Master Cylinder and Synchros? - LS1TECH



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Master Cylinder and Synchros?

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Old 03-02-2017, 05:28 PM   #1
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Default Master Cylinder and Synchros?

My 2000 Trans Am is a T56 car. First thing. 2nd gear will grind sometimes when I shift rather quickly from 1st or even downshifting from 3rd. Also Reverse will rake and cause the car to shake sometimes. I also have to keep replacing my Reverse Switch underneath because it goes bad causing the Reverse/Turn Signal fuse to pop when I put the car into reverse.

Can be slightly more difficult to shift gears during high RPMs as well. Is this a Master Cylinder issue (not enough fluid being pushed) or a Synchro issue, or both? Clutch seems fine - grabs well and has some play left. I believe it is stock. Car only has 56,6xx miles.

Would the drill mod help or should I just look at getting a T56 rebuild, new clutch setup and master cylinder, pilot and throwout bearing?
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Old 03-02-2017, 06:04 PM   #2
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My 2000 Trans Am is a T56 car. First thing. 2nd gear will grind sometimes when I shift rather quickly from 1st or even downshifting from 3rd. Also Reverse will rake and cause the car to shake sometimes. I also have to keep replacing my Reverse Switch underneath because it goes bad causing the Reverse/Turn Signal fuse to pop when I put the car into reverse.

Can be slightly more difficult to shift gears during high RPMs as well. Is this a Master Cylinder issue (not enough fluid being pushed) or a Synchro issue, or both? Clutch seems fine - grabs well and has some play left. I believe it is stock. Car only has 56,6xx miles.
That can sometimes be a master cylinder issue, sometimes just a clutch issue. As the stock clutch wears, it is known to do that. It could also just be some air in the system resulting in the clutch not quite fully releasing. It would be worth bleeding it before you tore it apart. This is the first thing I would do. Second, if you still have the factory fluid int here, I would change it. Check the fluid for debris, metal flakes, etc. Replace with a quality transmission fluid. There are plenty of threads that argue over that for your searching pleasure.

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Would the drill mod help or should I just look at getting a T56 rebuild, new clutch setup and master cylinder, pilot and throwout bearing?
Generally, the drill mod is only good for reingagement, NOT disengagement. What I mean is, the drill mod helps on the fluid return to the master when you let the pedal up, but does not affect when you push the pedal down. Imagine you're a GM engineer and about a month before you are going to roll out the 1998 LS1 F-cars, someone discovers that the LS1+T56 combination is destroying rear axles. you have two solutions available. You either punt on the rears, delay the car launch, eat all the money in rear axles you've already bought and paid for, etc. Or you find a way to cushion the clutch so it doesn't hammer the rear so hard. So, you decide to opt for the $0.62 o-ring restrictor in the clutch line to soften the blow to the rear.

What tends to happen is the drill mod tends to help when you are not getting full return pedal height or you get that random sticking/low pedal thing. Drill mod CAN help with that. Unless the real issue is the pressure plate finger adjuster mechanism that ALSO reduces the fluid return to master and presents with the same symptoms.

All that to say, most of the time people when they encounter these clutch pedal symptoms end up doing a master and a new clutch without the pressure plate and the drill mod before it is truly resolved.

Now, regarding the synchros. They're probably not damaged yet, but avoid the shifting situations where you get gear grind until you get the clutch fully releasing again. Again, i'd start with a good clutch bleed and transmission fluid change.
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Old 03-02-2017, 06:20 PM   #3
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Okay. Awesome. Thanks!

Ill look up the how tos for clutch bleeding and transmission fluid change. Ive always heard Manual transmissions have nearly NO fluid, as compared to an automatic transmission.
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Old 03-02-2017, 11:00 PM   #4
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Oh no, manuals hold 4 quarts from a dry fill.
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Old 03-03-2017, 04:03 PM   #5
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Okay. Recommended type of transmission fluid?

Whats the process to bleeding the clutch?
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Old 03-04-2017, 01:02 AM   #6
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I'm assuming here that there is no speed bleed or anything installed on your transmission. There are two ways that work quite nicely for bleeding the clutch:

1. Get the car in the air. Verify the reservoir is full. Have an assistant in the driver seat. Crawl under the car with an 11mm wrench. You'll have to feel for the bleeder on the driver side at about 10:00 on the bellhousing. Have the assistant press and hold the clutch pedal in slowly. After assistant confirms pedal is on the floor, crack the bleeder. Count three seconds. Close the bleeder. Have assistant slowly raise clutch pedal. Don't crack the valve and then push the pedal. Push the pedal then Crack the valve. After four of these cycles, check the reservoir. Assistant should be reporting the pedal feels better. If you cycle a few reservoirs full through you'll get most of the crud out of there. Don't let the reservoir go empty at any time during this.

2. Pull the carpet back near the gas pedal. Do a forum search for pictures of this. Drill a hole in the tunnel to expose the bleeder. Use an 11mm socket to operate the bleeder. Then, pedal down, bleeder open, bleeder close, pedal up. You just don't need the assistant and can do everything from the drivers seat.

As to trans fluid, drain is in the tail shaft housing. Pull the upper fill plug out center of tranny, 3:00 position on passenger side. Remove shifter. Full through shifter until you hear fluid coming out the hole where the plug was. Typically 3.5-4qt. Reinstall upper plug. Reinstall shifter.
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Old 03-04-2017, 11:24 AM   #7
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As to trans fluid, drain is in the tail shaft housing. Pull the upper fill plug out center of tranny, 3:00 position on passenger side. Remove shifter. Full through shifter until you hear fluid coming out the hole where the plug was. Typically 3.5-4qt. Reinstall upper plug. Reinstall shifter.
I just drain through the lower plug and use a suction/plunger type fluid pump to fill through the upper hole. Fill till it starts coming out the hole and reinstall the plug.
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Old 03-06-2017, 01:55 PM   #8
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Dex III not Dex VI
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Old 03-06-2017, 10:02 PM   #9
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Nice. Thank you guys, awesome info for a beginner!
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