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Location: Waynesville, NC
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Question Throwout bearing won't release - Grady, please help!!

I have posted previously about my trouble with my 911's fix.
previous post:
pics of 901 transmission clutch cable hookup

Anyway.....
I am in the process of moving to North Carolina, and due to work issues, I never got everything back together and in the car.

I took everything to a local garage just to get them to put the engine back in the car, and hook up the new clutch cable.

I have replaced the following inside the transmission bell:
Clutch
Throwout bearing
Flywheel
Resurfaced Flywheel
New Pivot pin on throwout fork
pinion bearing
flywheel seal and bolts

-------------
The garage called me today to say they had the engine back in and when they hooked up the clutch cable, the articulated piece broke.

This is the 3rd time this piece has broken on the car. He thought he hooked something up wrong, so he pulled the engine, seperated it from the transmission and called me to come over.

The fork appears to be seated properly behind the bearing, but you can't get it to move the throwout bearing no matter how hard you push on the lever.

Is this normal? The clutch and everything in there is brand new. any ideas?

thanks,
Neil

ps - i am moving to the mountains of North Carolina at the end of this week. Any pelicanite's up that way?

Old 09-19-2005, 03:29 PM
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If the clutch forks are situated behind the TOB, as they normally are in most cars, then they are situated incorrectly. At least in the 915 tranny they are. You see, the 915 uses a "pull-type" clutch mechamism rather than a "push-type." So, the forks PULL the TOB, rather than push it. The forks engage the TOB on its outside edge. The outer edge of the TOB is a big groove, and the forks sit in this groove. There are two access holes in the tranny bellhousing for the purpose of viewing the forks to ensure they are mated properly along the outer edge of the TOB.

I made this mistake. And I kept adjusting the cable until I finally wound up bending the fork against the bellhousing. Of course, the entire engine and tranny had to be removed again from the car etc, etc.
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Old 09-19-2005, 03:50 PM
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This is the 911 transmission, the one that was used in 71 between the 901 and the 915. it is a push type.

for the longest time i couldn't figure out how everything fit together because i thought it was either the 901 or the 915....

thanks for your reply though.
Old 09-19-2005, 03:58 PM
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Garage
The '70-'71 911 box uses the same clutch arrangement as the 915. In fact the 915 clutch is basically a bolt-in replacement for the 911 clutch. So the advice about the 915 from Superman still applies in your case.
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Old 09-19-2005, 04:21 PM
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Neil,

Sorry you didn’t get everything back together back when. Now, under time pressure it is more difficult.

Let’s see if I understand your symptoms correctly.

First you said:
“I have replaced the following inside the transmission bell:
Clutch
Throwout bearing
Flywheel
Resurfaced Flywheel
New Pivot pin on throwout fork
pinion bearing
flywheel seal and bolts”

I assume “clutch” means a new disc and pressure plate.
“Throwout bearing” is peculiar to 2.2. It is possible to fit a 2.4-> clutch release bearing but the ID is too large for the 2.2 guide tube. Could this be a problem?
“Flywheel
Resurfaced Flywheel” I assume this means you replaced your original flywheel with a different (resurfaced) one. What does it’s thickness measure? On a 2.2, a Factory new flywheel keeps the components in the correct position.
“New Pivot pin on throwout fork” Good. Does it have the proper washer and finger spring under it? Is the fork in good condition? Note the ball socket where the pivot sits, the fingers that contact the clutch release bearing and where the cable piece seats.
“pinion bearing” I assume you mean “pilot bearing” that locates the transmission input shaft in the center of the crankshaft/flywheel.
“flywheel seal and bolts” The seal on the crankshaft at the flywheel should be replaced at every opportunity. I personally consider the flywheel bolts a “use-once” part. Note there is a difference in length between 2.0 and 2.2 (2.4, 2.7) flywheel bolts. There is also a different thickness washer 2.0 -> 2.2.


When you said the shop reported the “articulated piece” broke, I assume you mean the piece that connects the cable to the arm. What was that piece; metal form our host, OE plastic or something other?

Is the guide tube the correct length? The 2.2 is longer than the 40 mm 2.0 tube.

I will speculate that a problem with the piece is due to the improper guide ring at the transmission differential side cover. It doesn’t seem that has been fixed.

Is the cable loop support properly in place?


With a 2.2 clutch actuation, every little detail needs to be as original for it to work correctly. There are two aftermarket pieces that improve on its reliability: replacing the plastic piece with a metal machined part and an aluminum replacement for the ring on the differential side cover.

Too often there are hamburger temporary “fixes” to an already Rube Goldberg clutch mechanism. Done right it works great.

Sorry that Denver isn’t on your route from Arizona to North Carolina.

Best,
Grady
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Old 09-19-2005, 05:19 PM
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Quote:
Originally posted by Grady Clay

I assume “clutch” means a new disc and pressure plate.
Yes, i bought the 3 piece set from Pelican, so I assume it is all the right parts.

Quote:
“Throwout bearing” is peculiar to 2.2. It is possible to fit a 2.4-> clutch release bearing but the ID is too large for the 2.2 guide tube. Could this be a problem?
I don't think this is it, I got the 3 piece set from PP for the 71... this should be the right kit

Quote:
“Flywheel
Resurfaced Flywheel” I assume this means you replaced your original flywheel with a different (resurfaced) one. What does it’s thickness measure? On a 2.2, a Factory new flywheel keeps the components in the correct position.
Not sure on this one... the garage handled this part for me. They took the flywheel in to be resurfaced. I don't know if they exchanged it for another one, or what. I will have them check the thickness. What should it be?

