Please help diagnose transmission noise [Videos]

[360glitch]

When I started the car up this evening to take it for a drive I noticed an odd noise as the engine roared to life. I lightly revved it and heard the noise again. It seemed like a rattling noise. I went to the front of the car and had my buddy rev it a little a few times for me and I poked around trying to find the source of the noise. This lead me to the transmission. I think that I have pinpointed it to the end of the trans closest to the passenger side front wheel. It also seems to be coming from the upper half, though that I am not as sure about. Here is what else I have found out about the noise:

1.) Makes the noise when the car is in neutral
2.) Does NOT make the noise when the clutch is pressed in when in neutral (nor any other gear)
3.) Does not make the noise when moving the car back and forth (under the power of the engine, in gear)
4.) Seems to make the noise at and above 1500 rpms

The trans was rebuilt approximately 1,000 miles ago. Here are a couple of videos of the noise. The noise seems louder and more violent in the videos than it is in person, but regardless here they are:

YouTube - What is this noise?

YouTube - What is this noise? (louder)

After going through all of this, I decided to take end piece off the transmission to see if I found anything that looked odd. As far as I could tell everything was tight and all was well (from my little experience with this trans), so I re-assembled it.

Any ideas anyone?

 

[Calan]

Probably your thow-out bearing (TOB), and the sound is being transfered through the input shaft to the rear of the tranny.

Very common problem and the symptoms match.

EDIT:

Ok... after getting my volume to work, that is not a TOB. Unfortunately I don't know what it is... but it doesn't sound good.

Almost doesn't sound like it's in the tranny at all on my crappy speakers here... you didn't see any wear on the end case or in the reverse syncrho area?

 

[BrokenTsi]

Sounds like the flywheel bolts are loose and the flywheel is vibrating. Stop doing it because it can ruin the end of your crankshaft if it hasnt already. Im pretty sure its not a transmission problem.

 

[360glitch]

Probably your thow-out bearing (TOB), and the sound is being transfered through the input shaft to the rear of the tranny.

Very common problem and the symptoms match.

EDIT:

Ok... after getting my volume to work, that is not a TOB. Unfortunately I don't know what it is... but it doesn't sound good.

Almost doesn't sound like it's in the tranny at all on my crappy speakers here.

Yeah for what its worth the TOB is fairly new, OEM. It doesn't sound nearly as bad in the person.

Sounds like the flywheel bolts are loose and the flywheel is vibrating. Stop doing it because it can ruin the end of your crankshaft if it hasnt already. Im pretty sure its not a transmission problem.

The noise is almost definitely coming from the rear of the trans, but as calan said above the noise could possibly be being transferred from the other end of the shaft.

 

[Calan]

Im pretty sure its not a transmission problem.

Kind of what I was thinking, but it's impossible to tell the true sound of it on these speakers.

Regardless, I think your looking at pulling the tranny out since you say it is fairly new and something definitely isn't right.

 

[hpexperts]

i had the same problem with my 1g, replace tB nothing ended up being countershaft bearings.

 

[Artago]

Ouch, that's sucky bro...I don't know what the problem is but here's a few quick and easy things you can check.

1. To check the clutch and TOB, remove your slave cylinder and pull back the fork boot. Get a small flash light and peak inside. Move the fork back and forth and observe the TOB. Also check the pressure plate fingers to make sure you have all of them (you'll need to rotate crank shaft to see the ones in the back)

2. To check the back of the tranny just pull the rear cover off and observe but I doubt your reverse and 5th gear are the problem.

3. To check the rest you'll have to drop the tranny and disassemble it.

Good luck,

Tom

 

[360glitch]

Ouch, that's sucky bro...I don't know what the problem is but here's a few quick and easy things you can check.

1. To check the clutch and TOB, remove your slave cylinder and pull back the fork boot. Get a small flash light and peak inside. Move the fork back and forth and observe the TOB. Also check the pressure plate fingers to make sure you have all of them (you'll need to rotate crank shaft to see the ones in the back)

2. To check the back of the tranny just pull the rear cover off and observe but I doubt your reverse and 5th gear are the problem.

3. To check the rest you'll have to drop the tranny and disassemble it.

Good luck,

Tom

Thanks for the tips. I really hope to get this sorted soon because yesterday afternoon I finalized the details on a trip to the Tail of the Dragon right after Christmas and there is not much time between now.

