rowen210

I have a NA 5.0 Miata and the hydrolic clutch system has failed me twice now.
It is a stock Miata master and slave on a custom bracket bolted up to a T5. I put a long threaded bolt on the business end of the slave for clutch fork adjustment. It has about an inch of travel.
I was riding on a stock clutch for about 500 miles with no problems when suddenly i could not grab any gear from a stop. The petal felt fine and still had clutch fork travel. So, for fun i put a centerforce clutch in and a new slave. (The master was replaced a year ago.) Bleed the clutch and i was back on the road... for about 50 miles. Now the same thing. No gears from a stop, no leaks, i have petal pressure, and fork travel. It feels as if i am trying to shift without a clutch. Do i need a different slave with more travel? Im confused.

rowen210

I made a new push rod for the slave. It has more adjustment and a large nut that was ground into a rounded shape to keep it centered on the hole in the fork.
I also put a new line from the master to slave. The original one went over the resivor making it impossible to gravity bleed the system. The new line roughts under the booster. Bleeds much better.
So, everything was good on a short trip around the neighborhood. As the car warmed up the gear changes got ridged. I quickly went home and let it idle in the garage. The longer it sat, the harder gear changes became.
So the problem is that gear changes become increasingly harsh to impossible as the car warms up... what is the deal? Any ideas would help as i am kinda frustrated.
I am guessing heat soak? I will try wrapping the header and slave. Wish me luck.

V8MiataMike

I started experiencing the same thing. Could not get it to go into any gear (especially reverse that has no syncro) when stopped and the engine running. In the end it was because the throughout bearing was just not getting pushed far enough by the slave. And (again for me that is) it was not the slave that has the problem it is the master not able to push enough fluid to the slave. The slave itself has plenty of stroke.

I have my T5 clutch fork drilled with a new hole closer in per Monster Miata instructions and using the Monster Miata slave bracket provided (of which I see ZERO and I mean ZERO deflection when the clutch is being operated) as well as having to notch the bell housing a bit for the slave rod clearance to be good.

I removed the entire clutch assembly from inside the car and adjusted that upper switch (cruise cancel I think) so that the pedal came up as far as it possibly could. I then made sure when reinstalled it went all the way to the floor stop that is on the assembly. After that was done, I measured the pedal push rod stroke (how far the clutch pedal pushes the rod out into the master cylinder) and I still was not satisfied it was enough. For this setup to work on my car, I had to have what I considered too much throughout bearing pre load. But it was working fine.

In the end I went with a Tilton master that bolted right up to the Monster Miata master adapter plate. It is 1/16 larger in diameter and the additional volume now provides ample stroke for the slave to fully disengage the clutch with no (none) pre load on the throughout bearing.

I noticed the increased pedal effort needed to push the clutch in right afterwords but now it seems completely normal and operating perfectly and consistently.

rowen210

Thank you for the response. Your suggestion of the master possibly being the culprit really got me thinking. I am not happy with the (in my opinion) excessive preload needed to make the clutch work. A master with a larger bore could increase the slaves throw. It lead me to this thread... Need Help with Clutch Master Cylinder - MX-5 Miata Forum
Also i am going to remove the cruise cancel switch right now to see how much that helps.

V8MiataMike

This is the Tilton I used.

https://www.summitracing.com/ga/part...875u/overview/

It fits really nice. I used the stock Miata master push rod. And with the line coming out the front of the master it makes it super easy to gravity bleed the system. You will have a bit more pedal pressure - a bit harder to push, but I have no master pre load from the clutch pedal push rod and no pre load on the slave to throughout bearing.

Working very nicely.

rowen210

Just what i needed! I will be ordering that master.
On another note. I removed the clutch petal assembly to remove the cruise cut out switch and hammer the petal stop down a little. Took it on a 30 min drive and it feels drivable. I can get around like this for a week or however long summit takes to deliver my new master.