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Old 06-06-2011, 12:54 PM   #1
banjo
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Default Caltrac adjustment

Hello,

Have a 74 nova, sbc 406, caltracs, Typically runs 6.50-6.70s depending on the air.

It seems to be unloading the tires while the front end is in the air, It gets worst when the track and air come around. Its not all the time. Only think that seems to help is to tighten up the extension on the rear shocks. But the problem with where I have them is it is making the car more sensitive to bumps in the track.

So I want to try and soften up the hit a little more so I can soften the shocks back up. I have the caltracs in the bottom hole. Will reducing the preload take some the hit out of the rear?

I am open for other ideas.

Thanks
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Old 06-06-2011, 01:01 PM   #2
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Default Re: Caltrac adjustment

The more gap you have, the more hit you have. If you want to take some hit out, add preload to the bars. Maybe 1 full turn after the force link contacts the spring.
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Old 06-06-2011, 09:54 PM   #3
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Default Re: Caltrac adjustment

what tire,trans,rrear gear, tire pressure, shock settings front and rear. perload ADDs HIT, NOT TAKES IT AWAY. you only get so much axle rotation to put pressure on the caltrac stop pin. by taking preload away you have to wind up the axle before you even start to put pressure on the tire then you run out of axle twist to keep pressure on the tire.. you could be doing 1 of a few things here. the better the track the worse it gets tells me you my be topping out the shocks. it hooks hard and hit the top of the rear shock and then unloads the chassis. thats way the tighting of extension helps. it slows down the topping out of the shock.....
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Old 06-06-2011, 10:17 PM   #4
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Default Re: Caltrac adjustment

Well, just a little more back ground, this started happening when I changed the converter. Same stall, but this comes in a bit softer then the previous converter.

Car has a 9x30 inch hoosier slick, PG with 1.80 first gear, 4.56 gears. Tire pressure is 15.5. I have the qa1 shocks they are set 3 clicks from full loose. I have ranchos in the rear and they are set at 8.

It seems to happen more in that in between state, went to dallas last fall where the air and track where awesome, and never had an issue. My normal track I race at, I am approximately .3-.4 slower. Adjustment of the shock significantly improved it. Increasing rear tire pressure seems to help some. I have tried to play with the front end, going full loose, to full tight, increasing and decreasing front end travel, only think that seems to help in that rear shock adjustment. I don't think it is rear travel upwards, I don't seem much seperation if any at launch, and when I change the rear tires, the rear drops a good 4-6 inches to drop the wheel out of the fender well.

here is a pick from dallas, pulling a 1.40 sixty. Maybe getting an inch of separation. I am going to try and get some video next time out.

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9.87@131(bumping the rev limitor)
Speierracing heads

https://flic.kr/p/dwzk8E

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Old 06-06-2011, 10:52 PM   #5
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Default Re: Caltrac adjustment

that's a radial slick right? this is what i would try. put the front full loose. put in 1 full turns of preload and set the rear shocks to 3clicks from full tight loosen 1 click at atime from there to you get to full loose. if you 100% nothing is binding or you not topping out the rear shock then great.. what front springs are you running and how old are they? you doing what 90% of the guys that come to me are doing! the car sit pulls a wheelie and spins 10-20ft out.. you need to stay on the tire harder. if what i said doesn't work with the bars in the lower hole go to the uppers and set the preload with the stop just touching the sprinds. start with 2 clicks from full tight and loosen the shock 1 click at a time to it stops doing what its doing.. if you get to full loose and it doesn't go away in either upper or lower hole you may have dead front spring or need to go to a d/a shock in the back... it may need full tight on compression and then extension adjustments...
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Old 06-06-2011, 11:12 PM   #6
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Default Re: Caltrac adjustment

That is a bias ply slick. I have run the radials, just dont get the life out of them. Also too, I think the car is spinning within the first few few on launch, and Its not really spinning, just turning the tire abit, it recovers on its on, and I don't have to lift, just knocks .01 off the sixty foot.

The front springs are the qa1 350 springs, they are about 3 years old.

Its also intermittent to, think I am good, and then it will do it. It effects reaction time when it does it which sucks. I think before I change anything further, I am going to get the car on the lift and conduct a thorough inspection to make sure everything is right.
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9.87@131(bumping the rev limitor)
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Old 06-06-2011, 11:35 PM   #7
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Default Re: Caltrac adjustment

well your 1 first issue is the qa1 setup!.. put a santuff or afco standard spring in it and a set of good shocks.. i have never been able to get the qa1 to work on anything other then very hi power cars.. 2nd issue is 15,5 in a bia's slick? i run 11psi in my 30x10.5 and 12psi in my 26x8.5's
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Old 06-07-2011, 07:19 AM   #8
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Default Re: Caltrac adjustment

fwiw, banjo i'm not in any way bashing your setup, i have setup so many cal trac cars know i lost count. i have had to have the qa1 re valved every time with guy that wont let me change out to a better more consistent setup. the qa1 spring isn't long enough to store energy for consistent launchs. they work once then on the next pass it doesn't hook and guy go round and round with this setup.. know on very hi power car you don't need as much help for weight transfer so they tend to work better! even then i have them re valved. i have been working with qa1 to get them to make some drag springs that are 4" longer then whats out there know. plus a little different valving for drag racing. will see if they do what i have talking about with there engineers...
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Old 06-07-2011, 03:07 PM   #9
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Default Re: Caltrac adjustment

I am having a simular issue mine tries to leave and as soon as the front reaches full extention it spins and recovers. I don't have good shocks on the car ranchos on the rear and just a 90/10 on the front i am going to try a different front shock this weekend and see if that helps. I have been all over on the rear shocks so far the best setting i have found for mine was 1 click from full soft any idea's Jeff this is a 70 nova bbc plate kit 3250lbs a 1.76 glide and a 26X8.5 tire. also running 14-14.5psi in the tires
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Old 06-07-2011, 03:11 PM   #10
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Default Re: Caltrac adjustment

where are the bars at . what front springs? rear gear? NOTHING IS BINDING FRONT OR REAR!!!!!
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Old 06-07-2011, 03:22 PM   #11
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Default Re: Caltrac adjustment

has moroso trick springs up front rite now going to upgrade this winter, gear is 4.10, bars are in the bottom hole and it doesn't seem to be binding any were free movement in the rear and front
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Old 06-07-2011, 03:33 PM   #12
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Default Re: Caltrac adjustment

how old are the front springs? put the bars in the upper hole set the caltrac stop right on the spring don't preload it..tighten the rear shocks up to half way and give that a try.. the front springs could be dead. the trick spring are good for 1-2 yrs and then there junk..
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Old 06-07-2011, 03:33 PM   #13
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Default Re: Caltrac adjustment

The car looks to bereaching full extention on the front before the rear is working thats why i thought the loosening of the shocks helped it to work sooner, but i thought putting tighter shocks on the front would slow the movment more and let the rear work.
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Old 06-07-2011, 03:34 PM   #14
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Default Re: Caltrac adjustment

power level of this car?
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Old 06-07-2011, 03:36 PM   #15
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Default Re: Caltrac adjustment

Quote:
Originally Posted by jeff c View Post
how old are the front springs? put the bars in the upper hole set the caltrac stop right on the spring don't preload it..tighten the rear shocks up to half way and give that a try.. the front springs could be dead. the trick spring are good for 1-2 yrs and then there junk..
they are definatly older than that i'll give that a try and see if it helps thanks

power is around 850-900

Last edited by faststang; 06-07-2011 at 03:38 PM.
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