Just curious.. Other than cost and service life, can you think of any others?

 

Urethane has some very good mechanical properties mainly abrasion and chemical resistance but it has poor vibration isolation properties due to its high hysterisis.

It has a good operating temperature range but its stffness and damping properties change significantly over that range. The cast material that is used in aftermarket parts suffers from creep and permanent set. From a process point of view the bond strength is not as good as vulcanised rubber when bonding it to metal parts.

The reason its used in aftermarket products is because its easy to mould with little or no tooling so its easy to start making parts unlike vulcanised parts which require specialist injection mould equipment and expensive tooling.

 

You sound like a Vibra-Technics aficionado.. Thanks for the additional info.

 

What urethane isn't "cast"? If it's cut from a blank, the blank was still cast.

 

By cast i mean poured into a mould under gravity as opposed to injection moulded. There are a lot of different processes that are used to mould urethane depending on the mixing and curing system. Most aftermarket parts use a casting system using pre mixed chemicals similar to an epoxy resin process. Its a good rapid prototyping material but the process needs to be spot on.

 

Here is a new rear mount that should correct the side to side play but still allow movement in the vertical plane.. Unlike some lines of thought about dyna mounts, the biggest issue IMO is to limit side play of the rear mount.. The true tracks and Sputhe do a good job in the front but fail in the rear.. Anyone that thinks the rear mount is OK hasn't been able to figure out how to fix it.. Hopefully this design will be an improvement over the rear link types..


Pic 1 assembled..

Pic 2 one side pulled off to reveal vibration isolation and the UHMW Polyethylene bearing to handle side thrusts..

 

. Is this the one you made yourself? Looks like a real quality piece

 

Yeah,

Thanks, It's an idea on trying to limit side flex of the rear motor mount by capturing the frame connection between the 2 plates that mount to the tranny. Haven't tried it yet.

 

. Looks great. I don't know if you're looking to produce these but if you need another tester I'm in!

 

Thanks for the vote of confidence but I need to test with some different materials first.. If it looks promising, I might try and get a short CNC run done on the block and plates.