How would you design an engine mount? Suitable rubber?
Discussion
I need to make an engine mount for a kit car project as the standard mount doesn't fit. I also want to replace one of the other mounts as its worn so I was thinking of trying to make both of them myself as a bit of an interesting exercise.
The main thing I am struggling on at the moment is where to source suitable rubber to use for an engine mount and how to find out what sort of stiffness I would need to be equivalent to a 'uprated' or 'hard rubber' engine mount. (how is the stiffness of rubber measured?)
The top engine mount that needs to be altered looks like this:
I am hoping to make a replacement similar to this vibratechnics design but with the correct bolt spacings I need.
The Gearbox mount which needs replacing looks like this:
Again I would like to try and make one similar to this design:
The third engine mount is a simple design where I can easily press a new bush in.
I have a lathe, press and welder etc. so if I can source some suitable rubber then I should be able to have a pretty good go at it. Any pointers or tips would be welcomed, especially on how to source suitable rubber to use.
The main thing I am struggling on at the moment is where to source suitable rubber to use for an engine mount and how to find out what sort of stiffness I would need to be equivalent to a 'uprated' or 'hard rubber' engine mount. (how is the stiffness of rubber measured?)
The top engine mount that needs to be altered looks like this:
I am hoping to make a replacement similar to this vibratechnics design but with the correct bolt spacings I need.
The Gearbox mount which needs replacing looks like this:
Again I would like to try and make one similar to this design:
The third engine mount is a simple design where I can easily press a new bush in.
I have a lathe, press and welder etc. so if I can source some suitable rubber then I should be able to have a pretty good go at it. Any pointers or tips would be welcomed, especially on how to source suitable rubber to use.
I did have a look on their website but all their bushes seem to be specifically designed to fit certain engine mounts and as such would be harder to make fit than if I could get hold of some suitable rubber.
Also the experience I have had of powerflex bushes was not good, I found they wore very quickly so I would prefer to use a harder rubber, or just a standard rubber but solid, rather than polyurethane.
Also the experience I have had of powerflex bushes was not good, I found they wore very quickly so I would prefer to use a harder rubber, or just a standard rubber but solid, rather than polyurethane.
Something from here may suit... http://www.smooth-on.com/Urethane-Rubber-an/c6_111...
PowerFlex said:
Powerflex Bushings are produced in one of three durometers – yellow (70A – stiffer than rubber), purple (80A), and black (95A – very stiff) measured hardness
Pet Troll said:
I did have a look on their website but all their bushes seem to be specifically designed to fit certain engine mounts and as such would be harder to make fit than if I could get hold of some suitable rubber.
Surely the metal is the easy bit to make, so you design it to take a bush that you can get?B'sides, it's not as simple as "some suitable rubber", or even "harder rubber" - the hardness of the rubber directly affects the amount of vibration being transmitted. You may find the rubber you use is too hard, and want to soften it up. If you can get off-the-shelf bushes in varying hardnesses, life's easier.
As said, I would look at designing the metalwork around an existing rubber element that has been designed for the engine load your dealing with.
These components are designed to absorb energy to reduce vibrations and also minimise no movement created by the vibration, torque etc.
If you try to get into the energy absorption hysteresis characteristics and force/stroke characteristics of natural and man made rubbers you will be researching for a long time.
These components are designed to absorb energy to reduce vibrations and also minimise no movement created by the vibration, torque etc.
If you try to get into the energy absorption hysteresis characteristics and force/stroke characteristics of natural and man made rubbers you will be researching for a long time.
MysteryLemon said:
As above really.
My way of thinking would be to make the car fit the standard engine mount rather than making an engine mount to fit the car.
Could you not alter the standard mounting locations so they are suitable for the standard mount? Saves faffing about with all that rubber.
The trouble with altering the mounting locations on the chassis means we would have to then send the chassis off for re-powder coating which will be a lot of expense and a lot of time as some parts are riveted on to the chassis so would have to be drilled out.My way of thinking would be to make the car fit the standard engine mount rather than making an engine mount to fit the car.
Could you not alter the standard mounting locations so they are suitable for the standard mount? Saves faffing about with all that rubber.
I will see if I can find a suitable bush and make a mount to fit around it.
MysteryLemon said:
Any chance of fabricating a bracket that goes between the two? Of course I understand this may be a silly/impossibru idea without actually seeing the car, mount and engine together.
I have thought about that and tried to work out a way for it to be possible but I can't see how it would work in this particular instance.Gassing Station | General Gassing | Top of Page | What's New | My Stuff