TRANS SHIFTING....Auto vs Manual

[HellOnWheels]

For those of you that have tried it, which has netted the best ET-shifting the trans manually or letting it shift itself??

HOW

 

[MSDGN]

I lost about 3-4 MPH in the quarter shifting manually at a different higher RPM's...I was shifting too high and out of my power band so after that I just let the trans shift by itself...I have a bigger cam going in a motor I'm building so I'll try shifting manually again with the new motor...just have to experiment to determine the power band and optimum RPM for shifting of your car...in many cases the trans does it better than you can...

 

[86BLACKT]

I had my transmission rebuilt by Dynotech a few years ago and they dialed in my valve body to shift at optimum rpm for each gear for my set up

 

[S10xGN]

I'd imagine it depends a lot on your combo, I'm way faster shifting manually @ 5700 than letting my trans shift @ 4600...

 

[HellOnWheels]

Originally posted by 86BLACKT
I had my transmission rebuilt by Dynotech a few years ago and they dialed in my valve body to shift at optimum rpm for each gear for my set up

How or what formula did the trans builder use to determine what rpm the trans should shift for EACH gear?


HOW

 

[86BLACKT]

Not sure how Fred determined shift RPM. It shifts at 5600 from first to second and 5800 from second to third WOT. Possibly torque curve of combo.

 

[Ttype6]

An automatic transmission that shifts itself at the corect rpm is the only way to go. The first reason this is good is the consistant shifts it creates. The second reason is it's one less thing to concentrate on during a race. The third reason is because you can. The way to change the 200 4R full throttle shift pionts is to change the spring in the TV limit valve in the valve body. A higher spring pressure will cause the transmission to shift at a higher rpm. This will not effect part throttle shifts.

 

[sixnboost]

I have heard that modifying the governor can change shift points, but I'm not sure what to you are supposed to do to it.

 

[Ttype6]

Originally posted by sixnboost
I have heard that modifying the governor can change shift points, but I'm not sure what to you are supposed to do to it.

Putting a weeker spring on the small weight of the governor will raise the rpm. of your full throttle shift. It will also raise the rpm. of your part throttle shift. If you like the rpm. of your part throttle shift,putting a stronger spring in the TV limit valve is the way to go. Again,this will only effect your full throttle shift points. I compress the spring to a specific height against a simple kitchen scale. A 2 ounce difference in measured pressure against the scale will make a noticable difference.