Caltrac’s and high rpm doesn’t mix

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o1heavy said:
The is actually faster when I “run at the converter “
But with the 5000 two step setting the car will cut a killer light
I use the car in a 7.0 index pretty much every weekend unless I break it
The class is setup on a 4ths pro tree
And if you can’t cut a .0teen light you will be a duck
Click to expand...

i used my car in a 10 flat shootout extensively on a 4 tenths pro tree. Never, or rarely was 0’s and teens on the tree though, nor was anybody else i ever raced against. And i won lots of races
.500 tree sure, not 400 tree.
If you have guys in 7.0 cars cutting that good of lights on a 400 tree i tip my cap. Never heard of that. Must be light.
Using a delay box?
 
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B3422w5 said:
i used my car in a 10 flat shootout extensively on a 4 tenths pro tree. Never, or rarely was 0’s and teens on the tree though, nor was anybody else i ever raced against. And i won lots of races
.500 tree sure, not 400 tree.
If you have guys in 7.0 cars cutting that good of lights on a 400 tree i tip my cap. Never heard of that. Must be light
Click to expand...
I lost left lane
Our 7.0 class is no joke good payout and very stiff competition
2DF9852B-E56E-4639-B6E4-A960DF367A56.png
 
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o1heavy said:
I lost left lane View attachment 1715579736
Click to expand...
I understand you guys have to deal with a bunch of silly questions from guys like
B3422w5 said:
Good light. Had the car run the number you could have beat the guy with a 60 light
Are you using a delay box?
Is it 400 or 500 pro tree?
Click to expand...
No delay boxes allowed
I dumped him on the big end he is one of the big dogs in the class so he had me off my game always a 4ths pro tree
This is with weight in the car before I went to using a restrictor plate and removed the weight
 
o1heavy said:
I understand you guys have to deal with a bunch of silly questions from guys like

No delay boxes allowed
I dumped him on the big end he is one of the big dogs in the class so he had me off my game always a 4ths pro tree
This is with weight in the car before I went to using a restrictor plate and removed the weight
Click to expand...

Reason i asked is i looked at several tracks and most 7.0 classes are on 500 tree. Easy to kill the tree on 500 tree with
What track do you race at?
 
o1heavy said:
I agree with loosening the rebound but
Won’t that allow the tire to be hit harder?
Click to expand...
Loosening the extension should allow more separation of the rear suspension. If it hits the tire too hard try adding some air.
 
skrews said:
Loosening the extension should allow more separation of the rear suspension. If it hits the tire too hard try adding some air.
Click to expand...
This could be part of my issue
I have been seeing how hard the tire is being hit and figured the tight extension
Would help control the hit
I’ve been playing with air and 14lbs seems rightish
 
o1heavy said:
I understand you guys have to deal with a bunch of silly questions from guys like

No delay boxes allowed
I dumped him on the big end he is one of the big dogs in the class so he had me off my game always a 4ths pro tree
This is with weight in the car before I went to using a restrictor plate and removed the weight
Click to expand...

i see. Just pointing out he left ya with tons of room.
Sorry about the “ silly “ questions. I race a lot too. 45+ years and counting
Got beat by 0005 the other night with an 011 bulb( i posted the time slip on here) in the 4th round at my track.
I saw the 85mph so knew you guys both layed them down on a 7.0 index a bunch..lol
 
I'd also try lowering the start line RPM down to let the motor get a run at the converter, this might help soften the hit.
 
skrews said:
I'd also try lowering the start line RPM down to let the motor get a run at the converter, this might help soften the hit.
Click to expand...
Can’t do that
Lowering the launch rpm hurts reaction time
I’m pretty set on making this work at a high rpm
 
I guess going in deep on a .400 with a 3500 hit is asking for a red?..it'll slow you up some, put a bit of power back in it?...works for us but on a .500.
 
Okay , now my Dart is a stick car with a 1 inch lower mono leaf Cal-Trac suspension and still running the 5 click Rancho shocks that came with the kit 18 or 19 years ago. I leave the line at 5000 off a 2 step and a micro switch mounted to the clutch pedal with Cal-trac's set in the top hole and 0 preload, front shocks are single adjustable QA1 set on 1 click, rear shocks I set at 2 or 3 clicks. The car usually will 60 in the low 1.50's, on well prepped track it will go high 1.40's. If I set the rear shocks on 4 or 5 and car hits hard it will porpoise like yours and I have to turn them down. I run a 3.04 first gear and a 4.10 rear gear for a 12.46 LSR( not optimum for a stick car). Now I can't tell you what my shock settings would equate to in a double adjustable shock( maybe some one else can). The first photo is the car sitting at static height and the other shows the amount of separation in the rear suspension, about 2 1/2 to 3 inches.

GREGG`PICTURES 025.jpg


1207191239.jpg
 
19DART66 said:
Okay , now my Dart is a stick car with a 1 inch lower mono leaf Cal-Trac suspension and still running the 5 click Rancho shocks that came with the kit 18 or 19 years ago. I leave the line at 5000 off a 2 step and a micro switch mounted to the clutch pedal with Cal-trac's set in the top hole and 0 preload, front shocks are single adjustable QA1 set on 1 click, rear shocks I set at 2 or 3 clicks. The car usually will 60 in the low 1.50's, on well prepped track it will go high 1.40's. If I set the rear shocks on 4 or 5 and car hits hard it will porpoise like yours and I have to turn them down. I run a 3.04 first gear and a 4.10 rear gear for a 12.46 LSR( not optimum for a stick car). Now I can't tell you what my shock settings would equate to in a double adjustable shock( maybe some one else can). The first photo is the car sitting at static height and the other shows the amount of separation in the rear suspension, about 2 1/2 to 3 inches.

