aaronk25 Posted June 12, 2012 Report Posted June 12, 2012 1977 M20J From what I read on other posts there has been some trouble with the cable getting rusty and sticking but I haven't read anything about the knob coming off. After take off last week (it was hot out) I immediatly reached up to turn the knob to let some air in and it came off in my hand. I felt a piece(s) like a set screw fall down but I couldn't pay much attention as I was only a few hunderd feet off the ground with terrain on both sides. (note to self, don't do anything but fly until safe altitude) Once back on the ground I looked at the pieces a bit closer and noticed that the shaft the knob slides on appears to be a "d" style shaft but the inside of the knob is round. I searched the entire cabin high and low and all I could find was a allen set screw that had threds on one end that matches up with the "worn" plastic threds inside the knob, but the threds were the same size as the unthreaded hole going though the center of the shaft. Im wondering if anyone knows is there a half-moon cotter key that is threded that acts as a insert between the shaft and knob that the set screw goes into? If so im guessing it found its way down the little hole in the floor that the trim chain goes down...what are the odds Any advice? puzzled on how to fix this one. Sorry for no pictures will have knob and screw back in hand this weekend. In chicago now, parts in MN. Aaron Quote
jpjp Posted June 12, 2012 Report Posted June 12, 2012 The knob should have a hex head set screw or a slotted set screw. I have only seen those two types. You're not missing any parts simply put the set screw back and tighten. Kind of tricky to tighten with the recess that the knob goes into but very doable. Quote
jetdriven Posted June 13, 2012 Report Posted June 13, 2012 Thats a Kurtz-Kash knob. They are out of business but I believe an amplifier knob with a 1/4" shaft wil work. Try eBay. The allen threads strip out. Ours did. Quote
Sabremech Posted June 13, 2012 Report Posted June 13, 2012 If this is a common problem, I'd be happy to make new ones and get them certified or can supply them as owner produced parts as they are not flight critical items. I'm in the business of manufacturing and certifying obsolete parts. Check out my website at www.vintageairworks.com I can be reached at 262-914-9589 or by e-mail at david@vintageairworks.com David Staffeldt Quote
tablor Posted June 13, 2012 Report Posted June 13, 2012 Quote: Sabremech If this is a common problem, I'd be happy to make new ones and get them certified or can supply them as owner produced parts as they are not flight critical items. I'm in the business of manufacturing and certifying obsolete parts. Check out my website at www.vintageairworks.com I can be reached at 262-914-9589 or by e-mail at david@vintageairworks.com David Staffeldt Quote
N33GG Posted June 13, 2012 Report Posted June 13, 2012 Quote: tablor Nice products, services, and website! Quote
N33GG Posted June 13, 2012 Report Posted June 13, 2012 Quote: tablor Nice products, services, and website! Quote
rob Posted June 13, 2012 Report Posted June 13, 2012 Quote: jetdriven Thats a Kurtz-Kash knob. They are out of business but I believe an amplifier knob with a 1/4" shaft wil work. Try eBay. The allen threads strip out. Ours did. Quote
aaronk25 Posted June 13, 2012 Author Report Posted June 13, 2012 The problem is that the screws's threads go into the plastic of the knob and not into the hole though of the metal 1/4" shaft. The hole in the shaft is not threded so i guess it relys on the tip of the set crew to barly protrude into the hole. Seems like its a design that is prone to failure becuse it has plastic threads which bare the torque and only affixed to the shaft by the tip of the set screw. Im looking for kurz-kash knobs now on ebay. Aaron Quote
jetdriven Posted June 13, 2012 Report Posted June 13, 2012 Best of luck. Our partner drilled and tapped a new hole for a set screw, as ours stripped. AFAIK its a 1/4 inch shaft and amplifier knobs from the 70s will do. Check eBay for source. Of course, David can machine up some knobs in aluminum and knurl and anodize them. David, I will take one. I like Blue. Quote
aaronk25 Posted June 19, 2012 Author Report Posted June 19, 2012 Thanks guys I was able to find a knob from radio shack. 1/4" with set screw works great! Not as big of a deal as I thought it would be. I bet the machined knob looks great! Wonder how much they would be? Aaron Quote
Derrickearly Posted July 22, 2015 Report Posted July 22, 2015 Does anyone have a vendor and part number for a metallic vent knob that works for our mooney's? Quote
rbridges Posted July 22, 2015 Report Posted July 22, 2015 I thought radio Shack used to carry a compatible knob but they closed most of their stores last year I thought mine was messed up but it just needed tightening. I did some research and like others pointed out, it's the same as some amp knobs. Quote
PTK Posted July 22, 2015 Report Posted July 22, 2015 These folks should have something that works. http://www.surplussales.com/shafthardware/knobs-2.html Quote
bonal Posted July 22, 2015 Report Posted July 22, 2015 Thanks guys I was able to find a knob from radio shack. 1/4" with set screw works great! Not as big of a deal as I thought it would be. I bet the machined knob looks great! Wonder how much they would be? Aaron You should have done the upgrade and got the STC for the one that goes to 11 "its just better" Quote
Randy_B Posted July 22, 2015 Report Posted July 22, 2015 LOL, I liked the Spinal Tap reference "it goes to 11, its just better". Quote
cnoe Posted July 22, 2015 Report Posted July 22, 2015 While on the subject, there's a fair amount of "slack" in my overhead vent knob ('78 J). When I turn to open the vent it goes a ways (maybe 1/2 turn???) before the vent door starts opening, and then when closing it the knob will turn a similar amount before it's closed tightly. Is this common, or is the cable sheath not secured well where it attaches? I really don't want to remove the overhead plastic to check it out unless I have to. Anybody? Quote
N601RX Posted July 22, 2015 Report Posted July 22, 2015 McMaster sells several aluminum knobs with 1/4 shaft and set screw. Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.