Original Rubber Drive Couplings (Donuts)

[Peter Barnes]

Following a conversation about the prices of reproductions of original GT40 parts, I decided to attempt to make the donuts.

I found a couple of experts in their field and between us set about the task.

The first batch turned out very well

The results in the photos below;

!st, and 2nd photo, scans, 3rd , steel insert casting, 4th and 5th, Ali Moulds, Last photo, finished Item.



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[Markus]

Interesting project....
Do you have any supporting struture inside the molded rubber?
In a former job I was in contact with flexible couplings - the used to have fiber bundles inside.

Regards
Markus

SGF Interesting facts - Süddeutsche Gelenkscheibenfabrik - English

www.sgf.de

 

[Graham Endeacott]

Following a conversation about the prices of reproductions of original GT40 parts, I decided to attempt to make the donuts.

I found a couple of experts in their field and between us set about the task.

The first batch turned out very well

The results in the photos below;

!st, and 2nd photo, scans, 3rd , steel insert casting, 4th and 5th, Ali Moulds, Last photo, finished Item.



View attachment 112326 .View attachment 112324 View attachment 112321 View attachment 112322 View attachment 112323 View attachment 112325

Nice work, I could be needing some of these soon.

Regards,

Graham.

 

[Neil]

The early '60s front-engine V12 Ferrari 250 series uses these doughnuts between their transmission and drive shaft. Check the sizes- they may be usable.

 

[Brian Coombs]

Following a conversation about the prices of reproductions of original GT40 parts, I decided to attempt to make the donuts.

I found a couple of experts in their field and between us set about the task.

The first batch turned out very well

The results in the photos below;

!st, and 2nd photo, scans, 3rd , steel insert casting, 4th and 5th, Ali Moulds, Last photo, finished Item.



View attachment 112326 .View attachment 112324 View attachment 112321 View attachment 112322 View attachment 112323 View attachment 112325

Hi Peter, they look great, very impressive, how are you going to test them? or are you going to use your car as the test rig?

 

[Peter Barnes]

Hi Peter, they look great, very impressive, how are you going to test them? or are you going to use your car as the test rig?

Hi Brian, Happy New Year. I have sent a pair to a respected GT40 man to look at. He has a test rig. I will set up a test rig myself soon but I am confident they are better than those made in the 60's ...... time will tell

 

[Brian Coombs]

Hi Brian, Happy New Year. I have sent a pair to a respected GT40 man to look at. He has a test rig. I will set up a test rig myself soon but I am confident they are better than those made in the 60's ...... time will tell

Happy New Year too, I will be interested to see how they go? It's not something I would have ever thought about making, but its amazing what you can do when you have to! Are the steel inserts forged, or did you cast them?

 

[Peter Barnes]

Happy New Year too, I will be interested to see how they go? It's not something I would have ever thought about making, but its amazing what you can do when you have to! Are the steel inserts forged, or did you cast them?

Hi, The inserts are cast.

 

[Peter Barnes]

A donut has been tested to failure. A bolt through two adjacent holes were hydraulically stretched apart , the rubber stood up extremely well and broke. The important point is that the rubber did not detach from the steel. This test checked the adhesion and strength of the rubber, however the donut would not undergo these extremes in racing use.

 

[Peter Barnes]

To help pay for the investment in this project I am offering a few donuts for sale, £ 600 for a pair, inc postage within the UK. Will post abroad by arrangement.

Thanks Peter.

 

[JohnM]

Hi Peter, they look great, very impressive, how are you going to test them? or are you going to use your car as the test rig?

Hi,
Hi all, I'm thinking of using doughnuts on a car I'm building and the Metalastik torque capacity data is very conservative imho, so any real word usage on a powerful car would be really useful to me. Do you know the PCD or the part number of the doughnut in the picture ? Did they fail... etc
Cheers
John

 

[Rob Klein]

Peter,
How are things going with the R&D?

 

[Neil]

Rubber drive couplings are shipped with a metal band around their circumference. Do NOT remove this band before installing them in place! My Ferrari used one in its drive shaft on the transmission output flange. I made the mistake of cutting off the metal band and I had a hard time getting all the bolt holes to line up. The band holds the rubber in compression so the bolt holes line up with the drive flanges. Cut the band and the rubber expands!