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Thread: Front+Rear Isolators

  1. #1
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    Front+Rear Isolators

    Hello all,

    As my application for an account on Badweb is still under review, I was posting up here to get some thoughts -

    Our front isolator is a part of combined part number that matches many other older harleys - I specifically have a 1996 FLHT (Electra Glide Standard), and found the isolator and the front mount on both to be the same dimensionally speaking. This is supported by websites like DennisKirk and the like showing cross compatibility listings - so I don't think there's going to be much rare that direction. I had planned on upgrading the Buell's front mount to a poly unit eventually.

    However I have noticed that the rear isolators are ridiculously pricey unless you can get lucky. In addition, they are rubber and no one appears to have poly setups anywhere. Is this incorrect?

    There's a dude I know who does polyurethane work, and I was wondering - inputs most welcome here -

    I am trying to devise a way to make a poly bushing the easiest way possible - in my mind the easiest way is:
    #1 - You mold the entire thing, then pour the entire thing - you have a solid poly bushing with no steel center tube or backside. - This sounds not good though as the center of the bushing appears to hold the frame center and the bolthole appears to be steel as well and the rubber just prevents side to side compression.

    or

    #2 - You take a mold of the entire thing. Then you remove all the rubber, clean all the rubber off the steel, and replace the steel in the mold and pour in polyurethane. This would require mounts to have good backing plates which I assume is generally not an issue in this community.

    So, thoughts? Anyone done this before? I was thinking of having it 3d scanned and getting a set of all steel ones custom CNC'd too, though that may be a more expensive task. I figure start small.
    Last edited by avenger09123; 04-05-2023 at 02:52 AM.

  2. #2
    Senior Member Cooter's Avatar
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    Welcome to the forum! Glad you're here and have the ambition to try to solve a specifically Buell issue You could collaborate with several of our members on here and even on Badweb that have tried to solve this issue for the XB line as well. Because it's been a bit more difficult than it seems. At least so far?


    Knock, Knock, Neo

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    Well look at energy suspension builder bushings the bushing slides in from both sides then you press in the metal inner tube it ma help with assembly. But post a couple pic’s I’m not familiar with that bushing.

    AND the solid poly XB isolator is working well I just haven’t taken the time to cast the second style with the window for front and rear “float”.

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    Senior Member Cooter's Avatar
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    Hey CVC! I don't remember you updating that thread? How it working out? Pics?

  5. #5
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by avenger09123 View Post
    Hello all,

    As my application for an account on Badweb is still under review, I was posting up here to get some thoughts -

    Our front isolator is a part of combined part number that matches many other older harleys - I specifically have a 1996 FLHT (Electra Glide Standard), and found the isolator and the front mount on both to be the same dimensionally speaking. This is supported by websites like DennisKirk and the like showing cross compatibility listings - so I don't think there's going to be much rare that direction. I had planned on upgrading the Buell's front mount to a poly unit eventually.

    However I have noticed that the rear isolators are ridiculously pricey unless you can get lucky. In addition, they are rubber and no one appears to have poly setups anywhere. Is this incorrect?

    There's a dude I know who does polyurethane work, and I was wondering - inputs most welcome here -

    I am trying to devise a way to make a poly bushing the easiest way possible - in my mind the easiest way is:
    #1 - You mold the entire thing, then pour the entire thing - you have a solid poly bushing with no steel center tube or backside. - This sounds not good though as the center of the bushing appears to hold the frame center and the bolthole appears to be steel as well and the rubber just prevents side to side compression.

    or

    #2 - You take a mold of the entire thing. Then you remove all the rubber, clean all the rubber off the steel, and replace the steel in the mold and pour in polyurethane. This would require mounts to have good backing plates which I assume is generally not an issue in this community.

    So, thoughts? Anyone done this before? I was thinking of having it 3d scanned and getting a set of all steel ones custom CNC'd too, though that may be a more expensive task. I figure start small.

    The Buell rear isolator is a specific Buell design with "ears" to catch the engine/trans if/when the isolator fails. Since the last models that used this design were discontinued over 20 years ago, and Buell was shut down, Harley hasnt had a reason to make that specific isolator. You can use one off some Harley models, but they will lack the ears and will likely be short lived. The same goes for the front mount, but like the front, there was a specific one made for the Buell application. You should be able to get this from Twin Motorcycles still, but you can use one from other Harley models to various degrees of success.

