How to fix sloppy rear wheel dampers

[wolfemanjack]

How to repair your original shrunken sloppy rear drive dampers for under 20.00

If you are experiencing drive train lash between braking and accelerating, good chance your rear wheel drive dampers are loose or shrunk from age. Hey we all shrink a little as we age! Don't forget to be thankful when you find this out that the lash is NOT your tranmission or your final drive pumpkin gears. When I replaced my rear tire I saw that they were all really loose in the wheel recesses by a considerable amount, maybe 1/8" or so. This confirmed the lash I've experienced for the past several seasons and was worried about. I did not want to purchase new ones as these seemed intact with the bushings still very much vulcanized and rubber still firm but flexible. They were not damaged, somewhat functional but only shrunk from years of use and age.

No way was I about to put my wheel back on without replacing them, then I thought about how I might be able to repair them. Eureka, remembering I had a small chunk of neoprene rubber left over from a project a few years back laying around I fetched it and made shims out of it. It was from McMaster-Carr and part number  8461K174. $12 strip of 3/16" thick  x  2" x 36" long. Originally it was enough material to make shims for 11 Valkyries!  

Why are they there and what do they do?  They limit the harshness of the braking and acceleration forces created from the road surface and or engine/transmission forces placed against the drive line. They serve to dampen, isolate, absorb or soften direct impact that might otherwise simply snap off gear teeth and overly stress the driveline components. And also help compensate for even greater forces applied when we horse on the gas or the brakes fully loaded.     

Here is the procedure: ( BTW, I take no responsibility for this retro repair and is for discussion purposes only)

Check your dampers for play inside your wheel, see photo, they are slightly tapered to match the draft of the wheel casting, mine were loose with about 1/8" of play. If the center steel bushings are broken loose from inside the rubber, forget about this fix and go buy new ones.


Closely inspect the damper end profile and see the raised bumps on the deceleration end ( end that is furthest to the center bushing )


The Neoprene can be ordered direct from McMaster-Carr, for those of you not fortunate to know about them...put your order in by 3pm, you will receive your package the next day UPS. No kidding UPS ground, don't ask, i dont know how they do it. Search Part Number  8461K174 its 60 Durometer A scale, medium hard neoprene with adhesive one side. It is resistant to oil, impact, weather and abrasion.

Cut rectangular shims from the neoprene with a utility knife and straight edge to 1" x 1-1/4" Make five of them.


Clean the wheel damper recess edge that you will be adhering the shim onto (brake torque edge) Opposite of the acceleration torque side. I used brake clean, and wore gloves.



Optional read, Ok to skip.

Ok, here is how I decided what side to shim. If you look at the dampers, the center bushing is molded in closest to one edge, That is the acceleration edge. The reason Honda engineers did that (I assume) is because on the rear wheel most of the torque is applied during acel and not decel... right? We all use our front brake for 90% of our braking I hope you do. That is why the bushings are closer to the acel edge...Why?  because there is less rubber to compress therefore limiting the  compression distance of the damper...this to match same distance of movement that will be on the lesser decel edge by putting more rubber in the space. So why did I put the shims on the decel edge?.... Cuz I thought if the rubber I had was either stiffer or spongier than the dampers engineering requirements, I wanted it to be on the weaker less torque side. Make sense?  Turns out the rubber is very close to the damper in stifness and not sure it matters much anyway. However, what ever side you decide to shim yours, just make it the same side on all 5 or your spline plate pins wont go in.


Adhere your shims sticky side to aluminum on the flat faces and not on the radius.



Next I clamp the dampers one at a time into the vice long side up.



And proceed to belt sand the curved ends slightly on the side you will be shimming. Sand just flat enough to fit snug into the wheel recess with the shim, Try to follow the same taper and make the first one very slowly to be sure not to sand it too much, better to try 2-3 times and get it just right.  You can always take more material off, cant put it back on. After the first one fits good, do the other 4 the same. They should be all shrunk the same, yours might be more-less shrunk than mine were.  


What they look like sanded.


Now position the dampers into the wheel recess and pound it in with a butt end of a hammer or use a block of wood. They should fit in snug, maybe 4-5 presses, If you have to pound on it for 10 minutes, its too tight! Make sure they go in the right face out, they are marked on the faces "outside"



Final fit!





When you put the spline plate back in, lightly grease the pins so they are free to slide in and not bind or sqeak during operation.

Good Luck and Happy trails.  

[KSDragonRider]

Great write up!  Thank you for sharing.

[quexpress]

Well done!!! 

[Ricky-D]

I'm not so sure that is an improvement.

Without trying to detract from the concept I feel that the modification, namely the grinding of the bushing to a contour different from the original design, has or will possibly, result in damage to the wheel over time and use.

