• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Elac Miracord Rubber Motor Mount Dimensions 10H, 40H, 50H, 770H to eliminate PAPST RUMBLE

monkboughtlunch

monkboughtlunch

Super Member
ELAC MOTOR MOUNT DIMENSIONS MEASURED SO NEW MOUNTS CAN BE SOURCED

Problem summary

If any of the three rubber motor mounts are out of spec in an Elac turntable equipped with a Papst motor, vibration noise from the motor will be audible during LP playback (especially between songs or quiet passages).

There is ZERO information about the dimensions of the Elac motor mounts in the Elac service manuals or anywhere online, including German turntable forums. There are currently no known replacements.

So, I pulled an Elac motor mount out and measured it! Hopefully, a suitable replacement for the motor mount can now be found or created using these exact dimensions from the original part.
  • Elac used three rubber motor mounts to support the Papst motor
  • Two mounts are used above the motor to hang it
  • One mount is used below the motor
  • It's possible Elac used this size motor mount found in the 10H for other models with the Papst motor, including the 40H, 50H and 770H etc.
  • Additionally, Elac might have used these mounts for other motor types too (i.e. shaded pole induction), but I'm not certain. Can anyone confirm?
Below: my measurements of the motor mount summarized in an infographic

gummipuffersize.jpg

Below: Location of the three motor mounts per the Elac service manual

gummipuffer sm 1.jpg

Below: Reference to the motor mounts in the Elac service manual (but no dimensions provided). Part number: Gummipuffer 10-416-121

gummipuffer sm2.jpg

Below: My measurement findings in text form. Note that millimeters ARE THE EXACT SIZE of the original measured part. I also added the closest approximate fraction (NOT EXACT) of an inch for cross-reference.

Bore Diameter (A): 4 mm. (5/32")
Groove Width (B): 4 mm. (5/32")
Groove Diameter (C): 7 mm. (9/32")
Outside Diameter (D): 10.50 mm. (13/32")
Shoulder Width (E): 4 mm. (5/32")
Shoulder Width (F): 2 mm. (5/64")
Overall Thickness (G): 10 mm. (25/64")
 
Last edited:
Register to hide this ad
LOWER RUBBER MOTOR MOUNT - EXTREMELY CRITICAL FOR RUMBLE-FREE PLAYBACK

I've confirmed that the lower rubber motor mount (beneath the Papst motor as shown in the below photo) is extremely critical for damping motor noise.

Over time, this lower rubber motor mount becomes less pliant, the bore hole widens from vibration and the motor shaft is then free to slightly wobble. This increased motor vibration transfers directly to the metal bracket, then on to the main chassis and is picked up by the stylus during playback.

Note that the black bracket is connected directly to the metal chassis so it is very critical that the single lower motor mount be in spec!

If you are still chasing a mystery motor noise heard between songs -- even after lubing the main bearings and refreshing the idler wheel--this lower motor mount may be the culprit.

To test the theory, I stuffed some damping material in the bore hole of this motor mount surrounding the metal shaft from the motor. The motor noise heard during playback then declined dramatically.

Now that this significant source of noise has been identified, where can new rubber motor mounts be sourced? See dimensions of rubber mounts in my prior post.

IMG_2265.jpg
 
Last edited:
1. Now that the dimensions of the ELAC rubber motor mounts are documented, does anyone know if a suitable replacement exists?
2. If not, is there enough demand across the collective Audiokarma North America (or worldwide) ELAC owner base to have some motor mounts custom made?
 
Last edited:
Solist said:
I know those motor rubbers very well. They disintegrated on my Elac, although it had a normal motor, not the papst one. I tried to make some diy replacement parts, but the main thing is to get the rubber hardness right.
Click to expand...

Were you successful in making new rubber motor mounts, and did you determine the correct durometer (hardness)?
 
Successful not so much. I did not find an adequate rubber, so I could feel the vibrating motor when I touched the top plate. I later just gave up on the idea and used the original rubber. You could try and reverse engineer to get close to the original specs or just try different rubber to see which one is the best at damping the vibrations from the motor. Time consuming process but probably the best way.
 
monkboughtlunch said:
Lord makes motor mounts for Papst motors in Empires and ROKs.

Anyone know what durometer Lord uses? I’m thinking the same durometer should work for an Elac changer with a Papst.
Click to expand...

They make them in multiple durometers, but I doubt they publish that info. Their catalog is on their website. They only sell to distributors, but may send some free samples if you talk to a customer service rep. I worked there for 41 years before retiring in 2016. There is a click for where to buy on the link below, a customer service number, and a .pdf catalog.

https://www.lord.com/products-and-solutions/vibration-and-motion-control/industrial/isolators
 
classic carl said:
They make them in multiple durometers, but I doubt they publish that info. Their catalog is on their website. They only sell to distributors, but may send some free samples if you talk to a customer service rep. I worked there for 41 years before retiring in 2016. There is a click for where to buy on the link below, a customer service number, and a .pdf catalog.

https://www.lord.com/products-and-solutions/vibration-and-motion-control/industrial/isolators
Click to expand...

