rockauto clutch

[wpavlis]

So I am building a 350 to replace my old 307 in my 68. I have a 3 on the tree. Will this clutch work?

http://www.rockauto.com/en/moreinfo....n=__GIP__412__

It's on closeout at rockauto right now. it's a 12" and I believe stock was a bit smaller. It is shows as compatible with a 1969 350.

Thanks!

[geezer#99]

How big of a left leg do you want?
THat's a heavy duty b&b style. THey usually take a lot more effort than a stock 11 inch to operate. And a 12 inch might not be drilled on your flywheel.

[wpavlis]

Well, I do need to work on my legs more. I didn't realize it was that type of clutch. Thanks for the input.

[Bigdav160]

A clutch with a diaphragm spring will be easier on the legs than a borg and beck or long style with coil springs.

[6768chevylover]

I had a hays B&B clutch in my truck and it wasn't that much of a pain. Its a little more pressure on the pedal than a diaphragm clutch. I've even sat in traffic with this type of clutch. I'd buy it just because it reminds me of old school..

[Wrenchbender Ret]

The diaphragm clutches are smoother & more reliable then the lever type clutches. That large disc will be hard on the syncros in that 3 speed trans. Bigger is not always better. I believe the 12 in will fit the same pattern on the flywheel as an 11 in.

[wpavlis]

I am not sure what size clutch is in there now. I guess I should wait until I have it pulled out just to be sure. Did some research on clutch types. Didn't even know the difference until now. Thanks!

[wpavlis]

So I found these two in stock at a local auto parts place. What is the difference between flat and raised diaphragm?

[geezer#99]

Originally Posted by wpavlis

So I found these two in stock at a local auto parts place. What is the difference between flat and raised diaphragm?

Attachment 1637147

It's in the design of the fingers.
Flat fingers are just that 'flat' or straight.
Raised fingers have a slight bend at the end. Easy to see the difference.

Diaphragm clutches had a problem in the high performance motors when they had flat fingers. The throw out bearing could push the fingers too far toward (overcenter) during shifting at high rpm (6000 rpm). The levers would stick and the disc would freewheel. THe clutch pedal would stick to the floor. THe motor would free rev. Sometimes catastophically. Reduced rpm would release the pedal and sometimes destroy the clutch or the input shaft on the tranny.
THe cure was a raised finger clutch.
No more stuck pedal, blown motors or tranny parts.
And easy to rev to 7000 rpm.
All because of a simple lever change.

Now with that bit of history out of the way there is one major difference. Flat finger take a long throw out bearing, raised finger take a short throw out bearing.

Either will work in your truck but for piece of mind I'd use the raised one. Just in case some day you think your motor might sound awesome at 10,000 rpm because you missed a shift.

Whichever you buy, always check the throw out bearing if it's supplied with the kit. It has been known to have the wrong one in the kit due to human error.

[crazy longhorn]

Originally Posted by geezer#99

It's in the design of the fingers.
Flat fingers are just that 'flat' or straight.
Raised fingers have a slight bend at the end. Easy to see the difference.

Diaphragm clutches had a problem in the high performance motors when they had flat fingers. The throw out bearing could push the fingers too far toward (overcenter) during shifting at high rpm (6000 rpm). The levers would stick and the disc would freewheel. THe clutch pedal would stick to the floor. THe motor would free rev. Sometimes catastophically. Reduced rpm would release the pedal and sometimes destroy the clutch or the input shaft on the tranny.
THe cure was a raised finger clutch.
No more stuck pedal, blown motors or tranny parts.
And easy to rev to 7000 rpm.
All because of a simple lever change.

Now with that bit of history out of the way there is one major difference. Flat finger take a long throw out bearing, raised finger take a short throw out bearing.

Either will work in your truck but for piece of mind I'd use the raised one. Just in case some day you think your motor might sound awesome at 10,000 rpm because you missed a shift.

Whichever you buy, always check the throw out bearing if it's supplied with the kit. It has been known to have the wrong one in the kit due to human error.

Take that to the bank! One old 'geezer" to another....we found that out in the school of "hard knocks" That said, if you go the 3 finger plate route, a street, or street strip is not so bad on the peddle pressure, but has a different feel. I have ran both setups, & will say that I prefer the high cone diaprhagm on the on the street. Longhorn