Spins on the flats

[kustombrad]

That AND rear tire roll out Pete! In roundy stuff that's also a huge part of car stagger. I've seen LOTS of guys checking air pressure but never roll out/tire circumference to see if they're the same size. If they (tires) say 80 lbs air pressure jack it up, put them at 75 lbs and measure the circumference of the tire. If ones a 1/2" shorter add air until they are the same, then fine tune it. When you're in line waiting, keep the sun OFF your tires because the heat expands the air and will make the tire bigger. This racing is like any other... It's all about the DETAILS!

[tortoise]

Brad, I really like your idea of adding a little wedge to the chassis to even the tire traction loading.

I'd think the more anti-roll you have, the less wedge you need, and the more consistent the handling with varying levels of force applied during the run. You also need a torsionally stiff chassis, but LSR chassis are a pretty stiff as a side effect of being crashworthy.

[Glen]

Brad is so right on the roll out, we had 4 new MT tires last year 2 were different

[kustombrad]

My deal isn't really wedge, it's like Tortoise said and more about anti roll and even weight on the back tires at all times.

[Peter Jack]

I don't want to get into a pi$$ing contest but I will add this. The anti roll bar is simply another spring and if you add preload through an anti roll bar you are jacking weight using a different tool.

I probably screwed up by A$$-u-me ing that everyone would be checking roll out to ensure it was equal. I've always bought tires in pairs and then in the good old days with bias ply tires if one was slightly small we'd over pressure the small tire and put it out in the sun to stretch it.

This is a really interesting debate with a lot of variables.

Pete

[tortoise]

I don't want to get into a pi$$ing contest but I will add this. The anti roll bar is simply another spring and if you add preload through an anti roll bar you are jacking weight using a different tool.

Agreed, but with stronger anti-roll, you need less pre-load, as measured statically on a scale.

[kustombrad]

It's all good Pete!  As far as being another "spring", that's kind of a yes/no thing. Tortoise said it perfectly. We're not talking about a little 1/2" twister like the old days. We're talking about a beefy bar with little to no (unless you have 4000hp) twist that's basically making your rear think it's on a swingarm, if that makes sense. As soon as the torque starts twisting and raising the right side, it's essentially raising the left the same amount and keeping both tires evenly on the ground. If it still twisted a bit all it takes is literally an 1/8" turn to even it out. This is very simple technology (and relatively inexpensive) that works. I'm not sure why the land racing community is afraid of stepping out and trying stuff that actually works. Just because we're "grass roots" doesn't mean we have to be behind the times!

[kustombrad]

And for guys with leaf springs, "Caltrac" bars made by Calvert Racing are really awesome!

[Sumner]

And for guys with leaf springs, "Caltrac" bars made by Calvert Racing are really awesome!

I've had them on my pickup for about 15 years but they haven't done anything to stop the salt damage  ,

Sumner

[kustombrad]

Hmmmmm... I'm really not sure what to say. I did some more homework on Speed Demon because the twist thing was bugging me on THAT particular car. Sure enough, they did it right on the back of that car and DID put a swaybar on it. I guess crazy amounts of horsepower will twist just about anything! I'd still like to ask George why it pulled so hard to the right though.

[grumm441]

This is Lionel West in Australia, spinning left

https://www.youtube.com/watch?v=jz74cgTYvlo

This is the in car
And if you look real close at about 1:39 you can see our new timing equipment

https://www.youtube.com/watch?v=kno02BFLxd0

So based on the evidence of one video........
G

[kustombrad]

Yep, it spun left!   

[vintageracecar]

KustomBrad,

Personally I think you have a very valid point with your observations. But using the Speed Demon runs
and specially the one where it crashed, is not really a good example.

Check out this video, called "Something Evil This Way Comes"

https://www.youtube.com/watch?v=XoriCmQD5zY

Look at about 12.25 and watch the rear camera.

Look at about 15.15 and watch the rear camera.


Then watch the video you had posted before.

http://youtu.be/oKpQDWtZkFo

Notice a difference in the runs?
Look at the following pictures from George's last run. (from Mike Cook's Shoot Out Page)






Look at the last picture and zoom in real close on the tires.





What do you think? I think the Traction Control was just not set up correct on his last run. 
In the video "Something Evil This Way Comes" George says "It's so easy to drive this car at 429 Mph",
well it was not on this run.
Really enjoy this Thread. Let's hope we all learn from every bodies feedback.

Mike

[Sumner]

.....What do you think? I think the Traction Control was just not set up correct on his last run. ....

In George's interview in BRN he said when the car is up to that speed (high 300's) he is the traction control (surprised me) and he said that it was a combination of more HP than previous runs, slick spot on the track and him being too aggressive with the throttle.

Again you guys are missing a lot of good info by not subscribing to Bonneville Racing News.  It is the best thing out there for land speed racing.  This site is great and also invaluable but you won't find the information here that the in depth articles and interviews there will give you.  They can really help you regardless of if you are a car or bike person.  Subscribe now and also order reprints of a number of the past interviews that are available and have info you would probably never get even talking to the bike or car owner,

Sumner

[kustombrad]

I received a great email from Tom Burkland about Speed Demon. My using that car as an example was both right and wrong. I still stick to my theory and observations of torque twist loading one tire but it's not really a fair analogy of George's car. Tom reminded me that it's essentially a long, narrow "tricycle" with no front axle. Without a "standard" front end to use as leverage the car will always be twisting regardless of anything being done. Was George driving left to keep it from going right? Absolutely! But by the design of the car there's nothing that could be done to change that apart from mounting the engine sideways and having the engine torque go front to back instead of side to side. When I started this thread it wasn't to point at or pick on one particular person, it was to comment on why I see lots of cars spin one particular way. If a car is planting both tires "evenly" and you're being easy on the gas, it won't blow the tires off (and potentially spin) until it hits its air "wall" and unloads the tires. Only then should you be adding either physical or air (down force) weight. LOTS of people forget this is racing and (or maybe it's just me) you want to ALWAYS be out thinking your competition. Using a peg-leg rear end or adding a bunch of weight "just because" is just some band aids for the actual issues. Fix the "actual" issues and seriously go after some records!