Excellent, thank you! Please let us know what they have to say.
And good luck with the new driveshaft.
Harmonic vibrations in Jeeps: A new theory (please read!)
- Thread starter psrivats
- Start date
Excellent, thank you! Please let us know what they have to say.
And good luck with the new driveshaft.
I'll need all the luck I can get! Gonna bail for now, Heading on my second road trip. Adjusted the pinion angle up 1*.
@psrivats if you're making a table, be sure and include Tcase type. Didn't see it in your original list.
Sure would be nice to have a NI data logger, a few accelerometers, and a Dyno. You could spin the various pieces of the drivetrain up to speed and find their natural frequency experimentally. Might give you a clue.
I didn't see in the other thread where we were talking about driveshaft construction. Did anyone find anything out there?
Here is another thought I'm having. The engine, transmission and Tcase are mounted in three locations. They have rubber mounts. So... Not only are you getting vibration, but you're getting enough to overcome the rubber isolation. I wonder what would happen if you added more or less rubber? How about a durometer change? Like try a set of poly motor and tranny mounts.
Sure would be nice to have a NI data logger, a few accelerometers, and a Dyno. You could spin the various pieces of the drivetrain up to speed and find their natural frequency experimentally. Might give you a clue.
I didn't see in the other thread where we were talking about driveshaft construction. Did anyone find anything out there?
Here is another thought I'm having. The engine, transmission and Tcase are mounted in three locations. They have rubber mounts. So... Not only are you getting vibration, but you're getting enough to overcome the rubber isolation. I wonder what would happen if you added more or less rubber? How about a durometer change? Like try a set of poly motor and tranny mounts.
Yes I will include Transfer case type. AFAIK, all 241s have the dampener. 231s looks like some years did, some did not. Looking at the FSMs now, just downloaded them all.
Don't think the discussion in the other thread went any further. Mounts certainly are part of the system. I think Dave already checked mine. It's good to think about them in this discussion. It should be on the list of items to check for sure, just like pinion angles. Now the topic of different durometers ... only way to know is to swap them out and see what happens. 55 MHz is a pretty low resonant frequency though (imagine those nasty subwoofers on cars on the road and how easily that sound penetrates and drones in your cabin).
55 MHz? Isn't that REALLY fast? Hz, KHz (1000), MHz (1,000,000). Most base (audio) signals are around 40 Hz. Human hearing range is 20 Hz to 20 KHz (20-20000 Hz).
It wouldn't cost too terrible much to replace the three mounts in question...less than 200 dollars. FAR cheaper than locking hubs or some of the other band-aids people utilize to fix the problem.
It would be interesting (if only from a purely academic standpoint) to go with solid mounts and see what happens.
I compiled the info from the FSMs (I looked at all years, slow day at work!)
Here is my summary @Chris @StG58
@ElectricWizard your Jeep is likely a 2001 sold as a 2000
Lots of companies do this nonsense. Can you please double check the 2000/2001 FSMs for me?
I would appreciate if a few folks can quickly check the FSM for their jeeps to make sure I did not mess up
Looking at this table, it looks like the only jeep made in the mid years with the 32RH auto did NOT get a damper. If there is someone who's following this thread with a 32RH, can you PLEASE take a look at your jeep irrespective of the year it was made? It would be really useful information in this context.
THe reason I am highlighting the taper fit for the companion flange in the 241 TC is because I know that these balancers usually have to be an interference fit for them to work properly. I think that is relevant information in the manual, they specifically highlight that.
Here is my summary @Chris @StG58
@ElectricWizard your Jeep is likely a 2001 sold as a 2000
Lots of companies do this nonsense. Can you please double check the 2000/2001 FSMs for me?I would appreciate if a few folks can quickly check the FSM for their jeeps to make sure I did not mess up
Looking at this table, it looks like the only jeep made in the mid years with the 32RH auto did NOT get a damper. If there is someone who's following this thread with a 32RH, can you PLEASE take a look at your jeep irrespective of the year it was made? It would be really useful information in this context.
THe reason I am highlighting the taper fit for the companion flange in the 241 TC is because I know that these balancers usually have to be an interference fit for them to work properly. I think that is relevant information in the manual, they specifically highlight that.
Clearly there is a reason that some of the TJs had harmonic balancers and some didn't. Someone out there knows the answer to that question, I just don't know who. It would be interesting to speak to one of the original TJ engineers and ask them about this.
The only thing I can think of off the top of my head is that perhaps after a certain year, they started including them on ALL TJs, and prior to that year, the ones that got them had a specific transmission / transfer case / gear ratio.
I'm 99.9% certain that ALL Rubicon model TJs had the harmonic balancer on the TC.
The only thing I can think of off the top of my head is that perhaps after a certain year, they started including them on ALL TJs, and prior to that year, the ones that got them had a specific transmission / transfer case / gear ratio.
I'm 99.9% certain that ALL Rubicon model TJs had the harmonic balancer on the TC.
I compiled the info from the FSMs (I looked at all years, slow day at work!)
Here is my summary @Chris @StG58
@ElectricWizard your Jeep is likely a 2001 sold as a 2000
I would appreciate if a few folks can quickly check the FSM for their jeeps to make sure I did not mess up
View attachment 61302
So it looks like it was never mentioned for automatics (with the exception of the Rubicon models, which we know have it on all of them), only manuals?
Yes. No mention of it in the manuals with respect to autos. I really want someone with a 32RH from 2001-2002 to check and confirm there is no damper. If that's the case, then we can conlcude that all jeeps from 2003 had the damper and rest assured that Jim Frens is 100% accurate with the '03 onwards having the design change prone to vibrations.
He most likely is 100% right on this topic.
You might have to post that as a new thread to get someones attention. I suspect most people won't dig this deep into this thread.
I too would like to know if there is a damper on 92-02 models equipped with the 32RH.
Jim Frens would know better than any of us I suspect... he did help design the TJ after all.
September 2000 build date with a 32rh. Although I have a SYE, I’m positive it didn’t have a harmonic balancer before the swap (I kept the old parts around for awhile).
No problem. I’ll be honest I just skimmed the thread, but I’m not aware of any 32rh that has had the harmonic problems of the 42rle.
I compiled the info from the FSMs (I looked at all years, slow day at work!)
Here is my summary @Chris @StG58
@ElectricWizard your Jeep is likely a 2001 sold as a 2000
Mine is a 2000, however you're right, it was built in May 2000 and I have noticed some things aren't typical to a 2000; for example, my exhaust headers and crossover pipe is for 2001. In this case I suppose mine is an oddball and could be considered an 01.
Thought so! It was a transition jeep and sometimes it's great to have those.
Certainly makes it more unique! Gave me quite a surprise when I had to replace my exhaust bolts
Stox5225
TJ Enthusiast
IN 6 HOURS THERE ARE OVER 70 NEW POSTS .... good thing I got some beers and time to kill [emoji106][emoji2532][emoji482][emoji41]
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jeepndogs
TJ Enthusiast
When I rebuilt my TC trying to see if that was the issue I did go with the larger chain and the upgrades to the planetary gears. And also Tom Woods built two shafts for the front of my Jeep trying to solve the vibration. Ended up refunding me my money because it didn’t solve the problem