turbo 400 question

[t3intercooled]

For anyone who is running it. Since turbo 400 do not have overderive are you folks just going without or getting a gear vendor unit to attach to it. Also what gears are ya running. I figure my 200-4R with 9" high stall converter with stock gears is around 3000 at 70 but if one goes to steeper say 4.10 gears and takes away overdrive that's gotta be an insane rpm at 70. Thanks to all who repond. Just trying to do it right the first time.

Brandon

 

[Scooter3800]

I run with 3.42 gears, 28" tall MT ET Streets, 2800 stall, works well. Don't do a whole lot of freeway cruising.

Search the transmission section for more info.

 

[Super6]

th400

i just got my car going with the 400 and at 70 mph with 26" tires i turn 3100. i am going to a 28" ,might drop that a little but i really don't like turning that high on the interstate. at the track though it's a different story..the th400 is at home. i been kicking the idea of a 4l80e with a manual reverse valve body. that would be having your cake and eating it too.......Bob

 

[yullose]

I've had 4 different experiences with Turbo Buick & transmissions.

Car #1 - '86 T-type
3.42 gears / 275/50's
Bone stock trans - shifts were mushy like a snowmobile

Car#2 - '87 GN
3.42 gears / 28x10.5's
Bone stock 200R4 - broken when I bought car. (no 2nd gear)
Swapped to a TH400 w/transbrake - went easy 10.90's - missed having the overdrive, but the bulletproof reliability was an acceptable trade-off.

Car #3 - '87 GN (see sig)
3.42 gears / 275/60's
Modded 200R4 - fresh built before I bought the car.
So far I'm impressed, but I am concerned about long-term reliability and the TV cable adjustment. I'm considering a reverse manual valve body to eliminate the TV cable. (I can't find the "happy place" for the TV cable... one extreme to the other)
The overdrive is really growing on me since I've put almost 1500 miles on the car since February. If there is a way to make the 200R4 survive into the 9's, I'll keep it in the car. Otherwise, I have no other choice but to replace it with a TH400 and live without the extra gear.
I'd consider a 4L80E... but at the moment they seem to be a bit expensive.

And, in case you were not aware, big gears don't work well in these cars. I think a 3.23 - 3.42 gear is about perfect.

 

[mygn276]

Have 400 trans,3.23 gears with 29 inch tires, 2600 rpm at 70 mph. Did you say 4.10