06-25-2008, 04:23 PM
The EB C4 will have a good "H" servo, 5 Forward clutches, and a hardened input shaft. I usually add one clutch to the Direct pack making a total of 5. I prefer to use Alto Red Eagle frictions and Kolene coated steels. On a C4 I run .005" clearance for each friction, .025"-.030" total in each pack. A Kevlar intermediate band is also a good investment.
Another couple worth while modifications are to the oiling system. The drain back check ball and spring needs to be removed from the pump stator housing. This restricts the cooler circuit to the cooler. Then I ream the return port to 3/16" and clock the rear bearing so that it allows full oiling to the output shaft. The #9 thrust washer needs to have a .125" hole drilled through it to this passage to prevent it from galling.
To help prevent a 2-3 slide shift I like to vent the Direct hub. This helps release the band and apply the clutches a little faster. Also you don't need to buy a shift kit. The valve body can be reprogrammed to shift as firm as you need without any parts. I also don't see a need to upgrade the Low/Reverse band or servo. Though it is cheap insurance to replace the Low/Reverse Sprag.
Remember the key things to make a C4 live is to make it shift quickly and keep it cool. I have also upgrade to roller thrust bearings before. But I don't think this is a necessary upgrade unless the tranny is going in a strip only drag car. The gains will not be noticed on the street or trail.
Another couple worth while modifications are to the oiling system. The drain back check ball and spring needs to be removed from the pump stator housing. This restricts the cooler circuit to the cooler. Then I ream the return port to 3/16" and clock the rear bearing so that it allows full oiling to the output shaft. The #9 thrust washer needs to have a .125" hole drilled through it to this passage to prevent it from galling.
To help prevent a 2-3 slide shift I like to vent the Direct hub. This helps release the band and apply the clutches a little faster. Also you don't need to buy a shift kit. The valve body can be reprogrammed to shift as firm as you need without any parts. I also don't see a need to upgrade the Low/Reverse band or servo. Though it is cheap insurance to replace the Low/Reverse Sprag.
Remember the key things to make a C4 live is to make it shift quickly and keep it cool. I have also upgrade to roller thrust bearings before. But I don't think this is a necessary upgrade unless the tranny is going in a strip only drag car. The gains will not be noticed on the street or trail.
'72 TBA...