Spins on the flats

[NathanStewart]

Ask guys who spin at El Mirage & you'll get "I hung with it to long" or "it happened before I knew it" type answers a lot of the time.

I had both of the above happen to me while driving Skip's roadster this year.  We could write a book about the changes we made over the year but my first spin (in competition) was largely a "front end" spin and I drove the car too aggressively and knew the spin was coming.  The spin was slow and fairly controlled.  We made a major change after that by locking out the rear suspension making the car solid in the rear.  The next month the car went straighter than it ever had until it snapped left and spun.  This second spin was a "rear spin" in that the rear tires broke loose (could see rpm spike in data log) and the back end of the car came around pretty quickly.

IMO there are too many differences between cars to come up with a valid theory as to why cars appear to spin a certain direction most frequently. 

[Jack Gifford]

... I do know the 180 degree power turn does the exact opposite with the nose of the quick change. It actually shoves the nose down...

I can't agree with that; as long the resulting torque on the axle(s) is in the forward direction, the resisting force (on the housing) will be to the rear.

[tauruck]

After close to 30 years in the timing venue I have seen more spins then I can remember. But it many cases a spin is caused by over correction when the vehicle is drifting to the side of the courses and the driver tries to correct and doing so over corrects. This results in the spin.

There's your answer.

[Ron Gibson]

"for every action, there will be an equal and opposite reaction"  If force at the front of the tire is moving down (forward direction), the force at the front of the housing (pinion) has to be up.
No dog in the fight but I did stay at a Holiday Inn Express 

Ron

[kustombrad]

I was telling Pete about the quick change in my friends sand dragster and how the car stopped carrying the front end after the install and almost plowed the 100 yds.. I could be and probably am completely wrong on that one. Yes, spins can happen no matter what just because of the tire spin, all I was commenting on was how many go right because of the right tire being unloaded by engine torque. I'd still do the sway bar deal, tighten it to take the slack out of the bolts and fine tune it from there. The solid cars will continue to haul butt but it has to be a smooth surface as any bumps will unload the chassis and cause instant tire spin. It's pretty cool seeing all the comments and different ideas on here and I love being part of this group! Hope to meet more of you this next summer! Brad

[Sumner]

... The solid cars will continue to haul butt but it has to be a smooth surface as any bumps will unload the chassis and cause instant tire spin. It's pretty cool seeing all the comments and different ideas on here and I love being part of this group! Hope to meet more of you this next summer! Brad

Take a look at Sparky's old lakester and it accelerating with a solid rear (runs a torsen though)....

https://www.youtube.com/watch?v=PtGmGTHK6qc&list=UUxFiJQoy2NEbltvkvT2q71g

.... try not to do this....

https://www.youtube.com/watch?v=fPnvgj1Bdgk&list=UUxFiJQoy2NEbltvkvT2q71g

..... The car later ran over 300 and got him in the 300 mph club  .  We've never been able to accelerate like that with the Stude and it is sprung and has almost twice the weight and about the same HP.  With a 1.93 first and a 2.47 rear never more than 50% throttle in 1st and about the same in 2nd.

Sumner

[jl222]

  The 222 Camaro runs a locked rear end and suspension and has run  280 mph at the 21/4 and 294 in the 1st mile
when it blew just before the end of 1st mile.
 Have to ease into throttle as wheel spin will cause a spin and the rear comes around to right.
 Adding new spill plates and spoiler flap should help acceleration and spin recovery.
 If you watch our videos in build diaries you can see Troy saving a spin a couple of times at El Mirage. I believe its because of his faster reflexes [ I always spin ] You can see Troy moving the wheel back and forth quite a bit.
 Anyhow I wonder if faster steering would help me catch the spin faster. Check out sprint cars, just reading that they have a 6-1 ratio. Not that fast for Bville but faster than what we have.

              JL222
 

[Rex Schimmer]

Just to through some thought on what Stainless said about his lakester and streamliner.

Stainless said "The lakester has spun left and right... the liner went left." Remember that in his lakester the engine is mounted cross ways to the chassis so engine torque has no effect on drive wheel loading and in his streamliner the engine is (was) behind the rear axle and unless it had a reverse running engine engine torque would unload the right wheel therefore spinning left!

Rex

[kustombrad]

If it unloaded the right, it would plant the left and go right.

[Rex Schimmer]

Brad, you are right! I stand corrected, as I said on their liner with the engine behind the axle the torque load would be opposite a normal engine so the spin, if caused by engine torque, would be to the left.

Rex

[kustombrad]

My initial comment was cars spinning to the right because of the right side tire unloading under engine torque. Tires spinning can make it spin any direction, but my comment was the right rear unloading under torque just enough the push the left down and make the car go right. It happens way more than to the left if you look for spin videos on YouTube.

[kustombrad]

To prove my point in the simplest way I know how, here's some in car video of the most famous car out there. This is what happens when the rear end twists and loads the left tire. Watch how during the pass and the motor is making power, he has to compensate and drive the car to the left. If both tires were planted evenly, this wouldn't happen to just one side. Then notice how the steering wheel goes dead straight as soon as he shuts it off. If it was wind blowing from the left, he'd still be turning to the left. On the last video, look how much input to the left that is happening right before the  crash.

Replay XD1080 The Fastest Camera on Earth: Speed …: http://youtu.be/B7tf6nGA1U4

2013 Speed Demon Run: http://youtu.be/T8oyW61fLCI

Crash dans le désert à près de 600 km/h (POV): http://youtu.be/oKpQDWtZkFo

[LSR Mike]

look at link below and comment... I'm 3rd up in the red roadster...nose went down in a soft spot, butt started to swing around, yep, I over-corrected and pulled the chute and a couple of buttons out of the seat padding.

http://www.landspeedracingvideo.com/videos/spins.wmv

[kustombrad]

Wow! That was some crazy, seat puckering videos! I was never saying they all spin to the right (but since we're watching that video, how many went right?), I'm saying that particular issue can be fixed easily enough, so you can get farther at speed until your NEXT set of issues arises! If BOTH tires are planted EVENLY and spin, it's a crap shoot on which way it'll go. I still look at this as a really long drag strip and always will. Obviously, you can't launch the same way, but the car twisting and unloading the rear tires on a dragstrip at half track is very much relevant in THIS sport! The drag guys got tired of fighting it and have numerous fixes for that problem without adding weight. Adding lead to one side or another is just a band aid for the actual problem ( you'd need to change the spring rate AND revalve the shock for the weight difference on how the suspension reacts), plus the added weight slows the acceleration of the car. Fix the problem first with something as simple as an airbag and add weight when the car hits it's wall/air barrier and unloads the rear end (i.e. spun the tires at 170mph, added 200lbs and went to 190mph before they spun again) and go to the next thing.

[Peter Jack]

Brad, I really like your idea of adding a little wedge to the chassis to even the tire traction loading. We use it all the time in oval cars to do the same thing but didn't think of using it for a straight line vehicle. Sometimes you have to look a little closer to see the obvious. 

Pete