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

Tires! After 4 different balance jobs. Goodyear, OK Tire, Integra Tire, Goodyear again, and still - all the symptoms keep pointing to tires. Vibes vary at times but generally come on above 50mph and really peak at 65. All these marginally skilled operators would find that the "last shop" was out by 1 or more oz. Finally I took it a local Ford dealer who Hunter identified as having the best "Elite" Road Force balancer in my area. They found one tire totally out of tolerance and one more marginal with heavy/high spots. This was only revealed when a pressure wheel is applied during the spin-up. That probably explains why the steering wheel vibration almost disappeared just swapping tires front to back.

So Goodyear is ordering two more tires and we'll see where that leads us. Won't know the results for about a week as I'm heading out of town for a few days. The TrailRunner AT's are generally considered to be a decent tire - and these are a stock 225/75R15s. I can't imagine what it takes to get larger tires dialed in. These tires would probably be fine mounted on anything else but Jeeps are light, short wheelbase, live axles, and stiff suspensions.
 
I'm going to drive the rest of the week without the front drive shaft and get a feel for the vibes, or lack there of, in different temperature variations. This morning's commute, a very, very slight harmonic at 55 mph. No vibes at 65 or above. It's not my rear pinion angle. I think I can put that one to rest. Starting to sound like I may be suffering the fate of @jeepndogs with a hub conversion, or re-gear down to 4.10's to slow the rotating mass down. Either option will probably lead to divorce.
 
bobthetj03 said:
I'm going to drive the rest of the week without the front drive shaft and get a feel for the vibes, or lack there of, in different temperature variations. This morning's commute, a very, very slight harmonic at 55 mph. No vibes at 65 or above. It's not my rear pinion angle. I think I can put that one to rest. Starting to sound like I may be suffering the fate of @jeepndogs with a hub conversion, or re-gear down to 4.10's to slow the rotating mass down. Either option will probably lead to divorce.
Click to expand...
With the front hub conversion, doesn't that require new wheels too? Oh..not good...divorce would probably be on the horizon.
 
  • Like
Reactions: bobthetj03
lowranger said:
With the front hub conversion, doesn't that require new wheels too? Oh..not good...divorce would probably be on the horizon.
Click to expand...

I'd probably sell the jeep and start over if it came to needing a hub conversion. To complicate that, I also have a Big Brake kit, so not even sure if that is an option with the BBK.
 
Getting pretty efficient at changing pinion angle. Compiling a pretty good database of pinion angles in the process. (-) is pinion angle set lower than DS angle. (+) is pinion angle set higher than DS angle.

DS angle:...................................Pinion angle:........................Net difference:
13.0* 12.5* = - 0.5*
13.8* 12.2* = - 1.6*
14.2* 11.4* = - 2.8*
14.6* 11.0* = - 3.6*
15.5* 11.1* = - 4.4*
15.1* 10.1* = - 5.0*
15.8* 10.6* = - 5.2*
14.2* 12.7* = + 1.5*
13.7* 13.4* = - 0.3*

After each setting, I went for a drive to note any change. After all these settings and test drives, the only setting that felt different was when I went to +1.5*, and that difference was a slight vibration at hard acceleration. I put it back to -0.3* and the hard accel vibe went away. Next up, I'm gonna slam it all the way to -6.0*, if I can, cause I'll be just about out of adjustment on the rear uppers, and see what happens.
 
I give you credit, you have much more patience with this than I did. My wife wasn’t real happy with the cost of the hub conversion. And I did go with the big bolt kit so I had to replace rims. Although that was a wash because I only had 2500 miles on the tires and wheels and I was able to sell them for the cost of the new wheels/tires. If I had spent one more night under that Jeep trying to fix it my wife would have divorced me!
 
  • Like
Reactions: bobthetj03
jeepndogs said:
I give you credit, you have much more patience with this than I did. My wife wasn’t real happy with the cost of the hub conversion. And I did go with the big bolt kit so I had to replace rims. Although that was a wash because I only had 2500 miles on the tires and wheels and I was able to sell them for the cost of the new wheels/tires. If I had spent one more night under that Jeep trying to fix it my wife would have divorced me!
Click to expand...

I'm coming to the end of my patience with it. Couple more adjustments then I'll just live with the vibes till something lets go.
 
  • Like
Reactions: DWLJ and jeepndogs
One other thing I have been observing over the last year or so is I don’t actually know of anyone that has a 4:56 or lower gear set with a 42RLE trans and up to a 33 in tire that doesn’t have this vibration. I think it is 100% linked to driveshaft speed.
 