 

[Calan]

Please post back and update us on what you find out.

Good luck!

 

[JackM]

You may have the 5th gear ring rattle issue which is common on the 90-91 units. Here is a vid of one I had make the noise when a unit was apart:

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If you gently move the shifter over to 5th gear until you feel a little resistance and the noise goes away, it's the 5th gear ring rattling in the hub. We are working on a fix for this for our units and I believe I finally have one, but it's still too soon in the testing phase to make the modification available to the public yet. The ring rattle is completely harmless and won't hurt a thing. It's just annoying.

Jack

 

[360glitch]

Please post back and update us on what you find out.

Good luck!

Will do man, I appreciate your input earlier.

You may have the 5th gear ring rattle issue which is common on the 90-91 units. Here is a vid of one I had make the noise when a unit was apart:

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/f0w49kC2Ecs&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/f0w49kC2Ecs&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

If you gently move the shifter over to 5th gear until you feel a little resistance and the noise goes away, it's the 5th gear ring rattling in the hub. We are working on a fix for this for our units and I believe I finally have one, but it's still too soon in the testing phase to make the modification available to the public yet. The ring rattle is completely harmless and won't hurt a thing. It's just annoying.

Jack

I'd love to think that this is the problem. The transmission that is in the car is in fact a 90-91 trans and I really feel that the noise is right there in that area of the transmission. I will try your "test" tonight and pray that is all that it is. Just to confirm, the test is to: with the engine on, and the trans in neutral, and the clutch not pressed in, gently move the shifter towards 5th until resistance is felt and see if the noise goes away?

I should note, the trans does not make the noise when idling, only when the engine is revved. So I would sort of have to reve the engine while pressing towards 5th gear to test it. (revving the engine would certainly cause more vibrations than idling... prothane mounts and no balance shafts)

 

[Calan]

I wrote an article a while back on isolating various DSM sounds, but I've never heard anything like that at all.

At least now you have the right guy in here to help you with it. If it's tranny-related, Jack will find it.

 

[JackM]

Yes, that is correct. Just be careful not to burn up the synchro ring and only bump it real quick.

The problem is those rings never have an issue in stock applications. Things like aftermarket disks with stiffer springs, or no springs at all, removed balance shafts, and higher compression creates more harmonics and torsional whip at the crank which goes through the clutch and right into the input shaft where that 5th gear ring sits. The added harmonics make it rattle. The EVOIII 5th gears use a much larger hub and slider assembly with a bigger ring that doesn't make the noise, so that is one fix for it. Another fix I have is modified keys that help hold the ring down a little farther, but I'm still testing that fix right now. So far, it seems to be working.

Jack

I wrote an article a while back on isolating various DSM sounds, but I've never heard anything like that at all.

At least now you have the right guy in here to help you with it. If it's tranny-related, Jack will find it.

Lol! That's pretty neat! Must have been a long article

Jack

 

[360glitch]

Yes, that is correct. Just be careful not to burn up the synchro ring and only bump it real quick.

The problem is those rings never have an issue in stock applications. Things like aftermarket disks with stiffer springs, or no springs at all, removed balance shafts, and higher compression creates more harmonics and torsional whip at the crank which goes through the clutch and right into the input shaft where that 5th gear ring sits. The added harmonics make it rattle. The EVOIII 5th gears use a much larger hub and slider assembly with a bigger ring that doesn't make the noise, so that is one fix for it. Another fix I have is modified keys that help hold the ring down a little farther, but I'm still testing that fix right now. So far, it seems to be working.

Jack



Lol! That's pretty neat! Must have been a long article

Jack

I really appreciate your information Jack. I can't wait to give it a try tonight, I am all for an annoying (but harmless) rattle, ha.

I read that article last night, was pretty long but also very helpful. Just not with this issue. Still helpful with other things though.

 

[JackM]

Does anyone have a link to the article?

Jack

 

[Calan]

Does anyone have a link to the article?

Jack

Here ya go:

http://www.dsmtuners.com/forums/articles-miscellaneous/337788-what-causing-irritating-noise.html

 

[BrokenTsi]

This is all good info.

The reason I believe its the flywheel thats loose, is because Ive had personal experience with the same issue. And considering all variables, it leads me to believe the clutch/flywheel was improperly installed 1k miles ago when the transmission was done.

Did you put a new clutch in it when you had the transmission rebuilt? Why did you rebuild it? Who rebuilt it? What was wrong with the transmission originally in the first place?

