shifting problem lt4
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
shifting problem lt4
The last couple of times I have driven my 96 lt4 I have had trouble shifting it through the gears. It doesn't seem like any gear in particular. It just doesn't go into gear easily and then after driving for awhile it gets nice and smooth again. I have had it for a few months without any problems and it has always shifted very smoothly and now it's acting up. I have never had a manual before so I don't know what to look for. The fluid is filled and looks clean. I have paper work from the PO for a new clutch done about 20k ago. The car now has 92k on it. The clutch feels okay. When I go to change gears it feels like something is blocking it from going in. any thoughts? Where should I start looking? Thanks guys
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
Possibly air in the hydraulic system working its way in when your Corvette is sitting.
A small minute hydraulic leak in the clutch system.
Driving again & working the clutch pedal,
air is worked out of the system once again.
And then the clutch disc is fully released from the clutch pressure plate & engine flywheel.
Clean gear up shifts because no air in the hydraulic clutch system.
Corvette sits, air works back in because of the tiny leak present somewhere.
Shifting problems resume.
A small minute hydraulic leak in the clutch system.
Driving again & working the clutch pedal,
air is worked out of the system once again.
And then the clutch disc is fully released from the clutch pressure plate & engine flywheel.
Clean gear up shifts because no air in the hydraulic clutch system.
Corvette sits, air works back in because of the tiny leak present somewhere.
Shifting problems resume.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
It's my DD so I had to drive it to work today and now it seems like the clutch has very little resistance. It just goes to the floor instead of having a bit of spring in it. I have to really push it against the floor to get it to shift. I guess I have to bring it in but I was wondering if there is anything that I can check on my own. I don't know how to check if there is a hydraulic pressure leak as suggested by the previous post. Any help would be appreciated. also, are there any upgrades that I should have done or any problems that I should be aware of when I take it in. I have a good mechanic, he actually did the trans on my 86 so I do trust him. Thanks
Race Director
Joined: Dec 2007
Posts: 10,064
Likes: 77
From: Elgin, IL
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
Check the fluid level in the reservoir. The clutch fluid reservoir is located under the PCM and to the right of the power brake booster. The easiest way to access it is by moving the PCM aside.
There is a dust boot that goes in the reservoir. Due to the boot, you don't need to put much fluid in the reservoir. If you fill the reservoir and don't put the boot back in, the fluid will squirt out the air bleed hole in the top of the reservoir lid.
If the fluid has disappeared, that means you have a leak. There are generally two places for this to occur...The clutch master cylinder referenced above or the slave cylinder that is bolted to the bellhousing. Check around the master cylinder, both in the engine bay and in the interior where the rod passes thru the firewall for leaks. Also pull the slave cylinder and look for dampness.
There is a dust boot that goes in the reservoir. Due to the boot, you don't need to put much fluid in the reservoir. If you fill the reservoir and don't put the boot back in, the fluid will squirt out the air bleed hole in the top of the reservoir lid.
If the fluid has disappeared, that means you have a leak. There are generally two places for this to occur...The clutch master cylinder referenced above or the slave cylinder that is bolted to the bellhousing. Check around the master cylinder, both in the engine bay and in the interior where the rod passes thru the firewall for leaks. Also pull the slave cylinder and look for dampness.
Melting Slicks
Joined: Jul 2008
Posts: 2,265
Likes: 141
From: Ottawa Ontario
Check the fluid level in the reservoir. The clutch fluid reservoir is located under the PCM and to the right of the power brake booster. The easiest way to access it is by moving the PCM aside.
There is a dust boot that goes in the reservoir. Due to the boot, you don't need to put much fluid in the reservoir. If you fill the reservoir and don't put the boot back in, the fluid will squirt out the air bleed hole in the top of the reservoir lid.
If the fluid has disappeared, that means you have a leak. There are generally two places for this to occur...The clutch master cylinder referenced above or the slave cylinder that is bolted to the bellhousing. Check around the master cylinder, both in the engine bay and in the interior where the rod passes thru the firewall for leaks. Also pull the slave cylinder and look for dampness.
There is a dust boot that goes in the reservoir. Due to the boot, you don't need to put much fluid in the reservoir. If you fill the reservoir and don't put the boot back in, the fluid will squirt out the air bleed hole in the top of the reservoir lid.
If the fluid has disappeared, that means you have a leak. There are generally two places for this to occur...The clutch master cylinder referenced above or the slave cylinder that is bolted to the bellhousing. Check around the master cylinder, both in the engine bay and in the interior where the rod passes thru the firewall for leaks. Also pull the slave cylinder and look for dampness.
with all of the above. Just topping up the clutch fluid will keep you on the road until you can determine what is leaking. I nursed mine through 2 summers before finally getting around to replacing the leaky slave cylinder. Also, I didn't need to pull the slave to know it was leaking - it was wet and the paint on it was all wrinkly. 
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
finally got the time to check it out and the reservoir is just about empty. It is not leaking below the cylinder or inside where the pedal comes in. I checked under the car and found what I think is the mess. Going from the front of the car to the back, just after the oil pan are some cooling fins and these were coated in fluid. obviously I don't know jack about a clutch so where do I go from here? What would the likely cause be and what kind of price tag am I looking at. although I have done quite a bit in my brief corvette wrenching career, I don't think I can really get into a clutch. I am going to fill it back up and see how long it takes to leak out. Can I cause any further damage by driving. also, recently, I was messing around and down shifting from 3rd to 2nd while stomping on the pedal and spinning up the tires. could I have caused this problem? Stupid but fun I guess. Thanks guys
Melting Slicks
Joined: Jul 2008
Posts: 2,265
Likes: 141
From: Ottawa Ontario
I checked under the car and found what I think is the mess. Going from the front of the car to the back, just after the oil pan are some cooling fins and these were coated in fluid. obviously I don't know jack about a clutch so where do I go from here? What would the likely cause be and what kind of price tag am I looking at.
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Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
are hydraulic clutch fluid and brake fluid the same thing? I picked up some valvoline synthetic brake fluid at advance auto. The guy there said that they are the same so i just want to check here with the experts first. Thanks
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
The slave swap is easy.
- Top off the clutch master cylinder to prevent air getting into the system when you disconnect the line.
- Remove the line from the slave cylinder and let the fluid drip into a container
- Remove the two nuts that secure the slave cylinder to the driver's side of the bell housing
- Install the line to the new slave cylinder.
- Open the slave cylinder bleeder valve and allow the air to escape. The specific procedure is in the Factory Service Manual.
- Once the bleeding is complete, install the new slave cylinder to the bell housing.
