Help Please! Driveshaft/Transmission Clearance

[mounty71]

Long story short, i'm installing fullsize bronco leaf springs on my mountaineer, and to keep the axle centered in the wheel well i had to move the front spring hangers back 1.5". But now it looks like the driveshaft slip shaft (not sure what it's actually called...the part that slips in and out of the transmission) might be pulled out too far.

I need to know:
How much of that splined shaft can safely be sticking out of the transmission?
How long is that shaft, from the flange to the tip of the splined end?

After relocating the axle back, this is how much of the splined shaft is showing at about ride height. It actually slips out about 1/4" more at one point throught he suspension travel. Is 3.25" an ok amount?

 

[mounty71]

Bump, i need to know so i can either button everything up on the truck or figure something else out.

 

[my pos mounty]

I don't think that your question should be about how much is sticking out, but how much of the slip yoke is still inside the transmission under full suspension drop?
How long is the slip yoke in total length?
How much movement (in and out) does it see under all conditions?

 

[mounty71]

Ya i guess you're right, but i don't know the overall length of it, so i can't really measure what's inside. Through all suspension travel, it has about 1.25" of plunge.

 

[mounty71]

Don't worry guys, i got it. The slip shaft is exactly 5". And according to a driveshaft shop, 1" should stick out to be safe.

 

[storlied]

Shouldn't the slip yoke in the middle of the driveshaft be taking care of the increased length between the axle and transmission? Something to think about..

 

[mounty71]

I'm not sure what you're talking about. I'm 2wd, so i'm talking about the rear 1 piece driveshaft. Are you talking about the front driveshaft? I should have clarified.

 

[Electrohacker]

sometimes people want the slip in the driveshaft in the driveshaft itself

if you wanted to do this with your 2WD you'd have to install a slip yolk eliminator. but it hardly makes sense since you dont plan on doing anything that would break the driveshaft and even if you did you wouldnt be able to drive away from such an even like someone with 4WD

basically if you remove the slip yolk you'll drain all your fluid and cause damage, and if you move the slip to the driveshaft it allows less binding i you were to lift WAAAAY high up


but you have a 2wd, so I dont think any f this applies

 

[mounty71]

If you're thinking 2wd means that it doesn't go offroad, you're mistaken. The truck sees offroad driving as much as possible, just not rockcrawling. I do the higher speed prerunning type of offroading, which cycles the suspension from full bump to full droop repeatedly. So any movement of the driveshaft that 4 wheeling causes would also be seen in my situation.

But regardless, i figured it out. The driveshaft has a little more than half of the slip yoke in the transmission now. That should be fine, and if it isn't then you'll all hear about it.

 

[storlied]

Wait, hold up... what I'm saying is check about a 4WD rear drive shaft, I didn't realize your 2WD one was a one peice... mine is two.. with a slip yoke thing in the middle of it to change it's length with suspension travel.... but instead of having that at the tranny.. my rear driveshaft Bolts to a flange on my tcase... I say find a slip yoke eliminator.. something that changes your output to a flange.. and use a 2 piece driveshaft... I'm pretty sure I'm onto something... how did that guy not think you off-roaded? lol..

 

[IZwack]

There's no need to go to an SYE unless you're jumping like 6 ft in the air - which is where SYE's help because the load during landing is transfered onto the casing (which can be made stronger) instead of the output shaft. The 1-piece will be just fine.

.. how much of the slip yoke is still inside the transmission under full suspension drop?

The distance between the rear axle and the transmission gets shorter as the suspension droops because the arch of the leaf spring increases (thereby making the shackle at the rear more vertical). On contrary, the distance between the transmission and the rear axle is greatest when the leaf spring is flat. So if the driveshaft is going to pull out, it will pull out during full stuff.

 

[Electrohacker]

Wait, hold up... what I'm saying is check about a 4WD rear drive shaft, I didn't realize your 2WD one was a one peice... mine is two.. with a slip yoke thing in the middle of it to change it's length with suspension travel.... but instead of having that at the tranny.. my rear driveshaft Bolts to a flange on my tcase... I say find a slip yoke eliminator.. something that changes your output to a flange.. and use a 2 piece driveshaft... I'm pretty sure I'm onto something... how did that guy not think you off-roaded? lol..

I was spooling out ideas, I dont friggin know who owns that pile of parts... GAWD DAMN!

 

[Electrohacker]

BTW, if you cant sense the sarcasm in my previous post... then read about it here, lol

 

[storlied]

lol, I think I have a good idea though... if he can get the 4wd one setup properly, maybe even a lengthened one??

 

[mounty71]

Thanks for the help guys. There actually looks to be very little plunge through the travel at all, 1/2" at most. And storlied, i never thought about doing the SYE thing, and i guess it could work, but i don't really see a big reason for me to do it. All i wanted to know was an appropriate distance, not how to eliminate plunge altogether. But thanks.

 

[storlied]

But I meant while getting rid of it, having a slip yoke [the same thing] in the middle of the driveshaft, much like my stock 4wd rear driveshaft. You could get it lengthened if needed because you have no tcase, get what I'm saying? Kinda thinking I'd rather have the movement come from the driveshaft rather than that end coming out of the transmission. If anything if you're gonna stick with how it is, I'm really curious as to if this would be a good solution.

Maybe even check other pre-runner type trucks, see if they have what you do, or the type I'm talking about.

 

[mounty71]

I get what you're saying. And i have no idea which would be better. Of all the time i spend on prerunner forums, i can't recall reading much about the pros and cons to a 1 or 2 piece driveshaft.

 

[storlied]

If anything, angle of the joints and/or amount of difference [in expansion length] allowed I can only guess. [The angles might be the same though] Hope it works out for ya.

 

[mounty71]

Thanks, i've had the truck back together for a couple of days now, and it drives fine, no driveline vibrations. With what little driveshaft plunge i have all the way through suspension travel, i think i'll be fine.

 

[storlied]

That's good. How's the ride now I'm curious? A lot more stiffer in the rear? Those packs looked pretty beefy.