Just wondering how you all run your automatics at the track. Do you manually shift or just let the auto do it's thing? Since my tranny has had some work, I usually just put it in 3rd and let it run. I used to think it can shift faster than I can work it. But lately, from datalogs, I dont think the rpms are getting up to where I want them, with the Auto doing the work. Adn I just found out my stock tach is off quite a bit at high RPM.

 

manual shift.

fully built 700r4 with custom 3200 stall converter. 3.42 gears. corvette governor.

don't fully trust shift points yet, trapping 102+ at 5000RPM or more in 3rd.

 

manual shift. my automatic does not have an automatic function any longer...

 

depends...

bracket racing? usually let it do its own thing, and if you have the governor set up to shift where you want it, then even when you're trying to go as fast as possible, just let it go and shift where you want.

 

Manual shift; shift light and B&M Pro Ratchet helps with the shifting consistency.

Dan

 

Yea, 1/4 mile bracket racing. I had my tranny worked on a while ago, first put in Transgo shift kit and corvette servo, and raised shift points. Then 3 years ago had to have it fully overhauled, since I had some problems with it. It shifts smooth and good, but since my tach is off I dont think it is really getting up peak shift point. Now I know you can raise these points more, with governor, but it also affect how it works on the street. right now I have this one backroad hill I go up, and it does wind up a bit till the road levels out, then shifts down. It would get worse if I raise the shift point more.
When I race, I just put it in 3rd and let it go. But I am thinking of getting a good shift light/tach, and manually shifting like at 5500.
Good stuff, keep it coming guys!

 

For bracket racing, if the tranny still has an automatic feature, let it shift by itself. That will be the most consistent. An aftermarket modulator for most automatics can be adjusted to raise or lower the WOT shift point.

For all out performance, and the tranny can hold each gear until it's shifted, manually shifting it can be quicker but it won't be as consistent.

With my powerglide I only do one shift and there's no automatic feature. I manually slam the shifter forward to do the shift when the shift light comes on. I also have a CO2 cylinder attached to the shifter for use with an RPM switch but I still haven't used it yet.

Trying to manually shift with a stock shifter may not always work. A good aftermarket gate or ratchet shifter (whatever you like best) provides a good positive shift through each gear.

 

Manual valve body so you have no choice.

 

My valve body is full manual. I can put it in high gear and drive away from a dead stop if I have to. A little hard on the high speed clutches but I can still do it.

 

I think i agree with you, that letting it shift on its own will be more consistent. That is what I do, but I want to get into the 13s real bad, so I might try shifting it manual. My shifter is stock, and it will be for a while. I will get a good tach/shift light first, and test it all out.
I am getting decent hookup, with 1.8-1.9 60' numbers. And I dont get much will spin anymore. A powerglide tranny is one of the BEST setups for bracket racing.

 

Yeah, manual shifting with the stock shifter definitely blows. If not careful, I would always overshoot when shifting from first to second and hit third

Dan

 

After my H/C/I swap, I let the tranny shift on its own at the track with the stock shift points. I ran it again and manually shifted at 6000 RPM, I gained a little over 2mph holding the gears out longer. But if your transmission is shifting in the correct spot for your powerband, I'd let it shift on it's own.

 

i was wondering about this too..

and those that let it run its course, do you use drive or overdrive?

 

Yea shifting it manually could be risky....just have to go out and practice. I think I would set my shift light to maybe like 100-200 below what I really want to shift at, just to take up "manual" slack time.
As far as the auto, I only use drive, which is 3rd gear. No need for OD. I think I picked my 3.73 gears so it would trap at 100 at 5500rpm, in 3rd gear. But it appears that I am not getting to that rpm, since I am only about 93-94 at the traps.

 

that's debatable...

 

I guess I'm killing my shift-kitted, re-timed 4L60E, then. If I leave it in OD or D, it shifts 1-2 at 5000 RPMs and really dogs it down. If I have it in OD or D, or I shift it 2-3 at 6000, it waits until 6500 to shift 2-3. If I wait until 6500 to shift it 2-3, it shifts at 7000. Something weird in the programming, I'd like to get it so I can leave it in D and have it do the shifting every time. But, until then, I'll keep on shifting it manually.

 

there is a table (and please don't ask me for details as i don't fully understand it, but hopefully i can get you in the right direction) that has engine rpm, and wheel speed in it, and this table controls WOT shift points. on cars with converters, you have to fool this table by manipulating the values. i can't remember exactly what, but i think you need to bring wheel speed down versus engine rpm, and it will help bring those shift points back under control.

when i had the baby cammed ls1/4l60e combo in it, we had to play with these tables quite a bit to get it to shift correctly. then when i built the 6.0l, i had to do it all over again, so when the 4l60e bit the dust, i knew i was going to go with something with a manual valve body in it, cause i can't handle not having the ability to tune my own car. waiting on others schedule was getting old fast.. i really wanted a 4l80e with a RMVB and a brake, but a $2500 transmission and a $1200 converter just wasn't in the cards, so th400 i went.