    If you want to go ahead and pioneer this, go ahead. The guys on Badweb would love you for it as well. As far as costs go, and if you are trying to recoup some of that expense by making a production run, remember that the cheapest part on a Buell is the rider.

  6. #6
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    Quote Originally Posted by 34nineteen View Post
    The Buell rear isolator is a specific Buell design with "ears" to catch the engine/trans if/when the isolator fails. Since the last models that used this design were discontinued over 20 years ago, and Buell was shut down, Harley hasnt had a reason to make that specific isolator. You can use one off some Harley models, but they will lack the ears and will likely be short lived. The same goes for the front mount, but like the front, there was a specific one made for the Buell application. You should be able to get this from Twin Motorcycles still, but you can use one from other Harley models to various degrees of success.

    If you want to go ahead and pioneer this, go ahead. The guys on Badweb would love you for it as well. As far as costs go, and if you are trying to recoup some of that expense by making a production run, remember that the cheapest part on a Buell is the rider.
    Aint that the truth. That last line gave me a laugh.

    Yeah that's what I was looking for. I ran across Mad Monkey Motorsports today who makes both a solid aluminum rear isolator and one with UHDPE that does a better job of absorbing the vibes that most I guess don't like. But I was wondering what the ears were for on the buell ones as that is the big difference and I guess now I know. This is interesting. So I was thinking about this and I understand the purpose of the ear on a two-material isolator - if the bonding fails it won't just drop out if the frame flexes while riding. But I would guess that is not necessary on a solid metal mount or metal + uhmw so it is less of a concern.

    My question is, I don't mind buying a brand new set to make a mold of, but I don't want to destroy them for the steel plates. Does anyone have a dead set with the steel in decent condition laying around they can send my way so I can cannibalize the steel for the first one? The dead ones on fleabay start at $70 and are corroded to shizzle.

    I will consider a production run, I am going to look through my company tomorrow to see if we have anyone that does this sort of stuff for aerospace projects. Otherwise I will do it myself or maybe in conjunction with a guy I know from the subaru world who does this as a side gig up in Fort Collins. I have no idea what I am doing and no experience doing this either other than whatever youtube videos I can get my hands on tomorrow.

    Quote Originally Posted by Cooter View Post
    Welcome to the forum! Glad you're here and have the ambition to try to solve a specifically Buell issue You could collaborate with several of our members on here and even on Badweb that have tried to solve this issue for the XB line as well. Because it's been a bit more difficult than it seems. At least so far?
    Knock, Knock, Neo
    Time to follow the white rabbit again...

    I will check out energy suspension.

    Interestingly - Engineered Velocity makes a solid aluminum insert for the stock isolators though - it'd be an interesting take if that's all you need with stock isolators to keep them from dropping out.

    Oh choices choices...
    Last edited by avenger09123; 04-06-2023 at 03:28 AM.

  7. #7
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    Quote Originally Posted by Cooter View Post
    Hey CVC! I don't remember you updating that thread? How it working out? Pics?
    I’m hoping to cast the window style this weekend and i can get a picture of the solid one sometime tomorrow.
    I’ll update the thread when I have a several ready to ship it is that time of year in most of the country.
    Last edited by cvc; 04-06-2023 at 06:58 AM.

  8. #8
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    Quote Originally Posted by avenger09123 View Post
    My question is, I don't mind buying a brand new set to make a mold of, but I don't want to destroy them for the steel plates. Does anyone have a dead set with the steel in decent condition laying around they can send my way so I can cannibalize the steel for the first one? The dead ones on fleabay start at $70 and are corroded to shizzle.

