Competition auto-needing wheel speed

[mfunderburgh]

I just pulled my truck the other night at hillsboro for the first time since some injectors, delivery valves and a new turbo. I was very dissapointed in my lousy distance of 203ft. I have been just starting out in 1st-4lo and shifting to second after I get rolling and rpm's up and just staying in second. I think i should have went ahead and went to 3rd though because my wheel speed was not enough. My question is what else should I look at as a way to get some more wheel speed out of this auto. I have been told not to go to 4hi until i get the updated output shaft and not to power brake the truck with the dana 70 I have in it. I guess if you had one or the other to do which would you do fist? Should I also stay with the 3. 54gears or go to 4. 10's? I'm thinking to try to shift to 3rd next time and put an 80 in the truck so I can build boost and get out of the hole stronger. It sucks to watch a duramax with less raw power come out of the hole in 1st- 4hi after ten lbs of boost squealin the tires and leave it first to put 40ft on me. :{ Matt

 

[Kyle03D]

Well well, we need to find a dyno there buddy. Then we can talk about raw power.



I need more wheelspeed too.



I like the :{ .



Kyle

 

[Strick-9]

I spent most of my time at Muncie this year closely watching wheel speed of all of the trucks. Most of the auto-equipped trucks were downright embarrassing to watch in the wheel speed department. It was clear to me why most serious pullers steer clear of the automatics. The auto's powerbrake and spin a little on take off, but as the weight comes up, the tire speed drops steadily.



If you download the available videos of even the best auto pullers, you'll see the same problem. Tire speed is 10 mph or less at the finish line (usually not near the 300' mark)



Shifting to third isn't going to help either. Your converter is too loose in fluid coupling. Your only choice to get serious wheel speed (and maintain it until the end) is to lock the converter clutch.



I don't see injectors in your signature so you probably don't have the power to pull 3rd gear with the converter locked. But 2nd gear, converter locked @ 3000 rpm will give you about 20 mph wheel speed all the way to the end. That will be a BIG improvement over what you have.



Not sure if your valvebody is set up to allow 2nd gear lockup or not, but that would be a cheaper option for you (and much more effective) than swapping to 4. 10 gears.



I've got to warn you. Many people have gone down the same road and locked their converters and broken parts. Loose converters tend to break input shafts and flex plates when they attempt to lockup during a sled pull.



Tight converters avoid this problem, but are harder to spoolup with large turbos.



I have no idea how tight or loose your converter is under power.



What is the true stall speed of your converter under full power? In gear @ FULL BOOST with the tires not moving? 2200? 2400?



My converter is fairly tight and I launch at 1800 RPM & 20 psi boost. At full boost, the stall speed is ever higher. It's more like 2400 RPM w/ 550 HP. What this means is that if my engine RPM is only 2400 RPM (near peak power) at the end of the sled pull, my tires can come to a complete stop. And it doesn't matter what gear you are in either because the input shaft is no longer turning or turning very slowly. That's why you HAVE to lock the converter to maintain wheel speed.



If you keep it in 4-Lo you have a very slim chance of hurting your output shaft.



I wouldn't hesitate to powerbrake the Dana 70 either. I'm still running a 70 and drag racing with a 1. 70 60 foot is much harder on the rear than spinning in the dirt.



I would powerbrake it to about 10 psi, let it shift into second and gain a few hundred RPM and then lock the converter.



I hope that answers your question.

 

[propuller]

I run 4 lo & let the trans shift on its own into 3rd(overdrive is shut off). I have a dtt 89% converter & my wheel speed is awesome. Im right at 600 horse on nitrous & my truck goes down the track very fast & my tires will smoke at the end on a clay track. As far as the dana 70 i always hold the brake to build boost until it pushes through the brakes when the brakes wont hold i let her go then the turbo lights nitrous comes on at about 30 pounds of boost she walks through the gears & the race is on. I love this dtt trans i dont have to use lockup anymore. The converter is so tight its like its locked anyways but its loose enough so you can get her rolling with a large turbo. With your setup i would run 2nd gear locked you could try 3rd unlocked but i dont think you have the power to pull the sled unless its real light on the pan coming out of the hole. Good luck. Kurt.

 

[Piston Slapper]

I don't understand why ya'll say to brake torque w/ the auto? Is it because of the larger B1 ya'll have? Mine was stock granted the first time I pulled, but built 20 lbs all by itself pretty quick.



I now have a comp on my 2x4 auto and will be pulling tomorrow. I was thinking I outta be able to lite the tires without brake torque cause I can pretty easily now on pavement with very little. It'll bust loose at about 6-8 pounds. Is this true? I also was thinking OD off, 2nd gear. Let it up shift itself. Can I have wheel speed and spinning on the other end in 2nd? I think 1st will be to slow(wheel speed)?



I also pulled twice stock back to back one brake torqued and one not. Pulled 157 ft brake torque, spin alittle off the line but soon quit. 187 without, never spun a tire. What gives?



Appreciate ya'lls experience.

 

[propuller]

I try to get the sled rolling as quickly as possible & with a big charger you cant afford to loose the 20 feet it takes for it to light. Kurt.

