Ford Muscle Cars Tech Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
152 Posts
Discussion Starter #1
Many performance C-4 builders have recommended drilling vent holes in the HIGH/REVERSE drum to better evacuate fluid. Would that still hold true with the FORWARD clutch drum? Any advantages?
 

·
Registered
Joined
·
473 Posts
Many performance C-4 builders have recommended drilling vent holes in the HIGH/REVERSE drum to better evacuate fluid. Would that still hold true with the FORWARD clutch drum? Any advantages?
Is this a full on race trans?
If so, sure you could drill the drum, beware of weakening it tho.

If it's just a street car, then no, no real advantage.
 

·
Registered
Joined
·
152 Posts
Discussion Starter #3
Full 1/4 mile drag racing only. This is related to topic "393W not running up to expectations" in another part of this forum.
 

·
Registered
Joined
·
488 Posts
I agree with Greg , no reason to drill the forward drum. In fact I quit drilling the high gear drums . Makes no difference on longevity or track performance in my testing.
Randy
 

·
Registered
Joined
·
152 Posts
Discussion Starter #7
Thank you for the input.

Moments ago, I discovered that my "parts" C-4 has a "factory" 1/4" vent hole already drilled in the side of the forward drum. Just FYI...
 

·
Registered
Joined
·
3 Posts
Retired trans builder doing research on a c-4 with a brake. In my research I have seen several companies that have stopped drilling the direct drum. They don't say why, just that they have stopped. Possibly from either, A weakening the drum or B shortened band life.
 

·
Premium Member
Joined
·
4,311 Posts
Thank you for the input.

Moments ago, I discovered that my "parts" C-4 has a "factory" 1/4" vent hole already drilled in the side of the forward drum. Just FYI...
That is not a drain hole . That is done during manufacturing , Put something down through it you'll see it lines up with the feed hole to the sealing rings
 

·
Premium Member
Joined
·
4,311 Posts
Retired trans builder doing research on a c-4 with a brake. In my research I have seen several companies that have stopped drilling the direct drum. They don't say why, just that they have stopped. Possibly from either, A weakening the drum or B shortened band life.
Be interesting to find out why :smile2:
 

·
Registered
Joined
·
488 Posts
Greg ,
The problem "I've" seen with trans brakes is slow release on the high gear clutches and that "kills" them because of the slippage versus "clean release". Nothing to do with drilled holes in the drum or lack of. I bought a trans brake from a very popular east coast company that uses the Winters reverse manual valve body ( like I already ran) and had the high gear clutches go away after 12 runs. I pulled it and went back to the unmodified Winters VB and have over 300 runs with no appreciable wear.
Randy
 

·
Premium Member
Joined
·
4,311 Posts
You know a lot of high clutches can be burnt even before they apply in top gear ... That's why i drill a bleed now for any trans that will see over 6000 in first gear ..
I think that can do damage also
 
1 - 14 of 14 Posts
Top