Is my front driveshaft too long?

freedom_in_4low

I'm a rooster illusion
Supporting Member
Ride of the Month Winner
Joined
Sep 26, 2019
Messages
8,462
Location
Arcadia, OK
Just picked up my LJ from getting the front axle re-geared (yay for matching axle ratios!).

I had not installed the front driveshaft 'cause I knew he was going to have to disconnect it anyway and I didn't want to do something stupid like forget my axles didn't match and put it in 4x4 (good move 'cause I did exactly that). So I had it in the back and asked him to install it when he was done. He told me that the driveshaft will go in at ride height, but was too long with the axle drooped, so he left it uninstalled so I wouldn't go droop it out and break my transfer case.

I haven't read about that happening around here so now I'm wondering what's going on. 4" shortarm with 11" Ranchos, Currie bump stops that are centered at full bump, high pinion Dana 30.
 
I think I would measure yoke to yoke at ride height then call Adams and ask them what length the drive shaft should be, but it shouldn't be too long at full drop.
 
Last edited:
  • Like
Reactions: freedom_in_4low
Install it and droop your axle to see for yourself. If anything, you'd pull the shaft apart.

I using my stock front shaft with 4" suspension and a tummy tuck. Also an HPD30 and my front shaft fits perfectly
 
Sounds odd but could be. Short arm lift? If the axle moves toward center rig as It droops could compress to max?
The axle should move away on droop some also though
 
  • Like
Reactions: freedom_in_4low
distance between yokes at ride height is 40.25". I can compress the shaft to 39.25, so there's an inch of compression, which indeed doesn't seem like much.

Thanks to the high pinion, the driveshaft is much closer to horizontal than the arms are. So as it droops the arms are going to shorten in the horizontal plane more quickly than the driveshaft will. If my math is right, it makes sense because it looks like the shaft runs out of compression around 3.5" of droop.

1614190128639.png


I don't know the exact measurements, but assuming the difference in pinion heights between HP and LP is 4", it looks like a LP might be ok out to 6" because it starts out longer at ride height, plus it's at more of an angle so it's arc shortens more quickly.

1614190398983.png



I can't explain why @tworley doesn't have this issue, I can only guess that maybe he put more effort into getting some wheelbase into his suspension setup.
 
Just picked up my LJ from getting the front axle re-geared (yay for matching axle ratios!).

I had not installed the front driveshaft 'cause I knew he was going to have to disconnect it anyway and I didn't want to do something stupid like forget my axles didn't match and put it in 4x4 (good move 'cause I did exactly that). So I had it in the back and asked him to install it when he was done. He told me that the driveshaft will go in at ride height, but was too long with the axle drooped, so he left it uninstalled so I wouldn't go droop it out and break my transfer case.

I haven't read about that happening around here so now I'm wondering what's going on. 4" shortarm with 11" Ranchos, Currie bump stops that are centered at full bump, high pinion Dana 30.
We run into that all the time. We check every front with the axle at full droop and the straps off of the caps. Reach in with a prybar and see if we can move the yoke back on the splines. If we can't, shaft is too long and we get it shortened.
 
We run into that all the time. We check every front with the axle at full droop and the straps off of the caps. Reach in with a prybar and see if we can move the yoke back on the splines. If we can't, shaft is too long and we get it shortened.

thanks, glad I'm not crazy for believing him and I didn't somehow fubar my suspension setup.

I noticed the same thing on my TJ when I couldn't install the front shaft, but at the time the shocks and track bar were out, CA bolts were all loose and it was drooped way beyond even what my LJ can reach, so I didn't even think anything of it and just waited to connect the yoke until I had it more put together.
 
any room between steering links when stuffed? and track bar to dif cover?
could you scoot the axle forward some?
 
any room between steering links when stuffed? and track bar to dif cover?
could you scoot the axle forward some?

It's as far forward as it can go without modifying components. It's close enough that if I ever need to dial out any caster or add pinion angle I'm probably gonna have to do it by lengthening the LCA's and shortening the UCA's by the same amount so the diff housing doesn't move forward. If I trimmed the JJ housing gusset on my Currie front track bar I might be able to squeeze a little more out of it, but only as much as I'm willing to grind out.
 
I think I've got the same problem. I just r and r'd my transfer case, and with the tires on the ground, it was pretty tight getting the front driveshaft off. At full droop the front driveshaft may be bottomed out.

Might explain some funky handling characteristics.

Gonna jack it up by the frame and check it out, tomorrow.
 
I drooped mine out and measured and sure enough, it's about 38 5/8; almost an inch shorter than the fully compressed stock shaft. The stock shaft seems to have about 2" of travel so having it shortened I'd have to hit right on the money to capture the range I can reach. Gonna be placing an order with TW when I can get to my computer. Definitely need the X spline.
 
Just ran into this myself with my LJ. About 3.75" total lift height, at full droop the front driveshaft was a bit too long and could have broken the transfer case.

New front driveshaft from Adams ordered.
 
distance between yokes at ride height is 40.25". I can compress the shaft to 39.25, so there's an inch of compression, which indeed doesn't seem like much.

Thanks to the high pinion, the driveshaft is much closer to horizontal than the arms are. So as it droops the arms are going to shorten in the horizontal plane more quickly than the driveshaft will. If my math is right, it makes sense because it looks like the shaft runs out of compression around 3.5" of droop.

View attachment 228867

I don't know the exact measurements, but assuming the difference in pinion heights between HP and LP is 4", it looks like a LP might be ok out to 6" because it starts out longer at ride height, plus it's at more of an angle so it's arc shortens more quickly.

View attachment 228868


I can't explain why @tworley doesn't have this issue, I can only guess that maybe he put more effort into getting some wheelbase into his suspension setup.
You need to have an inch cut out if it. Seen it more than a few times.
 
You need to have an inch cut out if it. Seen it more than a few times.

I did. Or, more accurately, I got one from Tom Wood that was an inch shorter (and X spline so it has more than enough travel in the slip joint).

It works, but in hindsight I would have gotten the dust cap instead of the boot. The boot is stretched a bit longer than it's natural length when the rig is at ride height, which makes it a PITA to install.