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Double CV driveshaft - instead of a SYE

fallacist

NAXJA Forum User
Location
Durango
So, I got my new Double CV driveshaft in the mail today from Bill's. Its beefy as all hell, so I'm pretty stoked to toss er in.

Of course, in my typical fashion with my typical luck, I sheared off half a bolt of the 4 holding the original driveshaft on. I even hit those dickwads with BG in-force, and hardly torqued it, still fell right out. I'm over easy outting, so I'll drop it in 4wd(fwd) and take it somewhere to pull the stud out tomorrow.

In the meantime, here's the comparison to the stock shaft I pulled off.

Dshaft.jpg
 
ahhhhh it all makes sense now. so just a double cardan joint on a slip yoke. How much lift do you add?
 
I have a 3" RC lift, but I got about 4" in the back, so I added a pair of 1" spacers up front to level her out and make it a theoretical 4" all around. I didnt really have vibes after the lift, but I noticed after the spacers.
 
If you make sure the pinion is at the same angle as the driveshaft (rather, a degree or so below it) I can't see why it would vibrate much, if at all.
 
The upper end now has 2 u-joints and the C/V girdle & centering ball, and that hangs out a long ways on an unsupported shaft. Even if the pinion is pointed right, that much rotating mass, especially when it's got to slide on the output shaft, might vibrate a bit.
 
....that hangs out a long ways on an unsupported shaft.

That's my worry. That stock output shaft doesn't take much stress to snap. I'd much rather have a fixed yoke on my tcase for strength purposes, but also knowing that the case is sealed and not relying on the shaft to keep the fluid in.
 
I definitely foresee sealing issues. Even if the vibes aren't noticeable to your butt I bet they'll be noticeable to that seal. There is a reason the factory put a fixed yoke where the double cardon was placed.
 
That's my worry. That stock output shaft doesn't take much stress to snap. I'd much rather have a fixed yoke on my tcase for strength purposes, but also knowing that the case is sealed and not relying on the shaft to keep the fluid in.

My thoughts/concerns as well.
 
Interesting thoughts. Turns out the shaft was about 3-4" too long, so he's sending another one out that should be spot on. I see what you guys are saying about the vibes with that big wad of mass there.

All I can say is that this guy, and this driveshaft came highly recommended on FR4x4. There are a few people that have em and are very happy with them, and are quick to recommend it.

Will update when I get it on. Hopefully should be by the end of the week.
 
yeah, but are the full-size K5 guys dealing with a spindly stock 27 spline NP231 output shaft that sticks waaay out of the case? I'm less worried about vibes, that is until the output bearing on the tcase starts getting smoked from all that unsupported weight...
 
I feel like its going to be fine. This place is popular and well liked enough that I don't think he would sell [as many of] these if they were destroying t-cases. Its not THAT much heavier than the stock shaft, and as long as it stays true and balanced, I can't see the additional weight being an issue.

I hear a lot of toyotas run the double CV set-up, even with longer shafts and steeper angles and have no problems.
 
You'll have to keep this thread updated.
 
My '72 olds 88 convertible had a double cardan joint with a slip yoke from the factory.

Make sure the bushing in the tail cone is in good shape and it will work just fine.


BTW, I was expecting to see this when you say double CV....

aa2s-131-131_MultDC_575x125.jpg
 
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who cares about vibes????? the real reason to do a SYE is to keep the fluid in the t case in the event of a break, also if you have an SYE you can carry a OEM front shaft for the front and rear, instead of carring two or being stranded when your tcase explodes from zero oil
 
who cares about vibes????? the real reason to do a SYE is to keep the fluid in the t case in the event of a break, also if you have an SYE you can carry a OEM front shaft for the front and rear, instead of carring two or being stranded when your tcase explodes from zero oil
I am not surprised to see this comment coming from someone who runs 38s on a dana 30.

Not even a little bit.
 
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