Motor Mount Height Question

[Hasselblad]

If your profile list is still accurate i have close to the same setup. But with a np231.

I didn't need to raise the motor even more to get the vibes settled. How old are the joints and centering ball in the rear shaft?

Really the main change that seems to have set this off is the belly up skid. I have some 1" skid spacers (defeating the belly up point, but it was already bought and installed so... at least not a shovel any more) coming to try out instead of adding more height to the motor. Lifting the motor is something I have decided to not be a good idea, as the 1" spacers already led to pinching wires that I had to have repaired above the trans. I may just have to settle for having the transfer case back down. It may be my imagination but it seems to have lost a little acceleration power alongside the vibes/shudder, but could be my subconscious babying it.

In any event I plan to take off the skid to adjust the transfer savvy case shift cable, and will be pulling the rear shaft to see if it developed issues. I tend to doubt it, but covering bases.

 

[JMT]

@Hasselblad whats your operating angle? That’s what I’m trying to figure out. They max out around 25*. I’m sure there are variances of tolerance among TJ’s.

Do you have a SS SYE?

 

[That'll Buff]

@Hasselblad whats your operating angle? That’s what I’m trying to figure out. They max out around 25*. I’m sure there are variances of tolerance among TJ’s.

Do you have a SS SYE?

Been quietly following this thread since it involves future projects I plan to do. @JMT's mention of the SS SYE reminded me of this thread I read a while back. Assuming it is driveline vibes, seems like it's (unfortunately) your answer as stated in Shawn's answer.

https://wranglertjforum.com/threads/super-short-sye-or-sye.60376/

 

[Hasselblad]

@Hasselblad whats your operating angle? That’s what I’m trying to figure out. They max out around 25*. I’m sure there are variances of tolerance among TJ’s.

Do you have a SS SYE?

Rubicon with DC, and 4 speed bestest trans

 

[Hasselblad]

Been quietly following this thread since it involves future projects I plan to do. @JMT's mention of the SS SYE reminded me of this thread I read a while back. Assuming it is driveline vibes, seems like it's (unfortunately) your answer as stated in Shawn's answer.

https://wranglertjforum.com/threads/super-short-sye-or-sye.60376/

But Shawn is talking about 4"+ of driveline lift.

If still light out enough to get under after work, I am going to peek into the hole in the new skid to see if anything is remotely close to it besides the obvious trans mount. The more I think about it the more I am blaming the new vibes on the new drivetrain angle introduced by the belly up. But still plan to pull the shaft and see if the joints failed. If I have to put up with the 1" loss of clearance with the skid spacers, at least I will get back to driving and not so much tinkering. Shit, I still have the EMUs and Ranchos to put on the front.

 

[That'll Buff]

But Shawn is talking about 4"+ of driveline lift.

There's a chance you fit that description. The TeraFlex Belly Up skid says it increases clearance by "up to 2 1/4 inches." Combine that with your 2.5" OME springs and that's 4.75". Sure most people experience the need with a larger spring lift, but seems like going above 4" total is the line. Like you said, the only change is the belly up skid, and again assuming that this is driveline related, that would be the smoking gun. The free.99 solution is like you said, put the T-case drop back on and adjust to see if the vibe is gone. Before that I would take some of the other's advice and check if anything is touching or if something is wrong with the driveshaft. If those come out clean and the drop fixes the vibe, seems like the SS SYE is the solution.

 

[Hasselblad]

There's a chance you fit that description. The TeraFlex Belly Up skid says it increases clearance by "up to 2 1/4 inches." Combine that with your 2.5" OME springs and that's 4.75". Sure most people experience the need with a larger spring lift, but seems like going above 4" total is the line. Like you said, the only change is the belly up skid, and again assuming that this is driveline related, that would be the smoking gun. The free.99 solution is like you said, put the T-case drop back on and adjust to see if the vibe is gone. Before that I would take some of the other's advice and check if anything is touching or if something is wrong with the driveshaft. If those come out clean and the drop fixes the vibe, seems like the SS SYE is the solution.

But again: Rubicon. No SY to E

 

[That'll Buff]

But again: Rubicon. No SY to E

Shoot you're right. I keep forgetting that the 241J does that, my bad.

