16 replies to this topic

[fotostars]

Just noticed this unloading the car from the trailer:

 

Listen carefully to this video. The sound disappears when I press the clutch pedal.

Note that this video is in Neutral standing still. The same is happening when engaging a gear.

It is clearly dependent on RPM (as heard in the video too)

 

Any clues? (Gearbox and clutch have less than 10 races on them).

 

http://youtu.be/8_xdyK9WKKg

[DES4]

Most likely a throwout bearing, but you need a stethoscope to confirm. Remotely diagnosing issues is a hit-and-miss deal.

 

Non-OSHA footware is distracting; at minimum, I'd add socks...

[Ron Alan]

^^this^^

[fotostars]

Can I safely run another WE? Is this just lack of lubricant on the main shaft?

[Glenn]

Most likely a throwout bearing, but you need a stethoscope to confirm. Remotely diagnosing issues is a hit-and-miss deal.

 

Non-OSHA footware is distracting; at minimum, I'd add socks...

Wouldnt the throwout make noise when the clutch is pushed in and not when the clutch is mated to the PP?

[chris haldeman]

It sounds like the input shaft bearing of the trans too me. If it was the throw out bearing the noise would go away with light pressure applied. It will last for awhile like that just not the best plan.

[fotostars]

It sounds like the input shaft bearing of the trans too me. If it was the throw out bearing the noise would go away with light pressure applied. It will last for awhile like that just not the best plan.

 

Do you mean the pilot bearing on the flywheel or the "internal" bearing or the input shaft?

[Alberto]

Sounds like the input shaft bearing to me also.  The trans on my RX7 was like that for a few years of street and HPDE duty before I finally replaced it.  

 

Is this from the recently installed used trans?  How long has the trans oil been in there?  You only noticed the sound now or was it always there?

[fotostars]

Yes, from the recently installed trans (built my M. Haag). 8 races on it. Swepco Fluid when installed.

I'm only noticing it now. It wasn't there before.

[chris haldeman]

I mean the actual large input shaft bearing in the trans. It will last a long time making noise but how long I can't say.

[chris haldeman]

It is possible the pilot bearing fell being the flywheel and is now allowing a slight misalignment of the input shaft. It happens I've seen it

[Alberto]

Yes, from the recently installed trans (built my M. Haag). 8 races on it. Swepco Fluid when installed.

I'm only noticing it now. It wasn't there before.

Well that sucks...  If you drain the oil, consider getting a sample and sending to Blackstone Labs for oil analysis.  

Call Mike too and see what he says.

[SaulSpeedwell]

My vote/guesses:

The noise is being made by a gear, not a bearing.

Bearings tend to make "grinding' noises whose pitch doesn't change like a whining gear does, and bearings fail quite fast once that starts.  Agree with others that the T/O bearing load is highest when the clutch is pushed - doesn't strike me as T/O bearing. 

Also agree that loss of pilot bearing (or input shaft bearing) could be WHY the gear noise began, and also WHY you "just noticed it".

Also agree with DES4 that these are educated guesses, at best

 

As I said elsewhere, flanged pilot bearings are a good thing.  Pilot bearings sized to be smooth when installed are a good thing.

 

I'd be taking this out ASAP and seeing what's up.

[Kyle Freiheit]

My original trans did this for a very long time, including racing on it for a season. I don't think I ever found out what it was. When I swapped out the trans(3rd gear crunch), I did the pilot and throw out but it was a new(to me) trans so I have no idea what the culprit was.

 

Kyle

 

 

On edit: I think mine was a rattle not a whine.

[fotostars]

I jacked the car up and ran through all the gears. It's making noise through all of them (including neutral)...

Fluid level checks OK.

 

Mike H. who built it a few months ago is replacing it (Thanks Mike for taking care of your customers!).

He believes the noise is from a gear mesh but he's not sure why.

[Ron Alan]

I jacked the car up and ran through all the gears. It's making noise through all of them (including neutral)...

Fluid level checks OK.

 

Mike H. who built it a few months ago is replacing it (Thanks Mike for taking care of your customers!).

He believes the noise is from a gear mesh but he's not sure why.

Some trannies only last half a season...for Mike to work with you is really cool! He is the only SM shop(that actually isn't racing/renting) that comes out and supports all his clients at almost every SFR SCCA or NASA event. His motors are consistently winning or in the top 5 at every regional event.

[SaulSpeedwell]

All the gears are constantly in mesh, but not all the gears are transmitting torque in every gear (see attached JPG, assuming it actually attached).    In 4th, none of the gear teeth are transmitting any torque (caveat for the technonerds that would jump my ass if I just left it at that---> ".... except for that needed to overcome the countershaft's inertia, friction, damping/windage, blah!").  This is why 4th is often called "direct drive".

 

Before you take it out, I'd do a little driving or dynoing in the different gears and report your results to your rebuilder - just in case nothing is obvious when he takes it out.

 

Let us know what happens . . .

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