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.

This message has been edited. Last edited by: SmokinChicken,

.370 or .400 or .500 tree ?

.400 Super Gas, no issues with full tree bracket racing.

Buddy if your at a Natl event that's not a .400 tree, its a .370 tree. They do it so the Bikes don't red-light. I hate a .370 tree

This was at divisional in St Louis, not national. So is it actually a .370 tree for all of Super Gas?

if your at a Div your on a .400. If your at a Natl your on a .370. Thats for S/G and S/C

Well guess I better try and figure this out before going to a national event.

quote:

Originally posted by SmokinChicken:
This was at divisional in St Louis, not national. So is it actually a .370 tree for all of Super Gas?

Yeah, that's a 370 pt. Anywhere a national or divisional is run on Compulink, is .370.

Anywhere Compulink timing equipment is updated / maintained well , is .370.

Bradenton is 370.

Yeah shock settings play in to it. I'll tell ya a quick 015 you can pickup, is take the delay box out of the equation. Once you work the car red, enter it back into the equation (re-install).

quote:

Originally posted by SmokinChicken:
.400 Super Gas, no issues with full tree bracket racing.

How much delay do you carry to hit the top bulb on a full tree?

You need to have 1.130 in the box on a full tree to be .000 on a .370 pro tree. 1.100 if it’s a .400 pro tree. What RPM are you launching at?

Look at the time slip, it might tell you what the tree is set up for. Here in div1 the divisional season are .370 for super gas and comp, but some of the local races are .400.

Delay box is zeroed out so its out of the equation. On a full tree bracket racing 1.118 to 1.124 is generally in the box. Car leaves/launches at 5600.

quote:

Originally posted by Dead On:
if your at a Div your on a .400. If your at a Natl your on a .370. Thats for S/G and S/C

I don’t necessarily believe this is true. I run divisionals and nationals on the same tracks and my delay never changes by 30

quote:

Originally posted by SmokinChicken:
Delay box is zeroed out so its out of the equation. On a full tree bracket racing 1.118 to 1.124 is generally in the box. Car leaves/launches at 5600.

Take the delay box out of the car, you'll pickup 015.

I left my delay box in for Lights Out 6.00 index, because I knew SGMP was 400 Pro Tree.





When I went to Bradenton 6.50 index I took the delay box out because Bradenton is 370 Pro Tree.

Trust me, take the delay out of the car, you'll pickup 015.

This is test hit at Bradenton on their 370 pt with a delay box in my car, two and a half weeks before lights out SGMP 6.0 index 400 pro tree.

The other little I picked up was chassis/shocks and testing buttons. Taking out the delay box was worth 015.

quote:

Originally posted by SmokinChicken:
Delay box is zeroed out so its out of the equation. On a full tree bracket racing 1.118 to 1.124 is generally in the box. Car leaves/launches at 5600.

You can also raise the tire pressure in the rears (fronts too) to get it to react faster. I’ve gone up a full pound in my dragster and it helps it react. Not sure if you’d run into drivability issues with a roadster doing that. If it was me I’d try raising the air pressure and going out and hitting the tree as hard as you can. Watch the top bulb just like you do for full tree racing. If you have 1.12 in the box for top bulb your lights would be .010 slower on a 370 pro tree.

This message has been edited. Last edited by: 183N,

A Big part of getting a Davis roadster to react is in the Four link set up. They work by popping the wheels up and out of the beams.

ACDELCO Canadian Nationals
Top/et Iron man Champion
57 Don Davis Super Gas roadster
SDPC Race Shop 582 Head Hunter on Methanol

quote:

Originally posted by Mike Rietow:
Trust me, take the delay out of the car, you'll pickup 015

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.

quote:

Originally posted by 57 Vette:
A Big part of getting a Davis roadster to react is in the Four link set up. They work by popping the wheels up and out of the beams.

ACDELCO Canadian Nationals
Top/et Iron man Champion
57 Don Davis Super Gas roadster
SDPC Race Shop 582 Head Hunter on Methanol

^^^This dude makes a lot of good posts. Best so far. He made the best one in the sky-down-it carb stumble thread too.

https://www.onallcylinders.com...k-suspension-system/

If I had a little short wheelbase roadster with a 555 BBC which wouldn't move well enough on 370 tree, I'd start adjusting the IC higher and I'd move any ballast in the car above and behind the neutral line.

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

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

That's a good one right there. Pickup 015 moving a wire is A LOT!!

You need in between a neutral to anti squat 4 link bar settling.

How that works is at the hit the shaft exits the main body of the shock, as soon as a relatively tight compression setting senses the tire grabbing traction, the shaft changes directions, and it pops the front wheels out of the beam.

Stored energy in the front springs, sitting on the starting line, can't hurt.

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.