Clutch bleed apprehension

ZoomZ

Good timing for topic.

When I had my OEM components, I did the old fashion two person method. As this was the normal practice. Did it twice on my 2017. never had issues.

Until recently, when I had the mysterious high engagement did I have issues.

I went ahead and replaced entire clutch system.

Now I am having a hard time bleeding the Tilton MC and CMAK slave.

One thing I noticed is the new SC will not RETRACT back far enough. I had to keep bleeder open and manually push the piston back (towards bleeder) and low and behold, tons of air bubbles in my hose.

Obvioulsy, this will introduce some air back UP into clutch hose towards MC.

So, I had to repeat this a couple more times and I have no bubbles showing.

However, pressing down on the RJM pedal, still feels spongy at top 1/2-3/4".

I'm going to go ahead and adjust pedal to where it should to start and see if some of that play will be taken up or still feels spongy.

Yes, I did bleed with pedal at 0 AFM, clevis fork set to longest stroke. (almost at end of MC rod near pedal attach point.

I left the switches out for maximum stroke.

Hope that helps.

Spooler

Did you bench bleed the MC before you put it on? If not, that was your problem.

BoilardZ

I've bled the clutch three times, and I've never had a problem. (Each time I was simply replacing dirty clutch fluid.)
Did the standard, simple 2-person method.
As others said, the key is not to let the fluid reservoir run dry. Otherwise easy-peasy!

NissanParty

Ok... I am still nervous, I had a G37 and now this car and heard countless problems from people where they tried to bleed it and had a failure and had to replace the CSC. What!!?? So it was fine until they tried to bleed it and then it failed?

Even the Infiniti dealership refused to bleed my clutch. How the heck can bleeding the clutch break it?

Back on topic - let's say I want to gravity bleed. I have never done this. Do I just take the top off, suck the fluid out, put fresh fluid in, then crack the bleeder with a tube on it and let it slowly drip out?

Will air get sucked into the cylinder when I open the bleeder? Any sort of prep I need to do beforehand?

Thanks very much.

ZoomZ

I followed the RJM instructions. Which essentially bench bleeds it but installed.

Actually, re-reading the instructions, I'm ok with that 1/2-3/4" softness.

"At this point if everything went well you should have a nice firm clutch pedal with no softness at the top
for OEM pedal units and no more than ½”to ¾” of soft travel at the top for RJM Pedal Units. Please note
if you’ve just installed a new RJM Pedal along with the new master cylinder then the pedal feel at the
top will be softer then you were used to. With the design of the RJM HD Master Cylinder any small
amount of air left in the upper lines after this procedure will quickly and automatically get purged from
the system as you start driving it or continue to slowly pump it.

"

THE BULL

At the end of the day this is a standard MC and CSC or Slave.
An even more simplistic approach, this is just a hydraulic system.

The reason why folks have a hard time with these:

• The shape of the line tends to trap air
• The clutch softner main culprit (circular piece that attaches to the hard line) all that it is is a chamber that restricts volume by using a restrictor like turbos.
• This chamber does not like debris at all and once debris enters it's really difficult to clean just by fluid exchange.
• Incorrect shaft or pedal lenght
• Lack of bench bleeds
• Deteriorating CSC will make bleeding difficult as well

I recently did a VHR swap on a 350z using 370z pump, CSC and line.

16k mile donor and a brand new CM, had bleeding issues. Little to no fluid coming out of the bleeder. Better flow coming out the CM but not enough.
I deleted the clutch softner and was able to get better flow to the CSC but it barely moved.

In the process of trying to bleed the new CM with the bad line/sofner I killed it. Exchanged the CM for a new one. Bench bled it and installed the cover nipple on the CMC to prevent fluid or air to go into it.

Once installed I set rod length to max and loosened all of my fittings and started pumping. I would get small bubbles as I would pump and once they would disappear I would tighten. Clutch bleeding was a success

Now the next issue was my engagement was about 1/8th of the way from the top and felt like it would work however I would get some stickiness when I would pump all the way.

The issue ended up being that now the rod length needed to be scaled back a few turns and she is golden now.

I took the opportunity of this to make that hardline as straight as possible.

I realized that in all of my MT cars almost all of my clutch hydraulic problems would disappear when I would install a direct braided hose and ditch the softner.