The reason I say this is that now the bushing with the newly ground end will result in more force of rotation being applied to the web cast into the wheel and specifically to the mid point of the web while the original shape of the bushing shows that the forces are intended to be mainly imparted to the web where it is strongest, that being where the web joins the body of the wheel.

I guess time will tell if this is indeed going to be an improvement.

***

[wolfemanjack]

Good question, I did wonder if the profile was there for some reason like to allow quicker initial damper compression from less material. Never thought about that the web being weaker at the center which is certainly a reason to consider.  If you see the surface sanded on mine, it is still "hollow" in the  center a bit so the forces being placed are nearly the same area. So the results would be the same with the forces applied through the shim at the same area as if it were not there.

I once saw a set that were made from a supplier who cast them new from uerathane, I did not see any nubs on those as those edges both sides were flat so if that theory is tru, any one who purchased those would also be at risk.  After thinking more about this and looking back, I might have been better served matching the rubber thickness needed and not grinding off the nubs at all. I used what I had and thought it worked very well. McMaster-carr does make different thicknesses. Might be best to try a test using a shim off wood to determine what thickness rubber to order. Good catch on this theory.

For a refresher on mine, fully inserted the slop was closer to .080 and not .125 as I previously said it was (1/8") reason was for a quick descriptor. The Neoprene I had was .1875 or 3/16". I removed less than 1/8" of the nubs so the new space or slop was was a bit over 1/8". Forced in I assume the assembly compressed by 1/16" or better. If I had 1/8" material it might have worked fine without grinding the dampers at all. This might be a good way to gauge what yours might require but try the wood shim test first and by all means try it without grinding the nubs.     

[Westsider]

 .......I think that will work all day... at least another 10k miles, change to new ones next tire change ..... ..... If you have the material  laying around.



Good write up / pics/  thanks
Paul.

[hubcapsc]

When we were kids we didn't have money to get new dampners for the rear
hubs of our little dirt bikes (you know, Yamaha 100s and Suzuki 185s and stuff).

Ignoring the worn out dampners ruined several of our hubs, including the one
on my Yamaha 100.

The mechanic at the Suzuki shop showed us to squirt silicone rubber in there
with the worn rubber dampners and squish it all back together. Nobody I knew of
who had silicone in there ever trashed a hub, don't know if it would hold
up to the 100 horsepower Valkyrie though...

-Mike

[Willow]

When you put the spline plate back in, lightly grease the pins so they are free to slide in and not bind or sqeak during operation. 

Greasing those pins may not be such a good idea.  It can cause them to slip out too easily resulting in the star separating from the wheel during rear wheel removal.

I note this from personal experience.

[alph]

When you put the spline plate back in, lightly grease the pins so they are free to slide in and not bind or sqeak during operation. 

Greasing those pins may not be such a good idea.  It can cause them to slip out too easily resulting in the star separating from the wheel during rear wheel removal.

I note this from personal experience.

not only that, but, the grease will attract dirt which will act as an obrasive.  just a thought (plus i believe it's not suggested in the manual)

[Disco]

Greasing those pins may not be such a good idea.  It can cause them to slip out too easily resulting in the star separating from the wheel during rear wheel removal.

+1

[GotValk]

I'm in the process now and they do say to apply a light coating of molybdenum disulfide grease to the drive flange pins, this is from the Clymer manual .

Don't shoot the messenger.

[Jeff K]

My Chrome RC Wheels had a lot of slop with the stock dampers in. I made some shims out of Gasket material. It made them a tight fit and that was 20-30 thousand ago. Still good. I wish I would have taken some pics.

[jammer]

I have shimmed them with  various rubber  material, such as inner tube rubber,  with good results. Never  altered the  original shape though.

G

[RP#62]

I greased the pins on mine once and it made it nearly impossible to remove the next time around.  As noted, the grease attracts grit and becomes lapping compound and it wears steps in the pins that mate with steps in the bushings.  Its better to use a dry film lubricant and if you can't get that, smear some moly on the pins, then wipe every bit of it off.  There will be enough remaining in the pores of the metal to provide adequate lubrication without attracting grit.
-RP

[John U.]

When we were kids we didn't have money to get new dampners for the rear
hubs of our little dirt bikes (you know, Yamaha 100s and Suzuki 185s and stuff).

Ignoring the worn out dampners ruined several of our hubs, including the one
on my Yamaha 100.

The mechanic at the Suzuki shop showed us to squirt silicone rubber in there
with the worn rubber dampners and squish it all back together. Nobody I knew of
who had silicone in there ever trashed a hub, don't know if it would hold
up to the 100 horsepower Valkyrie though...

-Mike

I did exactly that on my 98 Standard about four years ago. It worked fine fine until I replaced the dampners last year. They were still well glued in there and I could just as well left them as they were. I bought some of Gary's last run and so I dug they out. It did take a bit of digging. I had used RTV silicone and it adhered very well.