cnc hydraulic t5 clutch part 2-need suggestions

[pazcarguy]

I posted last week about having trouble bleeding my clutch. Last week I aerated the fluid using my mityvac and could not bleed the system properly. Tonight I used the gravity method and once I verified I had flow, I closed the bleeder and had my son push the pedal to the floor and then opened the bleeder. I did this 4 times in succession until only fluid came out (it actually was good on the second try but I wanted to be certain) The reservoir never went dry during this I made certain. I was able to see the slave cylinder piston move to the end of its internal bore with the rubber boot pulled away (I am guessing about an inch of travel after bleeding). I reinserted the slave on the trans and actuated the clutch pedal, with the pedal on the floor, I am only getting about 3/8 to 1/2 inch of travel total. I adjusted the slave end "bolt" until the throwout bearing was "preloaded" slightly but cannot get the clutch to disengage as I dont have the travel now. I am using a RAM powergrip that I bought from Summit. I am not sure of the Pressure plate rating but it is extremely heavy as I had to get an adjustable pivot ball to put the clutch fork on ( the bellhousing would not fit with the stock pivot as it would hit the pressure plate by a 1/4 inch due to the extra "depth or height" of the heavier pressure plate. My question is this. Would the force exerted by the pressure plate be greater than what the CNC system can produce therefore not allowing me to work the clutch? Has anyone run into this? Also, my pivot ball is adjusted so that I get clearance but I don't believe it is limiting my throwout bearing travel thus causing the problem. Any ideas?

 

[66Runt]

Hydraulic fluid is not compress-able

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[jcode68]

The force of the pressure plate i smore than the pressure in the slave cylinder when the peddle is NOT depressed. However, you should have a return spring attached to the clutch fork so that is helps fully return and not keep pressure on the TO bearing beyond that of normal pre-load. Also, it sounds like you need to bleed some more to get more travel out of the slave. You should get about 3/4" if I recall. I know you don't see any air when your bleeding, but it's in there and the only way to get it out is to continue bleeding. I probably refilled my resevior 6-8 times during the bleeding process before I was done. I know these hydraulics seem like a total PITA, but they are worth it once you get it working. Keep at it, you are almost done!

 

[jikelly]

Wow I can't believe the problems you are having with your setup, but I think the suggestions are on the right track. Glad to hear you're making progress.

 

[pazcarguy]

clutch bleeding

I finally resolved the clutch issue. I gravity bled the unit then put a socket into the end of the slave cylinder and held it in place with a c-clamp over the entire slave. I discovered that while I was bleeding the system, the slave piston would oscillate and allow air to be trapped that would not come out of the bleeder. By fixing the piston in place with the c-clamp/socket. I was able to bleed and have considerable pressure within 2 to three strokes of the pedal. After doing this three times, it was bled and I was able to get roughly an inch of travel from the piston. Would recommend even with the hassle of bleeding, now I know how to do it. It is a lot different than bleeding brakes because of the risk of aerating the fluid. It works smooth as butter and has a feel similar to my VW GTI unit. Thanks to all who had suggestions. Brian

 

[pazcarguy]

You don't even know the half of it. After successful bleeding I discovered that my clutch fork was hitting the pressure plate upon depression of the pedal. I didn't have this before as I did not have the stroke. After playing around with adjusting the slave rod I had to pull the trans again and readjust my adjustable pivot ball to make it 1/4" longer. This changed the "angle" that the clutch fork had to travel and allowed me the additional clearance I needed. I had to put the adjustable pivot ball in two weeks ago as when I changed from my fulcrum clutch lever to my t5 lever, the bellhousing would not fit with the stock pivot ball in place as it hit the pressure plate. (I have a reallly nasty 3200 pound long style pressure plate that is deeper than a stock unit) This install has been a real PIA but I am getting really good at pulling the trans(45 minutes removing everything and having trans on the ground and 1 1/4 hours all buttoned back up)

 

[jikelly]

AWESOME!!

I guess I never encountered that problem because with my setup there is a lot of pressure on the slave even at it's initial position.

 

[gjz30075]

I gravity bled the unit then put a socket into the end of the slave cylinder and held it in place with a c-clamp over the entire slave. I discovered that while I was bleeding the system, the slave piston would oscillate and allow air to be trapped that would not come out of the bleeder. By fixing the piston in place with the c-clamp/socket.

This is great news as I am soon to embark on same journey. If I understand this correctly, you basically held the slave piston at the bottom of its bore? Or you simply held the piston to keep it from moving?

 

[pazcarguy]

I did both. By holding the piston at the bottom of the bore it prevented it from "oscillating" and limited the volume that I had to bleed, thus reducing the amount of air that could potentially become trapped. Brian

 

[gsxrken]

Sounds like you nailed it, and discovered what I discovered with the clamp. Here's a link to my tribulations as documented on VMF:
http://forums.vintage-mustang.com/showtopic.php?tid/1305296/post/1305296/hl/clutch+gsxrken/