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Old 06-24-2020, 09:42 AM   #1
MikeSr.
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Default T56 Clutch issues

So - my ‘81 242 with LS V8 swap has had some clutch/ tranny issues. My setup used a stock Camaro clutch set, with a stock GM AP/ LUK slave cylinder in the bell housing.
I originally used a Wilwood 3/4” master cylinder and an AN-4 clutch line with a GM quick connect at the bell housing. This setup had consistent problems with shifting/ grinding. Clutch or tranny? I pulled the T56 and had it rebuilt. Synchros were shot and 5/6 gear set was toast. While it was out, I replaced the slave cylinder and master- I used another stock slave and switched to a Volvo 240/260 master. I also got a new clutch pedal from STS Machining.Concerned about air in the system, I bench bled the master, then installed and power bled the system with a Motive power bleeder. I then gravity bled the system 4-5 reservoirs full with no air coming out the remote bleeder.
Now it works and the transmission shifts smoothly, but I have1&1/2-2” of pedal travel until it engages, even with the clevis adjusted all the way out. The pedal engages near the floor, so it is hard to push a fast shift. Do I need a longer clevis/ rod? Thinking about adding a sleeve to extend it, but confused as to why this setup should have no adjustability if all the components are stock.
Thoughts?
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Old 06-24-2020, 10:22 AM   #2
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How is the pedal feel? Is it a light or heavy feeling clutch?
Sounds like you might need a larger MC. Most hydraulic clutches that use a slave on the input shaft need a larger MC bore depending on the pedal ratio.
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Old 06-24-2020, 10:45 AM   #3
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I know others have used the stock master with success on internal slave cylinders. Also- I had a Wilwood 3/4” master cylinder with similar results. I need more travel on the master- some is due to the play before engagement. Just not getting the push I should.
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Old 06-24-2020, 11:03 AM   #4
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Stock Camaro master is also 3/4”. Next I will cob together some kind of extension sleeve on the clevis/rod.
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Old 06-24-2020, 11:17 AM   #5
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The 260 clutch master is 3/4 inches as far as I know. I'm not using the T56, but it's a stock T56 slave and a HD T56 pressure plate/flywheel, etc. Just a custom disc with a Nissan center.

The pedal engage point is pretty good on mine, about the middle of the throw. It's just fairly heavy and the engagement point is very short and abrupt. Probably more to do with the clutch disc than the master and slave cylinders? On mine I'd almost want to go to a slightly smaller master to reduce the pedal effort and expand that engagement point some.

I had not real issues bleeding mine that I can recall, other than needing to loosen the line at the master to get fluid started going through the system at all.
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Old 06-24-2020, 11:31 AM   #6
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Quote:
Originally Posted by JohnMc View Post
The 260 clutch master is 3/4 inches as far as I know. I'm not using the T56, but it's a stock T56 slave and a HD T56 pressure plate/flywheel, etc. Just a custom disc with a Nissan center.

The pedal engage point is pretty good on mine, about the middle of the throw. It's just fairly heavy and the engagement point is very short and abrupt. Probably more to do with the clutch disc than the master and slave cylinders? On mine I'd almost want to go to a slightly smaller master to reduce the pedal effort and expand that engagement point some.

I had not real issues bleeding mine that I can recall, other than needing to loosen the line at the master to get fluid started going through the system at all.
So we have the same setup with a different clutch disc. I will try to extend the rod- apparently some of the Camaro guys have had to do this also. If that doesn’t work, maybe another clutch setup. PITA to pull that tranny again.
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Old 06-24-2020, 11:49 AM   #7
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I wonder if your slave cylinder is just retracting too far?
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Old 06-24-2020, 12:00 PM   #8
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It has a spring to keep it up- and I replaced it while the tranny was out. No adjustments with stock GM parts.
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Old 06-24-2020, 12:16 PM   #9
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At some point extending the push rod on the clutch pedal just doesn't make a difference. When the piston is retracted, it uncovers the vent hole leading tot he reservoir. If you go past that - then it might improve the throw, but in a dysfunctional way where new fluid can't flow into the system. Up to that point - sure - you're reducing the dead travel.
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Old 06-24-2020, 01:33 PM   #10
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Is the pedal ratio the same as the GM setup?
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Old 06-24-2020, 01:45 PM   #11
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That is indeed a very good question. It almost seems like Mike and I have opposite issues (albeit mine are pretty acceptable). Could be due to differences between the pedals.

I'm using a stock Volvo 260 hydro pedal, he's using an STS machining.

https://www.stsmachininginc.com/prod...o-clutch-pedal

I mean, I would assume they duplicated the Volvo pedal dimensions, but it probably wouldn't take much of a difference on that short lever to make a noticeable difference in pedal travel and feel.

Last edited by JohnMc; 06-24-2020 at 01:53 PM.. Reason: added link
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Old 06-24-2020, 05:00 PM   #12
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Yeah, but if you're using GM pieces, it's the GM pedal dimensions you'd want to duplicate.
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Old 06-24-2020, 05:44 PM   #13
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Quote:
Originally Posted by JohnMc View Post
That is indeed a very good question. It almost seems like Mike and I have opposite issues (albeit mine are pretty acceptable). Could be due to differences between the pedals.

I'm using a stock Volvo 260 hydro pedal, he's using an STS machining.

https://www.stsmachininginc.com/prod...o-clutch-pedal

I mean, I would assume they duplicated the Volvo pedal dimensions, but it probably wouldn't take much of a difference on that short lever to make a noticeable difference in pedal travel and feel.
The STS pedal is symmetrical with the brake pedal installed in the upper mounting position. Pivot arm is dead center in the hole for the master cylinder. Looks perfect.
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Old 06-24-2020, 07:11 PM   #14
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I'm running the same setup with a T56 (concentric slave), and I had a 3/4" master, but it was too light and required too much travel, so I switched up to a 7/8", and now it's pretty good.
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Old 06-24-2020, 07:23 PM   #15
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I would recommend getting a tilton slave master. It took my brother and I a while just to bleed the clutch on our 242. The willwood has no reservoir. Always had to top it off after three pumps. With the willwood I had to shorten the threaded rod on the slave as well.
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Old 06-24-2020, 07:29 PM   #16
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I used a Wilwood 3/4” master with similar issues.
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Old 07-05-2020, 01:02 PM   #17
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So- I got a clevis from STS machining that was about 3/8” longer than the one I was using. I had MikeJr drill and tap it For my threads and it works perfectly now. Pedal engagement is about midpoint and the rebuilt T56 shifts like butter now.
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