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RPM shift drop

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Louie L.

Habitual Line Stepper
Staff member
Joined
May 24, 2001
Messages
4,249
Whats the expected or correct amount of RPM drop during gear changes in a drag race situation?This would be on a high 10 sec car.

Thanks
 
Regardless of how fast the car is, this is mostly dependent on how "tight" the converter is. Consistent RPM drops of 1,000 would be great, but that converter could be too tight down low for your combination. A much too loose converter will drop less than 500 RPMs at a shift.

I personally see 800-850 at shift points. Note however that wherever I shift (5,700-6,100) the RPMs alway seem to drop to 5,100-5,200.

By graphing your RPMs, you can determine how "hard" the shift is by the slope of the line at the shifts.
 
Scott,
Thanks for the info.
i went through my logs and averaged the shift drop rpms. This was from 6 runs all at Bristol. The ave for the 1-2 shift was only 440rpm, 2-3 was 512 rpm drop.
So it looks to be kinda loose:(
 
RPM dropz!

Louie, I'm just the guy to reply to this!:eek:
I've been fighting this same problem for over a yr. I have had an ATD,[Hipster] 9" in my t-400, stage combo. It's been "restalled" 2 times and still is not right.
I am looking for the 800 to 1000 drop on shifts..
The initial install resulted in a drop of 50 - 75 rpm and temps thru the roof.. like 375*. [Car STILL went 133 mph!!]
The first "re-stall" got it to 400 and the 2nd got it only to 450. Temps went down by 175*, but the car also slowed down. [by 1.00 secs and lost 10 mph]. I was then "informed" by ATD that I needed a 10" converter!:mad: :mad: They said it costs this much.. SCREW that.. I paid for a verter that worked.
Next attempt was an Art Carr 9".. Same story.
During all this, I have researched a good bit and found that the 10" idea was a very common reply. [ALSO! don't rely on "someone else's combo" to get it right!! That didn't work either!!]
Since I have a mild combo, The "norm" for the stage engine does not apply here. The engine is a dead player at 6200.. However, it makes a TON of torque down low,[like 3400] and as such, can use a tighter verter.
The AC had a zero boost/ zero vac stall of 3600 and a recorded lag of 2100 behind engine rpm..WAAYY too loose.
Am now installing the new 10" TCI unit and will have results soon.
I have a data recorder installed and will post the results of the tests...
 
Originally posted by Louie L.
I went through my logs and averaged the shift drop rpms. This was from 6 runs all at Bristol. The ave for the 1-2 shift was only 440rpm, 2-3 was 512 rpm drop. So it looks to be kinda loose:(
Uh....yeah. Yank out the converter and send it to Bruce. Shirley those 9/11 converters can be restalled as easily as any other converter. Expect to have to shell out ~$120 plus shipping unless Bruce has a better policy on re-stalling a converter.

Tighten up the top end of that converter and hello 125MPH! Now I know how you were pulling those 1.4 short times....you were prolly leaving at 5,500 RPMs:eek:
 
Yes, I'm a Doctor...........and quit calling me Shirley. :D

Bad joke, I know. But I had to make fun of Scott for misspelling "surely."
 
Originally posted by Scott231
Uh....yeah.
Tighten up the top end of that converter and hello 125MPH!


Now I know how you were pulling those 1.4 short times....you were prolly leaving at 5,500 RPMs:eek:


DANGIT !!!! My secret is out!!!!!:eek: :eek: LOL !!!


Im know Bruce will take car of it. Just gotta box it up and give him a call.
 
"Damn right"Bruce will take care of it!This is why I always try to stay conservative. Louie, it hasnt been that long. If I missed it, restall would be free in the first year. Whats free you say? Well, I know it is a term that doesnt go well with Tr's but it means you pay nothing. :D ROFL


Bruce
WE4
 
Originally posted by WE4
"Damn right"Bruce will take care of it!This is why I always try to stay conservative. Louie, it hasnt been that long. If I missed it, restall would be free in the first year. Whats free you say? Well, I know it is a term that doesnt go well with Tr's but it means you pay nothing. :D ROFL


Bruce
WE4

Bruce,
U are so right ...lol:D FREE and TRs dont ever go together, But Bruce T and TRs do!


I still havent been able to give u a call. Been in the Hospital with my new born. He decided to come 7 weeks early which is not good. Ill get with u as soon as I can.

Thanks
 
THAT IS GREAT DADDY!!!!!

Awesome. Childs name? boy , girl?

Please provide an address so we can send a baby gift , (to the wife of course)

Why didnt you announce it? That is super and I hope the child is very healthy and doing well.

We would like to send a little something so please, please send us an address.

As for the converter, Sheesh dont sweat it. I just ( and I have the power) have extended your deal for as long as you need.
SCREW the trans and converter right now, take care of your better half and the new little half pint. THAT is what is important here.
Enjoy it now as this is the best time of both your lives. :D

Dont worry Louie, we will be here ready to assist as soon as you are back up and running.

again, enjoy and cherish this time.

CONGRATULATIONS!!!!!!

Bruce and Cindy Toelle and everyone at PTS
 
Guys,
Thanks for the kind words. Mama and I are now home, But my baby boy Joshua(4lb 10oz, 17in long) is still at the hospital. Hes in the neonatal ICU. He wont be home for 3-4 weeks:( :( :( :(
But overall hes doing great, hes off the respirator and breathing all on his own now.:D :D :D :D

Im going insane worying about him.So the only thing s i can do is take care of mama and go see him 2-3 times a days on specific hours.

Working on the car calms me down quite a bit, so until he comes home that might be some of my best "therapy":) Mama actually agrees and has ordered me to do some garage work today!

Louie
 
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