finish line rpm vs launch

4spdJohnny · 05-23-2012, 12:27 AM

I am in the process of going from 5.38 to 4.88 gears in a j/sa 70 Sport Sattelite wagon 383 is shifted at 6400 goes thru traps at 7400. Building a trans with a lower first 2.45 to a 2.77. Thoughts keeping the same basic gear multiplication down low and more in power band down track. Does this seem like a move in the right direction or is it normal to "over rev" a stocker that much? It sure seems out of breath last 300 ft. Is that to much of a jump?

Phillip marvetz · 05-23-2012, 01:28 AM

I made about the same move last year, The car had a better 60ft and ran faster with less RPM at the stripe.

Mark Yacavone · 05-23-2012, 02:11 AM

What MPH does it run now?

I'd guess it needs a 5.13

Jeff Lee · 05-23-2012, 02:22 AM

You may find short shifting the 2.77 out of first will help ET.
I would GUESS 5.13's as Mark suggested. Better to have not enough rear gear than too much rear gear.
4speed Johnny needs to put a stick behind that 383! That would be an awesome wagon!

4spdJohnny · 05-23-2012, 11:53 AM

Thanks Phillip, gives me a little confidence!

Mark, I have a set of 4.88's to try since I'm expirementing didn't wanna pop for new and 5.13 just seem like such a small change?

Jeff, I agree and in fact originally intended on putting 4spd in wagon but now my 16 year old son is racing it and we aren't quite sure if he inherited 4spd gene! rest assured my road runner is still a stick and am building another 70 road runner 440-6pak 4spd combo for stock eliminator. When you say short shift you would shift 1-2 even lower like 5800?

4spdJohnny · 05-23-2012, 12:01 PM

Sorry Mark, 12.70, 1.69 60 ft 102.8 mph in 3600 ft air with a 25 mile an hour cross wind (I'm sure doesnt effect this aerodynamically superior race car at all!) Brakes were also slightly dragging that day (Strange disc all corners) have since installed adjustable pushrod and springs inbetween pads in calipers seems to have cured. have also switched the car to cal-tracs now so we wil see. Nothing like changing 6 things at once in a combo but I think all right direction also took weight out to move from k to j since those time slips

Jeff Lee · 05-23-2012, 02:16 PM

Quote:

Originally Posted by 4spdJohnny

Thanks Phillip, gives me a little confidence!

Mark, I have a set of 4.88's to try since I'm expirementing didn't wanna pop for new and 5.13 just seem like such a small change?

Jeff, I agree and in fact originally intended on putting 4spd in wagon but now my 16 year old son is racing it and we aren't quite sure if he inherited 4spd gene! rest assured my road runner is still a stick and am building another 70 road runner 440-6pak 4spd combo for stock eliminator. When you say short shift you would shift 1-2 even lower like 5800?

Yes, shift 1-2 at a lower RPM than the other gears.
That 16 year old needs to start racing the right way. Give him the 4-speed and put the 2.77 trans in your wife's grocery getter!

Mike Taylor 3601 · 05-23-2012, 02:49 PM

Turn Junior loose w stick, the stick gene seems to be passed to each generation,if he can't drive stick,then I would go for paternity test then.LOL
My son was driving FWD nova w/stick @ 9 years old,took his 25 year old uncle for ride uncle told him he could'nt drive stick shift,he told his uncle I'll teach you.LOL
Mike Taylor 3601

4spdJohnny · 05-23-2012, 04:10 PM

You guys are making me feel so ashamed! I feel like I've betrayed the 4spd brotherhood. He raced our old 79 St Regis cop car when he was 14 and 15 in our local tracks "teen championship race" and actually won once and runnerup twice he's a pretty good light cutter but

had to leave it in drive so he wouldnt forget to shift! Last year he blew up the old farm truck driving it to town in low lock! This car was supposed to be a spend no $ and drive it deal and now I'm buyin slush box parts... how'd this happed that could have went towards jerico! Sons tow truck is a 93 cummins with 350,000+ on it with a 5 spd (pistol grip shifter out of road runner of course) if he gets through year getting 4spd trained with that then we'll consider J/S no A!

Mike Taylor 3601 · 05-25-2012, 08:31 AM

Maybe you need the shift point shock collar I just don't understand why I have'nt had any luck selling them. If you need shift light they work better than light driver can stare at light and wonder what is that light for,but the shock collar eliminates any daydreaming and missing shift points.
Mike Taylor 3601

05-23-2012, 12:27 AM	#1
4spdJohnny Member Join Date: Aug 2010 Location: Grand Forks ND Posts: 243 Likes: 506 Liked 137 Times in 46 Posts	finish line rpm vs launch I am in the process of going from 5.38 to 4.88 gears in a j/sa 70 Sport Sattelite wagon 383 is shifted at 6400 goes thru traps at 7400. Building a trans with a lower first 2.45 to a 2.77. Thoughts keeping the same basic gear multiplication down low and more in power band down track. Does this seem like a move in the right direction or is it normal to "over rev" a stocker that much? It sure seems out of breath last 300 ft. Is that to much of a jump?

