Dumb question: what is a block plate, how do I know if I have one (what does it look like)? graemlins/clonk.gif

I'm trying to reinstall my clutch and tranny after replacing the throwout bearing and I want to make sure the fork pivot is adjusted correctly. To that end CarlC posted in another discussion:

"The distance from the back of the block to top of the ball should be 4.750". If you are running the block plate then the distance from the top of the ball to the back of the block plate should be about 4 5/8"."

There is a large metal plate about 1/8" thick behind the flywheel that sits on a couple pins coming out of the block. The bellhousing bolts to or through it (in the case of the bolts that go into the block). Is THAT a block plate, and thus do I need to set the pivot at 4 5/8"?

Yep, you've got it right graemlins/thumbsup.gif

But here's the thing . . . why wouldn't you have a block plate? Without one, the bottom of the bellhousing would be open forward like a big scoop and the clutch would be exposed. It doesn't seem like anyone would not run a block plate.

I ask (again) because I wonder if the block plate is something else of beyond what I have. I need to have the clutch fork pivot point adjusted correctly.

All that to say, are you sure?

Use the block plate.

With that assumption, put the bellhousing on the bench with the engine mounting flange facing up. Put a straightedge across the flange face and measure down to the top of the pivot ball. The distance should be 4 5/8"

Add in the 1/8" for the plate and you're at 4 3/4".

I ran without a block plate because the bellhousing I bought did not have one. I never had an problems with that set-up....I will probably run it that way again when I swap back to a 4-speed simply because I dont have one.

If I can get some material and time I am going to make one.....but we shall see about that.

Carl, that measurement goes for every kind of clutch set-up?

I am fixing to put mine back in (centerforce dual friction) and wanted to make sure my measurments are correct.

Thanks.

Carl,

Does it make a difference if I'm running a short or tall throwout bearing? I happen to be running a tall one.

Whoa! I just tried mounting the bellhousing and with the pivot ball set to 4 5/8 I can't even get it to seat because the throwout bearing hits the fingers.

I'm guessing that my tall throwout bearing won't do it and that I need the short one - at least if I'm to mainting the 4 5/8 measurement.

Thoughts?

I believe that the 4 3/4" will work for most clutches but it is dependant on the bearing.

I don't know if the CFDF clutches use the tall or short bearing, but compared to what I have, there does not seem to be a way to make the bearing much shorter. Hence, I believe that the CFDF clutch uses a short bearing.

Basically, you want to balance out the sweep of the fork so that at mid-travel the fork is 90* to the bearing. This minimizes the amount fork-to-bearing wear and geometry changes.

I have the CFDF setup and, although this may not answer the question, I ordered the 'regular' Throwout bearing from my local parts store for my car.

Sorry guys, you lost me. What does CFDF mean? graemlins/clonk.gif

Carl - cluch fork at 90 degrees to the bearing at mid-travel? I don't even see how that possible because the fork and bearing don't travel more than and inch. They start out parallel to each other and maybe get to 30 degrees . . . but you're saying 90??? :confused:

I'm inclined to take out my tall (1.5") throwout bearing put the short (1" or so) bearing in and just adjust the pivot ball just so that the bearing doesn't ride the fingers when the clutch is completely out. Anything sound wrong with that plan?

CFDF=CenterForce Dual Friction.

The bearing travels on the nosecone of the transmission along the centerline of the crankshaft. The fork is oriented at approx. 90* to the bearing.

For a general rule of thumb, if the fork is angled slightly forward when the clutch is disengaged, is at 90* to the bearing at mid-travel, and has the same angle at full engagement as the disengaged, you will optimize fork alignment.

In other words:

1) With the cluth pedal up, the fork should extend slightly forward.

2) At mid-travel the fork should be 90* to the bearing.

3) With the clutch pedal fully depressed the fork should be angled rearward at about the same angle as in #1.

From memory, when laying under the car with your feet sticking out the passenger side the fork should travel from about 11 o'clock, through 12 o'clock, to 1 o'clock.

If the fork to bearing alignment is not correct there can be a host of problems. I don't have with me a bearing to measure but perhaps someone out there can take a measurement of the short bearing. From memory about 1" OAL is correct for our applications. If the bearing is too long the fork will be too far forward to be able to obtain a 90* referance to the bearing.

Ah ha! Now I get it. I think I need the shorter throw out bearing. Now I have to put it together and see if I can adjust the pivot ball to get those angels correct.

In case anyone is wondering, the tall one from Weber is 1 3/8" tall and the shorter one from Federal Mogul is about 1 1/4" tall.

Thanks Carl

Weber/McLeod, Centerforce, Hays, etc. don't make the bearing. Take a close look at it. Likley it's a BCA part available at almost any auto parts store.

Carl,

I looked at your '68, what a ride!
But isn't that top pic s t r e t c h e d a litte? :D