front motor mount
Tourer
Joined: Apr 2014
Posts: 288
Likes: 3
From: UK
This subject does crop up a lot so just to clarify the facts.
The original version (most commonly referred to as version B) measures approximately 880 lbs per inch whereas the version D is around 1540 lbs per inch so yes tit is a lot stiffer. This is not achieved through the rubber hardness but the physical shape of the mount, they are both about 45-50 shore hardness.
The Buell version which is popular as a swap out on the Evo bikes is softer than version B so may give good vibration isolation but a short life expectancy.
In summary, if you have a lighter Shovel of Evo motor the B version is the best one, if you can find one. The D version is a better match for the heavier Twin cam engines.
Cheap aftermarket clone parts tend to be based on the B version but I have measured one of these at nearly 3000 lbs per inch and the vibration was horrendous at low speeds. There is less control over stiffness on these parts so its pot luck what you get. That is probably why some folks have good results and some bad.
Not tested any Poly mounts so don't know where they fit into the range.
Road Warrior
Joined: Apr 2011
Posts: 1,596
Likes: 9
From: Cherokee Co. Georgia
This subject does crop up a lot so just to clarify the facts.
The original version (most commonly referred to as version B) measures approximately 880 lbs per inch whereas the version D is around 1540 lbs per inch so yes tit is a lot stiffer. This is not achieved through the rubber hardness but the physical shape of the mount, they are both about 45-50 shore hardness.
The Buell version which is popular as a swap out on the Evo bikes is softer than version B so may give good vibration isolation but a short life expectancy.
In summary, if you have a lighter Shovel of Evo motor the B version is the best one, if you can find one. The D version is a better match for the heavier Twin cam engines.
Cheap aftermarket clone parts tend to be based on the B version but I have measured one of these at nearly 3000 lbs per inch and the vibration was horrendous at low speeds. There is less control over stiffness on these parts so its pot luck what you get. That is probably why some folks have good results and some bad.
Not tested any Poly mounts so don't know where they fit into the range.
The original version (most commonly referred to as version B) measures approximately 880 lbs per inch whereas the version D is around 1540 lbs per inch so yes tit is a lot stiffer. This is not achieved through the rubber hardness but the physical shape of the mount, they are both about 45-50 shore hardness.
The Buell version which is popular as a swap out on the Evo bikes is softer than version B so may give good vibration isolation but a short life expectancy.
In summary, if you have a lighter Shovel of Evo motor the B version is the best one, if you can find one. The D version is a better match for the heavier Twin cam engines.
Cheap aftermarket clone parts tend to be based on the B version but I have measured one of these at nearly 3000 lbs per inch and the vibration was horrendous at low speeds. There is less control over stiffness on these parts so its pot luck what you get. That is probably why some folks have good results and some bad.
Not tested any Poly mounts so don't know where they fit into the range.
Tourer
Joined: Apr 2014
Posts: 288
Likes: 3
From: UK
Although these threads tend to be short lived I thought I would just add a bit more meat to the bones.
There were two US manufacturers that make similar standard parts to the HD front mount Lord Corporation and Barry Controls. The Harley mount takes the generic insulator portion but uses a non standard flange size making it unique. I am not sure which manufacturer HD used originally, maybe even both. The type B mount I have has got "Barry" moulded into it and the Barry part number, which was special to HD.
The fundamental difference between the type B and type D mounts is in the way the rubber used. Type B is an inner steel tube and a profiled outer flange (the profile is hidden by the rubber) The rubber is predominantly in shear.
The Type D mount is an evolution of the Type B with the same outer flange but the top washer is part of the inner sleeve and is bonded to the top of the rubber. This small but significant difference gives it the extra stiffness, and load carrying capacity.
The quirky thing on the latest type D mounts is that the "made in China" is moulded in the upside down which has cause some folk to bolt the mount in the wrong way up, it actually fits that way but is terrible for vibration isolation if fitted this way.
There were two US manufacturers that make similar standard parts to the HD front mount Lord Corporation and Barry Controls. The Harley mount takes the generic insulator portion but uses a non standard flange size making it unique. I am not sure which manufacturer HD used originally, maybe even both. The type B mount I have has got "Barry" moulded into it and the Barry part number, which was special to HD.
The fundamental difference between the type B and type D mounts is in the way the rubber used. Type B is an inner steel tube and a profiled outer flange (the profile is hidden by the rubber) The rubber is predominantly in shear.
The Type D mount is an evolution of the Type B with the same outer flange but the top washer is part of the inner sleeve and is bonded to the top of the rubber. This small but significant difference gives it the extra stiffness, and load carrying capacity.
The quirky thing on the latest type D mounts is that the "made in China" is moulded in the upside down which has cause some folk to bolt the mount in the wrong way up, it actually fits that way but is terrible for vibration isolation if fitted this way.
Last edited by 4_stroke; Dec 18, 2014 at 07:17 AM.
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