Wanna make a quick million and finally put an end to all war and famine?
Harmonic vibrations in Jeeps: A new theory (please read!)
- Thread starter psrivats
- Start date
Wanna make a quick million and finally put an end to all war and famine?
I found this...Its specifically talking about Harmonic balancers on the Crank...but there may be something to THAT as well. I've never known a harmonic balancer to fail...but apparently they do.
http://www.underhoodservice.com/harmonic-dampeners-fail-look/
Now I know how they 'work' which is what I suspected. Time to figure out how to tune them.
http://www.underhoodservice.com/harmonic-dampeners-fail-look/
Now I know how they 'work' which is what I suspected. Time to figure out how to tune them.
Been reading every post
. If I can think of anything else I'll certainly add it to the discussion. It really sounds like you've cracked open the magic can of worms and now we just have to make sense of it all!
@psrivats is going to go to Jeep West today to test drive his Jeep. He's going to take it on the highway at 65 mph plus and drive for a minute while it vibrates. Then he's going to turn the OD off and see what happens.
If the vibrations nearly go away with the OD off, then I think this will prove his theory. This is what's happening with mine at least, and given all the information he's dug up, it makes complete sense why he's happening. This is all linked to that pesky 42RLE and that ridiculous OD gear.
No wonder I never knew my vibrations existed after my re-gear. I had programmed myself to turn the OD off every single time I got in the Jeep. That being said, I'd never driven it after the re-gear with the OD on until that day where I had to drive it 35 miles on the highway out to Jeep West. When I got on the highway and turned the OD on, all of a sudden is was vibe city!
But when I turned the OD off, the vibrations were almost entire gone away (though they were replaced by very high RPMs and lots of engine noise of course!).
The more and more I think about this, the more obvious it is that the 42RLE is really the cause of all this.
If the vibrations nearly go away with the OD off, then I think this will prove his theory. This is what's happening with mine at least, and given all the information he's dug up, it makes complete sense why he's happening. This is all linked to that pesky 42RLE and that ridiculous OD gear.
No wonder I never knew my vibrations existed after my re-gear. I had programmed myself to turn the OD off every single time I got in the Jeep. That being said, I'd never driven it after the re-gear with the OD on until that day where I had to drive it 35 miles on the highway out to Jeep West. When I got on the highway and turned the OD on, all of a sudden is was vibe city!
But when I turned the OD off, the vibrations were almost entire gone away (though they were replaced by very high RPMs and lots of engine noise of course!).
The more and more I think about this, the more obvious it is that the 42RLE is really the cause of all this.
Hope you 42rle folks get it sorted. I've tried running in 4th gear, neautral coasting at 65mph with no change, so my vibes are related to something else. @rasband made an interesting observation a while back that mirrors my observation concerning driving when cold. I too notice a huge reduction in vibes in the morning on the way to work. First 5-7 miles into the commute I can barely hear them. That leads me to believe something in the rotating mass is changes as things heat up and tolerances tighten up. This is all great info guys, and an awesome thread!
@Ranger_b0b, clean explanation, thank you. Completely makes sense that manuals have a need for the damper in our Jeeps. I'm reasonably certain that I understand what's going on now.
Last night I also looked up if people had vibration complains after installing SYE ( no regear, just SYE which involves taking off the damper). Sure enough, there are LOTS of threads there as well. People even mention pulsing (ie harmonic) but have not connected the dots to the damper being absent.
I'm heading over to Jeep West in a couple hours. I'll post back on findings. Wish me luck gentlemen!
@Chris already has a super neat idea with a center dampener of similar design, but lower weight then OEM, and then a set of concentric rings that friction fit on top and add as much weight as needed for your rig. A machine shop will be able to make this pretty easily.
Take off Chris’ control arms while you’re there. He doesn’t need them :risas3:
I would not be surprised. Blaine hinted that Tom Woods may know in his post I posted a few pages ago. You should ask him next week when you chat with him.
jeepndogs
TJ Enthusiast
I do think you guys are on to something but I also think the TC has to somehow be involved. I have the 42rle and as long as only ONE shaft is spinning I have no vibration. I can pull the front and no vibes, if I put the front back in and pull the rear no vibes. I absolutely believe the OD has something to do with it, I have a 17 F-150 with the 3.5 eco boost and as soon as the OD locks up it has the same vibe as my Jeep. It does however go away if I slightly increase or decrease speed by 1-2 MPH.
I just looked up the top gear ratios of all the TJ transmissions with @Chris' help. I wanted to see if I can explain why the 97-01 Jeeps did not get the balancer. The model would be that earlier trans would have larger OD ratios. This is exactly what I found, so there is a method to the madness. Higher the OD ratio, less need for the balancer.
The 3spd auto had no OD.
AX-15 - 1997-1999 - 0.79
AX-5 - 1997-2002 - 0.85
NV1500 / NV2550 - 2003-2004 - 0.75/0.80
NV3550 - 2000-2004 - 0.78
NSG370 - 2005-2006 - 0.84
42rle - 2003-2006 - 0.69
So it looks to me like somewhere around 2001 Jeep noticed the problem with AX-5 and started including the damper. 30/32RH Jeeps never got it because there was no need! And NSG370 seems a better option by and far if you want to manual and 241 TC.
