Clutch hydraulics

[GCroyle]

Question: Not to confuse brakes and clutches but I look at those simple manual systems to be very similar.

Could you get an air trap out manually with the limited throw of the MC and even with a bleed screw, I'm thinking the limited throw of the MC as described in the video to be pushing the air bubble back and forth where it would be very hard to get something like that out.

Tim,

With a clutch external slave cylinders in many cases you can do things to it that are never even discussed on brakes. Like removing a wheel cyl or caliper and compress it by hand to push a bubble back out to the MC.

And even bleed screws on clutch cyl's didn't always have a barbed wheel cyl type nipple they were more of a vent. Makes it impossible to put a vacuum pump or reverse fluid inj pump on it.

Define the system being bled, I'll offer .02$ to bleed or burp.

Scott is or has installed a concentric slave cyl on a Mustang. They don't even have a bleed screw on the cyl. The process is dry vacuum bleeding not even touching the fluid. A different hammer for a specific combo of designs. That technique is futile on a tappet valve system "as installed".

These discussions almost need an adult beverage to sort out.

Gary

 

[GCroyle]

Tim,

Bingo. Visualize where the bubble is or most likely to be and now help it do what it wants to, go UP in a fluid all the way up and OUT if possible.

Gary

 

[BigPapa]

Scott is or has installed a concentric slave cyl on a Mustang.

Not yet, but will be shortly.

 

[Matt42]

Tim,

When I took a tech call on hydros one of the first things I did was look at pics of the units to see which MC basic design it was and IF it had an adjustable pushrod (imports were big on that) and only then did I choose my tech hammer(s) of choice.

Folks don't get confused that an adj mater cyl push rod it the answer to all that ails you each design has its designed in requirements and believe me an adjustable pushrod can get you into no mans land in a heart beat if you try to out think it.

There is no one technique that is "IT" but the outcome must be the same get the air out!

Gary

When Chevy/GMC was installing the 6.4 and up series V8 diesels in their trucks, I had a 1998 assigned to me. I think it had a 6.4 and gave lemons a bad name.

Those Chevy trucks also used the NV-4500 manual transmission and a hydraulically operated clutch. That clutch linkage was nothing like the linkage used on the Dodges. The Chevrolet system could be bled. That handy during September, '01 on a rainy morning.

I had been working in western Montana beginning on Sep. 8. (My attendance at a meeting in Lower Manhattan had been cancelled, the work in Montana was more important.) We were towing a 10K lb gravel testing plant. As we headed back home, up a steep pass, the transmission started getting noisy. At the top of the pass, the engine shut down. After letting everything cool down for a while, we coasted into the nearest town with a Chevy dealer.

It turned out that most of the Syntorq in the NV-4500 had leaked into the transfer case and ruined the transmission. So we were stuck several days getting the transmission replaced. The dealer didn't replace or refill the clutch hydraulics. The clutch would work, but it took a few pumps to get it to release. I asked my supervisor to scan the correct pages in the TSM, which I had left in the office, and email them to me. I looked at them overnight.

Chevrolet's slave cylinder had a bleeder screw, so I poured in enough fluid to fill up the reservoir, and then we did the pump-and-bleed while was underneath on wet gravel. Getting rid of about a tablespoon of overheated brake fluid fixed it.

The Chevy system is so different that it isn't adaptable to our Dodges. As for that Chevy truck, with its history of bad injection pumps and other breakdowns, my employer sold it and replaced it with a 1 ton 3rd Gen Dodge, which I drove for 14 years until I retired.

 

[SAndreasen]

I’m just glad the new part fixed the problem no voodoo no nothing . Napa sells the parts separately and actually couldn’t find the complete assembly under application but it came up on my computer at home so I had them order the part luckily it was identical to what came out of the truck and works perfect

 

[Bluefish157]

Several years ago as we exiting interstate 5 the clutch slave cylinder snapped off at the mounting flange. Lucky me just off the ramp there was an OReillys auto parts store. $40 for the part and $100 for the tools and miscellenous stuff later I was rolling on the ground, dripping with brake fluid, torqued off because I could not get a good bleed. So we limped home, 800 miles South with a very deep clutch pedal. Every shift was fun, but prodded me be creative. When we got home I grabbed some PVC pipe and cap, glued them together, put that in the lathe. Turned it to fit inside the clutch master leaving a shouder stop, and groove for and Oring. Drilled and tapped the cap, attached HVAC pump.... PERFECT PEDAL ON THE FIRST TRY!

 

[GCroyle]

Bluefish157,

It sounds like you might have used dry vacuum bleeding to burp the system, is that correct? If you can provide MMY info I can recommend a bleeding/burping procedure that matches the truck. Example my 2005 will NOT burp out via dry vacuum bleeding if done while installed. But my 1997 would dry vacuum bleed while installed in the chassis.

MMY is really required to know which hammer to use.

Welcome to TDR.

Gary

 

[Bluefish157]

Bluefish157,

It sounds like you might have used dry vacuum bleeding to burp the system, is that correct? If you can provide MMY info I can recommend a bleeding/burping procedure that matches the truck. Example my 2005 will NOT burp out via dry vacuum bleeding if done while installed. But my 1997 would dry vacuum bleed while installed in the chassis.

MMY is really required to know which hammer to use.

Welcome to TDR.

Gary

Gary,
The trick was that I did it with system full of brake fluid. The cap had additional volume provided to accmodate the fluid and "Champaning" effects. This allowed the low absolute pressure to be distributed everywhere that was suposed to be full of brake fluid. Any air in the system expanded by the very low absolute pressure, thereby forcing all the brake fluid into the resevoir and pvc pipe stub. The entire system was then nominally "Empty" of air. The brake fluid was therefore also degassed and dehydrated. When atmospheric pressure was then bled into the pipe stub on top of the fluid, the fluid then filled "Vaccum" of the lines and slave cylinder.
Yes , knowing which hammer to pick AND were to hit AND how hard is the art.
I was a TDR member when we got our "Bluefish", 2001.5 4x4 2500 HO Camper/Trailer special ordered from the factory.
Rich

 

[GCroyle]

Like this video that was done with a hand operated vacuum pump but you had access to an HVAC pump. Tricky part is the positions of the port that get the fluid into the MC body. Older piston port, nice and cooperative but the tappet valve on 2001 and up needs a little coaxing.