[ZNova]

My 60 fts are inconsistent, do I need new rubber?

Made five runs today and my MPH was consistent but 60' times were all over the place:


60'_______1.85____1.73____1.66___1.79____1.80
1/8_______8.03____7.91____7.81___7.96____7.98
MPH______85.5____85.6____87.1___87.0____86.9


After the first run I left at about 1200 RPM, anything higher than that and the tires just broke loose. But even at 1200, they still spun on the last 2 runs. I am running MT ET Streets 235/60-15 with 14 psi on all runs except the first (16 psi). I also running slapper bars with 0.75" gap and 3 deg pinion angle. Are my tires toast? I have 45 - 50 runs on them, maybe 3000 miles on the street from Aug 2007 to present. There is plenty of tread before is gets down to the wear indicators, but do I need to retire? The last four runs were with the same launch rpm and in the same lane. Why do my 60' times vary so much? How many runs are these tries usually good for?

 

[Real McCoy]

Was the track any good? If everyone was was hooking up and you were not then it could be your tires or your chassis. Just because the chassis worked a year ago doesn't mean it is good today. Shocks go away, stuff gets rusty and stiff or binds over time. RM

 

[ZNova]

Was the track any good? If everyone was was hooking up and you were not then it could be your tires or your chassis. Just because the chassis worked a year ago doesn't mean it is good today. Shocks go away, stuff gets rusty and stiff or binds over time. RM

I didn't hear of any issues with the track, it looked like most cars were hooking up good. I have about 5" of front suspension travel and am getting plenty of lift at launch.

I guess the real question is when traction goes on the ET Streets, does it go all at once or slowly? My third run yesterday was my best ever, I did everything the same the next two runs and my 60 fts went in the tank. My last time at the track was similar, one very good 60 ft and two very poor ones. Right now as I see it, my options are:

- change ET Streets (I would go to 255/60-15)
- go to a smaller gap on the slapper bars to make sure they are contacting the sring eye
- change to Cal Tracs
- change rear shocks
- add more pinion angle (currently at 3 deg down)
- go to a lower pressure (but I am already at 14 psi)
- other??

I just don't which option to choose at this point. Any suggestions?

 

[levisnteeshirt]

sliders

i'd look at a set of sliders and i would try giving the front suspension about 2 inches of travel. My theory is , if the torque of the rear axle is allowed to raise the body only , then its not being used to force the axle downward to plant the tires harder,,,, it worked for me :yes:

 

[ZNova]

i'd look at a set of sliders and i would try giving the front suspension about 2 inches of travel. My theory is , if the torque of the rear axle is allowed to raise the body only , then its not being used to force the axle downward to plant the tires harder,,,, it worked for me :yes:

That's the first time I have heard that theory. With the front end coming up it seems like the weight transfer would help traction, not hurt it.

 

[Dan_Lebherz]

If you aren't mini-tubbed I think it would be tough to fit a 255 on there.

Maybe someone running in front of you on the last two runs dragged some water up to the line. It could be a bunch of different things.

I went on Saturday and b/4 they prepped the tack I had 1.90-1.98 60 foot times on the first 3 passes. The track started getting some heat into it and they sprayed some VHT so the next 3 passes she hooked pretty good for 1.67-1.70. Then I pull up next to a 2008 Corvette, everything is the same, she spins and I get a 1.81 60 foot, for no apparent reason.

Out of 9 passes total, she spun on the first 3, hooked on the next 3, smoked the tires once, then hooked on the last 2.

That was OK, I still smoked the vette with a wagon.

 

[chevyIIheavy]

thats funny im having the same issues with my mt drag radials they 235s also ive been told by many that im overpowering the tires i cant get my car to hook at all on them i 60 ft the same as you im running the heidts 4 link in my nova sad to say im not really impressed with it. ive set pinion angle down but it still aint helpin i guess maybe i need to start with the springs next maybe stiffen them up a little :yes: as for you i would defentily put more pinion angle in it (down) i would switch to cal track bars although the slappers are fine too it also depends what are you doing your burnouts at i do mine at 5000 grand ive also done them a lower rpm to see if that helps how long are you doing a burnout doesnt need much

 

[ZNova]

it also depends what are you doing your burnouts at i do mine at 5000 grand ive also done them a lower rpm to see if that helps how long are you doing a burnout doesnt need much

I do short burnouts at about 5000 rpm. Everything I've heard says the ET Streets don't hook as well with long burnouts. How many runs do you have on yours? I am just wondering if street driving has hardened the tread to the point they won't hook anymore.

