NV3550 clutch and shifting noise - JeepForum.com
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 17 Old 08-03-2021, 07:29 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
NV3550 clutch and shifting noise

Hello all,


I'm having some interesting noises coming from the clutch/transmission, and was hoping to get an opinion on possible culprits before I pull the tranny.


When I push the clutch in, a whirling noise beings to appear after about 3-5 seconds. It sounds like a dry bearing, but unsure why it doesn't appear immediately when the clutch is pressed. I replaced the throw out bearing about 3 years ago, so I was thinking this was the leading suspect again.


What gets me is there is a second tier to this noise. With the clutch still pushed in, if I move the shifter into a gear, a very loud scraping noise then appears. This sounds much worse then a dry bearing, and more like metal scratching on metal. If I return the shifter to neutral(clutch still pressed in), the noise does NOT go away. The noise disappears when the clutch is released, or once a gear starts to engage.


Could all this noise be from the throw out bearing, or is something else at play here?


Thanks in advance!

Hoffertot is offline  
Sponsored Links
Advertisement
 
post #2 of 17 Old 08-03-2021, 03:30 PM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 3,168
It is the pilot bearing. When stopped, in gear, and clutch pressed, the pilot bearing needles are spinning. When moving in gear with the clutch out, the pilot bearing needles are not spinning.

97 TJ sport.
bobjp is offline  
post #3 of 17 Old 08-04-2021, 06:30 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
When stopped, in neutral, and clutch pressed, can the pilot bearing still be making noise too?
Hoffertot is offline  
 
post #4 of 17 Old 08-04-2021, 06:45 AM
53flattie
Registered User
 
53flattie's Avatar
1936 CJ2A 
 
Join Date: Aug 2012
Location: Easley
Posts: 346
Anytime the engine is running, the crank is spinning. The pilot bearing is inside the crank - so the pilot bearing is always spinning, regardless of the position of the clutch.


Sent from my iPhone using Tapatalk
53flattie is offline  
post #5 of 17 Old 08-04-2021, 04:18 PM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 3,168
The pilot bearing as a whole is always spinning if the engine is running, but it's not "working" unless there is relative motion between the flywheel and the input shaft of the transmission. The needles are not rotating about their axis.

Quote:
Originally Posted by Hoffertot View Post
When stopped, in neutral, and clutch pressed, can the pilot bearing still be making noise too?
There could be relative motion between the flywheel and shaft in that scenario. In the first post, you mentioned that scenario being quieter than when you put it in gear (while stationary, clutch pressed). That makes sense. When you put it in gear, you are stopping the input shaft of the transmission.

97 TJ sport.
bobjp is offline  
post #6 of 17 Old 08-05-2021, 01:20 PM
53flattie
Registered User
 
53flattie's Avatar
1936 CJ2A 
 
Join Date: Aug 2012
Location: Easley
Posts: 346
In neutral, the input shaft of the transmission is stationary. But the pilot bushing is still rotating around it, causing the needle bearings to spin.

No? I’m just thinking out loud…

When you shift into gear, the input shaft is then spinning at the same speed as the pilot bearing, at which time they essentially become one unit.


Sent from my iPhone using Tapatalk
TheBoogieman likes this.
53flattie is offline  
post #7 of 17 Old 08-05-2021, 02:52 PM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 3,168
Quote:
Originally Posted by 53flattie View Post
In neutral, the input shaft of the transmission is stationary. But the pilot bushing is still rotating around it, causing the needle bearings to spin.
If the clutch is not pressed in neutral, then the input shaft is spinning at the same speed as the engine. If the clutch is pressed, then the input shaft could be spinning some, but not much.


Quote:
Originally Posted by 53flattie View Post
When you shift into gear, the input shaft is then spinning at the same speed as the pilot bearing, at which time they essentially become one unit.
When you shift into gear while stationary, the input shaft comes to a stop. It doesn't start spinning again until you begin to let out the clutch.

97 TJ sport.
bobjp is offline  
post #8 of 17 Old 08-11-2021, 10:04 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
**Update**


I have pulled the tranny now, and it looks like a pilot bushing has been installed instead of a pilot bearing. All the noise symptoms I had seemed to lean towards the pilot bearing, so what else could potentially be causing all the noise? Could a worn bushing causing some grinding/binding else ware? I've attached some images of the bushing.