 

[mfunderburgh]

1st of all I forgot to update my profile. Add 370's and laser cut dv's to the equation. I need to find my receipt on the convertor. I can't remember if it's a high or low stall convertor. It sounds like I had better stick with 4low until I can get the better out put shaft. The turbo I have on now is a B1 SP which takes a little time to spool. I will have the Kwikspool version in a couple weeks(wrong one came last week). My transmission is set up to lock up in 2nd but i got to get to the dealer to have him flash my computer since it was an early 96'. This might get done by friday night. I am thinking I will try starting in 2nd, power brake, get the truck going and then lock the TC up. When I shifted the other night i buried the tach in 2nd gear (4000+). At what rpms should i or shouldn't i lock the tc up. And last of all Kyle don't you duramax people have your own sight. I figured you would probable read this post. We will find a dyno after my turbo swap, :-{} I stil think i have some more horses I just ain't gettin them to the ground. Your truck is runnin good(beter than mine) for no more than you have done I think that why the tow truck next year is going to be a duramax. :- Matt

 

[Strick-9]

I am thinking I will try starting in 2nd, power brake, get the truck going and then lock the TC up. When I shifted the other night i buried the tach in 2nd gear (4000+). At what rpms should i or shouldn't i lock the tc up.

Just so you know. The Chrysler trannies start out in 1st gear even when the shifter is in 2nd. You'll still be starting out in first gear.



As far as when to lock up. The higher the RPM, the tighter converters get. This means the drop into lockup will be less. More RPMS are better.



3000-3200 would be a nice point if your engine can pull that high rather quickly.

 

[jwilliams3]

Matt,

The best auto puller and one of the top single charger pullers I have seen pull is George Peterson. He runs an auto transmission and locks the converter in 2nd.

His truck breaks alot of parts, but pulls awesome and wins when he stays together.



If you could find him on the net, im sure he could give you some guidance.



--Justin

 

[propuller]

Justin,

Do you know if George lets his trans shift to 3rd locked?His truck sounds just like mine coming down the track. Except ive been lucky & havnt broke any parts YET. Then again i dont run locked. Kurt.

 

[jwilliams3]

Kurt,

If I remember right, he is running an ATS triplelok and custom transmission/valve body.

If he runs the ATS lockup controller, then yes he is probably staying locked up going into 3rd.



Start locking it up

 

[Strick-9]

There is no way George is pulling 3rd gear with the converter locked unless that's something he just started recently.



I've got several of his videos and his tire speed is very slow at the end of his pull. The nice thing about George's videos is that he usually puts a white stripe on his tire and you can count tire revolutions very easily.



If you compare his wheel speed to one of the serious sled pullers like Gene or Scheids, it isn't even in the same ballpark.



Either he's running in fluid coupling or something in his transmission is slipping.



-Chris

 

[propuller]

I dont need to lock it up my converter is tight enough to keep my wheels spinnin . Kurt.

 

[Johnboy3]

George's crew wanted me to pass this on to Strick 9...

Quit living in the past. Watch this video That's what wheel speed with an automatic is suppose to look like.

 

[Strick-9]

Thanks for the newer video. Like I said

There is no way George is pulling 3rd gear with the converter locked UNLESS that's something he just started recently.

That's a huge improvement in wheel speed over what he had at Muncie this year and all the pulls I've seen of him before that. Obviously he's made some recent changes. Good for him. I enjoy seeing the automatics do well.



Somebody got their feelings hurt because they USED TO have low wheel speed at the end of their pulls. A couple of other people jumped in to plug their products. The thread started with a guy asking about how to increase his wheel speed. Is anyone else going to answer his question or give him technical advice or should we all just climb in the ring now and slug it out until the end?







-Chris

 

[Piston Slapper]

What about the parking brake? Anybody ever torque up with the Parking brake on and releasing it or would that be considered "Jerk start"? I wonder if it wouldn't make you dig holes or would it help your wheel speed? I would think the operator would like it. Probably would be dangerous to the poor guy in the rear seat!



Just another rookie auto puller,

Gap

 

[jwilliams3]

Chris,

Judging by your performance at Muncie, you ought to call George and ask for some advice too!

 

[JDailey]

LMAO! That's exactly what I was thinking, Justin!

 

[Sled Puller]

Originally posted by Strick-9









If you compare his wheel speed to one of the serious sled pullers like Gene or Scheids, it isn't even in the same ballpark.







-Chris

Speaking of ballparks, Gene=20MPH, Kent=85!!!!



The automatic company George uses, seems to be the only one actually getting power to the ground in pulling situations.



Granted, he modifys the crap out of the parts before they get used.

 

[propuller]

Originally posted by Sled Puller

Speaking of ballparks, Gene=20MPH, Kent=85!!!!



The automatic company George uses, seems to be the only one actually getting power to the ground in pulling situations.



Granted, he modifys the crap out of the parts before they get used.

I disagree with ya on this one gene. I wish i had some video i could load of my truck going down the track. there was only 1 truck with a manual trans that got me this summer in a pull & it was a highly modified 24 valve with a mitchell twin disc. the only reason he got me that night is because i was 600 lbs light. I ran against him a month before & put 20 ft on him but we both weighed the same then. Ive pulled against a mitchell twin disc 12 valve that smoked like a freight train & revved to the moon & i got him also. Everybody there said i had better ground speed than both of them. Im not trying to start anything but theres other companys that can put the power to the ground also & do it unlocked. I do have to admit if i could get my truck to run like sleddys id be Oo. . kurt.