 

[67ChevyII]

If you aren't mini-tubbed I think it would be tough to fit a 255 on there.

Hmmm... I'd like to know if these would work in a stock 67 also.

 

[chevyIIheavy]

I do short burnouts at about 5000 rpm. Everything I've heard says the ET Streets don't hook as well with long burnouts. How many runs do you have on yours? I am just wondering if street driving has hardened the tread to the point they won't hook anymore.

i have maybe 30 passes on them i drive to the track i live near california speedway so i drive to there and maybe to work which is in rancho cucamonga sometimes . what is weird to me is after i do a pass i have little rocks stuck to the tires but they dont feel hot or stickey they actually feel dry i do short maybe 5 second burnouts at 5000 or lower im still working on that to i dont even know if my tires are broke in yet

 

[levisnteeshirt]

i might be totally wrong , but ,

That's the first time I have heard that theory. With the front end coming up it seems like the weight transfer would help traction, not hurt it.

In my way of thinking , ( but i never messed with drag radials ) you can harness the tortional twist of the rear axle to do 2 things. Raise the front end and it will transfer the weight to the back but then the car isn't moving forward its moving upward, or limit how much it can lift the body and apply the rest of this energy to the chassis so that the leverage of the traction device your using will force the rear axle down to apply more pressure to the tires to hook up. With just shackles on the rear this may not work though. I moved the pivot of the rear shackle forward approx 1.5 inches with longer shackles so the spring would rock forward on a downward motion. It kinda worked like poor mans floater but not as effective as a real floater/ladder bar set up i'm sure. I don't know how doing that would effect handling on the street but my car hooked at a track not known for good prep.

I was hesitant to add ladder bars or a 4 link to my car because those guys weren't hooking as well as i was using traction bars. I didn't like having a tubbed car with traction bars and mono-leafs but it was doing the job

 

[ZNova]

Hmmm... I'd like to know if these would work in a stock 67 also.

My other set of rear tires are 255/60-15 BFG Radial TAs on 7" rims with 3.5" BS. I have a Ford 9" that is 1/2" shorter than stock on each end and the fenders have been rolled at the top. I also had to cut a small bit of the fenders at the corners, but nothing that is visible from the outside. It is a tight fit and you need to double check all your measurements but they do fit. No problems with rubbing, even with a 1.5" drop on the back and 2" drop on the front.

 

[MiniTubbedNova]

The sidewalls could be shot. not planting the tire the right way.

 

[Dan_Lebherz]

I have 235X60X15s on 15X7 Ralley Wheels with 4.25" BS. My axle is stock width. I could not fit anything larger on here. The first gens have that styling indentation in the quarter panel that the second gens do not have. this limits room on the outside at the top.

I have kept these tires on the car since the middle of last year. Prior to that I would change at the track and then change again for the ride home. After 7 years of that I got tired of wearing out lug nuts. Now I just keep these on all of the time. I think I got the tires mounted near the end of the season of 2007, so I have over one season on them.

 

[teddisnoke]

C'mon, Bob. Lets start cutting and really get a set of rollers under you!!

I think its a water issue, being dragged up to the line. I've had it happen many times there at the track, most recently my last outing there. Don't sweat it too much. I'm still blown away about how many miles you run to get to the track to run!!! Share that with eveyone, and they will all be humbled!!!

200 mile round trip??

 

[bowtie0069]

Raise the front end and it will transfer the weight to the back but then the car isn't moving forward its moving upward, or limit how much it can lift the body and apply the rest of this energy to the chassis so that the leverage of the traction device your using will force the rear axle down to apply more pressure to the tires to hook up.

