Forum: HoseHeads Sprint Car General Forum (go)
Moderators: dirtonly  /  dmantx  /  hosehead

also was at castrol this weekend and saw this happened. after the crash i looked in his car and he only revvd 6200

never letting off.

I would would like to see the stop that fell off and try to put it back on the bar without loosing the bolt and if it went on try to torque and if it torque good I wonder if the bolt threads got messed up to where it felt like it was torqued but was really tight.. Crazy things happen.. Why so many now.. Time will tell..

Someone within the industry knows exactly what's going on. 

This keeps happening but no one seems to want to come out and tell what brand or brands stops are coming off.It's past time to be studying this and let people know what stops and bars this is happening with,there could be a pattern,and it just might save a life.

    The light weight sprint car parts deal has been going on for a very long time and will continue to do so.  The thing is it's not just rules but doing what makes sense.  I remember when I was on a sprint car crew and we ran syracuse in the early 90's and I remember standing on pit road during the final warmup for the sprint car event.  I was standing right next to Steve Kinser's car and I noticed how "they" drilled holes in the lapbelt hardware that fastens the belt around the frame and I stood there wondering how much those drill chips weighed when they were put on a scale? 

     The torsion stop falling off the bar is nothing new but making the choice to not use a piece of threaded rod and two flat washers to hold the stop on is a light weight fix that some either forget during a "thrash" to get the car out or just don't use and then we see the fallout.

    The 6-8,000 rpm hamburger grinder between the drivers legs should get some attention because when all is good it does a great job but when the u-joint, driveshaft or a crash make things come apart in a hurry we see the outcome. 

    I don't know how many people besides myself have noticed the amount of front axles that have been breaking in a crash leaving a front wheel and all the hardware getting airborne.  I am concerned how long it will be until we send this assembly into the stands and injure fans or worse? 

    While I'm at it one other "pet peeve" of mine is sprint car roll cage height.  I understand the principal of winged cars needing the underside of a wing to do it's minimal work but why not raise the cage height, for belt stretch and in the event of hitting a solid structure as in a wall or guiderail etc.? 

    One thing I do know about all of this is there isn't anyone in this sport who wants to see guys get hurt and have parts fail.  The whole struggle is to be the fastest car and the one to beat and with that comes innovation and taking what you have learned over a very long period of time in this sport and put it to task.   The reason I love sprint cars is simple:  the parts on a car are the ones there to make it fast, there is no extra built in like some other forms of racing.  Just remember somebody was the first one to put a wing on a car or to use a bump stop on the left rear and I'm hopeful someone will make or do something that catches on to repair some of these issues. 

Someone enlighten me please!   I don't really know how a sprint car suspension works, my mechanical experience is on stock cars.   I found a couple of diagrams of torsion bar suspensions.  Looks like the torsion stop for the right front actually is on the left side of the car, opposite the side of the right front torsion arm?   I assume that if this fell off of the car, then the suspension would collapse?   Then the frame digs on that side and turns the car hard right?     

We have witnessed this on the RF stop in the past as well.  We've been running 1/4" all thread and fender washers for about 3 yrs now, we also don't leave a much of a gap between stop/arm and torsion tube anymore.  The RF generally has little to no load on it and the problem is believed to be somewhat of a slide hammering effect of the rf bar and arm pulling itself out of the stop, this combined with grease on the splines not allowing the stop to actually clamp the bar itself tightly.

That is my thoughts exactly in a previous reply. If you never have tension on a moving part such as the rf stop & bar it does give it a sledge hammer effect every time it receives a snap effect because of lack of very little load on that corner. I personally witnessed Fast Freddie lose the rf  stop & bar 3 separate times in 1 night @Lincoln. Twice in the feature of which he was fortunate enough to win that evening!! The cause then was a local brand titanium stop.

The slide hammer theory has been discussed in these parts as well. As the right front loses it load during accelaration, a possible type of harmonics takes place, resulting in the whole bar assembly slapping back and forth and hammering the stop off. With the possibility of different brands and or materials of stops, arms, and splined bar sizes, resulting in less than desired clamping/retaining force, shit falls apart.

Yes, the new retainers as well as threaded rod should do there jobs. But like some other posts, it "IS" just a band-aid.

It would be nice to see a manufacturer step up and explain their findings, but in todays lawyer driven society, I doubt thats gonna happen. My personal best bet will be to wait till the Indy trade show, and into the evening hours when the drinks start loosening lips, listen for an answer...   johnny fahl

I wonder if we could learn anything by monitoring the RF stop and bar with a camera...

Funny you ask. I'm parked this year, waiting on a motor to be freshend. But planned on mounting a go pro to the front bumper during IRA qualifying at Plymouth (bullring), and Dodge county (1/2 mile). I'm thinking if we can swap the thing fast enough, we can probably get 3 or 4 drivers both nights. I'll keep ya posted. 

Just for the record, I'm no safety freak. I'm not big on rules that are forced onto car owners and drivers, that cost money. We make the decision to climb into these widow makers plain and simple. But when shit is falling off the car with no explanation... ain't nobody got time for dat!  lol.  johnny fahl

Just a note.  At a race the seat belt manuf. rep. saw Steve Kinsers seat belts and took them off of car and told Steve he could not use them.  They gave him a new set.

You are correct.  I am also thinking that as you go thru corner you car is winged down on left side.  As you  come out of corner it will settle more square and the stop comes off or stop was off before corner and since it was winged down on left it cornered ok.

When the stop comes off the bar and arm back out and jam the combo steering arm- locking the steering.

Due to the splines thereselves it doesn't allow for full and even 360* clamping load between the bar and arm/stop, this combined with the grease on the splines as I mentioned before results in what we see.  One solution would be to machine a groove in the bar and redesign the stop so the pinch bolt goes through this groove.  This is how all automotive OEM  splined pinch bolt style steering shafts are designed.   I wouldn't consider anything that keeps the stop from coming off a band aid, call it added security if you will.  Just like safety wire on certain bolts or drain plugs etc.

Here is a pretty cool video showing how much time the RF arm spends on the axle!

Wow, there is a lot of vibration and banging around; this is obviously a factor.

The LF, LR and RR arms/stops remain under constant load and most likely aren't subject to the vibration and banging that the RF is seeing.

I wonder if you attached a strong rubber band or bungee from the RF arm to the axle, so that when the RF arm isn't under load, the rubber band would prevent the arm from bouncing and banging around... this might help prevent the stop from working it's way loose.

Congratulations on a factual discussion instead of the usual silliness! Like Dryslick Willy, I don't know squat about sprint car suspensions. Could someone explain what the arm is attached to in the front? Why is it bouncing around instead of attached to axle?

That film is excellent, showed me what I needed to ask...

Ever try to read suspension tech articles in Circle Track? All Greek to me... a video like this would help explain it