[dimeforce]

The 400 shifts fine normal driving but when wot it slids into 3rd. The more power I put to the engine the longer it slides into 3rd (nitrous). While in 3rd it does not slip. It has a tci shift kit and 34 element sprag. The transmission is fresh.

Is there something I need to look for in the valve body to quicken the 2-3 shift up? I am afraid it will eventually eat up the direct clutches.

 

[gent]

you may have a large leak between the center support and case. you can install a 2004r center support seal to help.

 

[dimeforce]

What is the procedure to check for that?

 

[Darkhorsebob]

Either you'll need to partially disassemble the transmission and make changes to the center support sealing ring/direct drum or install a Transgo HD valve body kit.

The Transgo kit allows dual feed of the direct clutch circuit without disassembling the transmission. This will greatly increase the quality of the 2-3 shift.

 

[jakeshoe]

You need to do the dual feed, preferably internally. My experience is the TransGo kit runs into trouble at around 500 HP in a heavier car.

I would also recommend blocking the 2-3 accumulator to put the oil to the directs faster, the dual feed requires a greater volume of fluid to shift and effectively becomes it's own accumulator.

You also need to kill the 3rd gear cutback by modifying the modulator valve. With these mods you can have automatic function at over 800 HP reliably.

 

[gent]

What is the procedure to check for that?

you have to remove the v/b and seperator plate. you can then drive the seals into the case mating them up with the center support. while you are there make sure the 12 pt 3/8 support bolt is tight.

 

[dimeforce]

You need to do the dual feed, preferably internally. My experience is the TransGo kit runs into trouble at around 500 HP in a heavier car.

I would also recommend blocking the 2-3 accumulator to put the oil to the directs faster, the dual feed requires a greater volume of fluid to shift and effectively becomes it's own accumulator.

You also need to kill the 3rd gear cutback by modifying the modulator valve. With these mods you can have automatic function at over 800 HP reliably.

How to you do that jakeshoe?

 

[jakeshoe]

You'll have to tear down the trans, remove the center seal on the direct clutch, 2nd ring on the center support.
Fix the directs while you are there...

Re-assemble, install a cup plug in the reverse passage going into the center support, and the previously mentioned 200-4R sealing plug into the direct side.

Reverse side is the drivers side of the case next to the center support bolt. Direct side is opposite the bolt.

I install a 5/16" set screw in the passage that feeds the 2-3 accumulator in the VB, remove the accum spring, re-install the piston with a new seal.

3rd gear cutback requires grinding the largest outermost lands on the modulator. It prevents the presure drop going into 3rd that is designed into a stock TH400.

 

[dimeforce]

Do I ask for 200 4r sealing plugs at a tranny shop? What is the correct term for them?

I have the spring already removed in the 2-3 accumulator, but I put the piston in upside down is that ok?

When I grind the land, should I do it like the 1-2 shift valve mod as far as the grinding goes?

 

[jakeshoe]

Yes on the modulator, grind two flats on the land that is closest to the outside of the case.

200-4R cup plugs you might get from a trans shop. You also need a parking pawl cup plug to block the reverse side.

I have all the parts if you need them.

Jake

 

[dimeforce]

Can I get your #. I will call tomorrow. I asked a local trannyshop and they didn't want to break a kit??

I will get the cup plugs and some more direct clutches from you.

 

[Modified Street Mustang]

Yes on the modulator, grind two flats on the land that is closest to the outside of the case.

200-4R cup plugs you might get from a trans shop. You also need a parking pawl cup plug to block the reverse side.

I have all the parts if you need them.

Jake

You're talking about the modulator valve itself, inside the case?

 

[jakeshoe]

Yes the modulator valve inside the case.

dimeforce,
The shop # is 940-458-5564
Call and talk to Shawn he can gather up what you need and get it shipped.

I'll PM you later.

Jake

 

[dimeforce]

I talked to Shawn and is going to fix me up. Thanks Jake.

Shoot me a PM.

 

[Darkhorsebob]

When grinding the flats on the modulator valve, you need to block the hole in the separator plate which feeds that part of the modulator valve.

 

[chris718]

The previous statement is not completely true.Oil sent from the governor to the large land on modulator valve mentioned to be ground is used to cut back line pressure at high road speeds or when the car is already on its way.It is fed to the modulator large land thru a small orifice.This orifice combined with the rate governor pressure climbs in relation to road speed makes cutback happen(occurs at other times as well but not what we are concerned with because the 1/2 is assisted with int boost signal oil during manual 1/2) right around the road speed you get a wot 2/3 upshiftThis is because governor approaches line pressure at wot,and this is where cutback force would be the greatest. If you grind off the lands you are allowing governor oil to past the big land and enter the exhaust cavity on the far end of the modulator valve.This reduces pressure drop on a 2/3 wot .This doesnt allow governor oil to push the large land over to the left reducing the modulator valves effect on boost pressure at the pump.Simply pluging the hole WITHOUT grinding the land or lands is just as effective as grinding the lands,but without additional governor pressure,(derived from line)from bleeding off at the exhaust cavity after it passes thru the hole.

 

[chris718]

Forgot to mention,this dampens modulated kickdowns somewhat.I forgot why but a simple going over of the hydraulics will point it out for those interested.