On a small tire car you HAVE to make it transfer the weight or it isn't going to hook--limiting the front end travel with a leaf spring/small tire car isn't going to help anything unless you are trying to control wheelstands, and I don't think Bob is at that point yet!
Dale's car worked great on that tire with ZERO traction aids! It squatted hard in the rear, which doesn't work in some cases, but it worked just fine in his case. His front end came up very quickly, the rear went down, and it hooked. 1.6 60 foots on that tire with only 3.08 gears shows you it's possible to make it work.
Do you have adjustable snubbers on the bars? Try tightening the gap to where they actually pre-load the spring a bit and see what happens. If it worsens, go the other way.
And Bob, leave the girlfriend in the stands...not the passenger seat! Did you have her in the car Sunday? Kinda hard to be consistent making a run with a passenger, then another without....

 

[levisnteeshirt]

reaction times ??

whats your reaction times doing ? Limiting my front wheel travel made a huge difference there too. I had my car usually in the .00 range with a footbrake.

Eh , take anything i put on here with a grain as i think anybody should and try different things and see what works the best for your car.

 

[bowtie0069]

whats your reaction times doing ? Limiting my front wheel travel made a huge difference there too. I had my car usually in the .00 range with a footbrake.

That won't have any effect on E.T.--he's just trying to get the car down the track. After the car is working, he can work on the driver. A decent driver can make any car cut a light--ever read the Mr. Dirt series? Here's a brief selection of tips from Bret Kepner--"Mr. Dirt"

Tips From Mr. Dirt

NHRA race announcer, drag-racing historian, TV host, and event emcee Bret Kepner of St. Louis, a.k.a. Mr. Dirt, has been bracket racing since 1990, winning many thousands of dollars in the process, including a spectacular winning performance in a rental car he had acquired earlier on the day of the races, taking home $5000. He favors renting Tauruses and Sables because they're cheap and very consistent from place to place because they are all alike. He races 40 to 50 times a year and wins $250 to $800 every time.

Kepner conducts a free bracket-racing-basics school at Gateway International Raceway near St. Louis, "The kids won't come back if they lose early, so we teach them enough basics to help them win." He has developed a whole range of dos and don'ts for newbie bracket racers who want to win consistently:

Don't stage deep: Many racers roll their cars so far forward in the staging lights that the first set of lights goes out, figuring on a few inches of advantage at the start. Kepner says shallow staging, just barely blinking on the second set of lights, is the better way to go.
Always place the car in exactly the same spot left to right in the lane.
Always torque it up: With a rented car or your own automatic car, brake against the torque converter after staging right up to about 1800 rpm, and then lift off the brake to leave. He says modern computers understand that better than just stabbing the throttle from an idle.
Always turn off the traction control.
Leave it running: If you're racing a box-stock rental car or your own late-model stocker, let it idle all day long between rounds. It will be thermally stable and very consistent in output.
Don't be afraid to redial: Read what your time slip is telling you, and if your car is getting quicker or slower, ask the man to change your dial-in number. No sense breaking out or giving away a 10th of a second to the other guy.
Air is free: If your car's performance is drifting, add or subtract air pressure from the drive tires. One pound equals 0.001 second either way.
If you're renting, always buy the insurance: It's the rental company's car. Cover your butt for $12

 

[ZNova]

C'mon, Bob. Lets start cutting and really get a set of rollers under you!!

I think its a water issue, being dragged up to the line. I've had it happen many times there at the track, most recently my last outing there. Don't sweat it too much. I'm still blown away about how many miles you run to get to the track to run!!! Share that with eveyone, and they will all be humbled!!!

200 mile round trip??

Thanks, Dale. It's about 180 miles RT. To run on Thursdays, I have to take a 1/2 off to get there at 4 PM. Otherwise, it's just not worth it. Even then, it can get so crowded, I'm lucky to get 3 runs in somethimes.

 

[ZNova]

And Bob, leave the girlfriend in the stands...not the passenger seat! Did you have her in the car Sunday? Kinda hard to be consistent making a run with a passenger, then another without....

Mike, Cindy has yet to ride shotgun :no:. I told her she had one chance because after the first run with the new motor I knew they would not let me run without a helmet or with a passenger. She said thanks but no thanks. She is a trooper, but still not sure why all the fuss about 1.65 vs. 1.80 60 fts or 0.20 difference in ET :no::no:.

I will try putting a preload on the snubbers and see what happens.