  • Like
Reactions: bobthetj03 and DWLJ
jeepndogs said:
One other thing I have been observing over the last year or so is I don’t actually know of anyone that has a 4:56 or lower gear set with a 42RLE trans and up to a 33 in tire that doesn’t have this vibration. I think it is 100% linked to driveshaft speed.
Click to expand...

The driveshaft is going to make the same number of turns in each gear at any given rpm regardless of axle gearing.

Are you saying that only the guys with 42RLE transmissions who run short tires with ratios 4.56 or lower are getting unacceptable front driveshaft vibrations?

Are you suggesting that the combination of short tires and low gears makes people drive at high rpms to maintain acceptable road speed, which in turn results in the driveshafts turning more times per mile, and as a consequence causes driveline vibrations? If so, what rpm range is that?

I recently re-geared my '06 LJ Rubicon with 42RLE automatic transmission and 35" tires from 4.88 to 5.38 in . If the gear change has caused additional vibration in the front driveshaft it is imperceptible.
 
Mr. Bills said:
The driveshaft is going to make the same number of turns in each gear at any given rpm regardless of axle gearing.

Are you saying that only the guys with 42RLE transmissions who run short tires with ratios 4.56 or lower are getting unacceptable front driveshaft vibrations?

Are you suggesting that the combination of short tires and low gears makes people drive at high rpms to maintain acceptable road speed, which in turn results in the driveshafts turning more times per mile, and as a consequence causes driveline vibrations? If so, what rpm range is that?

I recently re-geared my '06 LJ Rubicon with 42RLE automatic transmission and 35" tires from 4.88 to 5.38 in . If the gear change has caused additional vibration in the front driveshaft it is imperceptible.
Click to expand...


What I’m saying is I have read through this thread, 10-15 other threads on this forum, countless other threads on other forums, spoke to half a dozen people or so at different Jeep events. Have driven in three different Jeeps in my area in local Jeep clubs that all have this vibration. There appears to be a few things in common from my observation. They all have 4:56 gears or lower, 33 in or so tires, and the 4 speed auto. I personally have not spoken to or heard of anyone with this issue with a stick, 3 speed auto, or anyone running a 35 in or larger tire.
 
jeepndogs said:
What I’m saying is I have read through this thread, 10-15 other threads on this forum, countless other threads on other forums, spoke to half a dozen people or so at different Jeep events. Have driven in three different Jeeps in my area in local Jeep clubs that all have this vibration. There appears to be a few things in common from my observation. They all have 4:56 gears or lower, 33 in or so tires, and the 4 speed auto. I personally have not spoken to or heard of anyone with this issue with a stick, 3 speed auto, or anyone running a 35 in or larger tire.
Click to expand...

@bobthetj03 is manual, no?
 
bobthetj03 said:
Yep. NV3550 5 speed manual. Vibes started the very moment I re-geared to 4.56's, with no other changes made to the jeep. Find me a solution.
Click to expand...
Mine is a NV3550 also. It is at the shop right now getting 4.88. Crossing my fingers I do not run into this issue.
 
  • Like
Reactions: tomtaylz
bobthetj03 said:
Yep. NV3550 5 speed manual. Vibes started the very moment I re-geared to 4.56's, with no other changes made to the jeep. Find me a solution.
Click to expand...


I stand corrected, I know ONE person with a stick and this vibration! For some reason I thought you had an auto, been following this post since the start and I didn’t want to have to go all the way through it to confirm. Lol
 
  • Like
Reactions: tomtaylz and bobthetj03
bobthetj03 said:
It's all good. Pretty sure it's a rotational issue based on speed and frequency. My jeep is being a beeotch!
Click to expand...

Harmonic vibrations can be a real bitch to solve. Reminds me of when the Harley aftermarket first came out with a 6 speed tranny for rubber mounted FL frames. They worked perfectly but had a harmonic drone that was unacceptable. They finally figured it out but I never heard what solved the problem.


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: Thunderhead
jeepndogs said:
Trust me, 5 gallons of gas and a highway flare sounded like a great option quite a few times when I was chasing this.
Click to expand...

If it wasn't my daily it wouldn't be as big of a deal, but I have to listen to it every day, so it wears on me. Good news is, top off season is fast approaching, so all the added noise will mask most of it.
 
  • Like
Reactions: Alex01 and jeepndogs
Top Bottom
Back