Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engaged

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Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engaged

Postby 93celicaconv » Thu Mar 01, 2018 12:51 pm

On a 1990 ST185, with cold engine idle (1,200 RPM), transmission in neutral, clutch engaged (clutch pedal not pressed-in), there is a slight rattle noise.

When the clutch starts to be pressed in, the noise goes away.

When the engine is at warm idle (800 RPM), if there is a rattle noise, its so faint it can hardly be noticed.

When transmission is in gear and clutch engaged (we're moving now), no noise.

Is there a typical cause for the rattle noise at this one particular situation on ST185's?

I've looked around and feel there are 2 possible causes (not ST185 specific):
- normal unloaded gear noise in transmission, caused by input shaft rotating with no load on gears
- clutch fork not lubricated

If the cause is gear noise from the transmission caused by it being in neutral and unloaded, my understanding is that this is inherent on some Aisin transmission designs and is considered normal.

If the cause is a lack of lubrication of the clutch fork, this sounds like it is correctable. Where is the lubrication needed, and can it be done without removing anything substantial on the car?

If the cause is something else (ST185 specific), please advise on that.

I consider this a very minor thing - just want to see if this can be resolved easily or not.
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93celicaconv
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby Menoxz » Sat May 19, 2018 8:25 pm

93celicaconv wrote:On a 1990 ST185, with cold engine idle (1,200 RPM), transmission in neutral, clutch engaged (clutch pedal not pressed-in), there is a slight rattle noise.

When the clutch starts to be pressed in, the noise goes away.

When transmission is in gear and clutch engaged (we're moving now), no noise.

Is there a typical cause for the rattle noise at this one particular situation on ST185's?

I've looked around and feel there are 2 possible causes (not ST185 specific):
- normal unloaded gear noise in transmission, caused by input shaft rotating with no load on gears
- clutch fork not lubricated

If the cause is a lack of lubrication of the clutch fork, this sounds like it is correctable. Where is the lubrication needed, and can it be done without removing anything substantial on the car?



I just did a Clutch release bearing replace because I had the exact problems you state, noise when clutch was disengaged, but as soon as I engaged the clutch (Moving the bearing towards the clutch splines) it stopped...
I have no idea if you can lubricate the fork from the outside, I did it when I had the transmission separated from the engine as it was also stated in the manual and mentioned by another GT4 owner, Ryan maroszek I think(Badnews)...

Should the fork fall off the ball it's seated on it could be bad news since it needs to be pushed back into it
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby 93celicaconv » Sat May 19, 2018 9:01 pm

Now that it is warmer, this issue is not present. And it was a slight issue. A mechanic friend of mine said when the clutch springs start to loosen up and don't have quite the tension, when the clutch is not engaged (springs are at their least tension), it is possible/likely they could rattle slightly. Given the clutch has no other symptoms, and it is generally used in warmer weather, I'm inclined to leave it alone for now.

I've also heard about lubricating the fork. I think this is a good idea, but I have no idea what to lubricate it with nor if it can be done with everything installed. Has anyone in this forum lubricated the fork without any disassembly for these type of symptoms? If yes, did it work? If yes, what did you use and how did you do it?
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby Menoxz » Sat May 19, 2018 11:31 pm

I used moly grease as stated in the bgb
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby 93celicaconv » Sun May 20, 2018 12:35 am

Menoxz wrote:I used moly grease as stated in the bgb

And how did you do it? During a clutch replacement? If not during a clutch replacement, how did you get moly grease to the fork?
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby Menoxz » Sun May 20, 2018 7:19 pm

93celicaconv wrote:
Menoxz wrote:I used moly grease as stated in the bgb

And how did you do it? During a clutch replacement? If not during a clutch replacement, how did you get moly grease to the fork?

I did it when I changed my clutch release bearing....

A sidenote.. There was some noise after the install. I used a mechanic stetoschope and it came from the rod and bearing...
Read online that it could be because if slack in the rod as I only heard it twice
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Re: Slight Rattle On Cold Idle-Trans in Neutral-Clutch Engag

Postby 93celicaconv » Sun May 20, 2018 7:40 pm

Came from the fork and throw out bearing?
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