Broken throttle rod…

[unclebilly]

So today just as I pulled into the highway and got on the throttle, the throttle Rob between the bell crank and the cross shaft between my webers broke…

I’ve never even heard of this part breaking before. Didn’t think it was possible. I think I threw these out on every 911 I parted out… except for a rusty one in a burnt car.

Ever heard of this breaking? Part 36 in the image…

[winders]

That part is the reason a number of Spec 911 racers have converted their cars to cable throttles. I have seen several of them broken.

[1QuickS]

Consider its design, a tube connecting two rods. Any vibration in the part will be concentrated at the joints between the rods and the tube ends resulting in a fatigue fracture. Also, it is a long part with the heavy tube in the middle of its span which makes it a have a low natural frequency that would allow it to go into resonance which would amplify the displacement during vibration thereby increasing the stresses at the connections.

Perhaps this is not your issue but the design is compromised.

[Uwon]

Originally Posted by winders

That part is the reason a number of Spec 911 racers have converted their cars to cable throttles. I have seen several of them broken.

Interesting mod for the Spec 911 cars. I have been searching unsuccessfully for more info on this. Would you be able to provide some information or direct us to where we can source the parts required, particularly the cable clamping at the throttle body?
TIA
Johan

[Dpmulvan]

Originally Posted by Uwon

Interesting mod for the Spec 911 cars. I have been searching unsuccessfully for more info on this. Would you be able to provide some information or direct us to where we can source the parts required, particularly the cable clamping at the throttle body?
TIA
Johan

https://www.carburetion.com/products/ProductDetails.aspx?Part=99006.103

[unclebilly]

So it broke about 3/8” from the braze joint. There was a crack about half way through and it broke the rest of the way recently.

Looks like it probably broke at the heat affected zone transition from the brazing.

I welded it up…





This will get me driving the 911 again and I will find a spare (the spare I have is bent and rusty).