Miata clutch issues, what are your thoughts?

JamesShort · **Posted:** Mon Oct 03, 2011 10:46 am

I posted this on miata.net. What do you folks think (obviously 'he' refers to Ram):

Quote:

My autocross codriver gets the car to the event and we run through our runs on Saturday. After a decently hard launch, he gets back into the grid and when he pressed the clutch in to get it out of gear, I heard a few chirp noises. Then when I got in the car, when I press the clutch in (even with the gear selector in neutral), it would intermittently make some chirping and when I was on the line and in 1st gear, the car seemed like it was very lightly trying to lurch forward. When we finished our runs and got back in the pits, when the clutch pedal was pressed in, it made some grinding/whirring sounds too.

All signs seem to point towards the throw out bearing being on it's way out. Then Sunday morning (2 day event) he starts up the car, rolls back and goes to engage 1st gear and it won't go in at all. I tell him to stop the car, put it in 1st, start it. He does and the car doesn't lurch forward and he drives off and it shifted into 2nd fine and during the short drive to the gas station it was fine (including going into 1st while the car was running). Seems like something 'frooze' over night and starting it in gear 'unfroze' it in the morning.

We take our final runs of the day (luckily the new course was easier on the launch) and I notice that it's not making any chirping or whirring noise and it seemed to engage the gears a lot more smoothly than before. After the event it, we took the race tires off and he drove it home and it's not making any noise with the clutch pressed in and had no shifting into 1st issues this morning after it sat overnight (and it got very cold last night).

What could this be other than a throw out bearing, and how could it 'self correct'??!?!?

Vincent Keene · **Posted:** Mon Oct 03, 2011 11:03 am

Been there, done that. If it's not the TO bearing I'd be shocked. However once mine started 'chirping', it didn't stop and went from a 'chirp' to an all-out 'scream' in less than 50 miles.

JohnByers · **Posted:** Mon Oct 03, 2011 11:07 am

I still think you need to throw a TO bearing in it and call it done

JamesMilko · **Posted:** Mon Oct 03, 2011 11:16 am

Change your slave before you do anything else. They are a weak point on the Miata. Can get to it through the passenger wheel well. The TO may be an issue as well but the "can't get into first/lurching forward" stuff screams slave.

e:
The definitive test would be if you could "pump up" the clutch and get it into gear the next time you have problems getting it into first. If that works then it's very likely the slave, if not then it's likely the TO.

Vincent Keene · **Posted:** Mon Oct 03, 2011 11:36 am

Regarding the slave, mine had an 'issue' for over a year before it finally gave up. The car drove and shifted fine and the only thing was a clutch dump would never yield wheel spin.

One morning I got ready to drive it and it started to lurch upon turning the key. I looked at the reservoir it 'appeared' full. Upon further inspection it was stained which looked like it was full when there was no actual fluid in it. When I pulled back to boot on the slave I found the missing fluid.

The good news is the slave is cheap and easy to replace.

JamesShort · **Posted:** Mon Oct 03, 2011 11:58 am

I just bled the clutch fluid last week too....no dripping/moisture around the slave cyl.

And yesterday, the trans went into gear so silky smooth (and no chirping)......even smoother than I ever remember Ram's car being.

Anyway, a clutch/pp/TO/PB kit is so dirt cheap that his car probably needs it.....6 people learned to drive a manual on Ram's car and it has 110k miles on the original clutch

.

If it is the TOB, it's almost like the TOB was starting to seize up such that when you had it in gear and were stopped, that the inner and outer race of the TOB were dragging just enough to make the car feel like it wanted to move forward. Then after we shut her down after Saturday (left it at zMax over night) and started it up, the TOB was 'frozen' and needed the starter to crack it loose. And then somehow fixed itself. Very odd.

Well, poor kid, he'll just have to DD the Cayman S now till we get that job done :mrgreen:

EDIT: VK....that's interesting because we really struggled to get wheel spin on Saturday (until Ram clutch dumped it at 7k rpms

), but on Sunday, the wheels spun very easily and it wasn't a hard launch either.

Vincent Keene · **Posted:** Mon Oct 03, 2011 12:06 pm

JamesShort wrote:

EDIT: VK....that's interesting because we really struggled to get wheel spin on Saturday (until Ram clutch dumped it at 7k rpms

), but on Sunday, the wheels spun very easily and it wasn't a hard launch either.

At a normal AX launch mine wouldn't spin the wheels at a 6K dump. Once I replaced the slave it would burn 'em, down.

JamesShort · **Posted:** Mon Oct 03, 2011 12:28 pm

So, I'm trying to reason in my head how a 'bad' slave cylinder would prevent the clutch from grabbing hard enough to spin the tires and I can't see why. If the seals are leaking then you'd think the slave couldn't even press on the release fork enough to disengage the clutch. But when you engage the clutch, the pressure plate fingers force the release bearing, and in turn the release fork back to 'neutral' which forces the slave cylinder piston back into the cylinder. I guess the piston can be stuck poking out slightly so it doesn't completely go back in.

Anyway, as it always seems to be the case, miata parts are so cheap and working on them is so easy that I mind as well just put a slave cylinder on it while I'm doing the clutch job

.

RamVennam · **Joined:** Thu Nov 11, 2010 7:31 pm **Posts:** 132

Here is the launch that broke it.....
:stick:

https://picasaweb.google.com/1081874774 ... 2954655122

JamesMilko · **Posted:** Mon Oct 03, 2011 8:27 pm

I blame driving with shoes on.

Steven Carter · **Posted:** Mon Oct 03, 2011 10:51 pm

Since you're replacing the clutch, you may as well replace the transmission and engine mounts...fun watching the shifter move around in the cockpit!

Dustin Fredrickson · **Posted:** Tue Oct 04, 2011 12:22 am

x2 for the slave. Mine never leaked, just caused wierd, "something's not right" behaviors. Finally figured out that the slave seal was leaking, but the rubber boot somehow wasn't, causing a ballooning shock-absorber effect on the piston that would neither let the piston fully extend nor retract quickly. If you do the clutch, do the slave too. Cheap insurance.

JamesShort · **Posted:** Tue Oct 04, 2011 8:03 am

Steven Carter wrote:

Since you're replacing the clutch, you may as well replace the transmission and engine mounts...fun watching the shifter move around in the cockpit!

Mazda competition motor mounts are on the to-do list. But there are no trans mounts.....solid mount to the PPF

.

Bernie Baake · **Posted:** Tue Oct 04, 2011 8:22 am

Most people totally neglect the clutch hydraulics. Look in almost any reservoir and you'll see black goo not clear fluid. If the piston has to push this goo into a small line it will do it slowly preventing the clutch from grabbing immediatly and thus causing the no burn out problem. If the piston is binding and not giving you full throw of the slave then you have the problem James and Ram had, if the binding piston breaks free then the problem misteriously goes away. I'd change the slave, and the fluid first and see what happens. I bleed the clutch everytime I bleed my brakes. On the C5's all I can do is suck the old fluid out of the reservoir.

JamesShort · **Posted:** Tue Oct 04, 2011 9:06 am

Let's say the issue was purely the slave cyl the whole time, what would have caused the chirping/whirring/mechanical noise only when the clutch was pressed in (and gear shift in neutral)? Jeremy Gast heard it when Ram was in the line for his run and immediately said throw out bearing.

Bernie, there was fresh Super ATE bled through the clutch hydraulic system just last week.

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Miata clutch issues, what are your thoughts?

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