quote:

Originally posted by 183N:

quote:

Originally posted by sr4440:

quote:

Originally posted by SmokinChicken:

But I need my box in for my timers.

Many have said to make sure my crank height is about 12.5 inches and travel on front struts is about an inch. This car seems to lift and move forward rather than just pop straight up.

On the box, move the transbrake wire to the the transbrake switch wire location, you will have 2 wires stacked on top of each other. box will still work for timers and you have bypassed the box for the transbrake.

Joe

This won’t work if you have a digital delay box like the mega 450. The digital delay boxes provide ground for the pushbutton switches. K&R boxes look for positive 12 V for the switch so you could do that if you have a K&R.

I run the Dedenbear Lightning Box

Unless you have an extra long and low instant center on your four link, shock compression shouldn't even be in this conversation. Extension is all you are worried about in the front and the rear. Id say tighten the extension on front to full tight, tighten the extension on rear shocks up as tight as you can get them without generating too much wheel spin, air the front runners up as much as you feel comfortable, and try that. If the car is squatting the rear at the hit as the second car in Mike's picture, put a shorter & higher instant center in the 4 link, then tighten extension on the rear shocks till it goes red. Last knob to me is adding a pound or two to the rear tires.

quote:

Originally posted by 183N:

quote:

Originally posted by sr4440:

quote:

Originally posted by SmokinChicken:

But I need my box in for my timers.

Many have said to make sure my crank height is about 12.5 inches and travel on front struts is about an inch. This car seems to lift and move forward rather than just pop straight up.

On the box, move the transbrake wire to the the transbrake switch wire location, you will have 2 wires stacked on top of each other. box will still work for timers and you have bypassed the box for the transbrake.

Joe

This won’t work if you have a digital delay box like the mega 450. The digital delay boxes provide ground for the pushbutton switches. K&R boxes look for positive 12 V for the switch so you could do that if you have a K&R.

Here’s your bypass plug wiring for negative triggered delay box.

Is the Dedenbear Lightning Box a negative box? I have never used one to know. K&R here

All Dedenbear products are +12v trigger

quote:

Originally posted by SmokinChicken:
Does rear shock compression play a significant role in reaction times? Been struggling with a 4 link Davis roadster and getting it to go red. Car weighs out to be 52% on rear so it isn't nose heavy, FTI trans Conv an Trans Solenoid, launching at 5600, 1 inch travel on front shocks with a small tire, 555BBC. Reaction times are consistent in the 30's with delay zeroed out. No issues with previous owner on east coast, the only difference is my 555 is iron block and his was an aluminum one.

As for how the shocks reacts is very dependent on where the instant center is.We really can not say how shocks are to react until we figure out how it is set up.

I do think you can pick up some reaction time from the four link but not sure about that much.

With a fast reacting IC (neutral to anti squat high bar) the OP would want a damper with a fair amount of low speed tailing off damping on rebound and compression. Looking at the dyno graph the hi speed is the hit, the shaft is moving out of the main body at "hi" speed, as it slows the force tails off, that's "Lo" speed. Once the tire grabs traction the shaft changes direction, when it changes direction it pops the wheels out of the beam, this happens so fast you can't see it without slow - mo video.

This is how my Ohlins TTX 36 are valved, with a fair amount of "dig"ressive valving controlled through the adjuster and part of the reason why my 3200 lb 10" tire sbc car can go double 0's 370 pro tree staged shallow.

This message has been edited. Last edited by: Mike Rietow,

Righto, please stop passing misinformation regarding damping curves.
Low speed damping is nearly always linear.
High speed damping is nearly always regressive, (incorrectly termed digressive but no one is going to change the industry nomenclature) meaning the slope of the high speed damping curve is less than the low speed damping slope.

Here is a picture of 3 different types of damping.


As for the OP's question, the CG of the car moved forward due to the iron block so there are only two ways to regain the dynamic weight transfer it had before: let the front come up higher or let the rear squat more, or some combination of the two. It's already been mentioned to twist knobs and/or move the IC so that's been covered.

SC- I still have Don Davis's hand written instructions on how to set up a roadster, PM me your email and I'll be happy to send you a copy

quote:

Originally posted by speedwrench44:
SC- I still have Don Davis's hand written instructions on how to set up a roadster, PM me your email and I'll be happy to send you a copy

Sent

Back at you

Hope this helps a little

quote:

Originally posted by speedwrench44:
Back at you

Hope this helps a little

Thanks, all info here is valuable to me. I appreciate everyone's comments and insight.

quote:

Originally posted by Triple Nickel:
Unless you have an extra long and low instant center on your four link, shock compression shouldn't even be in this conversation. Extension is all you are worried about in the front and the rear. Id say tighten the extension on front to full tight, tighten the extension on rear shocks up as tight as you can get them without generating too much wheel spin, air the front runners up as much as you feel comfortable, and try that. If the car is squatting the rear at the hit as the second car in Mike's picture, put a shorter & higher instant center in the 4 link, then tighten extension on the rear shocks till it goes red. Last knob to me is adding a pound or two to the rear tires.

First, all NHRA nationals and divisionals are run on a .370 tree.
Second, I agree 100% with everything triple nickel said here. Shock compression will have zero effect on your reaction, however, extension will. I am almost full tight on my super gas car. I have also gained a lot of reaction time by going up in rear tire pressure. Stiffen the sidewall up for less wrinkle. One more thing I would like to ad is, don't be afraid to go down on starting line rpm. The common thought is to chip up to get more aggressive. Not necessarily true. You could be wasting a bunch of energy. Sometimes lowering the chip can be faster.
If you have someone with you at the track, have them take a slow mo video of the car with the smart phone. A video will tell you a lot!

I agree with Triple Nickel as well in terms of approach with the rebound adjuster. I can see tightening rebound speeding up reaction times big tires light super gas car. The phenomenon which is occurring with drag racing shock valving which isn't known by the user is tailing off damping. At the hit the damper shaft is extending out of the main body at high speed, as it slows the damping goes from tight to loose (digressive) planting the tire. With a fast reacting high bar suspension set up the tire is planted at the hit, when the tire grabs traction after winding on the rim, the shaft of the damper changes direction and compresses, at the point this happens the car pops the front wheels out of the beams.

The less the tire winds on the rim the more numbers you need in the delay box 370 pro tree. This is done using the adjusters on the dampers, according to your interpretation of the damping curve on the dyno.

If it were a matter of just locking rebound, the suspend-sion settings wouldn't matter.

This message has been edited. Last edited by: Mike Rietow,

370 pro tree, supposedly it was not possible 10 x 28 tire all steel 3250 lbs.

Years ago Banjo posted Go Pro videos under his car showing how shocks work. It was very helpful to some.

quote:

Originally posted by Footloose:
Years ago Banjo posted Go Pro videos under his car showing how shocks work. It was very helpful to some.

For what Banjo has, his car is a rocket ship N/A. Small tire bracket racing he's smart paying attention to the minutiae. That's why he's fast on a small tire competitive bracket racing. I've always been impressed how Banjo has his car performing. There's not many like it any quicker/faster 23 sbc.

https://youtu.be/aAqWdGpQHXg

^^^ Here's youtube video basic explanation for any time you look at in these graphs, easy to understand language.

It says the video is private

quote:

Originally posted by TheBlueTruck:
It says the video is private

Stay tuned the next will cover two way adjusters for low and high speed adjustment.