Intermittent sound on downshift

[Malachi]

My '21 JL 6spd manual started exhibiting a disturbing behavior a few months back.

Once in a while when doing a heavy downshift from 2nd to 1st (RPMs at around ~3k in 2nd) a startlingly loud rubbing friction noise is heard. Think the sound of a semi truck whacking its brakes on the freeway, and about that loud too! Loud enough you can hear it echo off houses nearby in a suburb.

I took this (with all speed) to my local dealer who summarily found nothing and then came close to lecturing me not to downshift, which frankly just pissed me off. I've been driving manual vehicles for 30 years. I know compression braking is hard on the vehicle already.

Anyway, any idea what's going on here?

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[Malachi]

I'll post an update, just incase someone is interested.

Mechanic at local CDJR in Los Angeles says it's a "throttle bearing". He says yes it's normal for a Jeep clutch to make that sound on downshift sometimes. He suggested I'm not used to this kind of clutch and even implied I should downshift differently - though that last one he backed off of when I pressed him. I find this all hard to stomach.

Casual R&D on the internet for "throttle bearing" reveals very little, though I do get a lot of hits for "throwout bearing"

 

[J.Ferreira]

I'll post an update, just incase someone is interested.

Mechanic at local CDJR in Los Angeles says it's a "throttle bearing". He says yes it's normal for a Jeep clutch to make that sound on downshift sometimes. He suggested I'm not used to this kind of clutch and even implied I should downshift differently - though that last one he backed off of when I pressed him. I find this all hard to stomach.

Casual R&D on the internet for "throttle bearing" reveals very little, though I do get a lot of hits for "throwout bearing"

I've never heard of a throttle bearing, it very well could be the throwout bearing though. That sound being as loud as a semi engine braking is fucking wild though.

Also (not telling you how to drive or anything) but maybe until the recall is resolved...don't downshift into first? Unless you've already gotten an aftermarket clutch. Though if your throwout bearing is going, I can't imagine it's new. lol

 

[OrneryBear]

It's the thr

My '21 JL 6spd manual started exhibiting a disturbing behavior a few months back.

Once in a while when doing a heavy downshift from 2nd to 1st (RPMs at around ~3k in 2nd) a startlingly loud rubbing friction noise is heard. Think the sound of a semi truck whacking its brakes on the freeway, and about that loud too! Loud enough you can hear it echo off houses nearby in a suburb.

I took this (with all speed) to my local dealer who summarily found nothing and then came close to lecturing me not to downshift, which frankly just pissed me off. I've been driving manual vehicles for 30 years. I know compression braking is hard on the vehicle already.

Anyway, any idea what's going on here?

It's a throwout bearing, you heard him wrong. You're just rushing your clutch release on the downshift. These will do it brand new, and I've had other manual transmissions make the same noise. I got that noise on my 6spd frontier pro4x, and I get it on occasion when I drive our JL, but my wife doesn't because shes slower on the clutch on downshifts than I am.

 

[Malachi]

It's the thr

It's a throwout bearing, you heard him wrong. You're just rushing your clutch release on the downshift. These will do it brand new, and I've had other manual transmissions make the same noise. I got that noise on my 6spd frontier pro4x, and I get it on occasion when I drive our JL, but my wife doesn't because shes slower on the clutch on downshifts than I am.

He said it like 6 times. I repeated it back to him saying "I've never heard of a throttle bearing" and he did not correct me. Later while paying, while in front of the service manager I asked him to note his diagnosis of "throttle bearing" on the invoice. Nobody corrected me.

It has made this sound (in agonizing length) while releasing the clutch over 4 seconds. I can't imagine you are recommending slower than that, are you?

This clutch is not brand new, it started making the sound right around 30k miles

I do agree though he probably meant throwout bearing that just makes more sense.

 

[Malachi]

I've never heard of a throttle bearing, it very well could be the throwout bearing though. That sound being as loud as a semi engine braking is fucking wild though.

Also (not telling you how to drive or anything) but maybe until the recall is resolved...don't downshift into first? Unless you've already gotten an aftermarket clutch. Though if your throwout bearing is going, I can't imagine it's new. lol

Right?
Anytime I hear consumer grade machines making very loud (like, you need earplugs) friction sounds, I get concerned.
Yeah stock clutch, and DEF not new

 

[OrneryBear]

He said it like 6 times. I repeated it back to him saying "I've never heard of a throttle bearing" and he did not correct me. Later while paying, while in front of the service manager I asked him to note his diagnosis of "throttle bearing" on the invoice. Nobody corrected me.

It has made this sound (in agonizing length) while releasing the clutch over 4 seconds. I can't imagine you are recommending slower than that, are you?

This clutch is not brand new, it started making the sound right around 30k miles

I do agree though he probably meant throwout bearing that just makes more sense.

Ya i'm not sure what they are talking about. ya if its that agonizingly slow, it's not the same noise I'm mentioning.

 

[roaniecowpony]

A throttle bearing uses blinker fluid for lubrication. Sounds like you ran out of blinker fluid.

Seriously though, if you're at 3000 rpm in second and downshift to first, that's a pretty big rpm increase. It also engages the syncronizer (or "syncro ring") for first gear which might be making the noise you're hearing.

 

[Malachi]

A throttle bearing uses blinker fluid for lubrication. Sounds like you ran out of blinker fluid.

Seriously though, if you're at 3000 rpm in second and downshift to first, that's a pretty big rpm increase. It also engages the syncronizer (or "syncro ring") for first gear which might be making the noise you're hearing.

The most plausible path I've heard so far. Perhaps this "syncro ring" is experiencing premature wear. Thank you for this!

 

[roaniecowpony]

The most plausible path I've heard so far. Perhaps this "syncro ring" is experiencing premature wear. Thank you for this!

You might change the transmission gear oil. Maybe try some (shhhhhhh) Amsoil.

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