Online Community of Zenith Builders and Flyers
Hi all, I've just removed the Shock Ring on the nose gear as it needs to be replaced because its frayed and over 5 years old.
I measured the old one that came off and it was 25.5" long so I thought I needed a 1080 (5/8" x 8") but it looks to be too long when fitted (you can fit the ring on by hand and with the aircraft resting on 3 wheels the top of the nose leg sticks up by about 1/4").
The old ring was much tighter and the nose leg was flush with the top mount. Has anybody ever fitted a 1174 ring?
I'm looking into this too...I have the newer SP plans calling for 9010HD but I have the OLDER nosegear leg soooooo...
Aircraft Spruce sells the 8097, 1080HD and 9010HD...
Here are the contenders for replacement :
type size price Max Weight (lbs)
8097 (1-1/2" x 9.875") 20.75$ 400
9010HD (9/16" x 10") 23.95$ 475
1080HD (5/8" x 8") 29.50$ 900
I will have to look again at my plans to figure lenght and size as I wasn't aware that the nosegear post bungee retainers
had changed location over the years...DARN. Good thing I didn't order anything yet. Thanks guys.
Also, it maybe very easy to change over the bungee when the engine and other stuff isn't there BUT I expect a FULL DAYS work to get the new one in with all the stuff hanging from the firewall and in the way...
I may try with everything there but if it becomes clear that It won't work, I may be inclined to remove the engine/engine mount from the firewall (only 8 bolts) replace the bungee and stick the engine/mount back in...
Talk about a pain in the .....
on the photo the "home made" one is 14mm diameter, so I think the initial one was 9/16", it was the most looking like, sold -to the meter- as "aeronautical bungee" by the national dealer... hum hum
so the 9010HD seems to be a good one, 9/16" diameter and longer (10") , that's Michael Rand's idea as well, who found the 9010HDX wich is rated up to 700 lbs... Well, if I succed to get one with LAS / England, I' ll try it and get back to you !
The nose strut bungee cord has been changed to a fatter and smaller ring one to handle heavier engine. My first CH701 has 65 mm wide channel, while I build my second 701 with 80 mm width to make it easier to take the newer bungee. After some consideration, I modify my first for the newer bungee also.
Shown in the picture is a sketch of how I modify (my first 701) 7F7-2, the Lower Vertical (nose strut) Channel. I move the center of the bungee pin up by 60 mm. to the hole on a piece of .040" 40 mm X 55 mm, riveted to each side of the strut channel. Of course, riveting inside the narrow 65 mm channel IS very difficult, but I manage to get 4 rivets on each side, with care not to leave the rivet heads cutting the bungee cord. I make a mental note to clamp or weld a stop ring on the nose strut to save the propeller in case of bungee cord failure (from engine heat). Of course, a careful pre-flight can not be overlooked.
I checked my old plans and found out that the 8097 is used with the older nosegear post. I will order that one to replace my aging one. They are sold by Aircraft Spruce Can... Easy to come by, cheap and fast delivery. Changing for a bigger/stronger one only means that in a HARD landing more force will be transmitted to the airframe instead of being absorbed by the shock ring... By the way, what happens when the bungee fails on the nosegear ?
Well, you lose the front absorber and the gear post goes up till it hits something to stop it from going higher...
What happens to the front of the airplane ? Well the nose drops ... and the PROP hits the ground ! :-(
Well, to make sure that NEVER happens, you should check that nosegear bungee in your preflight routine and change it if in doubt. But, what if is gives up anyway ?
Well, I found a nosering guard of sort on this website http://www.macsmachine.com/ . Larry makes them and sell them cheap (relative to a prop, gearbox, prop strike...). They can be installed on the nosegear post so that if the bungee fails, the ring will stop the post from going thru and save that prop of yours.
I just got mine and will install it when weather permits.
Food for toughts...
Looks like I'm five years late to the "701 nosegear bungee blues" party.
I'm trying to replace the nosegear bungee on my CH701-SP (the newer "heavier" version) and having exactly the same problem as Martyn and Einar and perhaps others reported. The plane is built exactly per plans, and the original shock cord provided by Zenith with the kit was perfect. The new 1080 replacement bungee supplied by Zenith now is definitely too long-- is easily slipped over the stub at the front top of the nosegear by hand, and would likely fall off if I tried to use it like that. Another 1080 cord from Aircraft Spruce is exactly the same size as Zenith's, implying that a 1080 is the wrong size, even though that's what's listed in the plans.
The old (original cord) is getting ragged, but still seems to be retaining its original length. I slipped it over the bottom of a slope-sided 1-gallon plastic bucket to give it a good round shape and it measures at right about 7.5" in diameter, not 8".
Did anybody ever figure out what the correct bungee type is? I've heard good things about the "steel bungee" mod, but would rather not undertake that just now.
Just to close the loop (no pun intended) on this thread... I measured the original shock ring and all its various dimensions exactly fit those of an 1174 ring. I ordered one from ACS and it fit just like the original--perfect in length, and slightly too thick in diameter to slide smoothly into the U-channel at the top of the nose strut, but quite workable. I'm convinced that the 1174 is right one, at least for the way my 701 is built.