 

[Hasselblad]

Sounds familliar
https://wranglertjforum.com/threads/2004-rubicon-driveline-vibrations.13302/

 

[JMT]

But Shawn is talking about 4"+ of driveline lift.

Driveline lift is your total suspension lift + tummy tuck. What’s your total?

You have a Rubicon, so you don’t need an SYE. Sorry aboutthat side trip.

I don’t know for sure, but what’s your rear driveshaft length? I can’t recall.

Then I am into asking if the joints are good on the shaft and the splines have good engagement and not loose.

 

[Hasselblad]

Driveline lift is your total suspension lift + tummy tuck. What’s your total?

You have a Rubicon, so you don’t need an SYE. Sorry aboutthat side trip.

I don’t know for sure, but what’s your rear driveshaft length? I can’t recall.

Then I am into asking if the joints are good on the shaft and the splines have good engagement and not loose.

Hard to tell total because I did not go from stock. When i bought it it had somewhat of a lift in it (maybe around 2'?), and a TC drop spacer set installed. I did not measure the height increase of the trans from shovel to teraflex belly-up skid.

 

[GoldenGorilla]

But Shawn is talking about 4"+ of driveline lift.

Can't see in the photos, but you may also have some left-right angle introduced if you don't have have good centering via your track bars. Usually not an issue, but sometimes if you're on the edge, that 3D angle may be enough to cause some headaches.

When I installed the Barnes bolt-on aka no-lift skid it introduced issues with the rear shaft output angle. I had to run 1" spacers for a while. Ultimately I did a 1" MML with no body lift, DC rear driveshaft and brought the skid up. That combo sorted it out. My 241 is a bit different, but otherwise it sounds like we have similar ride height and setup.

 

[jjvw]

Can't see in the photos, but you may also have some left-right angle introduced if you don't have have good centering via your track bars. Usually not an issue, but sometimes if you're on the edge, that 3D angle may be enough to cause some headaches.

...

That is one reason to quit fixating on the specific number and just find the angle where the vibes go away.

 

[Hasselblad]

Can't see in the photos, but you may also have some left-right angle introduced if you don't have have good centering via your track bars. Usually not an issue, but sometimes if you're on the edge, that 3D angle may be enough to cause some headaches.

When I installed the Barnes bolt-on aka no-lift skid it introduced issues with the rear shaft output angle. I had to run 1" spacers for a while. Ultimately I did a 1" MML with no body lift, DC rear driveshaft and brought the skid up. That combo sorted it out. My 241 is a bit different, but otherwise it sounds like we have similar ride height and setup.

I have the BL (with the emus) for the 33s I am on, and BL really doesnt mess with drivetrain, yes?
Trackbar tweaking is already on the list, as the rear still has whatever nonadjustable the last owner had put on with a straight adapter. I have a tereflex adjustable and angled bracket to put on when time allows. But axle at rest is pretty centered in the rear side to side.

 

[Rickyd]

I have the BL (with the emus) for the 33s I am on, and BL really doesnt mess with drivetrain, yes?

Body lift doesn't matter. Except in that it let you tuck the drivetrain up

 

[Hasselblad]

Here's how my brain is visualizing this, does this track?:
Belly up brings trans up, tilting engine/trans down to front on MM pivot point, creating more angle at the TC end of the DC shaft. Either the DC does not appreciate that angle, or Ujoint(s) suddenly buggered, or both. No adjustment of the pinion angle will get rid of the TC angle issue (if that is the case), but the TC drop might cure it by lessening the TC to DC angle somewhat. Is there a known limit of angle to TC end of a DC shaft that one doesn't want to go beyond? (NOT pinion angle, angle of shaft to drivetrain)

 

[Rickyd]

Here's how my brain is visualizing this, does this track?:
Belly up brings trans up, tilting engine/trans down to front on MM pivot point, creating more angle at the TC end of the DC shaft. Either the DC does not appreciate that angle, or Ujoint(s) suddenly buggered, or both. No adjustment of the pinion angle will get rid of the TC angle issue (if that is the case), but the TC drop might cure it by lessening the TC to DC angle somewhat. Is there a known limit of angle to TC end of a DC shaft that one doesn't want to go beyond? (NOT pinion angle, angle of shaft to drivetrain)

Someone here might remember, but a call to tom woods would definitely get you a maximum operating angle answer. I doubt you are there though. Guys run 4" lift plus tummy tucks on their tj's.