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Author Topic:   Launching an auto w/o a transbrake?
65_289
Gearhead

Posts: 761
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Registered: Jul 2001

posted 07-29-2002 03:18 PM     Click Here to See the Profile for 65_289   Click Here to Email 65_289     Edit/Delete Message   Reply w/Quote
How do you do it? It seems to me like an auto will never launch as good as a stick, because you can't dump the clutch at 5500 in an auto.

What do you do? Just floor it on the 3rd yellow? Bring it up on the converter & rev limiter? Thanks!

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kid vishus
Gearhead

Posts: 4538
From: middle of NC
Registered: Oct 2000

posted 07-29-2002 03:56 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by 65_289:
How do you do it? It seems to me like an auto will never launch as good as a stick, because you can't dump the clutch at 5500 in an auto.


It may not feel "as good as a stick", but with the right convertor, it will out 60' the stick shift car. My convertor will stall to 6400 rpm in good air and always has a better 60' time than my buddy's stick shift car that runs the same et.

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65_289
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Posts: 761
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Registered: Jul 2001

posted 07-29-2002 05:40 PM     Click Here to See the Profile for 65_289   Click Here to Email 65_289     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by kid vishus:
It may not feel "as good as a stick", but with the right convertor, it will out 60' the stick shift car. My convertor will stall to 6400 rpm in good air and always has a better 60' time than my buddy's stick shift car that runs the same et.

Cool. So how do you launch it?

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Butch Jennings
Gearhead

Posts: 582
From: No. California
Registered: Apr 2000

posted 07-29-2002 05:43 PM     Click Here to See the Profile for Butch Jennings   Click Here to Email Butch Jennings     Edit/Delete Message   Reply w/Quote

I footbrake mine with a 2-step set anywhere from 3400 to 4200 rpm. I have the 2-step wired to the brake lights now so it's on the rev limiter when the brake lights are on, it seems to work better for me that way.


I used to bring it up on the converter without a 2-step and mash the throttle and release the brake at the same time, but car leaves better with the peddle on the floor using the 2-step and is much more consistent....for my combo anyhow.


When I stage the car, I light the top bulb then I bring it up against the limiter. Once it's on the limiter I let it creep into the second light, as soon as I'm into the second light I mash it to the floor and leave off the bottom bulb.


If I'm running a much slower car and have to wait an extra 5 or 6 seconds for my tree, then I'll wait until I get my top bulb to mash the throttle and leave off of the bottom bulb.

------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.231
Butcher's Home Page
"Friends don't let friends drive Chevys"

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Moneymaker
Administrator

Posts: 19704
From: Lyons, IL, USA
Registered: May 99

posted 07-29-2002 07:11 PM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
Years ago before I mastered a button with my left thumb, I always launched MM on the foot brake WITHOUT at two step. With my 8 inch converters and great brakes I could stall the car to 5000 RPM. We can stall Tony's Capri to 4200 RPM if we wanted to.

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kid vishus
Gearhead

Posts: 4538
From: middle of NC
Registered: Oct 2000

posted 07-29-2002 08:57 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by 65_289:
Cool. So how do you launch it?


Well....

unfortunately for this thread, I use my right thumb and use a transbrake. I was never very good footbraking it, and am a very good transbrake racer.

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70coupe
Gearhead

Posts: 357
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 07-29-2002 09:51 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by kid vishus:

Well....

unfortunately for this thread, I use my right thumb and use a transbrake. I was never very good footbraking it, and am a very good transbrake racer.


Hey Kid, I have a transbrake installed in my new C4 with an 8" 4500 stall. I've never used a transbrake and used to launch with a 2 step at 3400 on my 5000 stall. Any recommendations or pointers you can give me?
I currently have the 2 step wired into the brake peddle. Do you use a 2 step with your brake? Can they be wired together on the same button?
Thanks

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kid vishus
Gearhead

Posts: 4538
From: middle of NC
Registered: Oct 2000

posted 07-29-2002 10:02 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
Yep, I use a 2 step with it. I have the wire that feeds the 2 step on the wire that goes to the brake from the switch. That way, when the button is pushed, and the brake is activated, it turns the low side of the 2 step on (at least I think that's the way I have it wired up).

