You need wheel speed or you are just pissing into the wind.

Data will tell you what it’s doing under the different conditions.

Good luck.

 

Forgive my ignorance, I'm kinda late to this racing stuff and am still learning... You asked for wheel speed... Is that what I really need to be consistent and predictable? I'm not looking to improve the 60'... I just looking to be competitive index racing.

 

take some slow motion videos of the launch and share. The movements need to be smooth with no bouncing or crazy stuff happening

 

Paint a mark on the sidewall and get some slow mo video.

I'm willing, but can we really see a .020 difference at the hit?

Since we started looking into this problem, the kid has better video of just the rear tires, but here is one video from last years winternationals the kinda somewhat shows the tire spin at launch.. Once I talk with my son, I'll ask him if he still has the better videos from Phoenix...

You can clearly see tire spin at the hit, but I can not judge if there is a .020 or .050 worth of slippage.

BTW... since this video was taken, we have lightened the springs and changed shocks, which has toned down the launch a bit...

 

Paint a mark on the sidewall and get some slow mo video.

 

I’ve always done the paint mark on the sidewall with a slow motion video, because you can count how much the tire rotates before the car starts to move forward. If you can get the setup to where it rotates the same amount every pass before the car moves forward, it will give you a better shot at a consistent 60’. It needs a little bit with a slick, but not too much to where the wheel speed is not controlled

 

Get a Iphone and do the slow motion video from the drivers side at about a 45 degree an angle so you can see what is going on.

And that video you posted from last year I would be calming it down at the hit with a suspension change and shock settings to start. Its slamming the bars down before it even moves.

 

You’re not trying to measure et with a video, it’s purely to see the action of every piece. If it’s all herky jerky and bouncing around, it will never repeat on varying track conditions

 

Here is a couple videos from Phoenix... This is after shock and spring changes and I think it softened the hit...

Also, for those that dont know. You Tube allows you to slow down the video to 1/4 speed, hit the sprocket icon

147.47 1.530 60' 1675 DA

149.70 MPH 1.579 60' 2026 DA

147.73 MPH 1.542 60' 2517 DA

147.70 MPH 1.621 60' 3312 DA

 

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MAN, that thing sure doesn't do much on the launch??

I'm no expert, but shouldn't there be some kind of transfer, pivot.
Mine sure doesn't set the world on fire or do impressive wheelies, but it is definitely doing more than that.


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MAN, that thing sure doesn't do much on the launch??

I'm no expert, but shouldn't there be some kind of transfer, pivot.
Mine sure doesn't set the world on fire or do impressive wheelies, but it is definitely doing more than that.


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I totally agree.... however being an index racer, I could care less if its a 1.20 or 1.80 60'... as long as I can predict it... which is why I'm here.. My original questions is... Could running 9 - 9.5 of air pressure be too much and is that why I could be inconsistent? Our next race is Memorial Day and I was going to drop the pressure to 6 psi, unless someone tells me I'm looking in the wrong direction.

For the record, 3050lb car... 1050 HP, SST racing the launch is 4500 rpm, SG racing I'll bump it up to 6500 rpm. Tire PSI is 9 - 9.5 psi. Strange Dbl adj shock in rear, Strange Single adjustable struts in front... front/back half ladder bar car. On the stop for SST is .250 SG .1.25

 

I run my 10” tire car at 10 psi.
I run my 33.5-17-16” tire car at 6 psi.

I would definitely at least try a few hits down in the 6-7 range for more data.

 

I run my 10” tire car at 10 psi.
I run my 33.5-17-16” tire car at 6 psi.

I would definitely at least try a few hits down in the 6-7 range for more data.

Thank you... That is the plan for the Memorial Day race...

 

Just thought I'd give a quick update...

Went to the track yesterday and it appears the 60' numbers are starting to be more consistent... Only got 2 hits, one in the morning and one later in the afternoon after the rise in both the DA and track temp, Both hits were fairly consistent with 1.303 and 1.300 60'... Not sure why it got faster in the afternoon, but it looks like the majority of my inconsistency was too much air in the back tires..

 

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Too much air will drag down the wheel speed.
I know it sounds wrong, but the big boys have taught me my thinking was wrong.

It's a big thread, but my wheel speed thread has great knowledge in it!!!

It's in the drag racing section, I'll go bump it.
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So how much and which way do you go with air pressure and what dose it accomplish.

I read thru your other post with the .250 time and RPM. Looking at my logs I think I could defiantly smooth out the beginning of the DS (tire speed) graph.

 

so couple questions I also SST race how soon does the stop come on? my 60 ft is alot slower than yours in 149-150 on the stop with my small motor. will the car repeat back to back with out changing the timer? what is the cruise RPM and does it old that RPM while on the stop?

 

I'm lucky enough to have a car that can runt SST or SG... I prefer SST, but not all events have SST races, so I run SG..

When running SST, I launch at 4000 rpm, come on the stop at .25 seconds, rpm settles at about 4300 and will rise to about 4450 - 4500 depending how long I'm on the stop.. However, I believe I could adjust that to zero increase, but dont think its important enough right now to mess with..

The video above was a SG race this last weekend... I increased the launch RPM from 4000 to 6300 to improve the reaction time... I have it set to go on the stop at 1.25, which means its a fun ride for a second...

 

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I pulled off the nitrous and it's a pig, having all kinds of trouble right now.

We went from 6 psi to 5.25 and it liked it.
Wheel speed went up, 60' went down.
Only have 2 full runs, so that doesn't mean much, but at least it did what I expected.
Won't go below 5, and we knew it would be slow, just not that slow.
So we found a grid issue, and I'm rebuilding the carbs myself.
It's fast enough to qualify, so that's all that matters.


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so you are thru the 60 ft clock under power? my 60 ft is all different because I come on my stop at .1 shift to high gear at .2 and am on anywhere from 3 3.5 but I and hold 4300 all day long you will never predict if you can hold RPM on the stop. something else you should be looking at is your tune up if its having major swings like that with weather you are prob missing the tune up. last but not least how are your reaction time are the consistent or is the car pulling the wheels up on some launches and on others the car is moving forward.
what tire are you running in one of the videos it looks like the sidewall is rolling over it self is it a stiff sidewall?

 

so you are thru the 60 ft clock under power? my 60 ft is all different because I come on my stop at .1 shift to high gear at .2 and am on anywhere from 3 3.5 but I and hold 4300 all day long you will never predict if you can hold RPM on the stop. something else you should be looking at is your tune up if its having major swings like that with weather you are prob missing the tune up. last but not least how are your reaction time are the consistent or is the car pulling the wheels up on some launches and on others the car is moving forward.
what tire are you running in one of the videos it looks like the sidewall is rolling over it self is it a stiff sidewall?

The tries are MT ET Drag Slicks... not stiff sidewall... 32-14x15

Here is a pic of my Race Pac for 4 races in Vegas... I think its pretty consistent down track...

 

its looks flat on the stop I personally run 7.5 lbs in my MT.
do you monitor trans temp? we can generate alot of heat while on the stop could be things are getting hot and picking up et that way. do you cool the trans with a fan or anything? will the car repeat on the stop back to back runs and if you take say 1 second out of the timer will it run the # ?

 

Just a quck update for those following this post...

My last race at the Sacramento Nats ended in parts breakage..

I had two TNT passes with the 60' within .010 and then the pinion gear snapped in half on the next launch in Q1.

It sucked because I didnt get to race, but atleast I got a grade point...

 

You gotta cool your car off at least half hr 45 min or you'll break parts