05-23-2012, 01:28 AM	#2
Phillip marvetz Senior Member Join Date: Oct 2008 Location: Lynden ,WA Posts: 820 Likes: 0 Liked 3 Times in 3 Posts	Re: finish line rpm vs launch I made about the same move last year, The car had a better 60ft and ran faster with less RPM at the stripe. __________________ 2009 V/SA Record Holder

05-23-2012, 02:11 AM	#3
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,809 Likes: 2,899 Liked 5,111 Times in 1,948 Posts	Re: finish line rpm vs launch What MPH does it run now? I'd guess it needs a 5.13 __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

05-23-2012, 02:22 AM	#4
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: finish line rpm vs launch You may find short shifting the 2.77 out of first will help ET. I would GUESS 5.13's as Mark suggested. Better to have not enough rear gear than too much rear gear. 4speed Johnny needs to put a stick behind that 383! That would be an awesome wagon! __________________ Jeff Lee 7494 D/S '70 AMX

05-23-2012, 11:53 AM	#5
4spdJohnny Member Join Date: Aug 2010 Location: Grand Forks ND Posts: 243 Likes: 506 Liked 137 Times in 46 Posts	Re: finish line rpm vs launch Thanks Phillip, gives me a little confidence! Mark, I have a set of 4.88's to try since I'm expirementing didn't wanna pop for new and 5.13 just seem like such a small change? Jeff, I agree and in fact originally intended on putting 4spd in wagon but now my 16 year old son is racing it and we aren't quite sure if he inherited 4spd gene! rest assured my road runner is still a stick and am building another 70 road runner 440-6pak 4spd combo for stock eliminator. When you say short shift you would shift 1-2 even lower like 5800?

05-23-2012, 12:01 PM	#6
4spdJohnny Member Join Date: Aug 2010 Location: Grand Forks ND Posts: 243 Likes: 506 Liked 137 Times in 46 Posts	Re: finish line rpm vs launch Sorry Mark, 12.70, 1.69 60 ft 102.8 mph in 3600 ft air with a 25 mile an hour cross wind (I'm sure doesnt effect this aerodynamically superior race car at all!) Brakes were also slightly dragging that day (Strange disc all corners) have since installed adjustable pushrod and springs inbetween pads in calipers seems to have cured. have also switched the car to cal-tracs now so we wil see. Nothing like changing 6 things at once in a combo but I think all right direction also took weight out to move from k to j since those time slips

05-23-2012, 02:49 PM	#8
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,369 Likes: 348 Liked 292 Times in 101 Posts	Re: finish line rpm vs launch Turn Junior loose w stick, the stick gene seems to be passed to each generation,if he can't drive stick,then I would go for paternity test then.LOL My son was driving FWD nova w/stick @ 9 years old,took his 25 year old uncle for ride uncle told him he could'nt drive stick shift,he told his uncle I'll teach you.LOL Mike Taylor 3601

05-23-2012, 04:10 PM	#9
4spdJohnny Member Join Date: Aug 2010 Location: Grand Forks ND Posts: 243 Likes: 506 Liked 137 Times in 46 Posts	Re: finish line rpm vs launch You guys are making me feel so ashamed! I feel like I've betrayed the 4spd brotherhood. He raced our old 79 St Regis cop car when he was 14 and 15 in our local tracks "teen championship race" and actually won once and runnerup twice he's a pretty good light cutter but had to leave it in drive so he wouldnt forget to shift! Last year he blew up the old farm truck driving it to town in low lock! This car was supposed to be a spend no $ and drive it deal and now I'm buyin slush box parts... how'd this happed that could have went towards jerico! Sons tow truck is a 93 cummins with 350,000+ on it with a 5 spd (pistol grip shifter out of road runner of course) if he gets through year getting 4spd trained with that then we'll consider J/S no A!

05-25-2012, 08:31 AM	#10
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,369 Likes: 348 Liked 292 Times in 101 Posts	Re: finish line rpm vs launch Maybe you need the shift point shock collar I just don't understand why I have'nt had any luck selling them. If you need shift light they work better than light driver can stare at light and wonder what is that light for,but the shock collar eliminates any daydreaming and missing shift points. Mike Taylor 3601