+20 year old donuts (1966 M20E)

[Skydancer2992]

Same part number J-11968-14. At least Vans demand will help keep up the economies of scale going for this part.

 

Skygeek is the cheapest I've found today: 

Lord J-11968-14 Mooney Landing Gear Shock Disk

Part#: J-11968-14

by LORD

Our Price (Each): $120.82

Vans
GEAR ELASTOMER -10EA J-11968-14$138.00

 https://shop.vansaircraft.com/cgi-bin/shop.cgi?ident=1587389944-36-741&action=search

Aircraft Spruce:

LORD LANDING GEAR SHOCK DISK J-11968-14

 

0 Reviews3 Answered Questions

$122.75/Each

 

LASAR is the priciest: 

SHOCK DISC (ALL MODELS) – 530021-000

155.00

[ilikethewoods]

I just replaced mine today that we’re original from factory. Man, so many people who operate these airplanes have the IA’s who loves the ol six pack for payment. Can’t trust even the maintenance log books. I’d say just find someone who could loan ya the tool and replace them and be done. Scratch what everyone tells ya. Start your own maintenance program/dates and know for yourself. Just my two cents. Good luck...


Sent from my iPhone using Tapatalk

[Pasturepilot]

I’m under my mooney right now. 1965 M20C. My main gear discs are a 1968 date code.

Yeah, I know. So I bought some from a local MSC. Went to install them today. But wait, it gets better. 
 

Under compression, the gap under the collar is Right at limits. When I jack it up, they expand exactly as designed. 
 

The retaining bolt on one side is rusted and won’t come loose. I hit it with PB blaster and will try again tomorrow when the rain begins. For now it’s sunny and clear in Georgia, so I’m gonna button it up and go fly while the blaster does its thing. 

[carusoam]

I was expecting some really surface cracked rubber bits from 68....

Sure they aren’t inverted 89s.... 

Best regards,

-a-

[Ross Taylor]

47 minutes ago, carusoam said:

I was expecting some really surface cracked rubber bits from 68....

Sure they aren’t inverted 89s.... 

Best regards,

-a-

I'm also really surprised and impressed - I hope you get another 50 years out of the new set.

[LANCECASPER]

3 hours ago, Pasturepilot said:

I’m under my mooney right now. 1965 M20C. My main gear discs are a 1968 date code.

Yeah, I know. So I bought some from a local MSC. Went to install them today. But wait, it gets better. 
 

Under compression, the gap under the collar is Right at limits. When I jack it up, they expand exactly as designed. 
 

The retaining bolt on one side is rusted and won’t come loose. I hit it with PB blaster and will try again tomorrow when the rain begins. For now it’s sunny and clear in Georgia, so I’m gonna button it up and go fly while the blaster does its thing. 

Keep in mind that the part number ends in 68 also, that might not be the date code.

[Pasturepilot]

8 minutes ago, LANCECASPER said:

Keep in mind that the part number ends in 68 also, that might not be the date code.

3-68 is the entirety of the number string, separate from the much longer part number. 
 

I‘m guessing they got changed at some point with new (very) old stock. The record keeping from owners past is a bit spotty.. 

 

 

[cliffy]

Just like Dunkin; Donuts  as they get old they get crusty and hard

No need for special tools for the main gear  but do get the tool for the nose gear donuts,

[larryb]

I have replaced donuts on both my J and then a few years later on my Encore. It makes a big difference in taxiing. I think most owners don’t realize it because the deterioration is so gradual. Both of these were at my request and not because the shop told me it was time.

[Gert]

I have the alternative solution to expensive shock discs! I own and fly a Beechcraft Sundowner 180 and had to replace the shockdiscs. The costs were unbelievably high and I could not believe that such a simple device as a rubber disc can cost so much.

I decided to investigate if I can manufacture these discs at a more affordable price, since the FAA allows aircraft owners to produce parts. I found that it is absolutely possible and that under FAR section 21.303(b) I will be allowed to manufacture these discs for other owners as well. About two years ago I started collecting information on the composition and detail of the discs. I manage to stumble onto the original manufacturing specifications of the Beechcraft as well as Mooney discs. The manufacturing data and rubber composition for both discs were made available by a retired engineer from Lord who used to manufacture these discs. The Mooney discs have the same composition as the Beechcraft discs of the natural rubber and  percentage Poly-butyl-dye-lean which is slightly more dampened and stiffer. 

I went ahead and started manufacturing the Beechcraft Landing gear with great success at one third of the cost of similar products. I decided to manufacture the discs at cost + 10% to ensure the extended life of the "Baby Beech" line of aircraft and also to give back to the industry that have given me so much during the past 30 odd years. I also started a website www.avunlimited.co where Beech Aero Club members and other owners can read more and order the products. Profits so generated will be used to train disadvantaged young pilots.