Quote:

“New Pivot pin on throwout fork” Good. Does it have the proper washer and finger spring under it? Is the fork in good condition? Note the ball socket where the pivot sits, the fingers that contact the clutch release bearing and where the cable piece seats.
It has the original washer and spring. Fork appears to be in pretty good condition, anything in particular I should look for? The fingers that contact the release bearing seem to be be iin good shape as well as the cable end.


Quote:
“pinion bearing” I assume you mean “pilot bearing” that locates the transmission input shaft in the center of the crankshaft/flywheel.
yeah... sorry... brain is not working real well

Quote:
“flywheel seal and bolts” The seal on the crankshaft at the flywheel should be replaced at every opportunity. I personally consider the flywheel bolts a “use-once” part. Note there is a difference in length between 2.0 and 2.2 (2.4, 2.7) flywheel bolts. There is also a different thickness washer 2.0 -> 2.2.
Yes, a new seal and bolts for the flywheel. I read in the 101 projects book that this should always be changed when you are in there. Again, I am assuming the bolts are the correct ones. They were ordered knowing it was a 911 transmission, not the 901 or 915.


Quote:
When you said the shop reported the “articulated piece” broke, I assume you mean the piece that connects the cable to the arm. What was that piece; metal form our host, OE plastic or something other?
It was an OE plastic one from PP, and i ordered the metal one today to replace it.

Quote:
Is the guide tube the correct length? The 2.2 is longer than the 40 mm 2.0 tube.
It hasn't been changed, so I assume it is the correct one.

Quote:
I will speculate that a problem with the piece is due to the improper guide ring at the transmission differential side cover. It doesn’t seem that has been fixed.
No that hasn't been fixed yet, but I don't think it is that. We can't even move the release fork by hand. It simply won't pivot. I am 6'1", 270lb, and I couldn't get it to budge with my hand. The mechanic was concerened he had put it in wrong when it broke the plastic piece, so he seperated the engine/transmission and just put the clutch/pressureplate/TB into the transmission without it being attached to the engine just so he could get a better look at how it fits together.

even in this state, with the release fork situated between the TB and the Clutch/PP, if you stand at the open end of the transmission, and pull as hard as you can on the release fork (as if it were being pushed by the cable) it will not budge. How much force does it take? This is why the plastic piece obviously broke. And i am afraid, just putting in the metal one won't fix anything.

Quote:
Is the cable loop support properly in place?
Yes it is (if you are talking about the one at then end of the transmission away from the engine). is that the front or the back of the transmission? on a front engine car it would be the back, but since it is towards the front of the car, is that the front?

Quote:
With a 2.2 clutch actuation, every little detail needs to be as original for it to work correctly. There are two aftermarket pieces that improve on its reliability: replacing the plastic piece with a metal machined part and an aluminum replacement for the ring on the differential side cover.
Do you know where i could get the aluminum piece? or is it something that needs to be fabricated?

Quote:
Sorry that Denver isn’t on your route from Arizona to North Carolina.
Wish it were as well. Thanks for all your help!
neil
Old 09-19-2005, 06:09 PM
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missing entry...

I thought i posted the following earlier with, but for some reason it didn't show up. here it goes again:

Here are 2 pics from my previous thread:

This is the release fork in the tranny case:


This is the old clutch/throwout bearing assembly:


To clarify, are you saying that the fork should just be kind of loose in between these 2 parts?
I was under the impression that the fork ears needed to fit in the space between the tabs on the TB and the clutch springs such that when the clutch cable is pushed, the bottom of the release fork is pushed toward the rear of the car, the TB is pulled towards the transmission and away from the engine. Is this not the case?

and for that matter, do i have the fork in there properly? at the ends of the fork part there are pieces that kind of stick out a little on one side, i have them pointing toward the transmission so that they fit in the detents on the backside of the TB's tabs.


Thanks for the help, i am totally confused as to what i am doing !!

neil
Old 09-19-2005, 06:13 PM
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Neil,

What did your tech say about the flywheel?

I had another thought … did the washer get installed between the end of the crankshaft and the flywheel instead of under the heads of the flywheel bolts? This would move the entire clutch/flywheel assembly toward the transmission and probably not leave enough room for the bearing to release the clutch.

Take some images of the new clutch bolted on the flywheel.

Best,
Grady
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Old 09-21-2005, 05:14 AM
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Grady,

thanks for your input, and in fact, i believe what you just suggested was the issue. The mechanic took it apart and put it back together and everything worked properly.

it got working and was shipped out to the mountains of NC. I drove it for 2 days and then the bosch ignition unit failed. i just ordered the mds unit from pelican yesterday and hope to have it by this weekend so i can drive it up on the parkway before the leaves disappear.

Thanks for all your help, and expect new pics of my car in the mountains soon.


neil
Old 10-18-2005, 05:56 PM
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Neil,

GREAT! The Forum comes through to solve another problem. Thanks for the feedback.

You think my last post was the issue? If so, it shows how important it is to personally have and know all the technical information about our old 911s.

We will look forward to pictures. Of course it would be great seeing it (and you) cruising the Rockies next summer. You are more than welcome.

BTW, keep the Bosch CDI, it is reparable. You may want to re-install it someday.

Best,
Grady

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Old 10-18-2005, 07:00 PM
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