Thanks. Based on your experience at Lord, do you think they would be open to making a custom size mount that would fit the Elac mount? What kind of production numbers interest them? Is there a minimum order quantity?
 
monkboughtlunch said:
Thanks. Based on your experience at Lord, do you think they would be open to making a custom size mount that would fit the Elac mount? What kind of production numbers interest them? Is there a minimum order quantity?
Click to expand...

IMO, they would not be interested. A custom mount for a TT would cost way too much money, citing tooling costs and low quantities. They manufacture hundreds of thousands of their catalog sizes for various industries. There is no way it would be cost effective to enter the vintage TT motor mount market. I do know that they have supplied grommet mounts for Empire TT motors in the past for at least a couple of individuals, but have no idea which catalog number that woud be, or how the parts were acquired (customer service or distributor maybe). If you called customer service and offerred to send them the dimensioned print, they may be able to recommend a part number that would work. You would need to know the load requirements also.
I worked in the Aerospace division for the final 10 years or so of my career, so I was out of the loop on the Industrial parts.
 
Last edited:
Thanks - interesting that Lord manufactured a new batch of the Empire / ROK grommets in the modern era. Perhaps Lord still had the original tooling for the grommets they manufactured for Empire and ROK turntables back in the 50s and 60s, and that's why they were able to reproduce them today?

I wonder who originally made the Elac rubber motor mounts in Germany and if the tooling still exists to create a new run.

Alternatively, could a new Elac motor mount mold be 3D printed using an original rubber mount as a guide?
 
Last edited:
monkboughtlunch said:
Thanks - interesting that Lord manufactured a new batch of the Empire / ROK grommets in the modern era. Perhaps Lord still had the original tooling for the grommets they manufactured for Empire and ROK turntables back in the 50s and 60s, and that's why they were able to reproduce them today?

I wonder who originally made the Elac rubber motor mounts in Germany and if the tooling still exists to create a new run.

Alternatively, could a new Elac motor mount mold be 3D printed using an original rubber mount as a guide?
Click to expand...

The grommets used in the recent Empire application were standard catalog parts. Multi-cavity production molds, even small hand molds used for prototypes are machined from tool steel and cannot be 3D printed.
 
Last edited:
Update.

I contacted EBM Papst and Elac a few months ago about replacement motor mounts and the correct viscosity of motor oil.

Results:

1. No feedback from Elac.
2. Feedback below from an EBM-Papst Applications Engineer:

==============================

EBM-Papst Applications Engineer:

"I was unable to locate information on bearing viscosity due to the age of the part. All of our modern motors have maintenance-free bearings. Regarding the rubber mount; unfortunately, the original and similar components are no longer available. The closest thing I have would be like the image below. This is not something we regularly stock, and we would need to discuss further due to a required MOQ from Germany (my customer relations team would need to confirm an exact quantity). It may be best to find something similar from a third-party company that would work for you, through a component distributor that sources/stocks locally. I wish we could be of more help!"

papst.jpg
 
I have a 770 and 50 that I’ve been pondering about.
I understand the importance of hardness, but I’m thinking about this :
0FF6FC8A-0B18-4E5D-AD62-8E4495785EAB.png

If I can make 20 of them, for the price of the kit, I’m ok with each one only lasting a year. As far as their performance as noise isolators, it will have to be tested.
 
The Empire/ROK grommets are completely different is size, shape, and in having a brass tubular insert. They are used in all sorts of industrial motor applications, I believe, so there is continued demand and Lord keeps making them. You can buy the 'audio' version and pay a ton, or buy the exact same thing for much less. When parts are actually made specifically for an audio application, they cost a lot because they won't sell many - I think some of Esoteric's offerings are actually made for them since I haven't found them elsewhere. But while this isolation washer at the bottom of the motor maybe used elsewhere, it might be challenging to identify a source since you'd have to identify the similar use. Is this the sort of thing that could be made by a 3D printer? I can see it being a small money maker for someone who did some experimentation.
 
classic carl said:
The grommets used in the recent Empire application were standard catalog parts. Multi-cavity production molds, even small hand molds used for prototypes are machined from tool steel and cannot be 3D printed.
Click to expand...

Riddle me this: There’s an ebay seller in Hong Kong making new rubber Elac 10 and 10h idler wheels. How is he producing them in such low quantities if he didn’t use 3D printing for prototyping? Can you just make a mold of the old rubber part?
 
Last edited by a moderator:
You must log in or register to reply here.
Back
Top Bottom