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Post by urbantangleweed on Feb 16, 2024 20:05:43 GMT 1
Has anyone ever explored a modern alternative to the rubber engine mounting bushes situation?
I'm going to replace them on my next YPVS build and wondered if there's a modern solution that can be made to work, something like polyurethane instead of rubber for example?
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Post by 4l04ever on Feb 16, 2024 20:16:11 GMT 1
It would not be difficult to cast new ones with Polyurethane.
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Post by Tobyjugs on Feb 16, 2024 20:59:19 GMT 1
I have made polyurethane parts in the past and it was always a bit hit and miss with the shore once made.
Sometimes too hard and sometimes too soft using the same resin/compounds. The mixing seems to be very critical |
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Post by urbantangleweed on Feb 16, 2024 22:06:13 GMT 1
I was curious if there was something off the shelf that could be made to work such as a suspension bush that had the correct inner and outer diameters. Obviously, they wouldn't have the elongated centre piece, but that could likely be made up easily enough with a spacer tube.
When my cases come back from the vapour blasters I'll pull the existing ones out and see if there might be something suitable about.
Just ramblings of an eccentric mind really......
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Post by JonW on Feb 17, 2024 1:21:56 GMT 1
be careful removing the old ones, support the raised cast 'brackets' as pushing against them could crack the mounts.
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Post by reedpete on Feb 17, 2024 2:56:35 GMT 1
I have made polyurethane parts in the past and it was always a bit hit and miss with the shore once made.
Sometimes too hard and sometimes too soft using the same resin/compounds. The mixing seems to be very critical Curing temp and time profile is what changes the properties… |
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Post by urbantangleweed on Feb 17, 2024 7:17:35 GMT 1
I have made polyurethane parts in the past and it was always a bit hit and miss with the shore once made.
Sometimes too hard and sometimes too soft using the same resin/compounds. The mixing seems to be very critical Do you know what the ideal shore hardness would be? |
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Post by lcmarky on Feb 17, 2024 9:11:33 GMT 1
The lack of damping the rubber offers may cause some extra vibes getting through & shaking your fillings!!
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Post by dusty350 on Feb 17, 2024 10:00:42 GMT 1
Doesn't Norbo sell new originals ?
Sure they would outlast the bike if you fitted them.
I've never felt the need to change them on any of my engine builds. Maybe I've been lucky ?
A solution for the 4 dampers on a 250Lc wheel would be good though as they are Nla, and although Norbo lists them, he hasn't had them for some time, and can't get them.
🙂
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Post by Tobyjugs on Feb 17, 2024 16:40:43 GMT 1
I have made polyurethane parts in the past and it was always a bit hit and miss with the shore once made.
Sometimes too hard and sometimes too soft using the same resin/compounds. The mixing seems to be very critical Do you know what the ideal shore hardness would be? No sorry i don't but i could try to measure it for you if the meter is in the company workshop. |
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Post by urbantangleweed on Feb 17, 2024 17:36:51 GMT 1
Do you know what the ideal shore hardness would be? No sorry i don't but i could try to measure it for you if the meter is in the company workshop. No, really not worth going to all that bother. |
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Post by muttsnuts on Feb 19, 2024 10:12:40 GMT 1
I have a durometer for measuring shore hardness, I can check it, suspoect it will be around 70 to 75 shore, the tolerance is normal +/- 5 on the hardness scale anyway
New ones are still available from Yamaha and TBH making some isn't that easy, I've just been through the whole pprocess of getting some rubber made at the correct hardness/size etc and that was a learning curve for sure !
Swapping the bushes isn't straight forward and as others have stated, you have to be super careful not to crack the cases, I've made a puller and fitting tool up as I do a fair few and even with that, its still a good hours work at least to swap a set out
HTH
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Post by urbantangleweed on Feb 20, 2024 8:31:14 GMT 1
Swapping the bushes isn't straight forward and as others have stated, you have to be super careful not to crack the cases, I've made a puller and fitting tool up as I do a fair few and even with that, its still a good hours work at least to swap a set out HTH I'll likely go down the road of new Yamaha ones, just wondered if there was a more modern alternative that would do the job. I prefer the puller method to replace bushes in aluminium housings rather than belting them in with a 4lb lump hammer, so will probably make something up with threaded bar to make the process as easy as possible. The current scrap price for cast aluminium is about £1/Kg, so worst case (no pun intended) scenario is I'll get around 3 quid back if it all goes wrong.....  |
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Post by JonW on Feb 20, 2024 23:33:24 GMT 1
The yam ones are still working in many bikes 40years after being sold new and often lead a hard life, cant complain about that longevity. The problem with even pulling them is that you need to support the two raised brackets together etc. I hadnt even considered bashing these... eek... yeah, dont do that! |
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