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.

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

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.

oil on the clutch discs? are they kevlar?

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.

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

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

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?

matt need help tomorrow?

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

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

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

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

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.

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

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.

glad you finally figured it out man

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

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

i'd have already said yes if it was a 4-door and had under 180k.

Mostly, I just need somewhere to hang my spare wheels:

http://gallery.y8s.com/d/686-3/DSC00850.jpg

what're all yalls doin sunday?

Tilton cover the damage?

On/off topic, that is indeed a Tilton twin-disc right? How much did it bend you over for, how do you like it, engagement, power rating, etc.

tilton wouldn't cover damage from normal use... it's a racing clutch. i didn't even bother to ask.

It is a tilton twin disk, yup. I eschewed the cerametallic disks for organic disks (though you can run one of each and get something close to the best of both worlds).

It's not expensive. The clutch itself is $500. Two disks is about $90. But you either have to have the unobtainable flywheel or do what Brian did and make one out of a 1.6L flywheel (which is pretty awesome if you think about it). Bearings are the normal miata bearings. You do have to make the new pivot or better yet, do the 1.6 flywheel thing and make it the right height in the first place.

I would think that the outside, which is thinner, could get hotter than the inside, which is thicker and may have a better heat sink capability. So the outside would want to expand more than the inside making it coned not the other way around. Theoretically if the part stays the same temp everywhere as it heats up it should stay flat. But whatever, I'm glad you got it fixed, hopefully! Kind of a killer setup...

i dont know the actual mechanics of the expansion, but it's pretty consistent since I had an older pressure plate from way back when that had the same cone-distortion and tilton mentioned it specifically.

it could also be that the cross section of the ring is roughly triangular or that the outer edges have extra material where they lock into the clutch cover and dont get as hot so they dont expand as much. (those 6 notches)

needless to say, the new one looks beefy. I snapped a picture but it's on my camera at home.

... time passes ...

drove the car to dinner... other than a squealy-ass belt, it's running nice.

the clutch is smoov.

now.... the squeal is driving me nuts. it's a new belt. could it be the alternator bearing?

Umm, mine squealed because when i changed my belts the other ones were not as loose as the old ones and i didn't move the alternator tight enough to the left so it was to much to the right so the belt was loose hense the squealing, so try to push your alternator to the left more/so the belt gets tighter see if that helps, i used a pry bar then tightened the bolt. Or just squirt some oil or WD40 on the pulley and if it stops squealing then go get some spray grease shit or pulley grease, if that wont work try moving the alternator so its tighter.

yeah i'll recheck the tension and hopefully that'll fix it.

ahh yes that was the word i was looking for

Final update:

• Clutch: fixed. swapped in a new pressure plate and it's good to go.
• 3.9 Ring and Pinion: Done. Reused the spacer but it didn't whine much on the freeway so that's cool. also put in the Ben-sourced speedo drive. 3400 @ 70mph.
• Belt Squeal: fixed. reread the belt tension section of the service manu. tightened it up. silent.
• Exhaust leak I didn't mention: just had to line up the V-bands better.

so yeah, the car is solid.

nice all you need is a video to finish it off with all the new updates

great, glad my R&P worked for you!

me too. i felt the gas savings already.