tempest411

In the video you can see the throwout bearing IS moving back and forth. How long has this car been down? It's possible that the clutch disk is 'stuck' to the flywheel. It's happened to me on, on my motorcycle after not starting it for a few years.I've heard of it on cars as well. See if you can't wedge the clutch pedal down with it in top gear, then push the car back and forth, to see if it frees it up.

Dan Martinic

Dan Martinic

Well... that settles it. So much for high-priced refurbishment service!! Nonsense

I am happy to find that I indeed installed all correctly: other than some surface rust (it's actually two years ago; finding my old Zims receipt made me realize how poor memory I have!), everything else looks nice and proper. I put grease on both sides of the guide tube. My goodness how nice all the nuts and bolts came off: I put Copaslip on every fastener. They came off like butter

Wish I could say the same for the bellhousing. What a cruel German joke that is. The bolts at 12 & 9 o'clock are interesting to say the least, especially when you're lying on your back watching your breath in the cold while biblical rain falls all around. Then you finally get them out and the darn thing hangs up somewhere. A half hour later and it pops off, leaving you unsure exactly which motion did it.

But I got it done. A quick search suggests the forks are available again from Porsche. There is a new part number. Prices in USA range $350 to $450 USD. I will wait till Monday, call my closest dealer up here, and see what they offer. If new OE part is available, that's the obvious choice for me.

However, I have to decide on the TOB. It looks good.. isn't noisy.. but has a little vertical play. I don't remember what a new one feels like. Given that mine has been in operation with a crooked fork for many miles, perhaps it has worn significantly under the stress?

Video of my TOB play as currently sitting installed in the car:





Nearly a week of hydraulic bleeding... three litres of brake fluid... one oil can... one large syringe... a wifi boroscope camera... tubing and clamps in various sizes and styles... and hours spent cold and wet... all fruitlessly trying to fix a funny pedal

What the Fork is right!! lol

Thanks all for giving me an excuse to move my butt on this

tempest411

Wow! Did that happen with a stock clutch? I think the cost of doing the clutches in my own cars just went up by $350.00 a piece...

Dan Martinic

Mark called it... and yes, I will be putting the "POS needle bearings" (rebuilder's words) into my (hopefully; yet to confirm availability) new stock fork.

Pressure plate is stock: I used a "Turbo Cup" clutch kit from Zims and my understanding is it's all stock parts

FYI.. this fork rebuilder is well-know for other services and custom control arms. I won't mention the name. Maybe this is a one-off.. or maybe used forks are just a gamble either way. But the service did include "hardening"

MAGK944

Curious were the needle bearings replaced with a sintered bronze bushings?

Also, when I got my last clutch kit from Zims I sent in my fork as exchange for a refurbished one including bearings, reground and hardened tips and it was way under $200 iirc.

Dan Martinic

I believe so: something called "Oilite"

Along with the fork, I had to send my new fork pin to be "custom fitted" to the bearings. Now I don't know if the pin--which still looks new--can be re-used or if it was altered in some way? I'll try asking. Awkward convo though lol

MAGK944

So I just searched on Zims and they still offer the clutch fork refurbishment for $185 in case you want to go that route. I’m happy with the one I got from them over two years use so far, though I wonder if they will take a modified one as a core.

Zirconocene

I fitted the oiled bronze bearings in my fork when I had everything apart. I found that while I could get the bearings onto the pin when disassembled, once I pressed them in the pin wouldn't fit. I ended up honing the bearings a little bit once they were installed and then everything worked perfectly. I decided on that route for a couple of reasons: 1) the bronze bearings are well reviewed on RL and 2) my pin showed some amount of gouging/scratching from the old needle bearings. I've been pretty happy with things so far.

I'm glad you got it figured out. Not the failure point I would have expected but history was on the side of that possibility.

Well done.

Dan Martinic

The drama continues!

I sent a message to the fork rebuilder and he responded that yes, I can re-use my pin--bearings were machined to fit, not the other way around--and the following:

"It's not unheard of for a fork to break like that, but that is usually as a result of:- the release bearing binding on the guide tube,
- a broken marcel in the clutch disk or damaged diaphragm fingers
- incorrect flywheel grind/pressure plate match-up heights including disk thickness.

When only one finger breaks, it indicates that the release bearing is not moving equally on both sides. The hydraulic system is "self adjusting" in as much as the system will advance hydraulically to take up any play. To that effect, the slave cylinder will always stroke the full distance pushed by the master cylinder. If something causes binding, the hydraulic pressure can be strong enough to break something (6400 pounds at the clutch fork tips). Ensure that you check the rest of the system carefully and find the underlying cause of the failure or it will repeat."

Clearly, I am going to need to investigate further; this gentleman is a respected pro and I'm just, well, not a pro lol

This is what my guide tube looks like (installed) and the original one I replaced (next to it). Yes, I am in the habit of keeping all original parts for a while now






Anything? I do notice some wear.. on both... but the new one's extra scratchy wear could be *after* the fork broke, I guess

As for the other possibilities mentioned.... I'll take off the PP and clutch to inspect... but how can I check the flywheel height thing? I did have my flywheel resurfaced

GPA951s

I will check the lash on some of the PP's I have with TO bearings on them to see how the bearings compare lash-wise. Take your BH and Toss it in your PP on it and see how much of a Gap there is around that guide tube. The TO bearing really doesn't "ride" on it at all. There is quite a hefty gap from the O.D. of the guide tube to the I.D. of the TO bearing.
Another option that is out there is to convert to a Hydraulic TO Bearing. "Spec push type clutch"
I don't see how Resurfacing the FW had anything to do with this. Think about a SUPER worn out clutch disk where the disk is thin. It would move the PP closer to the FW is all. I don't see how it would pull un-evenly.
Having a re-worked fork the only thing that would come to mind is that the fork was not perfectly even across the face of the forks to begin with, essentially making one finger have more work, not spreading the lead evenly... After time it just finally was too much for it... and the fork finally "gave you the finger" LOL..

Dan Martinic

Great.. let me know on that TOB lash.

I will remove the PP and clutch and have a look. I still have my original PP and clutch; the disk--date stamped '08 '87--still has 1/2 thickness left to spec. I will use these to compare







When my original TOB went, I figured do the proper thing and change it all. New forks were NLA so I had mine refurbed. Man, I should have done like the quick-fix shops and left everything as is, switching only the TOB lol

I just ordered a NEW fork. They are available again. Up here, the dealer's price, with "classic car discount" is a whopping $509 plus taxes. Two-week wait from Germany.

Sunset is a good price though with exchange & delivery, it works out similar for me





Apparently, it comes with "bushings", which I hope means the needle bearings already installed. Otherwise, I do have a new pair that I never used last time

GPA951s

Oh That's not bad, its CDN So that's $236 USD... hmmm I might actually think about replacing mine. Im in the middle of building an Engine right now, and will change the engine in about a month.. Im still debating on the whole Cyl head deal. Not sure which way I'm going to go yet. But I have my pistons and Rods and block machined. Still have to pull the factory head studs out though.. That's always a fun project.

GPA951s

The TOB Bearing lash that observed was .015 I just set up a magnetic base dial indicator and placed it on the face and pulled up just like in your vid.

Dan Martinic

Perfect.. thank you. I happen to have a magnetic-base dial indicator too, so I'll do the same. Not tonight though: it's wet out and I'm enjoying my other hobby!