The Road to Drag Week 2014 - August 24

[jayb]

After putting up this post last night I checked the datalogs from the track on Saturday.  One thing I found was that the converter's stall speed was about 500 RPM lower than I wanted.  Definitely some power left on the table there.  Today I packed up my spare converter and shipped it off to Neal Chance Racing converters; they are going to modify that one to get the stall speed where I want it.  I won't have it back in time for this weekend, but I should be able to get it installed before Drag Week.

I'm thinking more and more about new tires, too.  But I'm not sure which way to go.  I think I'll put a post in the technical section about that...

[jayb]

Has anybody guessed an ET yet? I just plugged in my guess's into the wallace racing calc and it says 8.74@159. 

I wish!! LOL!

[Brutalbob]

Jay, I've never been happy with older slicks. On the car I sponsored we changed them every 2yrs. If you test with the current set this weekend and it doesn't work out, then you have another added problem. Better to eliminate that now rather than later. You can always use the old set another time when it isn't as important as Drag Week. Just my opinion. You know better then anyone what goes into prepping for Drag Week, eliminate anything you can now so you don't have to deal with it on the road!  Good luck Jay, you deserve it. Bob & Nahla

[cjetmech]

Has anybody guessed an ET yet? I just plugged in my guess's into the wallace racing calc and it says 8.74@159. 

I wish!! LOL!

Hey nothing wrong with being optimistic its just mathematics,,,,1000hp/3200lbs or so, perfect air,no mechanical probs, piece of cake!

[cjshaker]

Just an observation, but that right tire is not squating and grabbing near as much as the left. That probably has a lot to do with your spinning the tires off the line. No experience with 4-links though, so it's up to others to determine what causes that.

[jayb]

That's just the torque reaction, same as any other car.  You are right about that Doug, I didn't notice that before; great observation.  We added spring pressure and pre-load to the right side to try to compensate for that at the track, but maybe not enough.  I did add more preload on Sunday, so next weekend we'll see if that helps...

[Cyclone03]

Jay the car looks awsome!

Also no experience with a 4 link ,but with the weight balance being so heavy up front don't you want it leaving more like the Mach 1 than a current pro stock car ,more on the rear bumper than the front?
Or was the track so poor it was just spinning?

It doesn't look like it's moving any "weight" at all.

[Cyclone03]

Jay can you prep your drive way for some 60ft testing?

You have the "chicken coop" maybe now you need a "stock yard" or you could call it "the milking pad" ?LOL

[Rory428]

Frankly, I think playing with the 4 link is pretty much a wasted effort if you are blowing the slicks off on launch. For me, fresh slicks would be my first step. My SB 85 Mustang uses 9x29 Hoosier slicks, which also happen to be 3 years old (with plenty of wear hole left). They worked great when new, and fairly decent the 2nd year, but when I took the car out in July, the car spun badly, and the previous 1.37-1.38 60 foots have gone to 1.5s, and low 1.6s. I am dumping the clutch at over 6000 RPM, but I also have less than 500 HPand only run mid 10s. Time for fresh rubber Jay!(and me too.)

[jayb]

I've pretty much come to the same conclusion, Rory.  Do you run tubes in your Mustang?

[TimeWarpF100]

I've pretty much come to the same conclusion, Rory.  Do you run tubes in your Mustang?

Tires Tires Tires.

Many years ago we would always check tires with a durometer. Very surprising even after one season how much the tire would change.

Pick yourself one up,  I would be curious the difference between a new set and your current.

http://www.jegs.com/i/Intercomp/541/360092/10002/-1?CAWELAID=1710735231&CAGPSPN=pla&catargetid=230006180000848220&cadevice=c&gclid=CN7Ino6QsMACFZSFfgodm2YAeQ

http://www.jegs.com/i/Moroso/710/89585/10002/-1

http://www.summitracing.com/search/part-type/durometers

Really looking forward to what you run and how you do this year.

All the best!

[cjshaker]

That's just the torque reaction, same as any other car.

Frankly, I think playing with the 4 link is pretty much a wasted effort if you are blowing the slicks off on launch. For me, fresh slicks would be my first step.

I understand the torque reaction. And while I agree with Rory that new tires would help, if the right tire is not planting it will unload and a new tire will not help. That leaves one tire with weight transfer for traction. Impossible on a 900+hp car. It looks as if a combination tire/preload adjustment is needed.

Edit: That left tire seems to be doing all it can to hook. It wouldn't be wrinkling that severe if it wasnt.

[machoneman]

Edit: That left tire seems to be doing all it can to hook. It wouldn't be wrinkling that severe if it wasnt.
[/quote]

I notice that too: the left tire seems to be wrinkling just right and also seems to be hooking well.

Still, as Jay noted early on, the lack of traction at that crappy track has a lot to do with poor 0-60; times and can easily fool one into making changes perhaps not needed. In a sense, one really needs to tune a car's suspension 1st on a good hooking track for a baseline, then tune for a crappy track as he would encounter on the Drag Week tour...and not the other way around. Noted too not a lot of front end lift but again, a bad track can do this. JMO!

on edit: the durometer check is a great idea. Just as one baselines a suspension, with new tires run a check and log it for future reference and comparison as the tires age. 

[Rory428]

Jay, I don`t run tubes with either car. Maybe I have just been lucky, but since I stopped using tubes almost 20 years ago, I have found that by using the old dish soap trick on the inside of the sidewalls, both the Hoosiers and M/T slicks tend to hold air very well. The Fairmont has much bigger slicks, currently 13x31, have used 14x32s for many years, and on a 14" wide wheel, I normally run 10-10 1/2 psi, the Mustang usually has either 9x29 Hoosiers, or 9x29 1/2 M/Ts on either 8 or 9" wide wheels, at 12-12 12psi. Funny thing is, back when I ran a C6 (with transbrake), I had to run much less air pressure to make the car hook well, as low as 6 or 6 1/2 psi with the 14x32s.The natural rubber M/T tubes I was using were quite heavy, much heavier than a normal tube, close to 10 lbs each. I would balance the slicks at work, and after a few races, I would get a vibration, that got more severe as I made more runs. I checked the balance again, and the imbalance had gotten way off. It appears that the tubes had been moving around inside the slick, and wadding up, which put the tire out of balance.So after a while, I wound up having to remove the rear wheels, let all the air out, and then shake the slicks with the wheels laying flat on the tire machine, which would allow the tube to "flow out" evenly, so that when it was aired up again, it would be back into a balanced condition again. But I had to go thru this routine about every 20-25 passes. After talking to several Stock and Super Stock racers, it was almost unanimous to run tubeless. With new slicks, I normally can let the car sit the usual 2 weeks between races with no need to air the slicks up, the Hoosiers on the Mustang normally hold air for 2 months of sitting! Over the years, I have had some slicks lose a couple of pounds over 48 hours, but normally quite a bit longer. One thing II did notice, was if you dismounted the tires, and re mounted them, they normally held pressure less well than before. I`m guessing the stress of breaking down the sidewall beads caused some minor sidewall damage, causing air to escape easier thru the sidewalls. So I normally install new slicks, and avoid dismounting them untl they are due for replacement.

[jayb]

Thanks Rory, the consensus I'm getting here and also from talking to some local guys is to run tubeless.  I tried that in 2007, and had one tire that would lose 1 psi every half hour.  It was a huge hassle, and cost me several times when there was a delay in the staging lanes and I had to sit there for an hour before going to the line.  I did use bead screws in the wheels, maybe that was a mistake?  Do you put screws in your tires when you run tubeless?