Explain gear roll over noise

[BrianX128]

So I'm a bit confused by what I am hearing in my truck at times.

Side story that is relavant, when I got the truck it shifted hard at higher rpms and the previous owner told me the synchros were just worn for third. It wasn't that it was the gear oil he put in the zf5 3000 miles ago incorrectly.

So I dumped that crap out and put amsoil synthetic atf in (5quarts) and moved on.. Everything shifted super smooth. I waited 10k miles and two days ago drained it again and put five quarts in. In my searches here I've read great stuff about over filling it so I'm contemplating doing that. I'd also like to find a kit with new shifter bushings as my stick wobbles side to side just enough to annoy me when I'm in gear. I've done this with my m5od and t18 before but haven't found the kit yet and figured when I do this it would be easiest to overfill down the neck at the same time.

It does feel even smoother now that I've flushed it twice. Can gun it like I'm running from lava down a volcano rpms up at three and shifts like butter.

However just like always when I'm sitting at an intersection with the truck in second gear and clutch pushed in, I just hear an awkward shimmy noise at times. I can't explain it, it's not consistent sometimes never does it at all and it goes away if the truck is idling in neutral.

I turned my idle up to 700 and it basically left so I assumed maybe my dmf was dying but I never get any other noise even if I shut if off with the clutch out in neutral. Then I took inspection plate off while at shop undercoating my new fuel tank (buddy let me use his lift) and he peaks in and says I have a new ish looking smf flywheel. With all the paperwork that the previous owner did have for the truck I sure never noticed that.

So is what I'm hearing all along the annoying gear rollover noise and everything else has just really though needed addressed had nothing to do with this?

It KINDA sounds like this (not my truck just using as an example)https://youtu.be/mvh6sSpq84M

But it's nowhere near that loud and doesn't even do it in neutral. I recorded a video but it sucks so I'm going to try again tomorrow on my way to work. I know this is kinda useless without the video of my truck, but I have time to type it up today so until tomorrow description is best I got.

I just sit at the intersection in neutral instead of with it in second holding the clutch down if I know I'm gonna be there for more then a couple seconds. I've never heard the noise it makes on either of my other trucks before, but I hear all sorts of idi noises I've never heard before haha

 

[SDEconVan]

Hi BrianX128,
Have you eliminated the possibility that it's the Throwout Bearing? With clutch pedal pressed, in 2nd, you get the sound (sometimes.)
I know in other transmissions, the T.O. Bearing will occasionally misalign, making sounds, sometimes clattery, other times almost a musical
skimming sound.

See if you can get it to make the sound in neutral, with the clutch pedal pressed. Also, do it in 2nd, then let up on the pedal a little (not enough
to move the truck,) and see if the sound changes

Eliminate the easy stuff first.

Will be watching this thread, had a friend with similar and it was his T.O. Bearing. Of course I haven't seen your video yet.

There are other tests to see if the syncros are out but that would be more of a gear engagement issue.

Best regards,
George

 

[laserjock]

Gear rollover noise happens at idle and low rpm with the trans turning I.e. The clutch out. It is a result of the pulses from the engine transmitting through the transmission. When it's real bad, it sounds like the trans is full of rocks. If it makes noise in neutral and clutch out, then stops if you shove the clutch in, it's likely gear rollover noise. If it does it with the clutch in, I'd check the throw out bearing although typically when I have seen bad throw out bearings, putting a little force on them (just pushing lightly on the clutch pedal) the noise will change or go away.

This is the reason dual mass flywheels were installed from the factory. It damped the pulses and hence the noise. Typically unless you have converted to single mass flywheel you won't have gear rollover noise. If you still have the factory flywheel and it's not the throw out bearing, you better be checking the flywheel. They can and do fail catastrophically.

 

[SDEconVan]

Thanks laserjock,

and is it correct that the clutch pressure plate should be matched (in type and spec) to the type of flywheel?
So a single-mass flywheel with a dual-mass pressure plate would work but eventually would start making a fuss?
(I do not know this, I am trying to learn. I know it's true with BMWs.)

Best,
George

 

[BrianX128]

Well truck of course made a liar out of me this morning on the way to work and never made the noise once..

After reading what you guys both said I'm still not sure which I'm hearing when it does do it. Was really hoping for something to happen to get it on video. I'd think from what I've read both from you guys and searching that if it was the roll over I would always hear it, so maybe my throw out bearing is moody and only does it if things line up perfectly wrong. If it did it today I was going to try letting the clutch out a little and try recording it to see if that's what it seemed like, but of course silence.

 

[laserjock]

Thanks laserjock,

and is it correct that the clutch pressure plate should be matched (in type and spec) to the type of flywheel?
So a single-mass flywheel with a dual-mass pressure plate would work but eventually would start making a fuss?
(I do not know this, I am trying to learn. I know it's true with BMWs.)

