Buell XB high performance front isolator

[BambamXB12r]

Thanks for all your time and effort of the project. I would say keep us updated but I know you will.

 

[KevXB12S]

$400 is a great price but would they be even cheaper if i ordered say 5 or ten units?

 

[TPEHAK]

Yes, following parts should be way cheaper because the most time for the first sample machinist spends on G-code and testing, once the process is fully investigated and adjusted he needs only to put the aluminum blank in the machine and press the start button for each following part.

 

[TPEHAK]

Finally I have all necessary parts. I performed a couple quick tests and have some promising results.

Different rubber rods from McMaster

I cut the rubber rods with blade to necessary length

For the first test I prepared shore 40A and shore 60A polyurethane rods

Located them on the bushong

Slided the assembly in the isolator. First time I did it with no lubricant and with no chamfered edges so it was difficult to slide the assembly in the hole

Here is the sequence for the first test I performed

Install the flange. I had figured out that the holes are not tapped deep enough so I shortened the bolts with grinding wheel. I would use #8-32 thread, 3/4" long http://www.mcmaster.com/#90665a114/=11oarfx instead #8-32 thread, 1" long I mentioned before.

Installed the rubber washer to protect the isolator in case of sliding along the isolator bolt

Once I had tried to install the new front isolator I had figured out that the bump on the back side interferes with the engine case, so I ground 2 mm down the bump with file. I will fix the CAD file later before I will share the new tweaked and verified revision of the bracket

And finally I had installed the new isolator first time

Then I ran the motorcycle and noticed it vibrates worst than with the original isolator, but slightly better than with my old broken front isolator with fully cracked rubber. Even the bushing on the prototype is less stiffer than the the original isolator bushing. So I decided to change rubber rods. And the next issue is to remove the bushing from the isolator. The rubber rods with no lubrication are very sticky. So I bought a plastic pipe and a bolt with a nut with a couple washers in a local Home Depot.

Then I assemble the bushing puller

Polyurethane rods was not going to slide so I pulled the bushing trough the rods. Polyurethane is very hight performance abrasion and tear resistant material with extremely high tensile strength so I pulled the bushing trough the polyurethane rods with no any damage or marks on the rods.

 

[TPEHAK]

Before the second test I put chamfers on the edges and greased the inner surfaces of the isolator, so now the rubber rods slide in to the hole with no any difficulties.

The next configuration I was going to test is shore 70A + shore 30A rods. I used Buna-N shore 70A for the side areas and silicone shore 30A for the front and back areas.

Silicone has pretty low tensile strength so I used silicone rods only for back-forth load and located them in front and back areas, Buna-N has better tensile strength so I put it in the left and right sides areas for vertical support.

Then I installed the isolator on the motorcycle and performed a new test ride and it looks like this configuration feels pretty close to the original isolator. Maybe there are more vibrations at hight RPM but I can not say exactly because I'm tired and can be wrong. I need to perform more tests. I can be wrong, but visually for me it looks like isolator vibrates in vertical direction with bugger amplitude than the original isolator, so it might be that the shore 70A rods are still not stiff enough to provide similar stiffness in vertical direction, so maybe I will test shore 80A + shore 30A next configuration.

 

[Sirius815]

:up: Nice work!

 

[Chicknstripn]

Excellent write up, info, pics and work!
Wow. I'm truly impressed.
Just a thought, have you thought about call or sending an email to EBR asking questions about the original isolator?
I know EBR is alive again and I know from experience that they have been helpful in the past when I've asked Buell related questions. Hell, you never know, they might be interested in using your idea. How cool would that be.

 

[cjanderson_90]

Wow this excites me. Literally the only parts we wont be able to adapt are motor mounts and belts. But with belts we can switch to chain. This is a very good thing and I hope a manufacturer like Preeng or someone can help produce these if you dont want to go through with making them all the time

 

[Bullettooth023]

I may be able to help with machining. Send me some more info and I can see what our machine shop at work would charge.

 

[TPEHAK]

Thanks! I will post the files later, so anyone can try it.

It works! Finally I have found the acceptable configuration. The second configuration I mentioned before does not work well, it starts excessive vibrations after 2000 RPM and than higher RPM than worst vibration and at long trip it causes hands and legs go numb.

Today I decided to try asymmetric configuration, the same idea is on the original isolator, the rubber has smaller hole in front of the bushing and bigger hole behind the bushing, so the back area is softer than the front area. I used polyurethane rods shore 60A and silicone rods shore 30A.

Then I performed a test ride and now it runs surprisingly smooth at any RPM and while acceleration and deceleration. The first impression is it works even smoother than the original isolator.

Here is the isolator deflection with this configuration under engine weight

Will see how it will work in long run.

 

[mtz117]

This is truly awesome. Keep the updates coming, I'm really interested.

 

[TPEHAK]

Here is the zip archive with the updated STEP CAD models and drawings, so you can use it. The CAD models include the changes I implemented while testing.

https://drive.google.com/file/d/0B3I3sGuWsilzaFBKVkVWUkFUQ2s/view?usp=sharing

 

[Flatout]

Truly amazing and thorough! Even though you won't be producing these, I feel you deserve a few rounds of beer!

 

[chief_of_smoke]

I second that

 

[TPEHAK]

It looks like the isolator does not perform very well. The isolator has no excessive vibrations but after a couple rides the bracket has moved about 5 mm down on the bushing and the top faces of the polyurethane rods had been sheared by bracket edge.

You can see the cut rods

I have a couple thoughts how to fix this issue, but I'm not sure it will totally eliminate excessive wear without radical modifications of the bracket. The sharp edges cut the rods ends, so I'm going to increase the edges fillet radius using file. Another thing I can do is to use stiffer polyurethane rods to support the bushing and put them in another spots, but it will increase vibrations.

 

[fluffypancakes]

Good work.

I just want to know where you got the XB frame CAD file

 

[TPEHAK]

I found it in grabcad.com

 

[fluffypancakes]

Thanks! Keep working on this!

 

[redheadedshanny]

Hello, curious how you are coming with your testing.
Have you had a chance to try a different combination?
Have you thought about making the sides accept a smaller diameter tube?
Someone had suggested that the original isolater is oval shaped.
Maybe this has something to do with the tubes not holding up?
Maybe a smaller tube on the sides that consist of a harder compound to allow the shock to be absorbed through the tubes on the front and rear?
Just looking to assist.
If you do make a change and want to machine one up let me know.
I maybe able to squeeze one out.

 

[TPEHAK]

Thank you, but I have no time at the moment to try different options, maybe later. None of the configuration I already tested is acceptable because some of these configurations are too stiff and vibrate too hard, and some of these configurations wear out too fast.

Smaller diameter side tubes will not provide enough vertical support, so I believe different tube hardness is the best option, and it works, just wears out very fast.

There are few revisions of the isolator with different hole shapes and different rubber insert shapes. But for all of them the idea is the same, isolator is less stiffer back and forth direction and more stiffer left-right and up-down directions. The earlier isolator revisions have oval hole shape, the last isolator revision has round hole shape.