Need help on shifting by time??

Old 04-06-2012, 08:05 PM
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SPEEDNEEDS1
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Default 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.
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Old 04-07-2012, 10:06 PM
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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
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Old 04-08-2012, 10:01 AM
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roadkill2
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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 . .
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Old 04-08-2012, 12:20 PM
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hammertime
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You must have a very aggressive converter in there to do that I am thinking ??

Whats your shock settings at on the front ?
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Old 04-08-2012, 01:50 PM
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roadkill2
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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 . .
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Old 04-08-2012, 04:58 PM
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hammertime
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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.
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Old 04-08-2012, 05:48 PM
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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 . .
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Old 04-09-2012, 06:16 PM
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SPEEDNEEDS1
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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.....
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Old 04-09-2012, 08:58 PM
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zipper06
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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.
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Old 04-10-2012, 06:11 AM
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roadkill2
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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. . .
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