You can type here any text you want

more trans mods

Welcome!

By registering with us, you'll be able to discuss, share and private message with other members of our community.

SignUp Now!

matt69olds

Ain’t no feeling like Oldsmobling!
Joined
Feb 10, 2008
Messages
137
Ill be installing a new converter soon. I'm thinking of opening up the trans and seeing how the band and clutches look. I'm using the CK calibration kit and servo. Whats the opinion on dual feeding 3rd gear while its apart? I'm also considering blocking the accumulators as described in Chris's 2004r book. People on this forum describe spinning tires 10 feet on the 1-2 shift, mine is firm but could be better. Line pressure is textbook perfect, I'm using the factory linkage for the TV cable and have good pressure rise. Opinions, suggestions?
 
Dual feeding 3rd is an excellent mod but you need a billet forward drum to do it.
 
What does dual feeding do? Why do you need a billet drum to do so.
 
Dual feeding increases the apply area of the 3rd gear clutches.

There are 3 methods to increase the power capacity of a clutch pack.

You increase the pressure. Typically on a 200-4R the line pressure at full TV will be 230-275 psi for a performance build. Some run it a bit higher.
You are limited, you simply cannot run 500 psi reliably, so we build a bit of additional pressure, and just as importantly, we bring it on faster.

Secondly,
you increase the friction area.
More clutches. Again, you are limited by the size of the drum and how many clutches/steels you can stack in the available space. You also trade-off steel thickness for clutch count which CAN debatebly have some negative effects.

Third,
You increase the apply area.
This is what dual feeding does. You have an apply piston that you are only using approx 1/3 of the area for 3rd, you allow it to use the full area and you more than double (approx triple) the apply area, which in theory would approx triple the power capacity of the clutch pack.

The caveat is that dual feeding requires some calibration changes to work properly on a 200-4R.
It's a proven method for TH400's TH350's, 4L80Es, and other units, and on those units it doesn't really require calibration changes.

The 200-4R needs the changes to keep the band release timing correct.

Even so,
dual feeding brings the direct clutches on firmly enough that it often causes forward drum shaft breakage on a WOT 2-3 shift.
It may be possible with a very conservative shift calibration to use the stock drum but I don't see what the advantage is, calibrate them to come on quickly and take advantage of the dual feeding.
 
I'm using a hardened forward drum, forgot to mention that. I got into the trans several yrs ago for inspection, found the splines twisted. Figured I was on borrowed time and installed a CK drum. The stock drum is enshrined on the "Wall of Shame" with all the other broken parts! Any advice on firming up the 1-2 shift?
 
I'm using a hardened forward drum, forgot to mention that. I got into the trans several yrs ago for inspection, found the splines twisted. Figured I was on borrowed time and installed a CK drum. The stock drum is enshrined on the "Wall of Shame" with all the other broken parts! Any advice on firming up the 1-2 shift?

As far as firming the 1-2, you can take the center checkball out of the valvebody. That should firm up the shift and make it quicker. At least thats what my builder buddy says. I need to do that to mine and maybe a few other mods to the valvebody too while its out. Probably gonna crack open the Sonnax catalog.:biggrin:
 
Back
Top