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-   -   Need help on shifting by time?? (https://www.racingjunk.com/forums/showthread.php?t=31949)

SPEEDNEEDS1 04-06-2012 08:05 PM

Need help on shifting by time??
 
This past weekend I had my car out for the first time and shifted it at 2.200. After making the first pass not looking at the tach it shifted at 7500 and I wanted it to shift around 7000-7200. How much time do I need to take out of the shift to calm it down on rpm. I have it on 1.900 now and just wandering if that will be to much........ Car has 33" tire, 4.10 gear running 4.80's.

SPEEDNEEDS1 04-07-2012 10:06 PM

Ran car again today, switched to Goodyear 14.5x33 d-6 compound, put shift time on 2.000 and shifted on 7200, however it still has the traction issue. It launches great, out about 20ft and shakes like hell, after it shakes it will pick the front wheels up about 4" and carry it past 60'. But it only does it 1 pass out of 3 now. So I dialed it what I new that it would run and drove with both feet on the good passes. We got runner-up so it worked out but still having the issue.

It ran
1.066
3.115
4.851
142.50

roadkill2 04-08-2012 10:01 AM

Sounds like you need to shift a little longer than the 7200 rpm shift. You're possibly dropping too much rpm at the shift and your engine is trying to get back to the camshaft. Thus, you aren't maintaining enough wheelspeed to keep it from shaking. But you're probably going to have to live with a "happy Medium" or go to a slightly shorter tire. I think I'd take the shift back to 7300 or split the difference and see what happens.

Tires are expensive so I'd just keep driving through the shake if you can't eliminate all of it. That's assuming, of course, that it isn't all that violent.

One of the ways I figure out traction is with iPhone Videos. My Boss' better half videos the first 60' with her iPhone (Better video than I get with a high buck Sony) and then review the run in the trailer. Watch the back wrinkle of the tire. it should be about 8 o'clock on the tire at the light and never move much less than about 7 o'clock. If it tends to rotate towards the 6 o'clock position, you'll get shake. The Tire's rotational speed caught up with it's forward motion and is trying to decide wheteher to spin or hook up . . It's the fine line between tire spin and bog . . You have to keep the back defined wrinkle on the back side of the wheel center . .

My experience anyway . . . . Hope it helps . .

hammertime 04-08-2012 12:20 PM

You must have a very aggressive converter in there to do that I am thinking ??

Whats your shock settings at on the front ?

roadkill2 04-08-2012 01:50 PM

Re: "What will it run? thread. . . . It's a hardtail dragster, BBC, etc. .

I think he's got a little too much tire, but that's just a SWAG . .

hammertime 04-08-2012 04:58 PM


Originally Posted by roadkill2
Re: "What will it run? thread. . . . It's a hardtail dragster, BBC, etc. .

I think he's got a little too much tire, but that's just a SWAG . .

Its a hard tail .. but not front ;)

I think its under tires and rimed myself for the et it runs.

roadkill2 04-08-2012 05:48 PM

Dunno, but tire shake on Alky cars always indicated that the wheel speed wasn't keeping up with the wrinkle wall tire . . Once you let the wrinkle move below about 7 o'clock, either the tire will stand up or shake . . either way . . You lose, because your 60' time went into "Suck" mode . .

Way long time ago, a fella named Force (back in Diamond Bar) told me how to launch an Alky Funny Car using the wheelie bars . . And he told me about that damned wrinkle . . I have yet to see it disproved, and I've argued with it myself, several times . . Ole John is still right . .

Used to be, with the old stiff sidewalls, you could never be "Over tired" . . Today, with the selection of cams, converters and tires, nuthin to it . . Hell, with the old stiff sidewall tires, we used to use a narrower wheel and use the tire for the "overdrive" . . If the wheel was narrower than the tread, it'd stand up like a bicycle tire in the lights . . Damned things would grow to about 15% outside the max measureable tire diameter. Go back and look at the old photos of the Fuel Dragsters from 1973 to about '76. Look at Garlits doing a burnout or in the lights. He used a 10" wheel with a 12"+ tire . . Heh, heh, don't even try that today!

I don't know that our friend is over tired or under tired . . I'm just guessing. After all, how much is my house worth over the phone? But so far both of us have been in the ball park on several issues. I guess we'll have to let him sort it out . . But thanks, you are pretty damned knowledgable about our pasttime . . I appreciate it . .

SPEEDNEEDS1 04-09-2012 06:16 PM

Can't say if it is under tired or not but I think it is. I see every one else running a 16.5-17x33's and some with 34.5's. I have access to all of the 17x33.5 and 34.5's that I could ever use, but I have no 16" wheels. The car runs really well for what it is. The track that I have been running it at has several dragsters and most there have 565's with BB3 cylinder heads and we run the same et, so I figure that mine is running ok. I understand that the big tire will slow me down, but I ran with a few guy's that ran this same D2070 tire that I have and had 4.72-4.73 time slips like they was ran off of a coping machine. My car only moved .002 from the 330 to the 660 all weekend. Still ran 4.85 to 4.88 and 1.065-1.086.

