Doing the Front Driveshaft SYE mod..

[vetteboy]

Because it doesn't friggin work! The AX15 case length is much shorter than the AW4. This is what I've been trying to say a few times now. The original question in this thread is "will this work with an AX15" and there's all kinds of info coming out about how great it works with my AW4 blah blah blah...

I had 4.5" lift, a D44 rear, and the AX15. And ANY XJ front shaft fell a few inches short to be able to work for this. Dig?

 

[orchimaxi]

Thank you, thats the kind of response I was looking for - a first hand story of "hey, I gave it a shot - no dice." So, I suppose if I do an SYE in my manual XJ I'll either have to order a custom shaft or find another vehicle that has the correct shaft - probably pretty unlikely, huh?

 

[vetteboy]

There are a few options you can consider...

You know the actual slip yoke piece on the driveshaft (the half of it that connects to the pinion yoke on the front axle)? There IS a longer one of those that has the same size slip splines. I think it's about two inches longer. I don't know an OEM application for it but a friend of mine was able to get one from a driveshaft shop to make up for being a few inches too short.

If you're gonna be junkyard diving anyway, check out the front shaft from an S-10 Blazer. IIRC they might be just long enough. If you can get a 1330 yoke for the SYE conversion, then that opens up any of the Ford rear shafts, and a Bronco rear shaft is pretty close to the right length too. This was something else I considered when doing mine and JB Conversions said they'd change the yoke in their kit to a 1330 for another $20 or so.

I know when I've had to get shafts cut down I'll usually pay about $25-$30 for a shop to do it, I think retubing/lengthening one is around twice that. Even with replacing the u-joints you still end up way ahead of shelling out $200+ for a 'custom' shaft.

 

[shmoken875]

Because it doesn't friggin work!

I had 4.5" lift, a D44 rear, and the AX15. And ANY XJ front shaft fell a few inches short to be able to work for this. Dig?

Yep I dig, I didn't anything deffinitive in the previous posts, just "pretty sure" and that "it doesn't tend to work out" so I suggestest he go ahead and try (thats what I typically do). But first hand "it doesn't friggin work" is much more clear.

 

[vetteboy]

Yep I dig, I didn't anything deffinitive in the previous posts, just "pretty sure" and that "it doesn't tend to work out" so I suggestest he go ahead and try (thats what I typically do). But first hand "it doesn't friggin work" is much more clear.

:roll: Gotcha. It was that exact situation that kept me from doing an SYE in the first place so I'm still a little bitter about it.

 

[Powerman]

You do not want to lengthen your yoke. The whole point of doing a CV shaft is to move the CV closer to TC as well as the CV joint itself. The CV joint itself is a lot heavier and it needs to be closer to the bearing suporting it. Your TC shaft will flex causing vibes, or you will be more likley to break your shaft with a longer lever on it. Plus, lengthening your shaft reduces joint angles while shortening makes them worse. The whole reason for a CV shaft is because on lifted vehicles the joint angles are outside the proper range for u-joints. Bronco II shafts are 1 inch shorter and use 1210 joints not 1310s. Explorers use 1310 joints but are an inch shorter as well. I haven't found any CV shafts that use 1310 joints that are longer than XJs. Also, Bronco 1s have longer CV shafts with 1310 joints in the rear, but good luck finding one with good splines. I've only seen a couple and they were shot.

 

[vetteboy]

You do not want to lengthen your yoke. The whole point of doing a CV shaft is to move the CV closer to TC as well as the CV joint itself. The CV joint itself is a lot heavier and it needs to be closer to the bearing suporting it. Your TC shaft will flex causing vibes, or you will be more likley to break your shaft with a longer lever on it.

Yeah, that's not what I said. I referred to the part that connects to the pinion yoke, that's usually about 8" long or so, not the CV part...basically just changing the position of the slip shaft in the middle of the driveshaft. Potentially this could give you balancing and vibration issues if the splines are worn out and it makes it a little more open to rock damage, but that's the tradeoff for trying to make something work for cheap.

The whole reason for a CV shaft is because on lifted vehicles the joint angles are outside the proper range for u-joints.

Also incorrect. A stock 1310 joint has a maximum operating angle of 30*, while a stock 1330 and 1350 joint have maximum angles of 20*. Often the stock yokes bottom out on forging marks before the maximum angle is actually exceeded which is why you can get some additional travel with grinding. With modifications to CV housings you can get any 13xx double cardan to operate at 35* somewhat reliably. The 1410 joints and CV can get considerably more than this (a single 1410 can take up to 37*).

What a CV does do is reduce the operating angle per joint, reducing angular stress on them help keep them alive longer. It also gives a smoother rotation because of this (the double-cardan end has no phase at all, which is why you try and eliminate this at the pinion yoke as well). Also, removing the slip yoke does make the shaft longer, which lessens the overall angle, and by being able to rotate the pinion up it lessens the angle there as well, reducing vibration and stress.