    I will consider a production run, I am going to look through my company tomorrow to see if we have anyone that does this sort of stuff for aerospace projects. Otherwise I will do it myself or maybe in conjunction with a guy I know from the subaru world who does this as a side gig up in Fort Collins. I have no idea what I am doing and no experience doing this either other than whatever youtube videos I can get my hands on tomorrow.
    There was a NOS one on eBay awhile back for $25. You can always take a stock trashed one (probably find one at a Harley shop) and just weld in an ear to the steel insert and continue fabbing from there. It doesn't appear that you are after a concours d' elegance restoration, but just something that is functional and works. I've owned tubers with the non-Buell rear isolators in them and they were fine, you just had to keep an eye on them and keep up on your maintenance. You would probably be fine with the stock HD ones, as it appears that you will keep an eye on them, but for the "ignore it until it breaks" rider it can be dangerous.

    It would be nice if you could figure out how to redesign the isolator to make them easier to get in and out without the "frame spreader". The stock design also means that if you break a belt on the road, the chance of a doing a roadside repair is slim to none, unlike an XB.

  9. #9
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    Quote Originally Posted by cvc View Post
    I’m hoping to cast the window style this weekend and i can get a picture of the solid one sometime tomorrow.
    I’ll update the thread when I have a several ready to ship it is that time of year in most of the country.

    You're only interested in the cores with the round hole, right?

    I have a feeling mine is failing as I am getting a lot more vibration than I remember from my bike. It could also be that I forgot how much the paint shaker shakes.

    I have a NOS one in my collection, but I'd be interested in BUYING one from you, and swapping it out with my original. If anything, I can report back how yours feels (shut up CoOter!) compared to a suspected failing one.

  10. #10
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    Quote Originally Posted by 34nineteen View Post
    There was a NOS one on eBay awhile back for $25. You can always take a stock trashed one (probably find one at a Harley shop) and just weld in an ear to the steel insert and continue fabbing from there. It doesn't appear that you are after a concours d' elegance restoration, but just something that is functional and works. I've owned tubers with the non-Buell rear isolators in them and they were fine, you just had to keep an eye on them and keep up on your maintenance. You would probably be fine with the stock HD ones, as it appears that you will keep an eye on them, but for the "ignore it until it breaks" rider it can be dangerous.

    It would be nice if you could figure out how to redesign the isolator to make them easier to get in and out without the "frame spreader". The stock design also means that if you break a belt on the road, the chance of a doing a roadside repair is slim to none, unlike an XB.
    Well, I am not sure about concours d' elegance. The reality for that in my perspective thinking of "the consumer" 2fl5mo.jpg would be stripping and powdercoating the steel (which I don't know how to powder coat), and a vacuum chamber to pull bubbles out of the mold on pour to make it practically perfect. Am I going to go that route? Probably not, at least not at first.

    For me concours d' elegance is never having to replace it again, AND it looking stock or better. Right now the only way that occurs is with a solid metal unit.

    My goal really is to just make it both look as close to stock as possible and be as easy as possible, that's all at first. We can add complexity and target perfection later on. I will go upstairs and mull over the replacement without pushing on the frame - I have some ideas but nothing concrete yet.
    Goal #1 - Get it to bond correctly to the steel.
    Goal #2 - Get it to look like stock as close as possible.

    CVC what do you mean by "window style"?

    Ok I went outside and checked out the assembly - I can envision sliding in a thick urethane washer with a frame sized hole in the middle - then two clamshell pieces behind that next to the rear swingarm assembly that you tighten together with reasonable allen bolts and some loctite (side with the locating pin would have to go in first) - filling in the space between the frame and the rear assembly. Then you screw in some pipe of the same OD as the ID of the frame hole (not friction fit but snug) into that clamshell. and then pop the torx/allen screw in like normal to tighten it all together. - The only downside to this design would be that someone could put too much loctite on any one part and it'd require the tool to take out the old fashioned way. The other downside is that a threaded pipe would have a chance of scratching the inside of the frame hole on assembly - even IF the outside of the pipe had a pressed on urethane jacket. The upside is that you can have a much thicker assembly to take up space and could theoretically tailor your hardness of the urethane to absorb a set amount of the vibes and keep the clamshell the same across the board.

    It'd be a near solid assembly - similar to this - d61d5e_be0ff24bf0be467297a7947632a361ff_mv2.jpg but would require you to assemble the pieces between the frame and engine and put the center pipe in through the frame hole to support it all.


    Last edited by avenger09123; 04-07-2023 at 03:57 AM.

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