I can also  easily manufacture Mooney shockdiscs at below $50 per disc and would like to gauge interest from Mooneyspace members in this regard. Please let me know what you think or e-mail me at gert@avunlimited.co.za. You can also visit the BAC website and topic at http://www.beechaeroclub.org/showthread.php/13829-Rubber-Donuts-Now-at-reasonable-prices

Blue Skies

Gert

[cliffy]

Seems the BAC site is blocked from entry (only members allowed)

I can't imagine  that Mooney folks wouldn't avail themselves of a lower priced option should it be legally available.

In reviewing your information here I went to 21.303b and it talks about TSOs.

Are you suggesting that there is a TSO available denoting the shock discs? 

Do you require a PMA approval to manufacture to a TSO design and do you have same ?

I see by your email you seem to be from South Africa   Is that correct? I have been there many times . It is a very nice place especially the Garden Route. 

The less expensive option would probably sell quite well but as above I do have questions Please expand on you and your idea.

[0TreeLemur]

In Feb. the MSC doing the annual on our C recommended that we replace the shock discs to protect our investment in the tank reseal.  They were last replaced in 2006.   I was expecting it to be "bouncier" but honestly can't really tell any difference.  Based on this, I'm inclined to say that they weren't that bad, and could have gone a few years longer.  Based on what @Pasturepilot observed, they could have gone a lot longer...

[N201MKTurbo]

1 hour ago, 0TreeLemur said:

In Feb. the MSC doing the annual on our C recommended that we replace the shock discs to protect our investment in the tank reseal.  They were last replaced in 2006.   I was expecting it to be "bouncier" but honestly can't really tell any difference.  Based on this, I'm inclined to say that they weren't that bad, and could have gone a few years longer.  Based on what @Pasturepilot observed, they could have gone a lot longer...

I would put the ones you removed on my plane...

[N201MKTurbo]

The guy who says he can make shock disks for less that $50, is probably correct. Lord can probably make them for you for less than $50 too if you want un-certified disks.

I was doing a service call at a mining equipment company in Casper WY. back in the 80s. I looked over at a guy's desk and a Lycoming motor mount was sitting there. I asked him how much they were, He said $25. I said that was 1/4th of what I paid for them. He said they were used for stationary engines in the mines. They were exactly the same, in a Lord box.

[carusoam]

15 hours ago, Gert said:

I have the alternative solution to expensive shock discs! I own and fly a Beechcraft Sundowner 180 and had to replace the shockdiscs. The costs were unbelievably high and I could not believe that such a simple device as a rubber disc can cost so much.

I decided to investigate if I can manufacture these discs at a more affordable price, since the FAA allows aircraft owners to produce parts. I found that it is absolutely possible and that under FAR section 21.303(b) I will be allowed to manufacture these discs for other owners as well. About two years ago I started collecting information on the composition and detail of the discs. I manage to stumble onto the original manufacturing specifications of the Beechcraft as well as Mooney discs. The manufacturing data and rubber composition for both discs were made available by a retired engineer from Lord who used to manufacture these discs. The Mooney discs have the same composition as the Beechcraft discs of the natural rubber and  percentage Poly-butyl-dye-lean which is slightly more dampened and stiffer. 

I went ahead and started manufacturing the Beechcraft Landing gear with great success at one third of the cost of similar products. I decided to manufacture the discs at cost + 10% to ensure the extended life of the "Baby Beech" line of aircraft and also to give back to the industry that have given me so much during the past 30 odd years. I also started a website www.avunlimited.co where Beech Aero Club members and other owners can read more and order the products. Profits so generated will be used to train disadvantaged young pilots.

I can also  easily manufacture Mooney shockdiscs at below $50 per disc and would like to gauge interest from Mooneyspace members in this regard. Please let me know what you think or e-mail me at gert@avunlimited.co.za. You can also visit the BAC website and topic at http://www.beechaeroclub.org/showthread.php/13829-Rubber-Donuts-Now-at-reasonable-prices

Blue Skies

Gert

welcome aboard Gert...

There is a group of Mooney pilots that are in need of smaller rubber discs that are no longer in production... anywhere...

The Mooney Mites... M18s...

Helping them out would be great...

Since you are in the know regarding certified planes and user supplied parts... it would be interesting if you could share all the details that you use to make these available as defined User Supplied Parts...  

we have a couple of vendors we use around here that have this USP service... but rubber qualities, as you are aware, are little more challenging than selecting the same grade of aluminum or stainless steel.

Can you make a rubber disc made up of two different rubber compounds, with an inter-penetrating network structure?

