[NOS327]

I'm racing an event this weekend in a true radial class. My car has been 1.44 60' and 10.48 @ 128 on Quick Time Pros. I'm hoping I can make it work well enough on true radials to only fall off a second, but given the results from a few test hits, I'm searching for answers.. I've added some weight over the rear, pulled some timing at launch, lowered launch RPM to basically off-idle, raised and lowered tire pressure, and am not sure what to do with my shocks. Since they don't hook hard, would you loosen shocks to get the vertical force loaded harder or would that bounce the tire? It's a footbrake car. On sticky tires, my car works the best when the rear shocks are nearly full stiff and fronts are near 50/50. I've got adjustability all the way around, any tips would be appreciated.

Here is the event I'm racing if anyone within a few miles of Wichita KS is interested:
www.truestreetshootout.com

or I made a thread here about it: http://www.chevelles.com/forums/showthread.php?p=3182239#post3182239

Thanks in advance for any advice,
TJ

 

[Chevymetal]

That is a really nice looking '67 :thumbsup:

 

[VinceS427bb]

that sounds like a tough class
tire pressure to keep full tread flat not cupping in center
like you said weight in rear of car
i'm sure there are some real radial that hook better than others
what type of rear suspension are you running???
have no-hop bars or other to transfer weight to rear tires???

 

[pancherj]

Your car makes more power than mine, so maybe my experiences will not help...but here it goes:

1) Soft front shock settings and soft on the rears
2) 255-60R16 tire...Sumitomo HTZ. I ran them around 20psi and managed a few 1.8 60' times
3) Load the converter as much as the brakes can handle. Let off brakes and slowly roll into throttle. Don't try to leave at an idle. That never worked for me.
4) More weight over the rear tires. I had 4-80lb cement bags in my trunk.

Sounds like a fun class. Good luck!

 

[big_orange]

LOVE real street tire racing...makes it a drivers class!
I grew up draggin on plain old street rubber, in fact, been racing for 19 years and never made a pass on a true set of slicks til about 3yrs ago. What Jeff said above worked best for me as well, no matter what vehicle or power capabilities......get it up on the converter as much as you can, when the lights come down, leave your foot where it is on the gas, let off the brakes, roll out a few feet then roll into the throttle. one small slip of the tires in 60 feet = 2/10. Experiment with tire pressures, sometimes a true radial will work better with a bit MORE pressure than normal....whatever it takes to get a good, even patch across the tire is what you want. For a burnout, normally a 5 foot punch is enough to clean the tires off and get a LITTLE heat in em- that also worked best for me.
Ive managed consistent low-mid 1.7s on a 295-50/15 BFG t/a radial (NOT drag radial) with a best ever of 1.68, in my 66.
we're actually putting together another street tire shootout at the local track...it was a big hit last fall and a lot of fun!
Heres a vid from last fall, on the same exact 295-50s....10 years old and completely worn out. low 1.8 short times, a best of 7.32 and [email protected] This was a mid 7.5 pass @99.
http://youtu.be/fSwRFeCfAtk

 

[NOS327]

Thanks guys, I'll test the no additional gas at launch technique and soften the shocks

VinceS, I had Art Morrison upper relocators, but took them off and improved 60' on sticky tires (1.46-1.48 with them on, 1.44-1.46 back in stock holes). Car is rather low, still rears up a bit. Being a footbrake car, I was wasting a lot of motion just staging the car, see this video (http://www.youtube.com/user/NOS383#p/u/21/F6sK-lfiEWg, got to about 19sec in video) so I took them off. If it were a t-brake or a stick car, I think they would have been more effective.

I'm hoping to 60' in the 1.70s and at least get to full power in 2nd gear (th350 car).

I couldn't swallow buying new tires, so I picked up a pair of Cooper Cobra 275/60s and put them on my spare drag lites. Other option was my 255/55/17 on my torque thrusts, they are extremely hard and I figure a little more tread width and sidewall on the 15s can't hurt

 

[big_orange]

cooper cobras are a darn good tire for what youre doing...used a lot of them!

