12" Clutch question

[cash667]

Hi guys,
is anybody using a 12" lever style clutch setup?
I need to figure out if it will fit on my flywheel and therefore I need some measurements:



Can anybody supply the distances A, B, C and D?

any help appreciated!
Chris

[cash667]

I got the measurements from the manufacturer. 11.5" long style and 12" long style are more or less the same.
Bolt circle is 12.875". This should be found on most FE and big block flywheels.
A = 3.56"
B = 8.94"
C = 9.6"
D = 2.95"
This applys for Sachs K101501 (12"); AMS 07-514 (11.5") and AMS 07-050 (12"). All can be found on rockauto.

All above kits have 1-1/16" 10 splines disc´s.

There are differences in the clutch disc outer diameter AND inner surface diameter.
11.5" clutch disc surface: OD 11.5"; ID 7.008"
12" clutch disc surface: OD 12"; ID 6.501"

so be carefull when uprading from 11.5" to 12". Check your flywheel surface inner diameter. Make sure it is equal or less than the disc surface ID.
When upgrading from 11.5" to 12" it is also recommended to resurface your old flywheel when you don´t use a new one.

Maybe those information are helpful for some of you. A 12" clutch is easier to find and less expensive than a 11.5" setup. 11" Setups won´t fit the flywheel if it has the above mentioned bolt pattern. 11" long uses an 12.375" bolt circle.

here´s a chart from modern driveline with some popular bolt patterns:

Bolt Pattern chart.jpg

Thanks also to the Sachs and AMS customer support!

Cheers
Chris