Shift Kit Cupped Orifice Purpose

-
Ricks70Duster340

Ricks70Duster340

Child of the King
FABO Gold Member
Joined
Feb 8, 2021
Messages
1,277
Reaction score
1,002
Location
Sisterdale, TX
I've always bought shift kits that used the cupped orifice plug for the front clutch port in the case. The trans I had installed in my 72 Challenger does not have that plug, but does have a Cope Racing valve body. Shifts OK, but I'd like a little better 1-2 shift. Would installing the cupped orifice plug help with that? I had Alto Clutches installed when the trans was built.
 
I usually tap that opening and put in a drilled Allen set screw that way I can easily change the orifice size by using another drill set screw. I can post the set screw size later once I get out to the shop.
 
That particular plug doesn't affect the 1-2 shift. It helps firm up the 2-3 shift, if I remember correctly.
 
Copes in house valve bodies are constantly evolving because they are never working correctly.

consider a turbo action Cheetah manual valve body if you want a good one with no more trans issues. You can move on to other things on the car.
 
mcodecuda said:
I usually tap that opening and put in a drilled Allen set screw that way I can easily change the orifice size by using another drill set screw. I can post the set screw size later once I get out to the shop.
Click to expand...
The set screw size is 3/8-16 and the orifice size is 1/8”.
 
The cupped orifice is mentioned in the TransGo instructions of the 1970s. Not sure if it is in current instructions. It is used to control the 2-3 shift timing.
 
Right in the instructions it says the kit supplies 600% more oil to high gear. So u need to control the amount of fluid going to the front clutch that’s why the the cupped plug is supplied. Also it depends on the clearance in the front drum and the number of springs in the front drum. The spring rate in the front servo and the band adjustment comes into play also. Kim
 
My TG instructions also says: if fr clutch plates are worn, have excessive clearance & too many return springs, engine flaring maybe experienced shifting into high gear.
Fixes:
-adj throttle linkage for slightly later shifts & re-adjust fr band to 2 turns.

- if flare up still occurs, remove cupped orifice & adj fr band 1/4 turn looser than in step X.
 
You must log in or register to reply here.
-

Back
Top