How much exposed shaft?

SkylinesSuck

SkylinesSuck

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Asking for a friend. Seriously.

He bought a hot mess of a Jeep despite my warnings. 3"? lift with an 8.8 rear axle, no SYE, using a transfer case drop, and "new" rear driveshaft right before he bought it. He complained about a kind of slight knocking noise coming from the underside. After some futzing around we were finally able to replicate the sound at slow speeds. I immediately noted it was speed dependant and sounded like the right rpms to be a drive shaft. Shifting in to 4wd had no impact. I checked for play in both DSs but couldn't detect any. I did have him cycle between drive and reverse and noticed the rear driveshaft deflect a noticable amount. I think maybe his tranny mount is shot, but does this seem like a whole ton of exposed splines exposed at the back of the transfer case or an I crazy?

IMG_20230127_071214.jpg


Sorry for the fuzzy pic. I didn't take it. It's hard to tell, but it almost seems to me like the slip yoke is just barely hanging on to the end of the splines and that's where the play is coming from. Am i way off base?
 
SkylinesSuck said:
Asking for a friend. Seriously.

He bought a hot mess of a Jeep despite my warnings. 3"? lift with an 8.8 rear axle, no SYE, using a transfer case drop, and "new" rear driveshaft right before he bought it. He complained about a kind of slight knocking noise coming from the underside. After some futzing around we were finally able to replicate the sound at slow speeds. I immediately noted it was speed dependant and sounded like the right rpms to be a drive shaft. Shifting in to 4wd had no impact. I checked for play in both DSs but couldn't detect any. I did have him cycle between drive and reverse and noticed the rear driveshaft deflect a noticable amount. I think maybe his tranny mount is shot, but does this seem like a whole ton of exposed splines exposed at the back of the transfer case or an I crazy?

View attachment 395197

Sorry for the fuzzy pic. I didn't take it. It's hard to tell, but it almost seems to me like the slip yoke is just barely hanging on to the end of the splines and that's where the play is coming from. Am i way off base?
Click to expand...

It's hard to know for sure with the boot in the way. Is it possible that the forward clamp on the boot has loosened up and the boot has collapsed slightly, exposing more of the shaft?

My recommendation is to clean up the shaft where it meets the T-case and mark that spot with some tape. Then pull the shaft to see how much of it was actually engaged with the output shaft.
 
SkylinesSuck said:
... 3"? lift with an 8.8 rear axle, no SYE...
Click to expand...

It's also possible that your hearing noises from an unhappy driveline. You could try pulling the rear shaft completely out of the equation, then driving it in 4HI to see if the noise changes?
 
That's exactly what I recommended. Bonus points for pulling the rear driveshaft and seeing how much of the splines were being engaged.
 
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Seriously though. If the slip joint doesn't deflect when you try to move it i doubt its the noise even if its far from optimal. Can you see which end of the driveshaft is moving when he goes from forward to reverse? Axle rotation would be link joints. Is the tcase real close to the skid?
 
I see what you did there. Nominating for 'best of' thread titles.
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If the CAs are adjustable, I'd also check that they're not too far biased to the rear with that 8.8.
 
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RMETeeJay said:
I see what you did there. Nominating for 'best of' thread titles.
Click to expand...

I no idea what you are referring to.

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And yeah, adjustable rear lower arms. He said he didn't see the axle shifting around at the arms when I was cycling it back and forth loading up the drive train. They felt tight to me but I wasn't watching them while loading up the drive train. Worth double checking.
 
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