View attachment 1715579913

View attachment 1715579920
Click to expand...
Ok so when you tighten the rear shocks
It acts like mine and try’s to bounce ?
And would you happen to have any video
Of the car leaving?
 
Sorry but no I don't have any videos of the car hopping. But you could feel it and other racer would tell me what it was doing.
 
I’m I hate to say it but I may have to lower the launch rpm
Yikes that hurt to say
 
o1heavy said:
I’m I hate to say it but I may have to lower the launch rpm
Yikes that hurt to say
Click to expand...
You’re giving in/up that easy? How many different possible combinations exist for your shock settings, preload adjustment, tire pressure, hole location, etc etc etc??? Tuning a chassis to work, and work well is mind numbing no doubt. But do it. It’s worth it in the end. Almost no ones car lives up to the claim of how much power they say it makes on the drag strip. It’s because they don’t take the time to sort the car out and make it work. When you’re finished and your car runs the number you’ll be happy you did. Maybe you’ve already tried all the possible adjustments and in that case, just lower the launch rpm.
 
TT5.9mag said:
You’re giving in/up that easy? How many different possible combinations exist for your shock settings, preload adjustment, tire pressure, hole location, etc etc etc??? Tuning a chassis to work, and work well is mind numbing no doubt. But do it. It’s worth it in the end. Almost no ones car lives up to the claim of how much power they say it makes on the drag strip. It’s because they don’t take the time to sort the car out and make it work. When you’re finished and your car runs the number you’ll be happy you did. Maybe you’ve already tried all the possible adjustments and in that case, just lower the launch rpm.
Click to expand...
I have an index race Saturday
And I need the car to go down afterwards I’ll take a break from racing I will regroup and try to figure out if I Can make this work
 
o1heavy said:
I have an index race Saturday
And I need the car to go down afterwards I’ll take a break from racing I will regroup and try to figure out if I Can make this work
Click to expand...
I agree with Hot Metal, I also go deep on a .500 pro tree, I tried shallow staging but two very successful racers told me " go deep and stay with it " I run 11.50 index, leaving at 2 grand , 60 fts 1.58-1.60 ( 1.48-1.50 shallow ) foot braking on a 295/65 drag radial at 18 psi.. have been 004-020 average. I used to leave at 2500 , I now leave at 2000 and my lights and 60 fts are the same as leaving at 2500

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Late to the party....comparing the 2 videos, 5k launch (in slow mo) is crushing the tire and making it unload the chassis, where as your 3500 launch is not. Have you tried meeting in the middle on the launch RPM (4250)....maybe 4250-4500 would still give you a decent light, and possibly not kill the tire?

Are you on radials? I know others have said it, but more tire pressure may help....even if you can put it into a controlled spin (not ideal, but may work).

Sorry, I'm not too much help on the setup since I'm a foot-braker and my Caltracs are setup for that...and I leave at about 2500.
 
flyfish said:
Late to the party....comparing the 2 videos, 5k launch (in slow mo) is crushing the tire and making it unload the chassis, where as your 3500 launch is not. Have you tried meeting in the middle on the launch RPM (4250)....maybe 4250-4500 would still give you a decent light, and possibly not kill the tire?

Are you on radials? I know others have said it, but more tire pressure may help....even if you can put it into a controlled spin (not ideal, but may work).

Sorry, I'm not too much help on the setup since I'm a foot-braker and my Caltracs are setup for that...and I leave at about 2500.
Click to expand...
This weekend I’m gonna set the two-step to 3500 and tighten the front up to see if I can make it work and cut a light .
And as far as radials go I’m considering trying them sone experienced guys seem to think they will help.
But this all seems like the car will end up with either a 25 inches front spring segment or a set of ladder bars
 
o1heavy said:
This weekend I’m gonna set the two-step to 3500 and tighten the front up to see if I can make it work and cut a light .
And as far as radials go I’m considering trying them sone experienced guys seem to think they will help.
But this all seems like the car will end up with either a 25 inches front spring segment or a set of ladder bars
Click to expand...


I think you are going the wrong way tightening up the front end.

The car needs to pitch rotate, and yours isn’t doing that.

IMO, you are getting the cart before the horse. You are so concerned with cutting a light, you are handicapping the chassis.

When the chassis is correct and happy, the RT will come down. You need to make it hook first and move. Once you do that, the reaction times will come around.

IMO, you need to add some travel up front and then set your shocks so the front end travel is smooth and not violent from too little rebound dampening, and not so slow it won’t pitch rotate because you have too much rebound dampening.

Then you can maybe slow down the rebound on the rear, and definitely stiffen up the bump so the tire can’t act like a giant ball being hit with a huge hammer.

There is the misguided notion that says pitch rotation (a wheelie) is bad, but it’s not. When the car squirts off the starting line without pitch rotation, you have lost most of the load you can apply to the tire with the weight of the car. You don’t need to set it on the bumper, but 8-12 inches of pitch rotation is a good thing.

Unless you are running Comp Eliminator or Pro Stock and have a chassis for those classes, pitch rotation is fundamental.

I’m in the same boat as you are. My math says the very lowest RPM I can be on the 2 step is 5500, and most likely will be as high as 6500 with a clutch.

I can pull some timing at the hit, but I’d rather get it to hook and ADD some low gear timing, but that’s a different discussion.
 
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