Landing Gear Shock Disks Source?

[carusoam]

Tying two threads together….

In this thread there is a discussion about the origin and source of early Mite donuts….

Mack Truck engine mounts…?

With a connection to a KNR article…. Where KNR is a Mooney mechanic with great writing skills….

Best regards,

-a-

[Kevin Harberg]

April 10, 1950-Mooney Aircraft Inc. Wichita, Kanasa Speicfications for the M18C quote "Firestone rebound - control Shock Units and Firestone 4.00X4 Tire Equipment".

Wouldn't it be great if Firestone still sold the same units under some automotive part number (Perhaps Mack Truck)?

 

 

Edited November 21, 2022 by Kevin Harberg
Attachment removed.

[gummirat]

Hello all, Hope you had a good holiday. I have been trying to get a print of these parts to make a mold to make the shock disks for you guys. No print no mold. I don't understand why the reluctance to do this if they are needed. This is not the kind of project that will let me retire to some place sunny and warm. Mark

[Kevin Harberg]

2 hours ago, gummirat said:

Hello all, Hope you had a good holiday. I have been trying to get a print of these parts to make a mold to make the shock disks for you guys. No print no mold. I don't understand why the reluctance to do this if they are needed. This is not the kind of project that will let me retire to some place sunny and warm. Mark

Just finished reviewing my paperwork and was not successful in finding a usable print for your use. I did find drawings calling them Rubber Spring Discs and another reference as Rubber Shock Pads (Originally Firestone CRE 714-1). The ASTM Spec was unreadable. After reviewing the Smithsonian drawings available for reprint, the most likely drawing is Mooney 0662 (11/9/1948) - Models: Mooney M18 - Title: PAD-LOWER SHOCK (9" x 11" Drawing) Smithsonian Item # DD-0029142. This drawing is available from the Smithsonian for a small fee if no other drawings show up in future replies to your request. You can order this drawing by completing the request form available at:

https://airandspace.si.edu/files/pdf/archives/mooney-reproductions.pdf

Hope this is of assistance to you, and to the Mooney Mite Community. I have a spare set mounted on a gear spindle that could be freighted to you from Canada. I had hoped that even though they are old and likely hard, I at least had them as an emergency spare, however, having a source of new replacement discs would be better. Let me know if you would like me to send you my spare gear spindle.

 

[carusoam]

5 hours ago, gummirat said:

Hello all, Hope you had a good holiday. I have been trying to get a print of these parts to make a mold to make the shock disks for you guys. No print no mold. I don't understand why the reluctance to do this if they are needed. This is not the kind of project that will let me retire to some place sunny and warm. Mark

Hey Mark!

Happy New Year!

Sending this note to a friend… @Jonny

The Mooney Mite community needs rubber discs for their landing gear similar to all other Mooneys…

But, none in stock anywhere…. None being made.

MSer @gummirat is in the rubber business and can make rubber discs aka donuts.  Having a technical drawing would be great!
 

Best regards,

-a-

[Kevin Harberg]

Hello Mark @gummirat

I have two rubber shock pads for the M-18 packaged and ready to send to you for analysis and destructive testing. Please forward mailing instructions via Mooney Space messages and I will get them on your way.

Regards,

Kevin Harberg

 

 

 

[Fly Boomer]

2 hours ago, Kevin Harberg said:

Hello Mark @gummirat

I have two rubber shock pads for the M-18 packaged and ready to send to you for analysis and destructive testing. Please forward mailing instructions via Mooney Space messages and I will get them on your way.

Regards,

Kevin Harberg

 

 

 

Didn't look like the call to @gummirat got formatted correctly.

[gummirat]

Hi all, yes, I got the message. and have replied to Kevin. Wil keep you all posted on progress Thanks Mark

[Kevin Harberg]

Great news from Mark @gummirat

The used M-18 shock discs have been sampled and type of compound, elastomeric property, and type of cloth have been identified. Just waiting on measurements of unused discs to create mold.

[Guest]

2 hours ago, Kevin Harberg said:

Great news from Mark @gummirat

The used M-18 shock discs have been sampled and type of compound, elastomeric property, and type of cloth have been identified. Just waiting on measurements of unused discs to create mold.

