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-   -   clutch works fine. for 10 minutes. then sucks bawlz. (https://www.miataturbo.net/general-miata-chat-9/clutch-works-fine-10-minutes-then-sucks-bawlz-17134/)

y8s 02-16-2008 06:02 PM

clutch works fine. for 10 minutes. then sucks bawlz.
 
I'm pretty unsure what's going on since I can't see into the bellhousing but I suspect I have a warped disk or cracked diaphragm spring or something.

Basically I can shift until the car's warm and then I can't get it into ANY gear. I can even feel the car lurch if I try to force it from the syncros engaging.

And before y'all jump on me about clutch hydraulic anything, I did some stroke measurements at the slave (which is new, just like the master) and with the car hot and not shifting, the stroke was within .02" which i doubt is enough to prevent shiftage.

Basically: Argh!

Also basically: i'd rather not have to pull the tranny now and again when I swap motors. heh. how fast can I build a motor? I can have all the parts in-hand in a week or two if I try. Machine work is going to take the longest. Oh and rushing things sucks. Someone sell me a nice 4-door 5-speed E30 for $2000 in teh meantime.

Bryce 02-16-2008 06:09 PM

I've got the exact opposite problem. It won't go into gear when cold. Argh indeed.

magnamx-5 02-16-2008 06:33 PM

hmm so you can shift fine when cold, but once the car warms up you cannot? how long have you had this problem? Does it make any wierd sounds that would indicate a bad throwout bearing etc? This realy has me stumped sorry.

Ben 02-16-2008 06:46 PM

oil on the clutch discs? are they kevlar?

y8s 02-16-2008 06:52 PM

disks are organic. i hope there's not oil on them... I suppose I can stick a finger in there or something.

magna: this been goin on for maybe a couple months. was sort of an "all of a sudden" thing. no weird sounds.

bryantaylor 02-16-2008 07:05 PM

how is your trans fluid? it might not even be a clucth problem.

Ben 02-16-2008 07:07 PM

bryan--i have every confidence that mr y8s isn't that dumb ;)
also, it typically works the opposite way--the tranny wouldn't work when cold, but would function when hot, if it were low on fluid

my monopoly money is on oily discs

Ben

y8s 02-16-2008 07:11 PM

glad I got two spare disks when I bought them last time. but I'm gonna need an erl seal.

ooh or a valve cover gasket because I just had that apart to rig up my COP setup. I wonder if it's draining down the back of the motor onto my junks.

Think I can flood the bellhsg with disk brake cleaner spray? :D

patsmx5 02-16-2008 07:13 PM


Originally Posted by y8s (Post 215387)
glad I got two spare disks when I bought them last time. but I'm gonna need an erl seal.

ooh or a valve cover gasket because I just had that apart to rig up my COP setup. I wonder if it's draining down the back of the motor onto my junks.

Think I can flood the bellhsg with disk brake cleaner spray? :D

I did that to my trooper, I sprayed the hell out of the clutch to get it to quit slipping as bad. I was drivable for another 2 weeks. Course it was leaking more oil than burning gas....

I'm guessing an oily disk swells up when hot, causing friction?

Braineack 02-16-2008 07:14 PM

matt need help tomorrow?

y8s 02-16-2008 08:20 PM


Originally Posted by Braineack (Post 215391)
matt need help tomorrow?

how fast do you think we can R&R a transmission? :giggle:

magnamx-5 02-16-2008 08:38 PM

4-7 hrs tops. benefits of being around scot who with your help could probably get it done in 2-3 hrs ;)

bryantaylor 02-16-2008 09:19 PM


Originally Posted by Ben (Post 215386)
bryan--i have every confidence that mr y8s isn't that dumb ;)
also, it typically works the opposite way--the tranny wouldn't work when cold, but would function when hot, if it were low on fluid

my monopoly money is on oily discs

Ben

i know, just throwing it out there. i have seen strangers things happen :cool:

neogenesis2004 02-16-2008 09:24 PM

Sounds like a good candidate for a clutchnet clutch :) wink wink

y8s 03-02-2008 09:39 PM

lame update:

ripped the tranny out and the clutch looks relatively normal. maybe a little heat in the pressure plate, floater, and flywheel but otherwise nothing obviously wrong.

I scuffed up all the friction surfaces and set it aside for reassembly. Oh and I'm putting a different ratio pressure plate in to reduce pedal travel a smidge.

So while I had all this shit apart I also decided to swap the ring and pinion. I love anti-seize! But I'm a moron and forgot last time to put the sealant on the diff. I was wondering why it kept dripping oil. :D

I had to cut off the bearing on the pinion scott sold me. royal pain! I reused the spacer hoping it was within a few thou and not going to cause depth problems. we'll see.

I'll probably start reassembly tomorrow. Time to watch Dr. Strangelove.

y8s 03-05-2008 02:43 PM

Update!

So I've discovered that the failure mode of the Tilton setup is pressure plate warpage. The warp was enough that when it warmed up, it took up too much space in the clutch pack.

http://gallery.y8s.com/d/840-2/Dscn1597.jpg

Basically as the pressure plate (a separate piece shown in the upper right--the top of the two silver rings) gets heat cycled, the friction surface becomes cone-shaped because of the asymmetry of the metal. The inside circle tries to expand as much as the outside and the result is it pushes the circle out of plane since it has nowhere to go.

I spoke to Tilton about it. They have redesigned the PP to be a little beefier (more heatsink capacity) so hopefully I'll get that iteration when I get my new parts tomorrow.

I also asked them about the "hybrid" cerametallic-organic twins they make. It's exactly the same disks I use from clutchnet (should I sue for stealing my idea?) and has about 70-80% of the engagement properties of the two organic disks but is designed to wear longer. Kinda neat I guess.

M

y8s 03-06-2008 10:09 PM

my thread gets no love. so I shall stroke it myself...

put the tranny back in tonight. and amazingly, i didn't even get my hands dirty. nothing under the fingernails. nitrile gloves friggin rock.

so I got the pressure plate that's redesigned to be more beefy. I'd say there's about 20% more mass there so that's cool.

probably finish reassembly on saturday morning.

ok carry on.

bryantaylor 03-06-2008 10:23 PM

glad you finally figured it out man

Braineack 03-06-2008 10:38 PM

yay, maybe you can drive out sunday and help brad and me out.

MikeRiv87 03-06-2008 10:53 PM


Originally Posted by y8s (Post 215356)
Someone sell me a nice 4-door 5-speed E30 for $2000 in teh meantime.

I have a White 2 door 5 speed I would let go for about $1200 if your really serious.


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