hf-mx5t

Hey.
bit of an issue..

my 6 speed gearbox will now refuse to go into gear.. this Applies to any gear.
Clutch has the same bite point as before.
clutch will fully disengage and the car can stay still with the car in gear with the clutch pressed.
It will shift between gears with no problems in neutral at Idle.
Some times it feels ok but a bit notchy while driving.
other times you can not move the shifter into any gear (1-6 does not matter but seems 4/5 is worst).
If i fiddle around a bit i can most times get it to engage.
it does not make the sound you get if trying to shift while the clutch is not disengaged, it just is impossible to move the lever to the correct position.
When engaged the gearbox does not make any unusual buzzing or grinding.
all gears work fine when engaged.
oil change 2 weeks ago and has worked fine after that.
I have not abused the car on the trip down here and barely went above 200kph( very little throttle and almost no boost) for very short periods on the autobahn.
took out the shifter. And there is no play to be found. And the selecting rod seems to work fine. As i Said , no issues shifting while not moving.

any ideas what would cause this? Im baffled.

oh. I just street drove the 430whp stripped out caged mx5 with xidas for 1500km from Oslo to the nurburgring non stop the other day.. but now i need to get back. The track driving has been cancelled for me by this but i just want to get home.. shame having this monster here and not get to try it on the track.. but **** happens.

any ideas would be helpful.

Bronson M

iTrader: (1)

Sounds like your slave cylinder and/or master cylinder is leaking internally and not letting you fully disengage the clutch. But you say it fully disengages at a stop.....odd.

​​​​​​I have a theory that the thrust bearing in the trans is the first to go in high HP cars which does all kinds of odd things for shifting and allows the gears to not fully align resulting in broken gears. Does your shifter move forward and backwards as you get on the gas and transition to coasting? I noticed this on my 6 speed before I broke it with 250hp.

hf-mx5t

Slave and master are ok as far as i can see. Lots of travel at the clutch arm. Consistent movement and no leaks
your idea about internal thrust bearing might be om the right track. Pretty much impossible to repair for me now. I would probably need to just carefully drive it å good distance and jump a ferry the last half of the trip home to cut on miles driven with this issue. Hopefully it doesnt blow up before i reach the ferry.

adryargument

iTrader: (1)

To be honest I would just get it fixed asap by any means nessesary, take a week off work and hit nurburgring until I can't walk straight.

HHammerly

iTrader: (3)

Did you fill the transmission with oil using the side plug or took the shifter out to do so? I know that many 6 speeds have died when the wrong plug on the side of the tranmission is pulled to get it filled with oil...😧

hf-mx5t

Small update..
We never were able to fix the problem on site before our deadline to go home. i drove the car back home, while being more careful to shift. will replace master and slave, and maybe clutch.
There doesnt seem to be any issues with the gearbox while driving. the gearbox has the correct quantity of fluid, filled in the correct hole
A bit sad not getting to drive this car on the ring, but ill probably be back later (next year).
driving time on the one sunny day we had, was also cut short because of a massive 10 car pile up at one of the fastest parts of the track! not pretty..

ericsbestshot

iTrader: (2)

I had the same issue years ago and it was a throw out bearing. I had a heavier pressure plate and it overwhelmed the stock throw out bearing. Would not make contact will all of the pressure plate to release the clutch.Got a new one from flyin' miata that is super beefy.

hf-mx5t

Problem found.. Seems the clutch disk from flyin miata disentegrated.. it actually broke the metal holding the spring in place. The spring then went out of its holder and touched the pressure plate springs, causing it to push the clutch disc towards the flywheel and preventing it from releasing properly..
The clutch disc from Flyin miata is actually really poorly made compare to the ACT unit, the metal where it broke is almost twice as thick on the ACT unit..
My last clutch was a ACT unit and i dont think i will buy another "happy meal" clutch if this is the quality of them now..
good thing i have other toys to use while i was fixing this The panigale has been the toy of choice while the mx5 was out of order

sixshooter

iTrader: (12)

Thanks for the update. Satisfied ACT user here.

hf-mx5t

yeah, never had issues with the act clutches before, so i went back to that

gooflophaze

That looks like the same failure mode we had with our LFX that doesn't use a pilot bearing - https://www.miataturbo.net/build-thr...-87186/page10/ - might want to check your pilot bearing and input shaft runout.

hf-mx5t

checked. input shaft runout is ok. pilot bearing was like new.

Doppelgänger

iTrader: (12)

Hope you replaced the clutch pivot bolt while the trans was out. Sounds like an odd part to suggest, but I've managed to snap it before, as have some others. That one really sucks when it goes....and it's like a $2 part that'll go when you least expect it.