My converter was not set up for a dragster, was set up for my 2600lbs door car and it is a 8". Any ideas if this is what the problem is.....

zipper06 04-09-2012 08:58 PM

I'm not a dragster person, David and roadkill2 are more qualifed to answer than i am, but most of the guys around here running hardtails are running 16X33 hoosers and a loose 6,000 converter. Course they run hot (trans wise) between rounds, but don't seem to have the shake problem.

Like i said not a dragster person


Zip.

roadkill2 04-10-2012 06:11 AM


Originally Posted by SPEEDNEEDS1
My converter was not set up for a dragster, was set up for my 2600lbs door car and it is a 8". Any ideas if this is what the problem is.....

OK, you found it . . A converter built for a 2600 pound car won't play well in a lighter (or heavier) car . . I've learned that a converter works well only in the car and engine it was designed and built for . . That's why when you are in the process of buying a converter, the builder wants to know so much about your car, engine, weight and camshaft.

We use a Neil Chance 8" with a billet Stator, built specifically for the car it's in . . It has an adjustable (to a degree) Stall and it works great in the Ape. But it wouldn't work in an Altered that weighs 600 pounds less.

Well, it would work, just not well. . .

hammertime 04-10-2012 06:25 AM


Originally Posted by SPEEDNEEDS1
Can't say if it is under tired or not but I think it is. I see every one else running a 16.5-17x33's and some with 34.5's. I have access to all of the 17x33.5 and 34.5's that I could ever use, but I have no 16" wheels. The car runs really well for what it is. The track that I have been running it at has several dragsters and most there have 565's with BB3 cylinder heads and we run the same et, so I figure that mine is running ok. I understand that the big tire will slow me down, but I ran with a few guy's that ran this same D2070 tire that I have and had 4.72-4.73 time slips like they was ran off of a coping machine. My car only moved .002 from the 330 to the 660 all weekend. Still ran 4.85 to 4.88 and 1.065-1.086.

My converter was not set up for a dragster, was set up for my 2600lbs door car and it is a 8". Any ideas if this is what the problem is.....

Id venture to say them cars going 4.70s with the same tire have almost the same 60ft as you going a tenth slower ?

Do you know anything about where the converter flash stalls and fallback rpm is ? Sounds to me like you have a lot of wheel speed which makes me think the converter is on the tight side. With a smaller tire you need something a bit looser (6400ish) and more forgiving. From what your saying its good after the shift but from launch to that point its moving around, pull timing, looser converter or bigger tire would all help.

Example of how to calm them down at the hit, [email protected] last weekend first pass in my new car, I set the converter upto flash at 6750 and fallback just over 6900. Very loose, deadly and big mph. My 60ft was 1.088-1.090

shawnp 04-10-2012 07:20 AM

David is correct. Loose as a goose gets your down the track where you want to be. We are normally a 1.10-1.11 60 ' using a 34.5 tire and run 4.77-4.80 range at 145 mph. Unless you are looking to quick race and squeeze every ounce of ET out of your combo, loosen that converter and get the bigger tire on it. That thing will hook on an ice rink and repeat all day long.

SPEEDNEEDS1 04-10-2012 05:37 PM

I have talked to the guy's at hughes and they said that the converter will work fine, but if they had known it was going in a dragster when they built it I would be .4-.5 hundreths faster in e.t., and .2-.3 slower in 60 ft. I am sending it back to them next week.

My brother and I have been running this car together the last two weekends and I know that its kinda dumb now, but after talking to him last night he has been putting 6.0lbs of air in the hoosiers and goodyears. I feel certian that is not right. I am trying 4.75-5.0 this weekend.

When I have it shifting at 2.200 "7500" it falls back to 6500 if that helps.

SPEEDNEEDS1 04-10-2012 05:40 PM

On the shock setting, it is all of the way loose, then 4 clicks tight. Havent moved it either way yet, I need to go to test n tune and try looser and tighter just to see what happens.

hammertime 04-10-2012 08:24 PM

6lbs isnt that far out of line but 5-5.25 will likely be where you end up at.
Whats the #s on the converter, I am fimilar with hughes stuff. 6500 after the shift is a good spot to be though, big tire is the next option, remember not all cars are the same and if you get the option to barrow some bigger rims and tires from someone you should do it, what works on one will not work on the other. What did you say you were launch rpm was ?

Tigthen that shock up a few clicks also, thats on the soft side.

roadkill2 04-11-2012 08:52 AM


Originally Posted by SPEEDNEEDS1
I have talked to the guy's at hughes and they said that the converter will work fine, but if they had known it was going in a dragster when they built it I would be .4-.5 hundreths faster in e.t., and .2-.3 slower in 60 ft. I am sending it back to them next week.

My brother and I have been running this car together the last two weekends and I know that its kinda dumb now, but after talking to him last night he has been putting 6.0lbs of air in the hoosiers and goodyears. I feel certian that is not right. I am trying 4.75-5.0 this weekend.

When I have it shifting at 2.200 "7500" it falls back to 6500 if that helps.

Tuning the converter to your car's weight and Engine/tire combination will help immensly.

