Oldham Couplers

[Kool_Biker]

I wonder what constitutes a 'worn' Oldham coupler.
Clearly, mine are out of the motor so cannot assess audibly, and when coupled to their corresponding cams, there is an ever so slight play.
But what is normal? And what is excessive.

P1070895 (1).jpg

As you can see from the pic, I do have a pair of oversize ones I got sometime ago from the UK. But am reluctant to use' unless I have to, concerned about increasing axial cam loads.
Best, Aris

[daves79x]

Aris:
ANY play will cause at least some extra top-end noise. If yours have 10,000 or more miles on them, I'd replace them with the oversized ones. I know you have nothing to compare, but I installed a set in my 45,000 mile '79 a few years ago and it is absolutely silent (except for the clutch rattle when warmed up). Mine sounded like a noisy sewing machine before. It does work and I have never heard of a failure related to using them. Easy to do now when you are going back together.

Dave

[Kool_Biker]

Dave, my engine has 35,000 miles and there is definite play.
Good stuff, I will try them on.
Cheers, Aris

[EMS]

As you can see from the pic, I do have a pair of oversize ones I got sometime ago from the UK. But am reluctant to use' unless I have to, concerned about increasing axial cam loads.
Best, Aris

This is a very valid concern as Oldham couplers are by design used to eliminate radial load and if they do not slide between the coupled ends (which the oversized ones do not) they create exactly that: radial load.
I have used the oversized couplers only after very careful modifications which incorporated exact measuring with a micrometer and ever so slight sanding/polishing of the sides until they fit tight and still were sliding.
Some recommend freezing the couplers before installing them, so they would fit. I do not.
To those who will come back and say they installed them long time ago with the freeze method and the bike still runs fine: Good for you!

[Kool_Biker]

I have used the oversized couplers only after very careful modifications which incorporated exact measuring with a micrometer and ever so slight sanding/polishing of the sides until they fit tight and still were sliding.

So Mike, can you share a bit more of this, describe the process / tools used, in a little more detail?
Is this something you have done using hand tools only, or have used the services of a machine shop. Are the couplings hardened to begin with?
We all stand to benefit, although I too have heard of many people in the UK who 'just freeze them' to use with no complaints.
Seems to me like an interesting and worthwhile debate.
Cheers, Aris

[EMS]

So Mike, can you share a bit more of this, describe the process / tools used, in a little more detail?
Is this something you have done using hand tools only, or have used the services of a machine shop. Are the couplings hardened to begin with?
We all stand to benefit, although I too have heard of many people in the UK who 'just freeze them' to use with no complaints.
Seems to me like an interesting and worthwhile debate.
Cheers, Aris

Aris: I do it by hand. Unfortunately, I don't have a superb pictorial of it as you do of your projects and although the next job is due, I probably will not get to it before September.
I use 600 grid wet-sand paper and a piece of flat steel to wrap it around. I hold the coupler in a small vice and sand them very carefully, little by little, until they fit very snug into the cam ends and slide with a slight drag.
I measure the couplers during the process on both ends with a micrometer to ensure they stay parallel. I have not found a good way to measure the slot in the cams equally precise, otherwise, I would use a machine grinder in our shop to produce the perfect tolerance for a tight slip-fit.

[Don]

It would be interesting to get accurate measurements of the width of the slots in the ends of the cams that the couplers mate with . . . . center and at each end - Are those slots the same width all the way across??

Never having tried fitting couplers and cams together, take this as another one of my hairbrained 'theories' which may turn out to be all wrong

I would *assume* that as the mating surfaces wear, that wear would be concentrated toward the outer ends of the slots/tabs - The grooves in the cams get a little wider with wear and the tabs of the couplers get a little narrower, likely more at the outer edges and less in the middle, so they make oversize couplers with wider tabs on them to compensate for the worn grooves in the camshafts themselves

If you can determine that the slots in the camshafts are worn more at the outer edges and less in the center (no longer parallel all the way across) then I would think that what you need to tweak to make the couplers fit snugly would be the center portion of the cam grooves and not sanding on the couplers themselves . . . . unless the coupler won't fit even at the edges. Try fitting just the ends of the new coupler and the cam together . . . . the cam and the coupler would resemble a figure 8 when just one end of a coupler tab is fitted in to just one end of a camshaft slot - If those ends fit together OK but the coupler won't fit in the center of the cam slot, maybe the center of the cam slot is less worn than the edges and that's what needs to be sanded??

Don

[EMS]

The stock Honda couplers are probably softer than the cams, so that the cam slots will not wear. I have not checked the oversized couplers as far as hardness is concerned. That should be on my list.

[Kool_Biker]

I started this post in June 2011... Now with a thousand other priorities and two engine rebuilds in between, I never took the time to focus on, and replace my ailing OEM Oldham Couplers with new 3rd party oversize units.

But I did earlier on today, the opportunity being my 3,000 Km valve adjust chore.

What a difference! In one word this replacement has added 'class' to my engine.

Whereas the top end was noisy and chattery - my engine has done ~36,000 miles on the OEM couplers, I believe - it has now gone oh, so quiet and business like.

Installing them was surprisingly easy: The units themselves were frozen to -18'C and were carried to the workshop in a cold box. With no time to loose they were pushed into their cam gear slots by hand. I had to push hard, but it was just hand power. Then, the previously gently warmed cams were pushed into them, helped in both cases by a few (very) gentle soft hammer blows.

I am attaching a few pics with descriptions below:

P1060943.jpg

P1060930.jpg

P1060932.jpg

Overall a very satisfying improvement to my engine. I wonder how long they will last.
Now if I only remembered where I bought these from. It's been about 5 years ...

[FalldownPhil]

More than likely, you bought them from Louis.
Best,
Phil

[EMS]

More than likely, you bought them from Louis.
Best,
Phil

..or not. They actually originated somewhere across the Atlantic. I seem to remember it was from sellers in the U.K. and in Denmark that I saw them first. Louis then "marketed' them here in the U.S.

[FalldownPhil]

Mike,
I am sure that you are correct. I was just remembering that Louis was marketing them. I should think that Bert may have initially been behind them.
Very Best,
Phil

[daves79x]

Aris:

Glad the couplers worked out for you - they certainly have for me.

Dave

[Kool_Biker]

Definitely Europe, and 'Denmark' does ring a bell..