The 3spd auto had no OD.
AX-15 - 1997-1999 - 0.79
AX-5 - 1997-2002 - 0.85
NV1500 / NV2550 - 2003-2004 - 0.75/0.80
NV3550 - 2000-2004 - 0.78
NSG370 - 2005-2006 - 0.84
42rle - 2003-2006 - 0.69
So it looks to me like somewhere around 2001 Jeep noticed the problem with AX-5 and started including the damper. 30/32RH Jeeps never got it because there was no need! And NSG370 seems a better option by and far if you want to manual and 241 TC.
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Well, I came here but Jeep West was closed today.
I know they are open some Sundays, but today was not a day like that. I'll have to call Dave and get this checked tomorrow AM. Will update and will continue researching.
@Chris and I will have to likely meet Dave in person sometime to discuss the fix. This thread is way too long at this point for him to read given how busy he is.
I know they are open some Sundays, but today was not a day like that. I'll have to call Dave and get this checked tomorrow AM. Will update and will continue researching.
@Chris and I will have to likely meet Dave in person sometime to discuss the fix. This thread is way too long at this point for him to read given how busy he is.
Been reading the threads on SYE and Vibrations. Obviously I'm not the first person to think on these lines. This guy went far but seems to the (wrong) conclusion that it was the CV shaft.
https://bit.ly/2qtpl97
Most of the SYE threads indicate the same problem at higher speeds (where OD would be engaged), both manual Jeeps and 42RLEs. You guys can search and see, there are tons of threads really. No one seems to have linked to not having the balancer and these threads end up after a while as the OP gives up and moves on I hope I don't end up like one of them.
I emailed MrBlaine with a link to this thread. If he responds to me on email (or on the phone, will call him sometime this week), I'll post what he had to say.
https://bit.ly/2qtpl97
Most of the SYE threads indicate the same problem at higher speeds (where OD would be engaged), both manual Jeeps and 42RLEs. You guys can search and see, there are tons of threads really. No one seems to have linked to not having the balancer and these threads end up after a while as the OP gives up and moves on
I hope I don't end up like one of them.I emailed MrBlaine with a link to this thread. If he responds to me on email (or on the phone, will call him sometime this week), I'll post what he had to say.
I bumped the WF thread for an update.
I'm interested for Blaine's opinion. IMHO, he is the most knowledgeable of anyone on the forums.
I'm interested for Blaine's opinion. IMHO, he is the most knowledgeable of anyone on the forums.
I just realized it is a YJ .. but let's see if he responds. I would assume this applies to any Jeep, honestly.
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I may have hit paydirt! Found two different threads where people have confirmed that (1) vibration goes away when OD is disengaged just like @Chris did on his jeep (2) a report of atleat 1 person saying that the problem went away on an older jeep by replacing the damper.
@Chris we really need to go see Dave in person.
https://bit.ly/2PcrBQS
https://bit.ly/2zCkiYr
@Chris we really need to go see Dave in person.
https://bit.ly/2PcrBQS
https://bit.ly/2zCkiYr
Interesting take from an ROF post:
No new news just adding to the discussion
O5 TJ Rubicon, stock motor, 3.5 lift, regeared to 4:88, speed healer and 33's. Gas mileage similar to Aeroshots about 15-16 mpg on highway at 60-65mph. I'm never in a hurry and baby my Jeep. But I get pushed to higher speeds when on the highway keeping up with the Jeep club. At 70+mph I'm getting 10-12 mpg!
Bad vibration culprit on my Jeep was the harmonic balancer on the transfer case. Removed and run new yoke without it.
Utah BDR trip, Along the Colorado River Utah near Lees Ferry
No new news just adding to the discussion
O5 TJ Rubicon, stock motor, 3.5 lift, regeared to 4:88, speed healer and 33's. Gas mileage similar to Aeroshots about 15-16 mpg on highway at 60-65mph. I'm never in a hurry and baby my Jeep. But I get pushed to higher speeds when on the highway keeping up with the Jeep club. At 70+mph I'm getting 10-12 mpg!
Bad vibration culprit on my Jeep was the harmonic balancer on the transfer case. Removed and run new yoke without it.
Utah BDR trip, Along the Colorado River Utah near Lees Ferry
This is from Tom Woods website
http://www.4xshaft.com/rubicon/rubicon_rear.asp
We do not suggested that the yoke type conversion be done on vehicles with the manual transmission. As removing the mass vibration dampener hub will eliminate the torsional dampening effect of this hub and may induce some transmission gear clatter.
http://www.4xshaft.com/rubicon/rubicon_rear.asp
We do not suggested that the yoke type conversion be done on vehicles with the manual transmission. As removing the mass vibration dampener hub will eliminate the torsional dampening effect of this hub and may induce some transmission gear clatter.
Hopefully someone can put this theory to the test now beyond just words. At this point I think someone needs to actually test it out. Add some weight to the damper and see what the effect is, even if it's just a random weight for the time being. It would be interesting to see if it increases or decreases vibration.