Rear hinge pin popping out
 

My Madrat is starting to go really well, but the aforementioned problem is driving me to distraction - the rear left hinge pin won't stay in. Starting fourth in the B final on Wednesday, I was just passing the leader inside the first lap when he tapped me on the rear left wheel and it fell apart for the 3rd time that night - despite me changing the rear brace.

It seems to be caused by the inherent flex of the T-piece (the newer toughened one Battleaxe gave me at Oople - thanks again!) and the braces, plus the braces seem to get worn very easily.

I could solve it with the alloy hingepin braces and carbon fibre T-piece, but that would cost nearly as much as a B4, which is ultimately my other solution to the problem.

Are there any other cheaper fixes I can perform?

I've not heard of this issue before...and I've certainly not had an issue myself.

The alloy and CF parts you mentioned would probably fix this... combined they are only £39...that's cheaper then a B4 :)

K

Where is it coming out? Pinging out of the rear brace or pulling out of the front?

I've had it pull out of the front with a heavy collision but certainly not a tap. As a fix I sanded down the ends of the front brace and superglued washers onto it (so metal reinforcing the holes). I've seen rear braces snap and lose the pins but never a pin pop out...

possibly get a pin a couple of mm longer from a different brand of car? Not sure if the kit pin comes up a bit short?

It actually happened to me as well this week. My rear wheel hit a post while jumping so It was kinda expected... Anyways, I'm getting the alu brace.

it might be worth looking at the hingpins off the cat due to the fact that they have a screw that goes into eather end of the pin

check the u brace to make sure it's not cracked - that is a lot of flex for the pin to come out.

i would buy a new t peice it will come with the braces too i am not really sure where the one i gave you had come from:wub

with metal braces and carbon t plate i have broken many many of my rear arms... anyone else experianced it? brake them less frequently than i used to break braces and t plates so i'm not too bothered... but it seems strange ... the arms break down the middle!!

With a completely rigid rear chassis assembly as you have, the wishbones take all the force. It's an argument against the carbon T-piece at least.

I've considered a few solutions - drill out the braces and fit a tube of tougher material to hold the hinge pin, or tap a hole into the side of the braces and capture the pin with grub screws. A new T-piece is likely needed, anyway.

I took the rear chassis apart and examined the T-piece; the rear-most screw hole on the side causing the problems is deformed - the hole has stretched backwards, even causing a bump at the back of the T-piece. I'll get a replacement, but no rush, as I hedged my bets and got a B4 FT as well...