Something that could land softer, yet last longer, under the weight of an Ovation...

(I have been waiting for years to ask this question... to the right person) 

It might even be worth writing an STC for these donuts...

Looking forward to your response...

PP thoughts only, not a mechanic... I may have seen the inside of a polymer plant,  and my favorite house plant is a rubber tree...

Best regards,

-a-

[0TreeLemur]

2 hours ago, N201MKTurbo said:

I would put the ones you removed on my plane...

Sadly I trashed them before I realized that they were not all used up. 

[Gert]

17 hours ago, cliffy said:

Seems the BAC site is blocked from entry (only members allowed)

I can't imagine  that Mooney folks wouldn't avail themselves of a lower priced option should it be legally available.

In reviewing your information here I went to 21.303b and it talks about TSOs.

Are you suggesting that there is a TSO available denoting the shock discs? 

Do you require a PMA approval to manufacture to a TSO design and do you have same ?

I see by your email you seem to be from South Africa   Is that correct? I have been there many times . It is a very nice place especially the Garden Route. 

The less expensive option would probably sell quite well but as above I do have questions Please expand on you and your idea.

You will be able to peruse the BAC website forums without a subscription, use the search engine and verify that you are not a web robot.

I attach herewith an article published by Mike Busch that sets out the owner produced parts regulations quite clearly. When an aircraft owner wants me to manufacture a set of Rubber Donuts he gives me an instruction setting out the quality, composition and precise measurements as per attached document. This document is sent to prospective buyers and they fill it in with their details and any measurements or instructions. I have tested this methodology with FAA and they agreed on the validity and that the process and parts adheres to Section 21.303. The process and parts have been exhaustively tested by BAC members and we have retired FAA personnel as members of BAC who have assisted greatly in this process.

I am indeed from South Africa, the small town of Caledon at the start of the Garden Route.

OPP Mike Busch.pdf Avunlimited - FAA OPP Rev. A (Retractable Gear Disc) Export PDF.pdf

[Gert]

5 hours ago, carusoam said:

welcome aboard Gert...

There is a group of Mooney pilots that are in need of smaller rubber discs that are no longer in production... anywhere...

The Mooney Mites... M18s...

Helping them out would be great...

Since you are in the know regarding certified planes and user supplied parts... it would be interesting if you could share all the details that you use to make these available as defined User Supplied Parts...  

we have a couple of vendors we use around here that have this USP service... but rubber qualities, as you are aware, are little more challenging than selecting the same grade of aluminum or stainless steel.

Can you make a rubber disc made up of two different rubber compounds, with an inter-penetrating network structure?

Something that could land softer, yet last longer, under the weight of an Ovation...

(I have been waiting for years to ask this question... to the right person) 

It might even be worth writing an STC for these donuts...

Looking forward to your response...

PP thoughts only, not a mechanic... I may have seen the inside of a polymer plant,  and my favorite house plant is a rubber tree...

Best regards,

-a-

Hi

The rubber compound used in the J-11968-14 Lord disc is an elastomer blend type MX with a deflection of 1.0 inch for 3000lbs for a stack of eight discs. It is a multiple compound product with Natural Rubber and Polybutylene with excellent penetration and adherence to the metal discs. It is approximately 40% stiffer than the Beech J-11968-10 discs that I currently manufacture, but all measurements are exactly the same. I can thus use the same moulds, which will definitely assist to bring costs down. The material composition is such that it is more UV stable and can handle much more deflection cycles than the Lord type. 

In the past Beech members had to pre-warm the donuts before installation to counter splitting problems and to assist installation when ambient temperatures were low. This is no longer a problem with the material temperature range tested between -13F to 113F and installation is a lot faster as a result.

I am in the process to get an STC approved, but this will definitely push up costs as a result. If you need a softer or more flexible disc, why not experiment with the J-11968-10. The static deflection of 4 dash10 discs will be 0.75 inch compared to 0.5inch of the dash14 discs. It will however have a marked difference in dynamic elasticity, I presume. 

Best Regards

Gert

[cliffy]

7 hours ago, Gert said:

You will be able to peruse the BAC website forums without a subscription, use the search engine and verify that you are not a web robot.

I attach herewith an article published by Mike Busch that sets out the owner produced parts regulations quite clearly. When an aircraft owner wants me to manufacture a set of Rubber Donuts he gives me an instruction setting out the quality, composition and precise measurements as per attached document. This document is sent to prospective buyers and they fill it in with their details and any measurements or instructions. I have tested this methodology with FAA and they agreed on the validity and that the process and parts adheres to Section 21.303. The process and parts have been exhaustively tested by BAC members and we have retired FAA personnel as members of BAC who have assisted greatly in this process.

