Stuck Throttles

[HOUSTONLM04]

It looks like there were two major incidents this weekend due to stuck throttles. In both cases, luckily, the drivers appear to be ok but the cars are in need of major repairs.

 

Drivers – if you can’t remember the last time you replaced your throttle return spring, now would be a good time. It won't prevent it but it sure will mitigate the risk of it occuring.

 

I'll bet we see tech looking closely at throttle return systems in the weeks ahead...

[jracer98]

http://www.colemanracing.com/catalog/produ...roducts_id=1801

 

 

I put one of these in the TAMS 98. I tested it in Wichita Falls when I was out by myself and it worked. When you come off the brakes, the power to the ignition is restored so you have to bat at the power switches while the brakes are maxed out "on".

I have never heard the ignition cut out in a normal braking situation and I have made some pretty hard stops to avoid trouble.

For what it's worth.

Jay

 

--->just another thought...I have seen carbs with a little time on them get to where the throttle will go "over center" especially with too stong or incorrectly positioned springs that attach to the back of the intake. Several companies make positive mechanical throttle stops that act on the carb's linkage to prevent this.

[Budman]

Arn't steering wheel thumb actuated kill switches mandated by the various tracks and sanctioning bodies as part of the standard safety equipment for each car ? If not, they should be.

 

I've seen way too many stuck throttles over the years, including one lethal one. Hope I never see another one !

[Crazyhorse]

a kill switch will reduce the initial travel after the first impact-but if it sticks(even with a kill switch ) you're gonna hit hard....

like brad said just spent the time (30 seconds)every race to make sure you're return spring is good-and free.as a driver that is the one thing that i religiously check....more times than most though it's poor judgement on placement of a spring or the linkage for that matter...trust me after it sticks once,you'll keep the linkage and springs clear of everything by 5 inches-and wish it could be more than that....

[Budman]

At least with a kill switch the hit won't be under full power. Every little bit helps. Besides, its just cheap insurance. I put one on a pick-up I had (not for safety), but as an anti-theft measure. Put it on myself for less than $20 (in a location known only to me.)

[UMSCHEIDRaceServices]

i have also seen team take air cleaners and cold air boxes off car and put them back on and not check throttle clearances before going on the track if the linkage rubs the air box it will cause sticking.

 

J.C

[Crazyhorse]

i have also seen team take air cleaners and cold air boxes off car and put them back on and not check throttle clearances before going on the track if the linkage rubs the air box it will cause sticking.

 

J.C

the only one i ever stuck was on the air box (linkage clearance) ....

[JamesHigdon]

I can personally vouch for the fact that a stuck throttle isnt fun, when we finished our last car and begin testing it we had all kinds of trouble. It stuck on me at 6K RPM and i was lucky, it stuck on our best driver at 14,500 RPM and he was REAL lucky, then it stuck one last time and finally we ended up not lucky. We had tried diffrent springs, diffrent cables, diffrent pedal positions and nothing really fixxed it. It finally came down to something simple that i see very often on all kinds of racing vehicles, installing a spring that has to much tension is almost as dangerous as not having a secondary spring at all. When the external throttle return spring is too heavy it can bind the linkage or actually bind the throttle shaft inside the throttle body and actually physically hold the throttle open, just something to think about when everyone takes a second look at their setups...

 

James Higdon

[UMSCHEIDRaceServices]

just a question did you say that this car has a throttle cable?? if so how will a spring help a cable from being stuck when we ran Legends they had cable as well and i know we cant put a spring on them, the cable would just bunch up if the throttle became hung open.

 

Not really understanding ????

J.C

[JamesHigdon]

J.C. The system does use a cable and has multiple springs. By rules we are required to have both a spring to return the pedal to a closed throttle position and two springs to manually pull the throttle closed. The spring on the pedal actually does the work of pulling the cable back through the shething to pull the throttle plates closed, the springs on the throttle themselves are more of a way to force the throttle closed. You are right in that trying to force the cable back through the shething and force the pedal back up would not work, i can also vouch for that being learned the hard way.

 

Another question, we are required to run a switch within the reach of the driver that can kill the engine outright and it has saved many many FSAE teams and me personally from wrecking. This seams like a simple way to reduce the chances of a stuck throttle being catastrophic, don't most local tracks and touring series require something of this sort ?

 

James

[gundogC3]

I can say this-last year no one was allowed to touch the throttle on the 10 truck--except for the man that was mashing it. ROBERT!