TC lock up in 3rd and 4th?

['75]

What are the pro's and con's of dong this. Does it cause any problems?

 

[Chuck Leeper]

Is this on your Camry, or?
Under what conditions?
Big HP?
W/o some details, your ? is pretty much open to any kind of interpretation...

 

['75]

Mild 350 in a 75 corvette, not racing. Camry??? really?

 

[mikestertwo]

Depends on the build in the trans and torque converter plus the torque curve in the motor. If it's a stock trans with stock converter there is no con to locking in 3rd and/or 4th under normal driving conditions. If the trans has a performance build where the shifts are firm I probably would not lock the converter in 3rd. The 3-4 shift may be a little abusive. I would wait until the trans shifted into 4th before locking the converter. You could try it either way and see how it feels. What are you doing now as far as locking the converter?

 

['75]

Right now I have a AA trans in there and using the 4th pressure switch to lock up. I'm building a CZF trans that has the plug in the 3rd pressure port that also has pressure in 4th, so putting the switch there would give me lock up in both. Just looking for input from those who have had it both ways.

On another issue, I'm looking to hold 4th under aggressive throttle, what's the trick to that , short of shimming the 3-4 shift valve so it manually shifts into 4th when the shifter is in od.

 

['75]

The CZF trans will have a D5 converter, so maybe 2000 stall. I also have a vacuum switch I could put inline for the lock up and adjust it so it wouldn't lock up under acceleration.

 

['75]

Here is how I plan to wire it up, that way I can have the option to have 3rd 4th lock up or off or just 4th lock up.

 

[SS/GN]

On my Monte Carlo SS (Before Buick days) I had the switch like you pictured and only locked it in 4th over 50 mph. The vac switch and all the other gadgets never locked or unlocked when I felt it should have.

 

[Chuck Leeper]

Mild 350 in a 75 corvette, not racing. Camry??? really?

Since you gave no details as to what your car is, Camry was a guess..

 

[TexasT]

On another issue, I'm looking to hold 4th under aggressive throttle, what's the trick to that , short of shimming the 3-4 shift valve so it manually shifts into 4th when the shifter is in od.

Not really understanding what you are after here. I like mine to release the tcc and down shift if needed to accelerate. In od you'd have to be moving pretty fast to not down shift. Yesterday on the way back from the Texas GTG we were goofing around on the highway and mind will drop to second and really pull from a 60 hit. I'm also using an AA with some vb mods. But it will upshift to third off the end of the speedo and I dont have the cahones for an all out blast into fourth as it is a public road.

 

['75]

The problem is that I can't pull away from my stepson in his 2004 mustang gt. At 130mph, I'm running out of acceleration in 3rd, back off enough to get 4th and can't accelerate without it dropping back to 3rd.

 

['75]

I have 3.55 gears, I guess I don't have the horse-torques to get to a wot 3-4 shift.

 

[mikestertwo]

The CZ valve body and governor should yield what you want since it is programmed for 3.73 gears. By the way the LED indicator in your schematic is backwards. It has to be forward biased to illuminate.

 

['75]

Oh,good catch, that's a diagram I modified from what's in the car now, missed that part. That's good news on the czf vb. The aa does well (for my application) in every other area, I get a 5000 rpm 1-2 shift and can get a 4th to 1st downshift when I nail it from 30 mph.

 

['75]

So when I switch to the czf trans, my 1-2 shift may be at higher rpm even with the 3.55 rear gear?

 

['75]

Sorry for the ramblings, but will using a softer spring in the 3-4 shift valve yield a lower rpm shift at wot or does that just affect part throttle shift?

 

[TexasT]

I have 3.55 gears, I guess I don't have the horse-torques to get to a wot 3-4 shift.

So, does it stop pulling so it doesn't get to the 3-4 shift rpm? Valve springs fresh? cam in good shape? What does it act like when approaching the 1-2 ans 2-3 shifts? pulling hard then? Plugs, wires and ignition in good shape?

 

['75]

Yes all the tune is good, it's just a 3600 lb car with 325-340 hp. I run a 350 with dish pistons, 96 vortec heads, makes maybe 9-1 compression, cam is mild a summit 1103. It pulls pretty hard to the 5000 1-2 shift and then the 2-3 shift. I think it just takes more horsepower than I have to get this thing above that speed. Mid 70's corvettes don't have very good aerodynamics. Might be easier pushing a brick that fast.