Wheel Tethers

[Bardahl77]

Maybe I'm missing something, but in reading the GCR and specs for formula cars, why is FV the only class that has wheel tethers highly recommended? Isn't this something that would be good on all open wheel cars, at least? Do FVs shed wheels more often?

[alangbaker]

Maybe I'm missing something, but in reading the GCR and specs for formula cars, why is FV the only class that has wheel tethers highly recommended? Isn't this something that would be good on all open wheel cars, at least? Do FVs shed wheels more often?

If I had to guess (and I do), it would be because Vee use drum brakes and their wheels are attached to those drums...

...and those drums do fail.

[Purple Frog]

Tethers would be useless in the above case. The tether is attached to the hub, so if the drum failed the wheel would still be free to go yonder. Just saying.

Maybe they should be called "hub/wheel assembly tethers".

[Steve Davis]

FYI.. the FV tether recommendation is there because of the stock front SPINDLES - most of which were manufactured in the 50's. Back in the 80's we had a series of failures where the spindle broke clean off, sending a front tire bounding at speed off into .. who knows where. It took several years before someone came up with a "tether" solution that would (maybe) work and it was added to the rules as a recommendation. The left spindle (or was it the right?) already came bored from the factory (for the speedometer cable) and it was allowed for us to drill the other side as well to insert a rod (a head stud works quite well in that application) or a cable through the bore to anchor the assembly to the king pin. As far as I know, there has never been a broken spindle that ended up hanging by one of those tethers, but it doesn't mean it won't ever happen.

Steve, FV80

[Bardahl77]

Thanks for the info Steve. That makes sense. Great info on this site!

I wonder how many other formula cars have installed tethers for safety's sake?

[ExKartracer]

In the 80's I built and ran a Sharland FV. I broke the left front spindle on the exit of turn 4 at Willow Springs Raceway in Calif. That is the spindle with the speedo cable thru it. The wheel/brake ended up a quarter mile away in turn 8.
The fix we used at the time to strengthen the spindle was tap the outer end of the spindle and install a time sert or helicoil for an 8mm or 5/16" socket head cap screw. The head of the cap screw fit into the other end of the spindle hole which used to retain the speedo cable lock. I never had an issue with the right front spindles.
Another fix was to use 356 Porsche spindles. Their bearings used the same od but a larger id hence a stronger spindle. Illegal unfortunately and now almost unobtanium now.

[Dietmar]

Something I do for my customers for the left side spindle when requested...
Take a 5/16 carriage bolt, grind the od of the head to match the od of the end of the spindle. Take a nylock and thread it on the bolt. Remove the nylock and reverse it on the bolt and it fits very neatly into the socket on the spindle and does not interfere with the operation.
Never had an issue with right side spindles.
Crack checking every year is cheap insurance also.

Dietmar
Quixoteracing.com

In the 80's I built and ran a Sharland FV. I broke the left front spindle on the exit of turn 4 at Willow Springs Raceway in Calif. That is the spindle with the speedo cable thru it. The wheel/brake ended up a quarter mile away in turn 8.
The fix we used at the time to strengthen the spindle was tap the outer end of the spindle and install a time sert or helicoil for an 8mm or 5/16" socket head cap screw. The head of the cap screw fit into the other end of the spindle hole which used to retain the speedo cable lock. I never had an issue with the right front spindles.
Another fix was to use 356 Porsche spindles. Their bearings used the same od but a larger id hence a stronger spindle. Illegal unfortunately and now almost unobtanium now.

[problemchild]

A proper wheel tether system is, as pointed out, actually tethering the upright assembly. It needs to be incorporated into the car from the design phase with specific anchors on the upright and chassis, and passageways through the A-arm components. While the occasional car could be retrofitted (more so if European built in the last decade), most cars could not, without spending the value of the car in the process. While everybody loves to over-react to a spectacular accident, there are dozens of cost-effective detail/maintenance items that many club racers could do to make their cars safer.

Just one example is installing split pins in their anti-intrusion bars on their front A-arms. Those anti-intrusion bars are delivered as telescoping so the suspension can be installed and adjusted. Once the A-arm is installed, a 1/8" hole drilled and split pin installed, will significantly decrease the liklihood of that A-arm spearing the driver in a crash. A $3 bag of split pins, drill, and hammer, will let you do 25 cars, with about 5 minutes spent per car. If you walk up the grid at a club race, very few cars have had the treatment. Most will be unaware of the protocol.

Expensive safety updates will park many cars. We all have our own standards, regardless of our club rules. The one that blows me away is the 50s-60s F1 cars raced in Europe as "period correct" with no seatbelts.

[Bardahl77]

Expensive safety updates will park many cars. We all have our own standards, regardless of our club rules. The one that blows me away is the 50s-60s F! cars raced in Europe as "period correct" with no seatbelts.

Seatbelts made it hard to Ghostride the Whip. (Cliff Allison, Monaco, 1960)