I have a 2009 JK and have this annoying vibration behind my instrument panel left side which starts around 2300 rpm. If I put just a little pressure on the clutch pedal the noise goes away. Anyone ever have this problem and it turned out to be air in the Clutch Slave Cylinder or it turned out to be the Throw Out Bearing.

 

Is it noise or vibration? In gear or neutral? Go to 5000 rpm my JK vibrates, sounds and feels like a Jeep pre 2012 (no bells and whistles). Could be some form of harmonic motion.

 

It starts making noise in 3rd gear at about 2200 rpm. Sounds like a plastic vibration noise. I put a little pressure on the clutch and it goes away. Or dampens the noise. I've YouTubed the subject and they all point to air in the Slave Cylinder. There is somewhat of a vibration in the clutch pedal if you touch it. So far I've been told Throw out bearing.

 

Just in 3rd at 2200 rpm or in all 6. Not reverse ( think I did that once, almost did a quality control for the roll bars) and in 6th, I forgot a 3.8L is best for crawling, low end controllable torque not F1 Racing.

 

You can hear it in 3rd, 4th, 5th sometimes and maybe 6th. As the rpm increases or decreases it goes away. It won't do it in 1st or 2nd. There is a noticeable ticking noise coming from underneath the Jeep though. I always thought it was normal clutch plate noise. I think I must have done something to the mainshaft of the xmission while playing in 4Low. It's been out 2 times now at two different xmission shops. I don't think I'm going for 3rd attempt. Still waiting for a reply from the xmission shop if they think what I'm describing to be air in the Slave Cylinder. Which is a easy fix compared to the pricey dropping the xmission to replace a throw out bearing. If they say bearing, then I'm just going to drive the Jeep into the ground.

 

Air in the clutch slave cylinder would just make it spongy like when there is air in the brake system, I think. Drive shafts when made are balanced ( harmonic motion) like when you get a new set of tires. So at certain rotational speeds (rpm) they do not act wonky. Is it possible to nocked off a balance weight when off roading? If your through out bearing is bad, it would make it difficult engaging the clutch if I remember. Back in the good old days we learned how to speed shift, no use of the clutch, rev matching. I also have had a ticking sound forever, I just stay in high revs and my Magnaflow exhaust drowns it out. LOL

 

I'll make it a point to check those drive shafts for missing weights.

 

Drives Lines look Ok. I would have to say Throw Bearing is the problem. If I ease up on the speed and rpm no noise. I'm going to nurse this until next spring or summer. I'm a little tuckered out fixing everything. Thats all I did this whole summer. Home inside and out, the Jeep swing gate hinges and tire carrier and exhaust was replaced and have replace my windshield 2x in one year.

 

All my rides since 1975 have been sticks and I am a retired MET, pretty sure it is not the throw out bearing. Hope you resolve your issue, because that is a $$$ job (labor) for a inexpensive part. Replaced my tailgate hinges and carrier this summer cause the OEMs were crap and I have only 16in tires on. My summer OEM 17in Wrangler SRAs have been in my basement for over 10yrs. All Good

 

if its a noise that happens thats linked to a specific rpm and goes away with slight pedal input... i would be going after the throughout bearing.