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Instrument Panel Shock Mounts
Posted: Sun Oct 29, 2017 8:17 pm
by bjoness
Has anyone found a better instrument panel shock mount than the stock Cessna 0411059-1 mounts? The stock mounts don't last very long before the entire instrument panel starts sagging. Loading the stock mounts in sheer like they are was an incredibly poor design practice by Cessna, particularly for the B models with the large panel.
Re: Instrument Panel Shock Mounts
Posted: Sun Oct 29, 2017 11:06 pm
by c170b53
I initially thought they were all the same but although they look the same they may not be all equal. There’s a difference in the composion of the rubber which allow some to take more of a load. Only snafu, the much stronger shock mounts are quite pricey.”
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 12:04 am
by ghostflyer
In some speciality auto shops they sell similar mounts at the right price . They are used to support some of the air intakes and assemblies.
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 12:10 am
by c170b53
P/n 0413523-6 is a number I’m thinking about. 041059-1 is what is in the ipc and because they could be manufactured by a few others and used in different applications yet look the same, the problem might be the parts you have are not made to spec.
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 1:35 am
by DaveF
I don't know if they have an exact match, but you could check
Grainger.
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 2:05 am
by n2582d
If you search 0411059-1 at the top of the page you'll find there has been quite a bit of discussion about these shock mounts here. They cross to Lord p/n J6984-1. I agree with you in that they seem a bit wimpy for the load they are supposed to carry in shear. Looking at the
Grainger Catalog it appears that the max. shear load available for one with two 8-32 male studs is 3 lbs.
McMaster shows similar stats. Both of those are 5/8" diameter mounts. Lord
SMB003-0100-9 has the same shear rating but with a 3/8" diameter rubber. One way to get a higher shear load rating with a 5/8" shock mount would be to use ones with female rather than male ends.
- 2NPD4_AS01.jpeg (2.61 KiB) Viewed 15621 times
Each of Grainger's
2NPD2 mounts are rated for a 5 lb. max shear load.
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 12:12 pm
by n3833v
I found mine at MSC. Been in since 2003 and no problem.
John
Re: Instrument Panel Shock Mounts
Posted: Mon Oct 30, 2017 1:27 pm
by bagarre
It's worth noting the originals were brass or bronze (non magnetic) to avoid affecting the compass.
Any replacement parts should possess that quality.
Re: Instrument Panel Shock Mounts
Posted: Wed Nov 01, 2017 5:16 am
by ghostflyer
Wow, some in brass?, we have a heap of them from Cessna collected over the years in our store but none brass, as they are now a slow moving spare as they are very expensive and “others “procured from other sources have proved more servicable.
Stop the press. I have just been informed that brass nuts are used sometimes also .
Re: Instrument Panel Shock Mounts
Posted: Wed Nov 08, 2017 8:44 pm
by GAHorn
The studs are "phosphor-bronze" and the nuts are brass to avoid magnetic interference with the compass.
When I did my 2nd horizon project I replaced some of my shock mounts. Gary noticed that I'd used some "heavier duty" mounts. Here's what he posted for good information on the subject:
n2582d wrote:gahorn wrote:When I re-install the rubber mount, I will re-orient it to 180-degrees opposite it's previous position to relieve that offset. (By the way, these are available also from Aircraft Spruce.)
George, you're a man after my own heart: Cheap.
Sacramento Sky Ranch Lists P/N 6984-1 for $2.75 ea. As I researched these lil' buggers things got pretty confusing. First, the part number in our IPC is 0411059-1. When I ordered the "round shock mount as used on Cessna aircraft",
p/n 10-14700, from Aircraft Spruce they sent mounts that were 3/8" diameter. They matched the old ones I took off (which also were severely sagging like yours). Yours appear to be at least 1/2" diameter and if I'm reading correctly are p/n J6984-8. According to Wag-Aero,
Lord p/n J6984-8 is Cessna's p/n 0411059-3 and
Lord p/n J6984-1 is Cessna's p/n 0411059-1. Wag-Aero's catalog disagrees with
Sacramento Sky Ranch's as to which shock mount is the larger diamenter. Sacramento Sky Ranch says that the J6984-1 is "the large one" and J6984-8 is "the small one". I contacted Lord and they said that J6984-1 hasn't been manufactured in a long time. I asked for a cross reference to a current Lord p/n but they just referred me to Aviall who apparently stock J6984-8 and J6984-64.
Here's Lord's spec. sheet on Flex-bolt Sandwich Mounts. Notice that to get a larger diameter than .38" it would require having 1/4 X 20 studs. My wimpy 3/8" dia. mounts don't appear up to the job of holding up at least 13 lbs. of panel and instruments. The panel will accommodate 3/4" dia. shock mounts without interfering with the instruments. So to those thinking of replacing these shock mounts I would suggest that you confirm that the mounts are at least 1/2" diameter when you order them. In addition to the above links they are available at
SkyGeek and
Chief.