Spin Question

[jww36]

OK guys (and gals), I need some help. As documented in my Build Diaries (1934 Gas Roadster), I spun my roadster at Speedweek. Without ANY warning or indication what so ever, the car snapped left into a spun. I was on it pretty good, so I am certain I spun a tire or tires. MY QUESTION - If the car spun to the left, with a spool rear end, which tire would have broken loose to spin in that direction?

John
#114

[Glen]

With a spool both would break loose, the torque reaction and nosing over when the wheels started to spin and maybe a little driver reaction over steer could have caused it. There are several variables including a cross wind. What mile and what speed were you at when you got the 360 degree view of Bonneville? Hope the car is OK.

[DallasV]

Though I am no expert I am curious about the comment "without any warning". I noticed in your build that the car was very loose, did you add weight? We don't run any suspension, but the first thing that came to my mind was if this is a suspended car maybe if you added weight it loaded the suspension and during the run one side un-loaded. Once again I am no expert just another idiot with an opinion.

[SPARKY]

Remember circle track guys use caster and scrub radius to weight jack their cars to come off the corners better 

[sorry for using camber before]

[RichFox]

The only time my car went around I didn't recognize the warning. Looking back, it was there, but I didn't see it until the car had taken over. It seems that in your question if the left tire lost traction/drive. The right tire would push it around. But I don't have enough experience to do more than guess.

[jl222]

 
  As I commented in your build dairy [observed lots of loose salt on course #1 after meet and before moving course over next day]

  If your left tire was in loose salt your right tire would have more traction driving car left.

                 JL222

[jww36]

Thanks for the input. I just took the car off the scales.
Left front        639 lbs.
Right front       630 lbs.
Left rear          875 lbs.
Right rear         909 lbs.
Total weight of car with driver  3053 lbs. TOO FRICK'IN LIGHT??

[dw230]

Way too light.

Another '33 roadster has a 1/2" steel floorboard.

DW

[Pat Kinne / Salt201]

John - You have to remember IT"S A ROADSTER!!! - speaking from expierence, they do that to you just because - - -.   As Ken Shrader sez " You get a little behind in your steering (even if you don't know it) and these things happen" - All kidding aside - weight can be your best freind -  :-DPat

[Rex Schimmer]

We all need to remember that at the traction limit it only takes a very small offset force to cause a car to spin. I was talking with Neil with the Contrivance Engineering roadster and he was saying that his data was showing a coefficient of friction for the salt of .3 and looking at your rear wheel weights the right rear has 34 lbs more load which would make it generate about 10 lbs more forward thrust which, because roadsters have pretty wide rear axles, could be more than enough to cause you to spin. Adding weight will get you more traction and if you add enough it will get you away from the traction limit where this problem occurs. You will still need to really get your corner weights close.


Rex

[krusty]

John - As I said in your build thread, I think you need a bunch more weight, and probably a greater rear percentage. With the C engine (SB2.2) in the rear-engine car, we're a shade over 3900 without the driver. It hooked up well and ran 254 (all it was geared for).     vic

[Roadster943]

   I would like to see Glens question answered, how fast were you going and also what gear and how fast have you gone? That said with having never checked your build diary I have two thoughts, more ballst, and I would not get in your car again without confirming equal runout of the rear tires. My 2 cents.  Vince

[SPARKY]

IF you have a good bit of caster and a good bit of + scrub radius if it baresly started left and you coreected you would have put more weight on the RR which would have driven you left

There have been several very detailed post on this before!!

[Kiwi Paul]

Torque Steer really does create an uneven drive situation, especially, it seems, in Roadsters. During Speed Week I reinspected a roadster that had spun a number of times at 215-220 mph. The Team had a Video camera and finally observed the driver having significant steering input in one direction. The answer was to preload a lower rear four link bar a-la the Drag Strip, and go to a taller rear gear and sprung rear suspension. The car was finally able to be run through the 5 mile, and ran 240......Pretty sure there was more weight put in as well. Your tresults may vary, though. Roadsters vary hugely in their aero footprint, but it is curious that every Roadster I reinspected after spinning did so at that same speed....215 or so..

[John Burk]

Have any roadsters tries IRS so driveshaft torque doesn't load the left rear . A single torque arm to the paseger side of the driveshaft with the offset and length ratio the same as the ring and pinion does the same thing .