Custom Lifetime 928 Motor Mounts by Hans
11-01-2016, 08:46 AM
#16
Electron Wrangler
Lifetime Rennlist
Member
Lifetime Rennlist
Member
How shelf stable is the urethane? would it make sense to buy in advance rebuild kits for these or do they deteriorate over time making this impractical. Thinking - this is only a real benefit if you can indeed rebuild them later and for that you need the replacement urethane inserts, (unless these are of any standard size that is generally stocked for some other purpose?)
I think is is a really great idea - but I'd like to ensure the true longevity of the solution.
Alan
I think is is a really great idea - but I'd like to ensure the true longevity of the solution.
Alan
11-01-2016, 01:05 PM
#18
Rennlist Member
The urethane is certainly shelf stable. I am not casting these myself, they are injection molded into metal tooling with a proper urethane injector. I will gladly sell replacement inserts in advance if people want them, but I will offer replacement parts indefinitely.
I did size the isolators so in the event someone needs something custom, they can be cut from common sheet stock.
I dont have a firm price on the rebuild kit (need to consider carrying/storage costs, tooling amortization.. etc), but I can tell you it will not exceed $15/mount. I am thinking something like $25 for all four isolators in either 70D or 80D.
There is no hydraulic fluid to leak out, and the urethane used is incredibly durable and not susceptible to many environmental effects like NBR can be. Its main enemy is extreme heat - so the islolators would not likely survive something like an engine fire. However, the housings would come out just fine and the mounts could be rebuilt along with the engine.
I did size the isolators so in the event someone needs something custom, they can be cut from common sheet stock.
I dont have a firm price on the rebuild kit (need to consider carrying/storage costs, tooling amortization.. etc), but I can tell you it will not exceed $15/mount. I am thinking something like $25 for all four isolators in either 70D or 80D.
There is no hydraulic fluid to leak out, and the urethane used is incredibly durable and not susceptible to many environmental effects like NBR can be. Its main enemy is extreme heat - so the islolators would not likely survive something like an engine fire. However, the housings would come out just fine and the mounts could be rebuilt along with the engine.
11-02-2016, 08:29 AM
#21
Three Wheelin'
How shelf stable is the urethane? would it make sense to buy in advance rebuild kits for these or do they deteriorate over time making this impractical. Thinking - this is only a real benefit if you can indeed rebuild them later and for that you need the replacement urethane inserts, (unless these are of any standard size that is generally stocked for some other purpose?)
I think is is a really great idea - but I'd like to ensure the true longevity of the solution.
Alan
I think is is a really great idea - but I'd like to ensure the true longevity of the solution.
Alan
Thank you Hans for answering Alan's question by offering a reasonably priced rebuild kit as backup.
Cheers!
03-02-2019, 11:56 AM
#23
Drifting
Does anyone have a set they're not using and want to sell?
03-04-2019, 02:29 AM
#26
Rennlist Member
It would be a benefit to the 928 community for Hans's products to be produced in volume and become more widely available. One of the larger 928 distributors should approach Hans and become a stocking dealer if margins can work for all involved.
03-04-2019, 10:11 PM
#27
Rennlist
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Not to rain on anyone's parade, but a certain amount of thought and intelligence is required whenever anything is substituted for a product that was engineered around a specific application.
The hydraulic motor mounts that Porsche supplied were not just random chunks of rubber designed to hold up the engine, but were designed to "absorb" the harmonics and frequencies that the 928 engine generates.
Very specific harmonics and frequencies, unique to the 928 engine!
Sticking in a mount from a Volvo, from a Ford, or even this mount will not, almost certainly, be tuned to absorb those specific harmonics and frequencies....why would anyone think that they would be?
Just because someone makes or sells something, even really pretty stuff, doesn't mean it works or you should use it.
Remember....you've got to be 5% smarter than what you are working on to be successful!
The hydraulic motor mounts that Porsche supplied were not just random chunks of rubber designed to hold up the engine, but were designed to "absorb" the harmonics and frequencies that the 928 engine generates.
Very specific harmonics and frequencies, unique to the 928 engine!
