Rear wheel spacer

[effexer1]

There is another thread going about PTTR and left side tire wear, and some of the guys solutions have been to remove the spacer on the rear wheel.

 

My question is, does anyone know why the engineers put that spacer there? I would like to remove mine, but, if there is a reason for it to be there, I would like to know before the spacerectomy.

[Haynes]

Removing the spacer will change the distance from your tone wheel to your ABS sensor and may damage your brake caliper.

Do you have a definite reason to remove it?

 

I don't know why the spacer is there but it could be that the rear wheel has more than one application and adding the spacer corrects the geometry for pairing it to the RT rear drive.

 

I don't think that the 2mm (or so) thickness of the spacer will have a significant effect on the tyre wear or cornering characteristics.

[boatzo]

I have the spacer in place as designed and I do not have left side front tire wear as I posted in the other thread. I strongly agree that there is probably a good reason the engineers put it there.

[4wheeldog]

Removing the spacer will change the distance from your tone wheel to your ABS sensor and may damage your brake caliper.

Do you have a definite reason to remove it?

 

I don't know why the spacer is there but it could be that the rear wheel has more than one application and adding the spacer corrects the geometry for pairing it to the RT rear drive.

 

I don't think that the 2mm (or so) thickness of the spacer will have a significant effect on the tyre wear or cornering characteristics.

 

Mine is in place, and I see no reason to remove it. I do believe it is substantially thinner than 2mm.......More like .2mm.

[skinny_tom (aka boney)]

The left sided tire wear has more to do with the crown of the road than PTTR.

 

Everyone has theories about PTTR. I'm not sure if anyone had ever been able to correct it. My bike PTTRs, and I've not spent much time trying to correct it, but I'm going to investigate.

 

Two wheels in the same vertical plane will not pull one way or the other, so removing the spacer will not help. PTTR is apparently some other issue like imbalance or misalignment of the wheels.

 

BTW, mine didn't PTTR until the transmission was out for some warranty work. I know where I'm gonna start looking.

[Selden]

Removing the spacer will change the distance from your tone wheel to your ABS sensor and may damage your brake caliper.

Do you have a definite reason to remove it?

 

I don't know why the spacer is there but it could be that the rear wheel has more than one application and adding the spacer corrects the geometry for pairing it to the RT rear drive.

 

I don't think that the 2mm (or so) thickness of the spacer will have a significant effect on the tyre wear or cornering characteristics.

True for R1150RT, false for R1100RT. I can't say re other model oilheads.

 

[Mr. Frank]

This issue has come up before and the answer has been that the spacer provides a non slip surface on both sides to eliminate possible movement which could loosen the lug bolts. If you look at the spacer you will see it has a non slip surface. You'll also note that the maintenance manuals say to be sure all surfaces are clean when remounting the rear wheel.

[Selden]

Thank you -- this is an interesting explanation for the existence of this piece of metal, although for the life of me, I don't see how slippage could be involved, given by the geometry of the rear wheel hub. The wheel is located by four big honking bolts with tapered shoulders, that mate with tapered holes in the wheel, and are under a pretty serious torque load.

 

The service manual refers to this part only as a "spacing washer."

 

The spacing washer (1) and the contact faces on the rear wheel drive and the hub must be clean and free from grease.

Unless I have missed something, the spacing washer is used only for cast rear wheels, not with the spoked wheels on the GS and R models, which again leads me to believe its primary purpose is as a spacing washer.

 

Since Paul Mihalka and others have measured front/rear wheel alignment errors on oilheads, I'm sticking with the spacer theory. For a very thorough discussion, see this thread (with link to an engineering solution): Rear wheel offset stops oilhead pulling to the right.

 

[Paul Mihalka]

"Two wheels in the same vertical plane will not pull one way or the other, so removing the spacer will not help. PTTR is apparently some other issue like imbalance or misalignment of the wheels."

 

Correct and false, at the same time, as discussed by me and others a few times. Two wheels in the same plane will not pull one way or another if the weight is centered over them. On a two wheeled vehicle if you have more weight on one side of the center line than the other it will pull in that direction and you have to counter steer to go straight.

As far as no effected correction, as mentioned before I corrected it on my R1100RT by removing the shim and moving the swing arm to the right in the frame. By moving the wheel to the right in relation to the rest of the bike the originally excess weight on the right moved over the wheels. End of PTTR and end of one sided front tire wear.