I’ve got a set of new ones.  If there is a way to scan/copy them let me know.

[gummirat]

A machine shop with and optical comparator or a cmm, like a cordax. the former is like an overhead projector and you take the measurements off the image, the other uses a probe to touch the part at several points and take the measurement. my mold maker has a optical comparator he can load into a cad program and make the print. you can call me to discuss. Thanks Mark

[carusoam]

Most old school machine shops always had an optical comparator…

The engineers loved that thing…

Best regards,

-a-

[gummirat]

Kevin, do i have your permission to cut one of the parts to do some more thorough testing? 

[Kevin Harberg]

On 1/26/2023 at 1:34 PM, gummirat said:

Kevin, do i have your permission to cut one of the parts to do some more thorough testing? 

Go ahead and cut away Mark. It would be interesting to compare size and shape to original (New Old Stock).

[gummirat]

WOW Kevin are these things used! I got some dimensions of the metal washer and did a hardness test. 78a on the inside. need a picture of the metal side to see if is flat or a conical metal. Maybe M20 doc can get that and post it. Mark

 

 

 

 

 

[Kevin Harberg]

33 minutes ago, gummirat said:

WOW Kevin are these things used! I got some dimensions of the metal washer and did a hardness test. 78a on the inside. need a picture of the metal side to see if is flat or a conical metal. Maybe M20 doc can get that and post it. Mark

 

 

 

 

 

The bracket that held the two sample shock discs you received, has a thick conical top and bottom metal disc. The disc between the two shock discs is thin and conical, however, it could have easily been compressed into that shape. Don't know if Clarence @M20Doc has his gear legs apart to verify my findings.

 

Kevin Harberg

[Kevin Harberg]

13 hours ago, Kevin Harberg said:

The bracket that held the two sample shock discs you received, has a thick conical top and bottom metal disc. The disc between the two shock discs is thin and conical, however, it could have easily been compressed into that shape. Don't know if Clarence @M20Doc has his gear legs apart to verify my findings.

 

Kevin Harberg

Here's a photo of the metal shock disc mount showing conical shape for top and bottom of each rubber shock disc.

[Kevin Harberg]

On 1/30/2023 at 8:07 AM, Kevin Harberg said:

Here's a photo of the metal shock disc mount showing conical shape for top and bottom of each rubber shock disc.

Hello Mark @gummirat

Would you like me to send you the above piece for cone dimensions?

]

Kevin

 

[carusoam]

Looks like we are making headway!

Fingers crossed…

-a-

[gummirat]

Hi Kevin, not at this time, m-20 doc is supposed to get me some numbers on the measurements so we will see how that works. I'm having a tga and a ftir ran on the compound to verify composition. Thanks for the offer. Mark

[carusoam]

Gumi has all the right stuff going!

thermo gravimetric analysis… TGA

Fourier Transform Infra Red analysis… FTIR

Some serious polymer chemistry lab equipment…

Way cool…

Reminds me of my school days… a decade or four ago… or was it five?

 

Best regards,

-a-

[gummirat]

Hi All, got the test reports back and it is a SBR rubber with a high filler loading. The one I will use is a natural rubber that should give better resilience and compression set properties. I really need get the dimensions to build the mold. I need to prove the new print is based on the old print or nos part for certification.

 

[Kevin Harberg]

@gummirat Let me know if I can be of any assistance. I can send you the nosewheel bracket that has the bevelled steel mounting plates if it would be of any use. You may be able to access the aforementioned drawings from the Smithsonian as per my January 11th post. A scan of a "New Old Stock" rubber disc would likely give you the most accurate dimensions. I  have some more "used" rubber discs still mounted on a spare set of "Main gear legs" but I suspect they are in similar condition to those I previously provided.

[gummirat]

Hi Kevin, I tried to find them on the site you posted and didn't find anything ( not saying much, I'm not a wiz at computers).     If you can come up with the drawing that would put this project in getter done mode, I would proceed with the mold and certification process. Thanks Mark

[gummirat]

Hi All ,had a lab batch of the compound made and tested, 4300 lb tensile,600% elongation comp set 18% great numbers eh carusoam. m20doc any luck on the measurements? Kevin any luck on the print? I'm into this just south of 1k would like to see the interest or did I waste the money? Mark