Sticking in a mount from a Volvo, from a Ford, or even this mount will not, almost certainly, be tuned to absorb those specific harmonics and frequencies....why would anyone think that they would be?
Just because someone makes or sells something, even really pretty stuff, doesn't mean it works or you should use it.
Remember....you've got to be 5% smarter than what you are working on to be successful!
03-05-2019, 12:31 PM
#28
Rennlist Member
Cant argue with that - there is no substitution for a properly engineered hydraulic mount for maximum comfort (NVH)
My mounts were a solid design (although there are several voids in the structure that allow the urethane to deform and give some compliance and dampening) so not a truly rigid/fully-constrained design. They will always transmit more vibration into the cabin than a hydraulic mount, and I would never recommend a solid mount for anyone who wants the factory 928 silky smooth experience. To the best of my knowledge, all the mounts I made that are out there are still in service, and have not experienced any noticeable fatigue, but that is not saying much as the oldest prototypes are just now five years old. The urethane used in the isolators was properly injection molded into bespoke metal tooling under pressure (not gravity hand cast) out of a chemical and temperature resistant synthetic material, so should not degrade under normal usage at a premature rate.
Porsche did a great job of dealing with NVH with a combination of unique features to separate the human contact points with the vibration transmitting elements of the chassis and drivetrain. I do not believe that anyone will be able to improve on the stock design with NVH in mind (without a monumental budget for tooling). Properly designed hydraulic mounts require complicated molds, fluid injection, and valving between the chambers - something you wont see on a small scale. Compared to the price of other things, the factory mounts are not that bad a value any more. Last I checked, they were just a bit over $525/pair. Compared to the price increases on a lot of the other parts, its nice they have stayed fairly steady, and now seem like a much better deal than they did several years ago.
When my mounts were available, they were selling for $450 and I think that was actually less than my cost after all the anodizing and hardware (and a $0 labor line item). They are just not a cost-effective design unless made in large numbers - and I don't think there is a market for such a "solid" design. There definitely was no room in the price for a mark-up, so its even worse idea for one of the vendors to stock them. Even after a reasonable margin, they would cost considerably more than a stock mount - which we all agree is a great design
With the number of these cars on the road falling, and the the value rising, (as we should) we are seeing that more people are restoring these cars than playing with them.
Unless we see a whole new generation of people using the 928 for DE or other "motorsport" applications, It think this mount may be permanently retired.
My mounts were a solid design (although there are several voids in the structure that allow the urethane to deform and give some compliance and dampening) so not a truly rigid/fully-constrained design. They will always transmit more vibration into the cabin than a hydraulic mount, and I would never recommend a solid mount for anyone who wants the factory 928 silky smooth experience. To the best of my knowledge, all the mounts I made that are out there are still in service, and have not experienced any noticeable fatigue, but that is not saying much as the oldest prototypes are just now five years old. The urethane used in the isolators was properly injection molded into bespoke metal tooling under pressure (not gravity hand cast) out of a chemical and temperature resistant synthetic material, so should not degrade under normal usage at a premature rate.
Porsche did a great job of dealing with NVH with a combination of unique features to separate the human contact points with the vibration transmitting elements of the chassis and drivetrain. I do not believe that anyone will be able to improve on the stock design with NVH in mind (without a monumental budget for tooling). Properly designed hydraulic mounts require complicated molds, fluid injection, and valving between the chambers - something you wont see on a small scale. Compared to the price of other things, the factory mounts are not that bad a value any more. Last I checked, they were just a bit over $525/pair. Compared to the price increases on a lot of the other parts, its nice they have stayed fairly steady, and now seem like a much better deal than they did several years ago.
When my mounts were available, they were selling for $450 and I think that was actually less than my cost after all the anodizing and hardware (and a $0 labor line item). They are just not a cost-effective design unless made in large numbers - and I don't think there is a market for such a "solid" design. There definitely was no room in the price for a mark-up, so its even worse idea for one of the vendors to stock them. Even after a reasonable margin, they would cost considerably more than a stock mount - which we all agree is a great design
With the number of these cars on the road falling, and the the value rising, (as we should) we are seeing that more people are restoring these cars than playing with them.
