Transmission Grind
Thread Starter
Intermediate
Joined: Nov 2005
Posts: 34
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Transmission Grind
Hello all. Been reading the site for a couple months and you guys seem to have great info. I decided to take a dive and puchase my first vette a couple months ago just after graduating college, instead of buying "reliable" transportation. What can I say.....I'm young. Anyway today on the way to work my 4 speed started making a grinding noise when I down shift. As I shift down and have the clutch pedal pushed in It feels like something is spinning and grinding. If I let go of the pedal while in neutral (in between shifting) the grinding stops. Any ideas ? This is my first manual trans so I don't know much about them. Any ideas would be much appreciated. Oh yeah... 1973 Yellow Sting Ray orginally L42, but replaced with crate 350. Trans is 4 speed, but haven't had a chance to determing which one. Thanks.
Advanced
Joined: Oct 2005
Posts: 57
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I'm not an expert on transmissions, so anyone correct me if im wrong, but it could be synchros wearing out... which is why double-clutching (essentially what youre doing) may help a little. although, with bad synchros, it seems like thats something that would happen on upshifts as well...
Race Director
Joined: Nov 1999
Posts: 10,643
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From: Foxfield CO 1970 Convertible
I don't mean to point out the obvious, but when you downshift, are you revving the engine somewhat higher? This will help because it will match the rotating rpms within the transmission. If it doesn't help, like someone said, the synchros may be going out.
Thread Starter
Intermediate
Joined: Nov 2005
Posts: 34
Likes: 0
Yes, I do rev the engine slightly when down shifting. This problem just started after 2 months, so I am assuming it is a mechanical problem and hopefully not operator error. I have driven plenty of manual cars, just never had to work on one. Hopefully this weekend I'll get a chance to look under the car. Thanks for the responses.
Le Mans Master
Joined: May 2003
Posts: 8,875
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
It sounds as though it might be something as simple as the pilot bearing or the throwout bearing. Not expensive -BUT you have to drop the transmission.
Richard
Richard
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Racer
Joined: Apr 2005
Posts: 365
Likes: 1
From: UK without vette :(
with everyone above who says it is a synchro problem, mine was doing the same thing whenever I shifted into 3rd. If I shifted slowly then it was not as bad, you may want to try that. I landed up pulling the trans and going with a complete rebuild kit $169.....I pulled the trans myself and had a buddy rebuild it for $200. Don't know if you live near me, if you do let me know and I will give you my trans POC. Good luck.
Instructor
Joined: Jan 2006
Posts: 128
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Throwout bearings "grind" when you engage the clutch. But that happens on up and down shifts...
Try this for perspective:
Put the car in fourth and let the clutch up slowly.
If the car rolls you're looking at clutch replacement.
If it stalls you're not. UNLESS you hear a spinning grinding noise as you step on the clutch pedal then the throwout bearing is worn and needs replacement in which case do a complete clutch replacement.
Try this for perspective:
Put the car in fourth and let the clutch up slowly.
If the car rolls you're looking at clutch replacement.
If it stalls you're not. UNLESS you hear a spinning grinding noise as you step on the clutch pedal then the throwout bearing is worn and needs replacement in which case do a complete clutch replacement.
Thread Starter
Intermediate
Joined: Nov 2005
Posts: 34
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As for the clutch I believe it was replaced. I also remember one of the reciepts showing a linkage adjustment. I will look take a look at the reciepts.The car has only had 6000 miles put on it in the last 6 years so I don't think the clutch has too much use.
Instructor
Joined: Jan 2006
Posts: 128
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I've also had the following experiences with manual shift cars:
1: A worn bearing in the transmission (5 speed Alfa Romeo 164S) would only make noise as the transmission was loaded and unloaded in the direction of the bearing wear.
2: A car that has sat unused for a fairly long period of time has had the disc rust onto the trans. input shaft causing a variety of problems.
1: A worn bearing in the transmission (5 speed Alfa Romeo 164S) would only make noise as the transmission was loaded and unloaded in the direction of the bearing wear.
2: A car that has sat unused for a fairly long period of time has had the disc rust onto the trans. input shaft causing a variety of problems.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Originally Posted by Slow Driver
Yes, I believe so. Haven't had a chance to really check it out, parked it as soon as I got home. I didn't want to tear anything up. I'll check that out this weekend.