I was running an XACT flywheel and ACT 2600 with a street disc when it happened to me. Somehow, the flywheel bolts came loose, and I used the recommended flywheel bolts for the install. I rev my car to just about 10k, then all of a sudden one day I noticed a "growl" at high rpms. It did NOT make the nose with the pedal pushed in, just like you.

Ive also lost 5 gear before. I was cruising down the highway one day, when all of a sudden 5th gear popped out. Literally. The 5th gear forced itself out of the end of my transmission and I watched it pass me on the highway. It was unreal.

After that, I had another transmission in which 5th gear backed out and it started to push itself through the case again. I noticed a crack in the end of the transmission and fluid started to leak. So I removed the end case off and I tightened down the large nut and it was good to go.

Either way, remove the transmission and at the same time you can inspect the clutch/flywheel/tob AND 5th gear at the same time. Its pretty easy to do.

 

[360glitch]

This is all good info.

The reason I believe its the flywheel thats loose, is because Ive had personal experience with the same issue. And considering all variables, it leads me to believe the clutch/flywheel was improperly installed 1k miles ago when the transmission was done.

Did you put a new clutch in it when you had the transmission rebuilt? Why did you rebuild it? Who rebuilt it? What was wrong with the transmission originally in the first place?

I was running an XACT flywheel and ACT 2600 with a street disc when it happened to me. Somehow, the flywheel bolts came loose, and I used the recommended flywheel bolts for the install. I rev my car to just about 10k, then all of a sudden one day I noticed a "growl" at high rpms. It did NOT make the nose with the pedal pushed in, just like you.

Ive also lost 5 gear before. I was cruising down the highway one day, when all of a sudden 5th gear popped out. Literally. The 5th gear forced itself out of the end of my transmission and I watched it pass me on the highway. It was unreal.

After that, I had another transmission in which 5th gear backed out and it started to push itself through the case again. I noticed a crack in the end of the transmission and fluid started to leak. So I removed the end case off and I tightened down the large nut and it was good to go.

Either way, remove the transmission and at the same time you can inspect the clutch/flywheel/tob AND 5th gear at the same time. Its pretty easy to do.

Thanks for the elaboration. If it does not turn out to be 5th gear ring rattle, the trans will have to come off to inspect things. I'll be sure to check the flywheel bolts, amongst everything else.

Glad that I did not see my 5th gear rolling down the road beside me. Lol

Edit: Alright, so here is the "update". Got in the car tonight, started it up, did not hear the noise. Revved it a bit and was able to hear it, did not seem as loud as last night though. I performed Jack's test as mentioned above and the noise did in fact stop. Thank God. Do I truly have nothing to worry about at this point?

 

[BrokenTsi]

I would say so. If Jack says you're good, then you're good.

Jack, he should be able to just remove the end case off the transmission, right?

 

[JackM]

Yes, he can pull the end case off to get to 5th gear, but even if he replaced the synchro it will still make the noise. The only way for him to get rid of it is to either get something like the EVOIII taller 5th gear, or put a stock clutch back in it, !

If he wants to be another guinea pig, I can send him my fix for it and see if that works for him.

Jack

 

[360glitch]

Yes, he can pull the end case off to get to 5th gear, but even if he replaced the synchro it will still make the noise. The only way for him to get rid of it is to either get something like the EVOIII taller 5th gear, or put a stock clutch back in it, !

If he wants to be another guinea pig, I can send him my fix for it and see if that works for him.

Jack

PM'd

 

[car46999]

Any one know of a fix for this "5th gear synchro rattle problem"?

I have a 1991 Laser that I think suffers from this. More info here, but no solution
Jacks Transmissions Forums &bull; View topic - DSM 5th Gear Synchro Ring Rattle

I might call them tomorrow, and see if they are still working on it.

 

[BrokenTsi]

Turn up the radio.

 

[car46999]

Why didn't I think of that, I am gonna call Jack's today. Will post result.

Here is the response from Jack's Transmission:

We do sell a "kit" that will fix the 5th gear synchro rattle. The cost is
$25 shipped and will consist of modified synchro keys for the 5th/reverse
gear hub & slider. If you would like to purchase this kit, payment can be
sent directly to us via PayPal at: [email protected] or we can
collect card information over the phone. Also, if using PayPal, please put
in the note section that payment is for the 5th gear synchro rattle fix.