Unless we see a whole new generation of people using the 928 for DE or other "motorsport" applications, It think this mount may be permanently retired.
03-05-2019, 01:59 PM
#29
Cant argue with that - there is no substitution for a properly engineered hydraulic mount for maximum comfort (NVH)
My mounts were a solid design (although there are several voids in the structure that allow the urethane to deform and give some compliance and dampening) so not a truly rigid/fully-constrained design. They will always transmit more vibration into the cabin than a hydraulic mount, and I would never recommend a solid mount for anyone who wants the factory 928 silky smooth experience. To the best of my knowledge, all the mounts I made that are out there are still in service, and have not experienced any noticeable fatigue, but that is not saying much as the oldest prototypes are just now five years old. The urethane used in the isolators was properly injection molded into bespoke metal tooling under pressure (not gravity hand cast) out of a chemical and temperature resistant synthetic material, so should not degrade under normal usage at a premature rate.
Porsche did a great job of dealing with NVH with a combination of unique features to separate the human contact points with the vibration transmitting elements of the chassis and drivetrain. I do not believe that anyone will be able to improve on the stock design with NVH in mind (without a monumental budget for tooling). Properly designed hydraulic mounts require complicated molds, fluid injection, and valving between the chambers - something you wont see on a small scale. Compared to the price of other things, the factory mounts are not that bad a value any more. Last I checked, they were just a bit over $525/pair. Compared to the price increases on a lot of the other parts, its nice they have stayed fairly steady, and now seem like a much better deal than they did several years ago.
When my mounts were available, they were selling for $450 and I think that was actually less than my cost after all the anodizing and hardware (and a $0 labor line item). They are just not a cost-effective design unless made in large numbers - and I don't think there is a market for such a "solid" design. There definitely was no room in the price for a mark-up, so its even worse idea for one of the vendors to stock them. Even after a reasonable margin, they would cost considerably more than a stock mount - which we all agree is a great design
With the number of these cars on the road falling, and the the value rising, (as we should) we are seeing that more people are restoring these cars than playing with them.
Unless we see a whole new generation of people using the 928 for DE or other "motorsport" applications, It think this mount may be permanently retired.
My mounts were a solid design (although there are several voids in the structure that allow the urethane to deform and give some compliance and dampening) so not a truly rigid/fully-constrained design. They will always transmit more vibration into the cabin than a hydraulic mount, and I would never recommend a solid mount for anyone who wants the factory 928 silky smooth experience. To the best of my knowledge, all the mounts I made that are out there are still in service, and have not experienced any noticeable fatigue, but that is not saying much as the oldest prototypes are just now five years old. The urethane used in the isolators was properly injection molded into bespoke metal tooling under pressure (not gravity hand cast) out of a chemical and temperature resistant synthetic material, so should not degrade under normal usage at a premature rate.
Porsche did a great job of dealing with NVH with a combination of unique features to separate the human contact points with the vibration transmitting elements of the chassis and drivetrain. I do not believe that anyone will be able to improve on the stock design with NVH in mind (without a monumental budget for tooling). Properly designed hydraulic mounts require complicated molds, fluid injection, and valving between the chambers - something you wont see on a small scale. Compared to the price of other things, the factory mounts are not that bad a value any more. Last I checked, they were just a bit over $525/pair. Compared to the price increases on a lot of the other parts, its nice they have stayed fairly steady, and now seem like a much better deal than they did several years ago.
When my mounts were available, they were selling for $450 and I think that was actually less than my cost after all the anodizing and hardware (and a $0 labor line item). They are just not a cost-effective design unless made in large numbers - and I don't think there is a market for such a "solid" design. There definitely was no room in the price for a mark-up, so its even worse idea for one of the vendors to stock them. Even after a reasonable margin, they would cost considerably more than a stock mount - which we all agree is a great design
With the number of these cars on the road falling, and the the value rising, (as we should) we are seeing that more people are restoring these cars than playing with them.
Unless we see a whole new generation of people using the 928 for DE or other "motorsport" applications, It think this mount may be permanently retired.
Just don't forget about the replacement pieces.
03-05-2019, 02:00 PM
#30
And it hurts that people are not cleaning more when they put parts in the car (pictures above).