Which bungees?

[sbmackie]

Original PA-20 (wide gear) with 0-290. Use is fun and some instruction, 70/30 grass/pavement. Grass is not terribly smooth, but neither is asphalt. No off field, ever. I notice some bouncy-ness on pavement. Annual coming up. Which bungees?

Thanks?
Scott

[dgapilot]

Wide gear uses 2 1080HDs on each side. Some prefer 1080s rather than the HD, others prefer a 1080HD and a 1280HD on each side.

[Glen Geller]

New bungees will not be less bouncy than older ones.

1080 are 5/8" dia shock cord (ie, 10/16) on the bench, not installed and stretched on the hydrosorb.
1280 are 3/4" dia shock cord (ie 12/16)
Here is info on how to read color codes for date of mfr (ya want relatively fresh rings, not five year old - rubber degrades in air!) and the test ratings of dia and Reg/HD cord:
https://www.aircraftspruce.ca/catalo...hock_rings.php
https://www.univair.com/content/Shock-Cords.pdf


It can be hard to tell what size you have installed, the 1280 rings look like they barely fit on the "ears" of the shock, because they barely do.
The 1080 rings fill the space on the ears but don't look like they are overfilling it.
Best to look at the logbook and see what was installed, and when. Over four~five years in use and they might be getting old. YMMV.
If you look at the belly from the front, and see the inner gear legs "hidden parts" exposed 0.5" or more, the inner legs are not flush with the belly, they are getting worn and maybe need replacement.

If you decide you do need to replace your rings, there are many threads (pun intended) on this site with hints and tips about how it's done and how to buy/borrow/rent the tool needed to SAFELY replace shock rings on hydrosorbs.
It's a good opportunity to check condition of the hydrosorbs, looking for bent/cracked parts, replace the attaching hardware if necessary, and general inspection of the critical area and components.

What is your tire pressure? Over-inflated tires can make for a bouncy landing, and squirrelly handling too.

Good luck,
GG

[sbmackie]

Any idea on why some choose 1080, 1080HD, or 1280? I keep my tires at 20PSI. By bouncy I mean a soft ride on takeoff across uneven pavement, like a Suburban vs a Corvette.

Thanks
Scott

[dgapilot]

1080 is soft (and likely won’t last long), 1080HD is a little harder. 1280HD is stiffer yet. There isn’t enough difference between 1080HD and 1280(no HD) to even consider them. One 1080HD and one 1280HD would be about midway between the 1080HDs and 1280HDs

Depending on the size tires you are running, you might consider lowering the air pressure.

I guess the question nobody has asked, why do you think you need new bungees? Are they sagging? Do they show signs of abrasion when you look at them? I’ve seen some that need changing after a couple years, I’ve seen others last 10 or 15 with no issue.


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[Steve Pierce]

I'd install the 2 1080HDs and if too soft then you could cut one off and install a 1280.

[Pacerfgoe]

I put new 1080HD’s on my Pacer a couple of years ago, and I find them too stiff and unforgiving. My plane still has the narrow gear, and next time will just do 1080’s. I also mostly fly alone or with just one other person.....

[andya]

I had 1080HD's installed 4 years ago and in my opinion they are still too stiff.

[Steve Pierce]

Good current info, thanks guys.

[dgapilot]

I put new 1080HD’s on my Pacer a couple of years ago, and I find them too stiff and unforgiving. My plane still has the narrow gear, and next time will just do 1080’s. I also mostly fly alone or with just one other person.....

With the narrow gear it is supposed to be a single 1380 on each side, not two 1080HDs each side.


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