Disclamer, this is on an 87 yj that a previous owner did a NV3550 swap on it
Attached Thumbnails
20210810_220503.jpg   20210810_220458.jpg  
Hoffertot is offline  
post #9 of 17 Old 08-11-2021, 03:33 PM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 3,168
What do the condition of the bushing and the input shaft look like? Any gouges/scars? Do you have calipers to measure the ID?

Inspect your clutch disc. I had a cracked clutch disc that made a scratching rattling sound whenever I was at a stop with the trans in gear and the clutch pressed. The noise went away when the trans was taken out of gear.

97 TJ sport.
bobjp is offline  
post #10 of 17 Old 08-12-2021, 06:37 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
The is a shallow gouge on the face of the bushing, you can kind of see it in the picture as a darker spot, but the ID of the bushing and the input shaft look and feel quite good. No concerning grooves, or wear marks. From what I can see, the clutch disc also looks good, no cracking that I can find. The clutch and pressure plate were also replaced a few years ago along with the first throw out bearing I did.



The flywheel and pressure plate surfaces also look real clean with no noticeable grooves or gouges. I do have calipers, but the bore of the bushing is too deep to get it in there. Going to grab something from work today to help measure.


I can't remember how much resistance there should be on the throw out bearing, but I can give it a good spin by hand, and it will keep spinning for a few seconds.
Hoffertot is offline  
post #11 of 17 Old 08-12-2021, 06:38 AM
53flattie
Registered User
 
53flattie's Avatar
1936 CJ2A 
 
Join Date: Aug 2012
Location: Easley
Posts: 346
Just for comparison, this is what the pilot bearing looked like in my 3550.




Sent from my iPhone using Tapatalk
53flattie is offline  
post #12 of 17 Old 08-12-2021, 06:41 AM
53flattie
Registered User
 
53flattie's Avatar
1936 CJ2A 
 
Join Date: Aug 2012
Location: Easley
Posts: 346
And this is the bad one that came out of it.
Hard to tell from your pictures, but perhaps the roller bearing in the center of yours is gone like mine was…






Sent from my iPhone using Tapatalk
53flattie is offline  
post #13 of 17 Old 08-12-2021, 10:07 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
Oh man, that thing was toasted! I have yet to pull the bushing so it is possible only a thin outer race remains that I couldn't see from initial inspection.


Did you find metal shavings/roller bearings during the disassembly, or had it all worked its way out? Initial inspection I do not have any signs of metal shavings around this bushing to indicate the bearing deteriorated. I plan to pull the bushing tonight, so maybe I'll learn more.



Thanks for the pictures.
Hoffertot is offline  
post #14 of 17 Old 08-12-2021, 05:13 PM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 3,168
You have the bushing type pilot while 53 has the roller bearing pilot. You're not missing any parts.

The scenario you described in your first post: Noise while stopped, in gear, clutch pressed eliminates the transmission as the culprit. And going between in gear and out of gear in the same scenario isn't going to make a difference to the TOB.

So there's something off about the pilot bushing, the clutch disc, or pressure plate.

97 TJ sport.
bobjp is offline  
post #15 of 17 Old 08-16-2021, 10:05 AM Thread Starter
Hoffertot
Registered User
 
Join Date: Aug 2016
Posts: 7
To this point everything has been pulled.


Confirmation of just a pilot bushing. ID measures 0.77, transmission shaft measures 0.75. No signs of wear marks at all on shaft. Is this gap acceptable?
A lot of inspection on clutch disk, no signs of cracking, scratches, pitting, etc.
Pressure plate also looks good, just shinny metal on end of the fingers where the throw out bearing meets. Looks like normal wear here.
Clutch fork, pivot ball, retaining clip all were in place and look good
Throw out bearing spins freely, no binding/grinding, but of course unloaded. Throw out springs to fork are a little loose.


I'll need to get a picture, but the only oddity I see is in the very end of the main bearing retainer. The tip of the snout end looks ground down to a very thin sharp point. Almost as if maybe it was in contact with something, pressure plate fingers maybe? Could the pressure plate fingers when compressed make contact with the main bearing retainer snout? I have only driven maybe 5k miles since all the clutch component were replaced, but I would think if that was the case, the noise would have been present immediately, and not related to shifting into gear.


Maybe I'm off base here, but any other suggestions? I can get some more pictures if that would be helpful.


Thanks.
Hoffertot is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome