4l80e Driveshaft Conversion Question

[Step'67]

Question for any that can answer, I am in the process of converting my sm-420 to a 2006 4l80e. When I purchased the transmission it came with a slip yoke, and of course the stock one on the 420 is the fixed, bolt on style. This is the only thing holding us up, converting the driveshaft. Now I know that I have to get the shaft shortened, but if I am to keep the rest of the driveline, how am I to go about mating the 4l80e to the stock driveline. Because of the carrier bearing and the crossmember it mounts to, there isn't any room to use a slip yoke. Are there bolt on yokes available for these transmissions anywhere? Or should I just drop some cash and really give the driveline guy something to think about? I'd prefer not to convert it to a one piece because of the associated cost. Here is a picture another member posted of the same driveline I am dealing with just for visual reference, the right hand going to the transmission, the left to the rear end, and a slip yoke in between.

[jfortvalley]

there is a couple of ways you can go do you have a good driveline shop close by ? look at the back of the 4l80 and see if the output shaft is threaded in the middle . or dont look at all and buy a slip yoke for a 400 same as 4l8o take youre measurements as describe by the driveline shop and have them add the yoke during the shortening

[Step'67]

The output shaft isn't actually threaded, so a fixed yoke won't work (got my hopes up because dad's '67 Camaro project had a fixed yoke I could steal). I feel kind of silly during all of this, and here is why: I've got a 72 long bed with a turbo 350 that i pulled the drive line out of some time ago. It of course has a slip yoke on the trans side, the same carrier bearing/slip joint combo in the middle, and a fixed rear u joint. Now, I honestly can't remember how I got it apart, because if I could, this setup would be exactly the same. I can figure out how I removed the rear section of the drive shaft, but as for the front section, not so much. Was there enough yoke travel that I was able to pull the carrier bearing off of the crossmember? But then there is the splined shaft sticking out past the bearing so I wouldn't be able to pull that out of the crossmember. I know it can be done with this slip yoked 4l80e, as the factory trucks come with basically the same setup, but I can't remember how it is assembled. And on a another note, I would also replace the carrier bearing when getting the driveshaft shortened. With doing that, would it just be better to go to a single driveshaft? Truck is a shortbed stepside, lowered 2" in the rear, and plan to lower it more later on. Seems like clearance would be okay?

[jfortvalley]

best thing to do is lower where you want it now then you dont have to cut shaft twice. they make a slip yoke you can use you will just have to buy a u joint to fit and cut the shaft due to lowering it

[jfortvalley]

the front half of the shaft is mounted to the truck solid with carrier bearing and the back half at therear end slips back and forth

[Step'67]

I agree that I should lower it first, and cut once. But this is my daily driver, so I can't be without it running too long. Over this 4 day weekend I'm on, we pulled the old motor, rebuilt the new and transferred all the top end components, removed the old transmission and crossmember, got everything ready for the new trans, and this is the only thing holding us up. Kind of sucks to be stuck on something minuscule in comparison to the rest of the weekend. So as I stated in the first post, I do already have a slip yoke for it. Can you (jfortvalley) or anyone else be more specific in how a slipjoint driveline is removed so that in my head I can figure out how the new one would work? I've done it before, but looking back it seems impossible for some reason.

[jfortvalley]

if you want to seperate the 2 halfs right ?

[jfortvalley]

at the center bearing ?

[Step'67]

Well I know how to do that, my question is how to get the front drive shaft section out. Like I said, If there is enough slip yoke travel, I can push the shaft forward and get the bearing off of the crossmember, but then there is the splined shaft sticking out the other side of the bearing. Theoretically, that would have no where to go as the yoke would be bottomed out in the transmission, and the shaft would be still sticking into the crossmember.

[jfortvalley]

un bolt the center bearing from the crossmember and pull the shaft out . is the center bearing bolted to the truck now ? and are the ujoint straps still bolted to the transmisson yoke ?

[clinebarger]

Originally Posted by Step'67

Well I know how to do that, my question is how to get the front drive shaft section out. Like I said, If there is enough slip yoke travel, I can push the shaft forward and get the bearing off of the crossmember, but then there is the splined shaft sticking out the other side of the bearing. Theoretically, that would have no where to go as the yoke would be bottomed out in the transmission, and the shaft would be still sticking into the crossmember.

Take the driveshaft out as 1 piece from the rear on 67-72 coil spring trucks.
Two slip yolks is fine, I run two on my Burb.

Driveshaft length on coil spring trucks doesnt change that much, Be worried about Pinion angle & Panhard bar length when lowering

[Captainfab]

Remove the outer steel housing from the carrier bearing, and then remove the rubber cushion. The rest should slide thru the crossmember towards the rear.