On the tire thing. Goodyears are sensitive to both air and heat . . at least in my experience. A quarter of pound of air, one way or another has a fair amount of effect. Goodyears also like a little heat in them, somewhere around 110, 120 if you can get it and keep it while staging.

Hoosiers, on the other hand, will work really well on a specific setting. Once you find the air pressure the tire likes, leave it alone. An acquaintence running an Undercover 4 Link, 560+ BBC has 5.5# of air and it seems to hook up good. Track conditions, or even track temp doesn't seem to have much effect on them. Big Burnouts are actually detrimental to their performance . . We stage with about 90-95 on a 90 track (average) and they work really well. Personally, I wouldn't use a Goodyear on a tugboat . . but that's just me . . Also, on the Hoosiers, it takes about a half pound of air to make a difference. And you'll know right away, because, like I said, Hoosiers (at least in my experience) are kind of "one setting" Tires . .

shawnp 04-11-2012 10:14 AM

With the Hoosiers on our old Nelson car that was hardtail/front suspended we ran 33.5's with 5.25-.5.5 on the air pressure. Current swingarm car with 582 we run 6.0's in the 34.5's. Now changing to the aluminum block that may or maynot change for this year.

SPEEDNEEDS1 04-11-2012 06:05 PM

launch is at 4800 and goes to around 6400-6500 as soon as the trans brake releases. It hits the tire really hard. I accidently left the three step switch on one pass and left wide open and it slowed down...... I no longer use the three step switch, just try to keep it under 7000 in burnout.

hammertime 04-11-2012 08:13 PM


Originally Posted by SPEEDNEEDS1
launch is at 4800 and goes to around 6400-6500 as soon as the trans brake releases. It hits the tire really hard. I accidently left the three step switch on one pass and left wide open and it slowed down...... I no longer use the three step switch, just try to keep it under 7000 in burnout.

Have you tried to launch lower ? Sure seems like you have a lot of wheel speed.

roadkill2 04-12-2012 05:57 AM


Originally Posted by hammertime

Originally Posted by SPEEDNEEDS1
launch is at 4800 and goes to around 6400-6500 as soon as the trans brake releases. It hits the tire really hard. I accidently left the three step switch on one pass and left wide open and it slowed down...... I no longer use the three step switch, just try to keep it under 7000 in burnout.

Have you tried to launch lower ? Sure seems like you have a lot of wheel speed.

Dunno. If he has tire shake, it's usually because one doesn't have enough "Wheelspeed" to maintain the wrinkle and tire shape. If you can "Drive through it" that usually means that it's very minor and you're just "on the Edge" of tire distortion.

But . . I don't know of anyone who runs Hoosiers that have "Tire Shake" to any degree, unless they have too heavy a car for the sidewall design. On the other hand Goodyears will shake if they have too low an air pressure for the wheel speed being applied . . Sometimes, with Goodyears, an eighth of a pound will make a difference. not so much with Hoosiers . .

Basically, shake still goes back to the sidewall wrinkle and the fine line between grip and wheelspeed . . My opinion, anyway . .

I think I'd try launching at 5000, just for more data, and to see if the shake will go away . . Watch those RPMs in the water. The water box has killed more BBCs than all the races they've been in put together . . We keep our burnouts to 6500. If you can't clean and warm a tire with that, 7 grand won't do it either!

hammertime 04-12-2012 08:04 AM

I've had hoosiers shake, beadlocks fixed that issue :) Tire shake can go both ways but in this case to much wheel speed seems to be coming into play based on the current problem and 60ft. A 390 gear also would help this issue, I've done that too.

SPEEDNEEDS1 04-12-2012 05:20 PM

I am going to Z-MAX this weekend to watch the big boy's play so my brother is going to run the dragster. He is trying it at 5.0 psi the first pass and then he is moving the two-step down then up 400 rpm, after it is as good as its going to be I told him to tighten the coilover 2 clicks at a time to find what the car wants. He is testing Friday and racing Saterday.

TheYellaBrick 04-12-2012 08:08 PM

http://www.youtube.com/watch?v=mfJejgODr3E

http://www.youtube.com/watch?v=hR_QedH-yRE


http://bangshift.com/blog/watch-an-i...rag-slick.html

http://www.youtube.com/results?searc...450.0j12.12.0.

shawnp 04-13-2012 03:58 AM

In some cases lowering the launch RPM makes things worse as you flash the convertor to hard. Sometimes a higher RPM with less flash can settle things down. Don't be afraid to take that tire pressure up as well.

SPEEDNEEDS1 04-15-2012 05:25 PM

I talked to my brother last night and he said test session went bad. The roll over valve fell apart and after the car would get to 150ft.out it would fall on its face. Done this 4 passes in a row before he found it. Went to put fuel in after the 4th pass and it was laying where he could see it.

He was afraid to try any different settings until he made the car run again. Saterday's race he raised the launch and lowered the tire press. to 5psi. I ran 1.061-1.065 all day. Seems to work good like that for now but on a 95 degree day in July when th track is really greasy I think I will have to go with the 17x33.5 Hoosiers that I have, in search for 16" wheels....


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