I roll in, turn the bottom stage bulb on, push the button, take the rpm up slightly and release the brake pedal, and when the first amber comes on, floor it, and at the flash of the last amber, let go of the button like it's 200*. (actually, I have to wait till the last bulb is fully on before I can let go of it bottom bulb racing or else I redlite)

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70coupe
Gearhead

Posts: 357
From: Toronto,Ontario,Canada
Registered: Aug 2000

posted 07-29-2002 10:13 PM     Click Here to See the Profile for 70coupe     Edit/Delete Message   Reply w/Quote
Well at least I wont have to change my launch too much. I launch when the last yellow is bright as well,with the 2 step.
I guess the key is not to go on the transbrake too soon or it will burn out? Does the launch feel any different or did your 60' get any better? From what I've been told by this board my switch from stock C6 with 5000 stall to my Lentech C4 with 8" converter and brake will be a pretty decent decrease in my ET. I'd love to see some 11's

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kid vishus
Gearhead

Posts: 4538
From: middle of NC
Registered: Oct 2000

posted 07-29-2002 10:24 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
It doesnt burn the brake out, but it does make a bunch of heat in the convertor the longer you sit there on the 2 step. When I top bulb race, as soon as both cars have turned both stage bulbs on, I stick it to the floor. So I tend to sit there a littel while like that, and it deosnt appear to be hurting anything. I did it all of last year, and the car still 60's the same now as it did then.

My 60' times got better when I went from footbraking to transbrak-ing , but since you were already leaving off a 2 step, I would suspect most of your gain will be due to the transmission swap, with a little coming from the brake.

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n2oMike
Gearhead

Posts: 1547
From: Spencer, WV
Registered: Jan 2001

posted 07-29-2002 10:32 PM     Click Here to See the Profile for n2oMike   Click Here to Email n2oMike     Edit/Delete Message   Reply w/Quote
The smaller the engine, the looser of a converter you will need to get a good 60ft. A 6500 rpm 289 or 302 (not using the bottle) will need an 8" converter stalling around 4-4.5k rpm to get decent 60ft times.

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
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steve'66
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Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000

posted 07-29-2002 10:49 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
Definately get a t-brake, they are leagal in street in Div 7 anyway. (west coaster's) They hit the tires hard! But controllably w/o shooting the pinion out of the 9" rear like the t-5 did. LOL

The best of both worlds, and when you use your practice tree you're releasing the button. Just like driving w/a t-brake.

SteveW

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65_289
Gearhead

Posts: 761
From:
Registered: Jul 2001

posted 07-29-2002 10:52 PM     Click Here to See the Profile for 65_289   Click Here to Email 65_289     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by steve'66:
Definately get a t-brake, they are leagal in street in Div 7 anyway. (west coaster's) They hit the tires hard! But controllably w/o shooting the pinion out of the 9" rear like the t-5 did. LOL

The best of both worlds, and when you use your practice tree you're releasing the button. Just like driving w/a t-brake.

SteveW


Aren't those hard on the transmission? How often do you have to freshen the trans when you use one?

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RickBook
Gearhead

Posts: 140
From: Houston, TX
Registered: Apr 2002

posted 07-29-2002 11:55 PM     Click Here to See the Profile for RickBook     Edit/Delete Message   Reply w/Quote
For the "low class" guys in here (like me - who don't have no lectroniks), I've found out the following on 'my particular' set-up.

FLASH!

I drove my very-heavy '90 Mustang convertible to it's best 60' times (1.5X) leaving at 1,000 r's on a 3200-3600 rpm 10" stall converter in an AOD.

"Flashing" the converter allowed the r's to increase over foot-breaking the converter to near-stall. (plus I didn't push my car through the red-beams anymore )

My 60'went down by .15" - .2" using this method.

Again, this was with my particular set-up. "Results may vary in other states." Got nothing to lose (except a race) just trying it.

This launch wasn't one of my best, but it gives an idea of how hard a heavy street car could leave off idle.

edit: btw, the 347 and tranny in this car are the ones going in my 'much-lighter' '70 Maverick Grabber. And, oh yeah, that's an 1/8th mile track


[This message has been edited by RickBook (edited 07-30-2002).]

[This message has been edited by RickBook (edited 07-30-2002).]

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Rustang1
Gearhead

Posts: 110
From:
Registered: Nov 2000

posted 07-31-2002 12:56 PM     Click Here to See the Profile for Rustang1   Click Here to Email Rustang1     Edit/Delete Message   Reply w/Quote
Every combination's different, and the best thing to do is take it to the track and test different launching techniques. Tight converters seem to like flashing from low idle best. This requires a good tune on the accelerator pump shot, etc.. On my last combination (may it rest in pieces) I had a 4500rpm stall (which was way too tight for this particular motor) that I'd stall to about 3000rpm. This gave me a best 1.52 60 footers with slapper bars and 275-60 BFG drag radials.

------------------
1968 Mustang,Clevor,C4
1969 Torino 351C 4spd
1978 F150 460 C6
1978 F150 351W C6

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