Also, Bronco 1s have longer CV shafts with 1310 joints in the rear, but good luck finding one with good splines. I've only seen a couple and they were shot.

I've only ever seen fullsize bronco shafts with 1330s. They use that goofy flange adapter at the axle too. I've got about 8 Bronco shafts of different lengths in storage over at my buddy's shop that all have decent slip splines and 1330 joints all around, that I was gonna use before I scrapped the whole stock XJ drivetrain anyway.

 

[Powerman]

Yeah, that's not what I said. I referred to the part that connects to the pinion yoke, that's usually about 8" long or so, not the CV part...basically just changing the position of the slip shaft in the middle of the driveshaft. Potentially this could give you balancing and vibration issues if the splines are worn out and it makes it a little more open to rock damage, but that's the tradeoff for trying to make something work for cheap.



Also incorrect. A stock 1310 joint has a maximum operating angle of 30*, while a stock 1330 and 1350 joint have maximum angles of 20*. Often the stock yokes bottom out on forging marks before the maximum angle is actually exceeded which is why you can get some additional travel with grinding. With modifications to CV housings you can get any 13xx double cardan to operate at 35* somewhat reliably. The 1410 joints and CV can get considerably more than this (a single 1410 can take up to 37*).

What a CV does do is reduce the operating angle per joint, reducing angular stress on them help keep them alive longer. It also gives a smoother rotation because of this (the double-cardan end has no phase at all, which is why you try and eliminate this at the pinion yoke as well). Also, removing the slip yoke does make the shaft longer, which lessens the overall angle, and by being able to rotate the pinion up it lessens the angle there as well, reducing vibration and stress.



I've only ever seen fullsize bronco shafts with 1330s. They use that goofy flange adapter at the axle too. I've got about 8 Bronco shafts of different lengths in storage over at my buddy's shop that all have decent slip splines and 1330 joints all around, that I was gonna use before I scrapped the whole stock XJ drivetrain anyway.

Good info. It really does not matter what the maximmum operating angle is. It isn't like the joint is smooth and vibe free at 29* and then it is bad at 30*. At the lifts we have, with the joints we have, at the angles we have, we get vibrations and accelerated wear which is why we switch to CV joints. They can operate more comfortably at higher angles. Can we agree on that?

I looked up everything with 1310 joints and Broncos came up under that. The ones I looked at had 1310s, but I could be wrong. If you have good ones, congradulations. I have a hard time believing that I am going to find a OEM DS that is 30 years old to be in good shape. I have a harder time believing that I am going to be lucky enough to find a rebuilt one on a 30 year old vehicle. I'm not saying it isn't possible, I'm just saying it isn't probable for me.

And yes, I miss read you. I too tried to find a longer yoke part but was unsucessful. I had some Ford and XJ shafts I was trying to make work that were too short. I looked at all kinds. The splines were not right, or if they were, the length was not that much different. I gave up, but it wasn't an extensive thorough search. It would be cool to find a OEM replacement out there. We could use any short DS and lengthen it with another OE part.

 

[vetteboy]

Good info. It really does not matter what the maximmum operating angle is. It isn't like the joint is smooth and vibe free at 29* and then it is bad at 30*. At the lifts we have, with the joints we have, at the angles we have, we get vibrations and accelerated wear which is why we switch to CV joints. They can operate more comfortably at higher angles. Can we agree on that?

Sure. In my situation though, I'm gettin pretty close to having some angle issues at the front of my rig. When a CV maxes out, rather than the joints becoming the weak link, it's the ball & socket at the middle that lets go. One guy I wheel with regularly recently blew up a 1350 "1-Ton CV" from High Angle Driveline because his rear axle dropped out when it started hopping on a climb and maxed out the CV. If it had just been a regular u-joint in that position it would have been an easy trail fix and a much cheaper part to replace, but instead his $250 rear shaft got turned into a piece of scrap. Same thing might end up applying to the front shaft in my rig but it's not far enough along in the build to know for sure at this point. A lot of guys with more dedicated trail rigs don't run CV's for this reason and just grind the yokes out a little instead.

But yes, a CV will give smoother rotation overall, and is a more 'friendly' solution (if not the most trail-effective).

I looked up everything with 1310 joints and Broncos came up under that. The ones I looked at had 1310s, but I could be wrong. If you have good ones, congradulations. I have a hard time believing that I am going to find a OEM DS that is 30 years old to be in good shape. I have a harder time believing that I am going to be lucky enough to find a rebuilt one on a 30 year old vehicle. I'm not saying it isn't possible, I'm just saying it isn't probable for me.

Where are you getting 30 years from? All the ones I have sitting around are from mid-90's trucks.

