throttle seems to be binding

moll780 · #1 01-12-2015, 08:10 AM

The throttle cable on my 9A (0-320) seems to be binding someplace.
I unscrewed the lock to remove it as a possible culprit but it still seems to be binding.
I haven't taken the cowl off yet but I wanted to ask the community for ideas of places to look.
logically ill check the cable itself and the linkage at the carb but any ideas before I take a deeper look this coming weekend would be helpful.
thanks!

Kahuna · #2 01-12-2015, 08:15 AM

Cables wear and must be replaced. Heat & friction gets to them.
If your doing a lot of throttle movement like we do flying formation, they wear quickly. We have cables that wear out in a couple hundred hours. We have tried many things to increase their life. But they fail regardless. Starts by increased friction, then a ratchety feel, then lockup.

moll780 · #3 01-12-2015, 08:58 AM

My throttle seemed to jump from working fine to needing loads of right arm to push and pull.
Could it be something in the carb itself? this is my real fear... replace a cable, ok no problem. carb issue? now im scared.

Quote:

Originally Posted by Kahuna

Cables wear and must be replaced. Heat & friction gets to them.
If your doing a lot of throttle movement like we do flying formation, they wear quickly. We have cables that wear out in a couple hundred hours. We have tried many things to increase their life. But they fail regardless. Starts by increased friction, then a ratchety feel, then lockup.

clutch22 · #4 01-12-2015, 09:13 AM

I had the same problem on a 172.
The accelerator pump went bad, and required a lot of force to push the throttle in.

JonJay · #5 01-12-2015, 09:22 AM

Disconnect the linkage from your carb and you can eliminate that right off the bat. My bet is it will be the cable itself, but you never know.
Most failures I have seen are due to heat.
Pay close attention to the cables proximity to your exhaust. These cables will degrade in the area they are getting exposed to excess heat. If that is the case, you can rework cable routings or use heat shields to mitigate it down the road.

noelf · #6 01-12-2015, 09:22 AM

Disconnect from carb and then do the push-pull test?

Steve Melton · #7 01-12-2015, 10:46 AM

my first check would be, remove the friction lock and apply mouse milk lube at the plastic ferrule.

Infidel · #8 01-12-2015, 01:06 PM

I'd remove the lower cowling and go from there. I recently experienced a similiar problem and discovered the scat tubing from the carb heat crossover to cabin heat was a little too close to the throttle linkage on the carb. Inhibiting just enough that I wasn't getting the last 1/4" of full throttle. But as suggested earlier, if your linkage isn't binding anywhere, disconnect from the carb and check how smooth/rough the throttle cable will be.

GeneL · #9 01-12-2015, 03:57 PM

My 7 has the original cable 600 total hours 400 in formation still smooth. should I worry? Gene (Whiskey Flight)

RV6_OKLA · #10 01-12-2015, 05:29 PM

I had the same problem in my RV6. Turned out the exhaust heat was causing expansion which made the cable get tight during flight. I put firesleeve over it and wrapped in silver foil tape. Sleeve goes from firewall to the bracket that has the nut that holds the cable in place by the carb. No problems since. Coincidentally, my engine is an 0-320 too.