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Author Topic: Who here run caltracs?  (Read 2599 times)
Hemidoug
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« on: September 09, 2009, 03:45:59 PM »

I have some questions.....how does the suspension react to adding/removing preload on the springs? I have tried both upper and lower holes so far and can feel the difference in tire hit, but there must be more tuning in the preload other then getting the car to go straight right?

BTW...best run of the weekend was 12.1, best MPH was 116. I know she has mid 11s in her and I know I'm loosing it in the 60 ft....
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71 440 6pak, 4spd & 69 Hemi, 4spd
elacruze
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« Reply #1 on: September 11, 2009, 10:04:17 AM »

What are your 60' times?
What tires are you running? Pressure? Spinning any?
What is your gear ratio/stall? Engine? Weight?

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1968 505" EFI 4-speed
1968 D200 Camper Special, 318/2bbl/4spd/4.10
---
Torque converters are for construction equipment.
Hemidoug
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« Reply #2 on: September 11, 2009, 10:24:03 AM »

What are your 60' times?
What tires are you running? Pressure? Spinning any?
What is your gear ratio/stall? Engine? Weight?



Well, my best is 1.87, with Hoosier QTP 28 x 11.50....tried everything between 11 psi and 20 psi...410s, 484 Hemi, 4000 lbs, 4 speed.
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71 440 6pak, 4spd & 69 Hemi, 4spd
elacruze
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« Reply #3 on: September 11, 2009, 10:29:35 AM »

What is your flywheel weight?
Launch RPM?
Do you ever spin the tires?
Are you getting any air under the fronts?
Does the car go straight every time?

I'm playing telephone diagnosis again, I know I'm not directly addressing your original question about adjustments.
Seems to me you should find 1.7's for your 60ft times easy enough.
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1968 505" EFI 4-speed
1968 D200 Camper Special, 318/2bbl/4spd/4.10
---
Torque converters are for construction equipment.
Hemidoug
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« Reply #4 on: September 11, 2009, 11:12:51 AM »

What is your flywheel weight?
Launch RPM?
Do you ever spin the tires?
Are you getting any air under the fronts?
Does the car go straight every time?

I'm playing telephone diagnosis again, I know I'm not directly addressing your original question about adjustments.
Seems to me you should find 1.7's for your 60ft times easy enough.

stock flywheel, 4k, spins every time, don't know, but it's as close as you can get without getting air (see pic below), yes it goes straight.....I believe I should be in the 1.6 zone.....
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71 440 6pak, 4spd & 69 Hemi, 4spd
elacruze
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« Reply #5 on: September 11, 2009, 03:27:13 PM »

I don't know anyone with personal experience with Hoosier QTP's, but this guy does;

"...my only experience with the Hoosier QTP was on my Mustang and all I will say about them is they sucked! No traction on the street or track.
...My SC went from a best of 1.84 60' on drag radials to a 1.64 60' on MT slicks with no other changes.."

I know it's a F**d but it sounds exactly like yours. Sure would be nice if you could borrow a set of slicks to eliminate the tires. If you've been everywhere with the pressure and you're still spinning, especially if you're spinning more than two or three revolutions it just sounds like you're overpowering the tires. I'm sure you're making significantly more power than a SC Mustang.
Are you spending enough time in the burnout box? I know that personally, I can't do a proper burnout without a bead of sweat over the 'wasted' rubber lol.

FWIW, I'd go with the lowest holes and give the 'tracs some slack, so you get some inertia to drive the tires home.
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1968 505" EFI 4-speed
1968 D200 Camper Special, 318/2bbl/4spd/4.10
---
Torque converters are for construction equipment.
Hemidoug
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« Reply #6 on: September 11, 2009, 03:57:48 PM »

Well, burnouts are a little complacated because I didn't have line lock in the car, but I did get the tires to grab. I think one of the issues is I'm hitting the tire to hard as well....
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71 440 6pak, 4spd & 69 Hemi, 4spd
elacruze
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« Reply #7 on: September 11, 2009, 04:15:07 PM »

I was stand-in driver once a month for my neighbor's '88 Daytona/Mancini car. 8.60's, mid 140's mph, 1.24 best 60'.
I _always_ had better 60' and E.T.'s than the regular driver, which totally confounded the owner and the driver because they were always on my ass that I didn't get the tires hot enough in the box. I could never get them to grasp a couple things; 1st, tires get their best traction at about 10% slip, so hooking 100% means you're not using all the tire. 2nd, that the car worked better when it didn't hook so hard (It was an '80's ladder bar chassis)
That car was a 572" wedge with Indy top end and a powerglide auto.
Anyway, point is the car went fastest when I could feel it slip just enough to take the violence out of the first car length, then hook hard right when the weight got on the back. Without watching your car or driving it, I can't know how your weight is transferring, or when. If you can keep the back of your car down during the launch, you should be able to hook the tires in about a car length. Try raising the front end a couple inches, see if that helps. Maybe go to a test and tune day where you can do 60' shots without running the entire track. Throw 100 lbs of sandbags in the trunk and try a launch! You'd be amazed at what you can learn with some out of the box experiments.
I think you don't have enough tire. By-the-book, you'd need slicks the same size as you have for a fast 440 and you have more power than that.
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1968 505" EFI 4-speed
1968 D200 Camper Special, 318/2bbl/4spd/4.10
---
Torque converters are for construction equipment.
Hemidoug
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« Reply #8 on: September 11, 2009, 04:44:58 PM »

Cool! Thanks for the insight! I'm gradually going away from the "street" and trying to learn more about setting a car up for the track. The lessons I'm learning now I can apply to my 65 Plymouth that I intend to make my track car. I haven't done a whole lot of track time but enough to start building some experience....I want to run the car in Nostalgia Super Stock as well as a 10.0 or 10.5 index....I don't want to be too wet around the ears.......so every insight I can get is greatly appreciated!  2thumbs
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71 440 6pak, 4spd & 69 Hemi, 4spd
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