The 78/79 bronco with the HP44 used 1310s in the front shaft, and the yoke on that HP44 is a u-bolt style one that makes a nice interchange piece in place of a later-model strap-style Dana yoke on our stock axles. The 9" from that same truck made its way into my buddy's newer bronco and he kept using the same rear shaft he always had.

And yes, I miss read you. I too tried to find a longer yoke part but was unsucessful. I had some Ford and XJ shafts I was trying to make work that were too short. I looked at all kinds. The splines were not right, or if they were, the length was not that much different. I gave up, but it wasn't an extensive thorough search. It would be cool to find a OEM replacement out there. We could use any short DS and lengthen it with another OE part.

Sounds just like my quest. While I wouldn't really recommend it for something that sees daily use, I ended up just running the stock NP231 output at 4.5" lift with a 1" t-case raise. The yoke knocked a little bit when the rear was fully drooped but other than that I drove it around a while in that configuration with minimal vibes because I still had the angles matched properly...I also have the AX15 though so it makes the rear a little longer. Only reason I really did that though was because I had plans to abandon that whole drivetrain in the near future.

 

[ILLXJ]

I have a FDS from a 2.5/AW4/242 combo that is quite a bit longer than the 4L version. I'll check the measurements, it might work for you guys. JIM.

 

[OBXJ]

to answer the original question, the stock front DS from an auto tranny Xj will be too short to use as a rear with an AX-15. I know, i tried. i ended up getting the front DS i purchased lengthened 2.5" at a local DS guy for 125 bucks. works like a charm now.

to the OP, here is the guys address that did it for me. great old fella that runs his business out of a shop behind his house. he's located out in Durham County.

Triangle Driveshaft Svc
3424 Paulwood Ct
Durham, NC 27704
919-688-2544

 

[Dr. Dyno]

to answer the original question, the stock front DS from an auto tranny Xj will be too short to use as a rear with an AX-15. I know, i tried. i ended up getting the front DS i purchased lengthened 2.5" at a local DS guy for 125 bucks. works like a charm now.

You could potentially also add 2.5" to the length of the driveshaft (becomes 33.16" instead of 30.66" collapsed length) by adding a double cardan joint at the axle end in addition to the existing double cardan joint at the TC end. Has anyone considered it or even tried it?

 

[vetteboy]

Yes, considered it...advantage being it really wouldn't matter what the pinion angle was.

It would still be a custom piece though - you'd either have to do the fab yourself or find a driveshaft shop that would do it - but my biggest concern would be draggin the hell out of it on rocks and messing up the double-cardan coupling. Then you're left with finding a pinion yoke that would mate up with the proper thru-holes to bolt to the CV companion yoke.

I have heard of people doing this in situations with terrible driveline angles, but I know of no OEM parts sources to accomplish it.

 

[ILLXJ]

I have a FDS from a 2.5/AW4/242 combo that is quite a bit longer than the 4L version. I'll check the measurements, it might work for you guys. JIM.

My mistake this FDS is 2" shorter than normal. It is the rear shaft from this combo that is longer. JIM.

 

[PW1XJ99]

Did you guys use shims? I've got some, but not sure what degree they are..
Can you tell by measuring the high side of the shim?

 

[BADaXJ]

I have the RE H&T with a front ds and a rusty's 3" full leaf kit plus 1.5" shackles, a 1/2" block and an extra stock leaf. its extended a little further than i'd like but i've flexed it and its not going to come out. as far as the ds being too long, i dont think it's an issue, the ax-15 is shorter than the aw4. make sure the front ds is from an auto, the manual driveshafts are a bit shorter. which i guess if it was too long (HIGHLY UNLIKELY) you could get a 5-speed front ds.
I think it'll work out just fine.

Guess i didn't do much good buy forgetting to say that i have the AX-15 too:banghead: note that you have to have the 8.25 rear axle for the front ds mode to work...
I promise you it'll work if you have the 231 t-case and 8.25, mine does and i'm just a little over 5" actual lift.
here is proof:

 

[vetteboy]

I see two things I dislike in this picture.

One, that H&T "SYE" sticks out every bit as far as my factory slip yoke did.

Two, all I see is a bunch of exposed slip yoke on the rear. No where near being midrange on the shaft.

I guess it works if you don't like your t-case rear output bearing..?

 

[BADaXJ]

One, that H&T "SYE" sticks out every bit as far as my factory slip yoke did.

i'd have to disagree with you on that one; it's cut shorter than RE specifies in the instructions... also, no probs with the ds being extended, i've beat the piss out of it and it has yet to be a problem. if it is at some point, i'll just get another one for free

 

[orchimaxi]

How far extended SHOULD the DS be? I truthfully don't know how much travel it has. And does the fact that a H&T was done mean that the output is longer than if I did the PORC HD SYE?

 

[WobblesXJ]

I have an HD SYE not an H&T, and a front shaft was too short with my setup.

Just for further info.