thought they were all the same...

Rocketbrian, i think 7.5" is more than enough yoke to work with, 4 9/16"s spline coverage would be great if I dont bottom out in the trans... What would can I cut a yoke with? (machine shop??)

How can I measure the longest possible shaft the 400 trans can take till it hits the wall in the trans, just put a skinny steel rod and see how far it goes? Whats at the end, is there a noticeable wall no matter what I stick in there or will it be hard to do this?

Jayycobb

Right now, with the yoke chopped, only having 3" of total "seal riding" area, would it be safe to just buy a 4.5" "seal riding" yoke and call it a day?

Run to Rund

Anything 4" plus should be fine; you don't need 6-7". Be sure the u-joint taken by the yoke is correct; stock is Saginaw but some yokes may be for the different Spicer 1350.

Jayycobb

So NO 1350, right?

Hows this one sound? its a 1310, 4.5 spline length, is this correct?

http://www.ebay.com/itm/NEW-DRIVESHA...item43a2ddc6bf

507OLDS

The u-joints that you currently have,or originally had,are the 3R joints.

RocketBrian,
Thanks for all of the measurements.It all makes more sense now.

Jayycobb

Hmmm... Im still lost, d'you think this yoke will work?

Rocketbrian

Glad to help guys. If it's any use to anyone, I can measure the amount of the yoke that is exposed on my SX, as it has the exact same drivetrain as my 442. With the exposed part of the yoke known, I can determine the amount of the yoke that is inside the tranny from my 442 measurements. I know there is an "O" ring seal on the tranny tailshaft. I don't know if the yoke butts up to it or slides over it. Jayycobb, when looking for a yoke, the originals have a vent hole built in, others don't. I don't know if it is necessary to have a vent holed yoke when used in conjunction with the "O" ring seal, but that's what the factory did. I had the opposite problem when I got my SX. Someone swapped out a T400 from a 77 Pontiac, which I found out did not have an "O" ring in the tailshaft, so everytime I had the car parked uphill, tranny fluid would leak out the vent hole in the yoke. I kept thinking the rear tailshaft seal was leaking until I found a correct 71 Cutlass T400 and noted the "O" ring. Long story short, just giving you a heads up on yoke differences.
Good luck.

507OLDS

When I have purchased aftermarket yokes with no hole,I just drill a small relief hole.It also acts as a pressure relief.

Run to Rund

Olds and Pontiac used a big u-joint, siimilar in size to the Spicer 1350 but not interchangeable with it. 1310 is the smaller Chevy u-joint. I don't remember the exact sizes across but they were something like 3.12" Chevy and 3.62" Olds.

507OLDS

I think the u-joint he is looking for is the 3R. I bought a newTH400 yoke last year with the 3R joint size. ULESS you are going to have a new shaft made.THEN I would do everything with the 1350 joints.If your rear joint is the 3R,which I think it is,then get an adapter u-joint,or also know as a hybrid joint,for the rear joint,that is 1350 on one side,and 3R on the other.That way,IF you ever upgrade rears or change the rear yoke,you can go with a 1350 on both sides.

Make sense?

Rocketbrian

If you want the exact yoke, brand new, it is available from Supercars Unlimited. It is part #46-110 and measures 6.74 " from ujoint centreline to end of yoke. It has the correct set back or recessed splines as I described mine has. It is $139.95. Something else for you to consider. Cheers.

Run to Rund

I do have a good used GM yoke for T400 with the big Olds joints, if you can't find one locally. I also have a 4" steel aftermarket driveshaft with Spicer 1350s, used very little. It is 55.5" center to center of the joints; the Spicer yoke is 2" from center of u joint to beginning of the seal surface, vs. GM yokes which are 1.5". Thus, when comparing it to a GM shaft, the 55.5" is like a 56" shaft with the GM yoke. If your rear end companion flange is for the little 1310 Chevy joint, seriously consider upgrading to either of the big joints.

507OLDS

You can get that yoke for about half that,or less,if you shop around.Mine was an actual Spicer part,for about $65.00 with the shipping.Maybe it was a Dana.One of those.

Rocketbrian

We'll that's even better. Ah, the power of the internet and knowledgeable people.

Jayycobb

Just got back from the garage, heres the specs.

-Shaft from midpoint to midpoint 54 1/8"
-Shaft from end to end 55.5"

-yoke from cap to cap 3 19/32"s or 3 9/16"s or 3 5/8"s
-yoke seal surface OD *1 13/16"s
-yoke end caps ID 1 *1/16th
-31 splines and 1 gap w/no vent
-5.5"s total yoke length
-5.5" of output shaft space till wall
-3.5" of splines on output shaft from seal going in
-says 667 on yoke
Are these inside or outside clips?

Jayycobb

I took a video of the play on the output shaft, is there excessive play?

http://www.youtube.com/watch?v=aseUVwsSIlA

I also took a vid of how close the shaft would be to disengauging from the transmission while driving. If you look closely I drew 2 lines, one where the seal sits when the shaft is installed and suspension loaded and one 1inch from there going towards where the shaft was chopped off. I only did this because I wanted to know if it was absolutely too short to drive with before I started looking for another yoke or shaft that might take a few weeks to find...

http://www.youtube.com/watch?v=4844GqdhNys

Here are some more pics, I guess they used a 31 spline but then put in a relief spline so the air would come out, does this mean I can get a 32 spline yoke and just drill a vent, how would I stop the fluid from coming out on inclines?

Jayycobb

I will call them in the morning, all the ones on ebay have A too narrow CAP TO CAP MEASUREMENT,except for this one

http://www.ebay.com/itm/NEW-DRIVESHA...item336e1db6dc

I need 3 5/8"s... its a 32 spline, so I would have to drill a relief hole, correct?

507OLDS can you explain the relief hole in detail please?

Next issue is I only have 3.5" of spline length on the output shaft so I might have to cut this one with a hacksaw?! its only 70bux shipped, thinkin about getting this one...

J-(Chicago)

Once you remove the stock u joint, there will probably be 2 grooves that will become exposed, to use outside clips.
The new u joint will be skinnier from cap to cap to allow you to seat the new clips in the grooves.

The stock stuff doesn't have clips, but is usually held in by molten plastic that you have to heat til' it oozes out of the little puke holes.

Your cap to cap measurement may change once you see what you need for your new yoke.

507OLDS

Don't worry about the relief hole right now.That can be done later,if needed.The yoke in the ebay link looks like the right one.I have purchased some other parts from Southwest Speed,and have been happy with them.I would not cut the new yoke at all.I believe there should be a total length for the yoke,and the barrel length.They make & sell a bunch,so just check those critical measurements to make sure.

Run to Rund

The replacement u-joints use internal snap rings; there will be machined flats on the inside of the cup areas of the yoke to accommodate them. The ebay yoke probably won't work because it looks like the u joint to seal surface distance is too great with that step. It won't slide into the trans far enough and your driveshaft would be too long. you definitely need another yoke, however, as yours has munch marks etc. on it as well as being cut too short.

Run to Rund

BTW, the yoke and shaft are considered 32 spline. The deleted spline is a venting arrangement.

Jayycobb

Jayycobb

By accident my phone posted the quote. Run to rund, im not replacing the u joint, at least i hope i dont have to...
507olds- i might have to cut it, its 7.5" long, might be too long, will a hacksaw do the job?

J-(Chicago)

You really have no choice, once you remove the stock yoke. As previously stated it is held in with plastic. You will have to melt it out, thus rendering the stock ujoint useless.