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Re-geared, now I have a vibration above 50 mph

JMT

The Jeep Guy
Supporting Member
Ride of the Month Winner
Feb 27, 2017
7,895
Texas Hill Country
I was coming here for someone to make my day, someone who recently had an anniversary. Now I'm disappointed.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
My rear ds felt ok. I greased the centering yoke and tube while I had it out. Movement of the CV feels smooth and effortless. I did notice some in/out play in the tc output yoke. Not sure if that is acceptable, but it was enough play to see it. Rear diff yoke has zero in/out play.
 

psrivats

TJ Addict
Supporting Member
Jun 4, 2018
1,467
OR, USA
No other recent changes since new tires, other than removing the rear seat, which, by the way, weighs 65lbs and is awkward as hell to remove.

I haven't had my rear seat since prior to the re-gear. I was actually surprised at how light it was. Mine came out without fuss.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
Ok, 15 gallons of fuel later, my pinion angle went from 2.2* lower to 1.4* lower. That is pretty dang close to a full degree up from an empty tank. Throw 175 lbs of dogs in the back and I don't think I should raise it any more?
 

toximus

TJ Addict
Supporting Member
Mar 29, 2018
1,987
Northern WI
Ok, 15 gallons of fuel later, my pinion angle went from 2.2* lower to 1.4* lower. That is pretty dang close to a full degree up from an empty tank. Throw 175 lbs of dogs in the back and I don't think I should raise it any more?
Load it with what you normally carry.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
Load it with what you normally carry.
I run it pretty light as it's my DD, so it's pretty much how it is most of time sans the rear seat. The hard top will be coming off next month, so that's another 75 lbs. Suppose I could toss three 60 lb. bags of redimix back there to simulate the dogs and see how it feels.
 

Fouledplugs

TJ Addict
Supporting Member
Jun 19, 2017
2,509
Alabama/South Carolina
I'm having some issue making driveshafts last. They keep making a rumbling sound coming from the centering ball. The rear is doing it again 500 miles after a rebuild and the front started doing it after 6000 miles. Primarily 0-35mph, I need to keep them greased every 500 miles to keep them quiet above 35mph. I scheduled a Roadforce tire rebalance at the local Ford dealer to make sure that's not causing some of the issues.

I can feel it in the steering wheel and gas peddle.
What brand parts are you using?
 

pagrey

TJ Enthusiast
Apr 10, 2018
506
Los Angeles, CA, USA
Ok, 15 gallons of fuel later, my pinion angle went from 2.2* lower to 1.4* lower. That is pretty dang close to a full degree up from an empty tank. Throw 175 lbs of dogs in the back and I don't think I should raise it any more?
I run air springs for this sort of thing. Not gas but loading gear. They aren't too expensive and work pretty well. These Jeeps just have really soft rear springs and when you start loading cargo it helps.
 
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chino1969

TJ Enthusiast
Apr 14, 2019
166
Oxford, PA
I don't have a dog in this fight but can offer this. Anytime a rotational object is modified or changed there are physical aspects to consider like natural frequency and resonance. Power plants that have 180 ton turbine spindles rotating at 1800 rpm's have a balance group with specialized training to keep vibrations within acceptable limits. I'm hearing some of the same components that have contributed to vibration issues in power plants on this forum; i.e. rotating shafts, higher rpm's, etc.. The difference is a group of specialists with sophisticated equipment that are trained to minimize these vibrations in power plants. I am not knocking anyone here or criticizing just adding this for consideration.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
Wish I could hire a team to cure mine. So, put the rear ds back on for the trip home last night. I now have vibes starting at 45 mph+ worse than before removing it. I inspected the ds, greased it, and installed it with new bolts at the output yoke because I was too lazy to clean the loctite off the threads. Nothing else was changed other than a full tank of fuel and removal of the rear seat.
So this morning I inspected it to make sure the caps were seated properly in the yokes and the bolts were all tight. Everything looked normal. I removed it, again, flipped the ds 180* and used the old bolts at the output yoke. Should not make any difference which way it was installed, but I'm out of ideas. I'll take it for a spin at lunch and see what we get.
 

tomtaylz

LJR Addict
Supporting Member
Ride of the Month Winner
Feb 18, 2018
1,898
San Francisco, CA, USA
Wish I could hire a team to cure mine. So, put the rear ds back on for the trip home last night. I now have vibes starting at 45 mph+ worse than before removing it. I inspected the ds, greased it, and installed it with new bolts at the output yoke because I was too lazy to clean the loctite off the threads. Nothing else was changed other than a full tank of fuel and removal of the rear seat.
So this morning I inspected it to make sure the caps were seated properly in the yokes and the bolts were all tight. Everything looked normal. I removed it, again, flipped the ds 180* and used the old bolts at the output yoke. Should not make any difference which way it was installed, but I'm out of ideas. I'll take it for a spin at lunch and see what we get.
Bet that lake is nice and full!
 