 

[Dr J's Performance]

you need to do whatever this guy does.....and a big old burn out!!!!

this is my heavy junk on a 255/60/15 real radial

 

[NickeyChevelle]

My understanding (from magizines articles) was that RADIALS hook up better when they are slightly OVER-inflated and BIAS PLY hook up better soft?

The Mickey Thompson website says: "Most racers will usually end up with ½ to 2 pound more air pressure in a Mickey Thompson tire."

http://www.mickeythompsontires.com/tech.php?bulletin=s3

 

[Dave427]

I found that BF Goodrich Radial T/A was the slipperiest tire out there, so a friend of mine was a dealer of these Hercules HP 4000's.
#1 they were alot cheaper than a BF Goodrich
#2 they actually hooked alot better

The Cooper Cobra's are the same as a Hercules HP 4000.

Dave

 

[big_orange]

I found that BF Goodrich Radial T/A was the slipperiest tire out there, so a friend of mine was a dealer of these Hercules HP 4000's.
#1 they were alot cheaper than a BF Goodrich
#2 they actually hooked alot better

The Cooper Cobra's are the same as a Hercules HP 4000.

Dave

:yes:

cooper cobra 295-50/15......gone in 10k
identical size bfg- 25k, 10yrs and still on car but about gone.

definitely liked my coopers better though. seems like once you slip on the bfg's you might as well let off and throw in the towel....

 

[thunderstruck507]

a lot of guys say the Firestone Indy 500 are pretty good for hooking. I have only ran them on the front so far but they are definitely better than the BFG they replaced.

Between lack of traction, price, and never being able to buy the darn things I won't ever run a BFG T/A again. Not being able to get a new tire without waiting 11 months is BS.

 

[Doug F.]

Start in second gear?

 

[NOS327]

Start in second gear?

Not a manual valve body, although I have caught myself in a few impromptu street races while on true radials and I find if I get it in second as soon as I can, then I can mat it and drive out on the conveter.

Been contemplating throwing my 3.31 gears back in tho, kind of a lot of work for one weekend deal.

 

[Doug F.]

Short shift into second quick then.

Wish they did something like that here. Would be fun.

 

[NOS327]

Tow up here this weekend, you can stay at my house!

$750 to win, $350 r/u, $150 semis. Primary sponsor for this class throwing in $100 bonuses for best MPH, quickest ET, best R/T (and extra 100 if best r/t is .000).

 

[NOS327]

Well guys, just wanted to say thanks. Took all of your advice into account and it went my way, ended up winning the event running the best pass of the night in the finals, 11.24 @ 124. Field of 16 cars, were 4 of us running 11.50s or better. Primary concern is simply knocking the tires off at launch. The stall/stage the car on the footbrake then only let off the brake while giving no additional gas technique was the key (although made for poor reaction times on .400 pro tree due to slow roll-out). I could roll into full throttle and the 200 n2o kit in 1st gear before 100'. 60' times in the mid 1.80s was the best I could do, which accounts for .4 of the total .7 my car fell off compared to my quick time pros. I tried giving the car just a little power at launch once and it was instant tire spin. Through the three rounds of qualifying I went 11.55, 11.62, 11.50 (these all getting into n2o in 2nd gear), and in eliminations (getting into n2o in 1st gear) went 11.44, 11.32, 11.35, and 11.24 in final.

As far as car set-up goes, I bolted 200# of lead in the back of the car (which probably accounts for a couple of the other tenths), put all my shocks just one click off full loose (fronts and rears), tires at 20psi. I ended up with all my timing back in the motor. Between a couple rounds I brushed some VHT track bite on the tires, but by the time I drove to and through the staging lanes and did a little burnout to clean debris off the tires, it was basically all gone...and although the rules didn't forbid it, the other racers weren't real keen on it.

Anyhow, the videos dont look nearly as impressive as wheels up 1.4x 60' launches, but here's a link to a compilation of our event. My three qualifying passes show up at 0:55, 3:00 (this is the one I actually tried to launch it and spun), and 5:50. All the others were friends of the filmer, so not total coverage of the event.

Thanks again!
TJ