For starters, this post will be ripe with innuendo. Moving on...

So, I've finally got around to doing the T56 swap this winter. I'm buttoning everything back up and I've run into a bit of an issue. I got my driveshaft shortened but I may have erred in my measurements; rookie mistake... Now when I insert the driveshaft (at regular ride height) the spline shaft sticks out 0.5" further than before the trans swap.

So with the 4-speed it was inserted 2" into the trans with only 1.5" of actual spline engagement since the splines start .5" from the shaft tip. Now I've got 1.5" insertion with an actual spline engagement of 1". Although the shaft feels just as secure, this doesn't seem kosher to me. Does anyone have any knowledge of the minimum required engagement or at least a general rule of thumb?

Thanks for any help!

 

Here is a pic if it helps any.

 

And with the "booted" seal there's actually likely less than you speculated but it's difficult to tell. Your issue is this, the slip-yoke isn't likely inserted into the bushing in the extension housing OR it's only partially inserted. This is what I might do first before deciding the "fix". Measure the length of your drive-shaft "center to center" of the u-joint caps. That dimension could be used to determine if possibly a D36 drive-shaft can be used without modification for a fix.

The image that you posted also hints that you need a slip-yoke anyway. Those grooves in the slip-yoke are an indication you'll have issues.

You started with a D36 4AT car OR it was an early MT car?

I'm guessing an early MT car with a D44 so if you purchased a D36 AT drive-shaft you would maybe get close to where you need to be.

Post the dimension I mentioned and let's see what you've got now!

You'll need one of those to start with anyway or have a complete drive-shaft built.

***A longer slip-yoke is NOT a fix!

 

Darn I was contemplating a longer yoke!

Its a D36 with a 700R4, or it was before the swap. The U-joint cap to cap measurement is ~3.22. Also the trans tail shaft splines end flush with the boot.

I found a website that sells new yokes. I believe I've got what they're calling the 700-10. If I went with the 700-30 I would gain back that .5" and end up with it inserted a total of .25" farther into the T56 than it was into the 700R4. It sounds like that's not a good way of going about it?

http://www.driveshaftspecialist.com/...ns%20yoke.html

Thanks for the help!

 

Looking for a "length center of cap to center of cap" dimension. A D44 is 26 3/4 +/- and a D36 is 27 3/4 +/- and I believe you mentioned shortening your original so depending on how much that's the dimension I would have expected. It looks to me that if you had a D36 stock shaft you would be OK. Your slip-yoke does seem to show considerable wear maybe so a slip-yoke maybe also. The bushing in a T56 is longer I believe than some and you need the slip-yoke to extend through the bushing and not just to it.

With a D36 stock drive-shaft you might need to loose the "booted" seal and just buy a conventional seal for the extension. Only fitting the drive-shaft will answer that.

The T56 I believe is dimensionally the same as an A4 and I based my length thought on that.

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FROM DENNY'S:

My driveshaft is too short. Can I put on a longer slip yoke to make it fit better?

This is a common problem and many times this seems like an inexpensive way to make it fit better but this type of fix should be avoided. We never recommend installing a longer slip yoke when the shaft is actually too short for the application. Some transmission slip yokes are available with a longer barrel but they were designed longer for a specific application and not for the purpose of extending a shaft. Using one on a driveshaft that is actually too short for the application can lead to vibration and output shaft bushing failure. In extreme cases the internal spline can twist and bind up the slip movement. Don't do it!

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Did you do new u-joints when you had the drive-shaft shortened and you did have it balanced?

Ideally you would like a slip yoke without the dampener on it so if you found a D36 with out the slip-yoke for cheap it could be a plus and then buy the correct length slip-yoke "locally" where you had it shortened maybe. I believe I can give you a slip-yoke preference if you want to shop locally. I'd avoid if I could an Internet buy unless absolutely required.

 

Disregard everything you thought about on the link you furnished. The Corvette slip-yoke is not a match to any of the mentioned 700R4 that it mentions. The closest fit is the 350-10 in their product line. It's actually less than 1/2" longer than the stock A4 slip-yoke but less the dampener.

The 700-10 that you thought was yours is actually 1" longer than what you have now the way that they measure. The 700-30 uses incorrect u-joints.

 

Good eye. I went to where I've been working on the car (I don't have a garage) and pulled the driveshaft. I broke out the calipers and went to town. Here is what I have:

driveshaft center of cap to center of cap (after shortening)= 25.25"

U-joint diam = 1.1"
U-joint width = 3.22"

Slip yoke width at u-joint = 3.475"
Slip yoke length = 5.665" (tip to cap center 4.966")
Slip yoke diam = 1.5"

So you're right on, it doesn't match a single one of those on the website. I guess that means there's no inexpensive way out of this. Time to hit the junkyard.

Thanks for setting me straight!

 

You should be able to get a D36 drive-shaft in the "C4 Parts" for less than the buy at a salvage yard. I'd maybe check there first, post a "wanted to buy". If you buy a D36 without a slip-yoke this Spicer slip-yoke will fix you up and I believe I'd just do new anyway and get a balance at the shop where you had yours shortened.

Slip-yoke less dampener: 2-3-4911X Spicer.

Here's a link for dimensions. You could buy it here also or at the shop that shortened your drive-shaft. This slip-yoke is splined to the end.

http://www.northerndrivetrain.com/pr...2-3-4911X.html

Here's a link to one. I do NOT know the seller/vendor but it's what you should expect to shop for by price:

http://forums.corvetteforum.com/c4-p...condition.html

IF YOU INSISTED ON TRYING your original idea here's a slip-yoke that is +.002 diameter, splined to the end and long enough that you could have cut to a length for you to use with what you have. I wouldn't and suggest you don't but........ here's dimensional information. It's also nickel plated and used in 4X4 and similar HD applications. Your extension bushing should accommodate the +.002.

http://www.northerndrivetrain.com/pr...-3-14861X.html

 

Thanks again for all the help. I've done some more reading and I'm with you. This needs to be done right. Thanks for the suggestions, I'll start surfing the parts for sell sections.