Flib

TJ Enthusiast
Apr 15, 2018
394
Nova Scotia
Glad I came across this because I am experiencing the same thing after the re-gear.

I know the slip yoke on my rear drive shaft is slightly wore so I need to replace that (I assume the shaft from the transfer case is hardened steel and the wear is in the yoke). I'll do that before I get too deep into things.

Mine seems to be getting slightly better the more miles I put on it, was starting to wonder if this is normal when re-gearing until things "mesh" together.

SYE is in the future plans but the toke is easy enough to replace and try.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
Glad I came across this because I am experiencing the same thing after the re-gear.

I know the slip yoke on my rear drive shaft is slightly wore so I need to replace that (I assume the shaft from the transfer case is hardened steel and the wear is in the yoke). I'll do that before I get too deep into things.

Mine seems to be getting slightly better the more miles I put on it, was starting to wonder if this is normal when re-gearing until things "mesh" together.

SYE is in the future plans but the toke is easy enough to replace and try.
There is a small percentage of folks that experience vibes after a re-gear. Each case I've read is slightly different than the next, so it's hard to pinpoint a common issue. My vibe issue might be unique in that I've been chasing it for a long time, thrown a lot of parts and experiments at it, and have made improvements, but still no total resolution. There has been discussions where resonant frequencies are introduced as a result of the gear change and drive shafts spinning faster, ujoint critical operating angles, and the like. If you can, try to pinpoint which drive shaft might be creating the vibe. Try pulling the front on first. Many folks with the 42rle auto trany find pulling the front shaft cured the vibes, some it did not.
 

Flib

TJ Enthusiast
Apr 15, 2018
394
Nova Scotia
There is a small percentage of folks that experience vibes after a re-gear. Each case I've read is slightly different than the next, so it's hard to pinpoint a common issue. My vibe issue might be unique in that I've been chasing it for a long time, thrown a lot of parts and experiments at it, and have made improvements, but still no total resolution. There has been discussions where resonant frequencies are introduced as a result of the gear change and drive shafts spinning faster, ujoint critical operating angles, and the like. If you can, try to pinpoint which drive shaft might be creating the vibe. Try pulling the front on first. Many folks with the 42rle auto trany find pulling the front shaft cured the vibes, some it did not.

I got the jeep out of the gear shop on friday, the front DS was already out as I was replacing the U joints. Friday night I went to my buddies place and we replaced a U joint on the rear (it was really bad and ready to fail). It was when we were reinstalling it that we noticed the slip yoke had some play (on the t-case shaft).

Saturday I installed the new u joints on the front shaft and installed it, did not make the vibes any worse. I'm keeping my fingers crossed that it is the slip yoke causing my vibes.

I'll post the results and contribute to the knowledge base here :)
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,658
NorCal
Wish I could hire a team to cure mine. So, put the rear ds back on for the trip home last night. I now have vibes starting at 45 mph+ worse than before removing it. I inspected the ds, greased it, and installed it with new bolts at the output yoke because I was too lazy to clean the loctite off the threads. Nothing else was changed other than a full tank of fuel and removal of the rear seat.
So this morning I inspected it to make sure the caps were seated properly in the yokes and the bolts were all tight. Everything looked normal. I removed it, again, flipped the ds 180* and used the old bolts at the output yoke. Should not make any difference which way it was installed, but I'm out of ideas. I'll take it for a spin at lunch and see what we get.
Ok, post lunch drive has us back to where we started prior to removing the rear ds. I just don't understand how such a small change dramatically changes the balance. It leads me to the conclusion that some improvement can be made with this ds. I may have to try that hose clamp balancing test that @psrivats linked to see if I can improve upon it.
 
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psrivats

TJ Addict
Supporting Member
Jun 4, 2018
1,467
OR, USA
Ok, post lunch drive has us back to where we started prior to removing the rear ds. I just don't understand how such a small change dramatically changes the balance. It leads me to the conclusion that some improvement can be made with this ds. I may have to try that hose clamp balancing test that @psrivats linked to see if I can improve upon it.
FWIW, I am told that the local shop that did the active balancing did make a perceptible improvement to the vibration, but it is not fully cured yet. They are going to try another round today/tomorrow. I am hopeful they can dial it out where it is not an annoyance. If you attempt it, make sure you are as systematic as possible so that you don't have to restart over and over.