Best,
George

It's not so much the pressure plate but the clutch disk. On a DMF, the springs to dampen the vibrations are in the flywheel. The clutch disk is solid. On a SMF the flywheel is solid and the clutch disk has the springs in it.

There is a really good thread on here where a guy got ahold of a really heavy duty clutch disk (had the wrong weight and number of springs) by mistake and his trans sounded like a rock crusher. His handle I believe is reklund. Search his name and flywheel and you should find it.

 

[BrianX128]

https://youtu.be/EAW4k4JKelw

Well I added another quart of atf. That's all I ever hear, I cranked the audio up so whatever you hear will be more pronounced but I think I might be a you tube internet hypochondriac with thinking I might have something wrong when I watch something, I don't know. That really doesn't sound that weird after watching it next to some other videos.. What's it sound like to you guys?

 

[SDEconVan]

Hi BrianX128,

Your truck is standing still, right? Unless you have 4x4 and the transfer case is in neutral, the internals of the trans are not spinning.

That sound is a spinning/rhythmic sound, probably the T.O. Bearing. Seems to get the sound of it transmitted through your shifter
linkage in certain positions (maybe your shift lever or linkage is metal-to-metal in those positions.)

The fact that that sound goes away at times also points to the Throw Out Bearing, since it sits in a spring-mounted cradle, with time
the alignment can be off at times, then run perfect during others.

I've replaced T.O. Bearings just because they bugged me, they worked fine, but chirped a bit.

Question: "You keep mentioning adding the ATF, do you think there is a connection to this sound?" If so, please explain (there may
be stuff we are not sharing or assuming we know about your situation.)

Best regards,
George

 

[BrianX128]

Guess I should have explained what I was doing in the video a little bit, my bad.

Truck is sitting in the driveway and when you hear the changes in the engine tone and the trans make some noise that's me letting the clutch out and pushing it back in at first trying to simulate what the comparison video I linked was. Then I put it in second towards the end of the video and hold the clutch in to try and get it to make a noise that way. But honestly the noise I hear with the clutch let out in neutral just sounds the same as what it does in either of my other manual transmission trucks. Maybe I'm just "listening" more carefully when I drive it then I do with the others. Not sure.

 

[laserjock]

I forget, forgive me it's been a long week, does your truck have a DMF or SMF? I don't hear anything really scary there but I'm no expert.

 

[riotwarrior]

Sound in 2nd w clutch depressed...to....NOT GEARS as trans is uncoupled from engine every time clutch in.

In N with clutch out...trans spins mainshaft only IIRC so a larger clearance on mainsjaft bearing thrust could be at play. I am not hearing a jar of marbles rolling around myself.

As mentioned if truck is 4x ...block wheels...place tcase in N and then run trans in gear to listen for rollover....or whilst driving.

Sounds fine to me but eh...*** do I know.

 

[franklin2]

However just like always when I'm sitting at an intersection with the truck in second gear and clutch pushed in, I just hear an awkward shimmy noise at times. I can't explain it, it's not consistent sometimes never does it at all and it goes away if the truck is idling in neutral.

Do you normally sit at the light with the clutch pushed in the whole time? That's ok if you know you are getting ready to leave, but if you are going to sit there for awhile, it's good practice to put the shifter in neutral and let the clutch out. A little bit less time on the throwout bearing, and a little easier on the thrust bearing on the crankshaft inside the engine. Nothing that bad if you want to hold in on the clutch, but it's easier on your leg also.

 

[BrianX128]

No, I try to leave it in neutral but most of my lights when I'm in town are quick so it doesn't always happen. Honestly the neutral noise had me start to leave the clutch pushed in but I was only idling at 625-650 and now that it's right at 700, some of the noise has went away so that seems to be the sweet spot. I had it at 750 but turned it down some and it's definitely the best for noise and helps the ac compressor a little bit being at 700 versus 650.

 

[MTKirk]

Thought I'd post this up as my truck has classic gear roll over noise. T-19 trans with solid flywheel. Noise isn't bad at all, can't hear it while truck is moving, only while stopped in neutral. Mostly it sounds like every loose part in the trans is vibrating, probably doesn't hurt the T-19 much, but I would imagine it would eventually crack an aluminum case trans.

https://www.youtube.com/watch?v=kiSUrBgCmzg&feature=youtu.be

 

[MTKirk]

Do you normally sit at the light with the clutch pushed in the whole time? That's ok if you know you are getting ready to leave, but if you are going to sit there for awhile, it's good practice to put the shifter in neutral and let the clutch out. A little bit less time on the throwout bearing, and a little easier on the thrust bearing on the crankshaft inside the engine. Nothing that bad if you want to hold in on the clutch, but it's easier on your leg also.

Our throw-out bearings spin at crank rpm any time the engine is running, whether the clutch is engaged or not.