I am indeed from South Africa, the small town of Caledon at the start of the Garden Route.

OPP Mike Busch.pdf 2.29 MB · 1 download Avunlimited - FAA OPP Rev. A (Retractable Gear Disc) Export PDF.pdf 240.91 kB · 1 download

Sounds like you have  a winner on your hands if you want to proceed. I suspect you will secure many Mooney customers as this is one area (or part) that due to the cost, many owners defer doing maintenance on. I venture that the vast majority of Mooneys  have worn out donuts.

The procedure of doing Owner Produced Parts has been beaten to death on this website several times over the years, It IS a very viable way to procure hard to source parts for vintage airplanes. Before Mike Busch there was a retired FAA Senior Level Maintenance Specialist that also promoted and explained the process for OPPs. The hardest aspect to make it legal has always been finding approved data to make the part. You seem to have that covered. 

The methodology you use for directions from the owners follows what a company over here does for the manufacture of engine control cables. The process works quite well (I have used it). 

I will predict that you will secure near 100% of the Mooney market by going forth with your plan. Many more Mooney owners will consider replacing their donuts with your pricing.  I don't see any need to pursue an STC for this. I think it would be a waste of time and resources and have no real benefit in the end, for the additional cost to you and the end user. 

Obviously you have overcome any import issues shipping from over seas. 

We have friends near Warmbaths (Bela Bela) and more over the border in Windhoke, Namibia. Have been from the red sands of the Kalahari to Tzaneen, Dullstroom and Phalaborwa    The tea and citrus plantations near Tzaneen were  interesting as were numerous other locations through which we traveled. 

[carusoam]

It would be really interesting to test drive a different compound...

But, like everything else it may be a compromise...  that may effect steering or something else...

When the donuts compress permanently... we often have sensor challenges... on the birds with a squat switch...

On the nose wheel... changes of the compression might result in changes in the nose wheel support geometry... this could cause a wild ride...

Just some ideas to consider, from a PP, not a mechanic...

 

Gert,

Do you have a friend in SA with a Mooney?

 

MS has a couple members down there...

 

I’m thinking this topic hasn’t been touched by the factory in about 50+ years... there may be some improvement available by a guy with some rubber technology... but it may need being, or working with, an A&P and STC writer...

If it is the same as the lord disks, that last longer... that would be good too... but hard to know until 10 years pass...

PP thoughts only, not a mechanic....

Best regards,

-a-

[carusoam]

@Gert

Other needs for Mooney rubber products that may be of interest....

Are you familiar with the Brittain Wing Leveler autopilot?

They use a rubber bladder as the working part of a vacuum based actuator...

The company that made them has fallen on lean times and could use some support to make these rubber bladder devices... they had a mold problem, and couldn’t get it fixed...

Have a look at this thread to get an idea...

Many have been patched over and over, and are on their last legs...

This AP system is many more birds then just Mooneys...

Best regards,

-a-

 

[Browncbr1]

It seems you have the same process as proven by McFarlane for OPP...  process sounds no different from when I ordered control cables for my throttle, mixture and prop.   

My current discs were installed in 2004.  I noticed they feel harder during taxi and less forgiving on landing than they were 5 years ago.  

I’m  ready for a new set of discs this August annual.  

[MooneyJohn]

24 minutes ago, Browncbr1 said:

It seems you have the same process as proven by McFarlane for OPP...  process sounds no different from when I ordered control cables for my throttle, mixture and prop.   

My current discs were installed in 2004.  I noticed they feel harder during taxi and less forgiving on landing than they were 5 years ago.  

I’m  ready for a new set of discs this August annual.  

I agree, it would be the same proven process.

[Matt Ward]

So @Gert are you looking for beta testers in the us? Mine are more than twenty years old as the post title says!

[0TreeLemur]

On 4/28/2020 at 12:59 PM, Pasturepilot said:

I’m under my mooney right now. 1965 M20C. My main gear discs are a 1968 date code.

Yeah, I know. So I bought some from a local MSC. Went to install them today. But wait, it gets better. 
 

Under compression, the gap under the collar is Right at limits. When I jack it up, they expand exactly as designed. 
 

The retaining bolt on one side is rusted and won’t come loose. I hit it with PB blaster and will try again tomorrow when the rain begins. For now it’s sunny and clear in Georgia, so I’m gonna button it up and go fly while the blaster does its thing. 

 

One thing Jeremy, if they are that old- your aircraft is probably missing some SB items.   They added a shock link collar, and the shock links themselves can and do wear out.  The one in the nose gear of our plane was found in badly worn condition during our last annual.  That means that it wore out since the last replacement of our disks, which happened relatively recently in 2006.   We found a used one.   Good luck.