Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Centa compensator?

From what I know and what I have heard/been told;
1) it's not a case of if the original type of compensator fails it's close to a certainty and may involve a flat bed to get home. The later ones with the grease nipple are better but still not great unless they are frequently greased and the revs are kept up to avoid over-running the ramps and lots of care is taken to drive smoothly.
2) the Centa unit appears to just work (so far anyway) though it does rattle a bit if you do load the engine at the kind of low revs that S&S say you mustn't use because it will damage the engine and they're not really interested in the transmission.
3) the rubber barrels in the Centa, in common with all mechanical components, must wear out eventually. Centa have a very good reputation for the longevity of this type of system and my suspicion is that failure is more likely to be down to gradual wear on the rubbers till it reaches a point where increasing noise and play in the drivetrain will make itself felt at which point it would be an engine out job to fit new ones. I doubt if a sudden total failure is at all reasonably likely to leave you needing the flat bed.

I've had all three variants and am quite happy with the Centa - again, so far!

I usually give my compensator about 10-15 pumps of JCB high pressure blue grease every 1500 miles or so.

Keeps the ol' gal nice n quiet.

First compensator expired big time at 1200 miles.

Yes I uphold my objection to the term compensator which was the essence of my OP.

Whilst interpretation is subject to semantics, to me the term in this context suggests some negating force to correct an undesirable power delivery.

As yourself I prefer the term cush drive as that's what it is. Whether employing ramps and springs or rubber inserts, it simply reduces the amplitude of the short term torque peaks, which I understand can exceed the average by a factor of ten or more, by spreading them over a greater rotational angle, hence time.

A balance shaft to correct an inherantly unbalanced engine would better suit the term compensator if its to be used at all.

Another term I have heard is "torque converter"

That is it's function, at its most base level. It's a necessary bit of hardware used to keep the transmission from imploding under the impulses.

As long as it works you are all invited to call it what you wish.

I'm still paying mine off...

As Michael says, call it what you wish...

But I agree to disagree.

If anyone has been around Harleys for the past 40 or 50 years, you'll agree that it's called a compensator. How it came to be know as that, who knows.

As you all know, the M3W used a modified Harley device called a compensator, so hence the name compensator as used in the M3W.

The Harley "B" motor does in fact have a balance shaft, or two, to smooth out the vibrations of the motor. But it still does little to smooth out the torque pulse derived from the firing of the pistons.

The purpose of the compensator is to absorb, or store the pulse energy on the firing stroke and then release that energy on the coast stroke thus balancing out the torque pulse, not necessarily literally balancing the rotating mass, but more so to take out the shock loads in the crank to the transmission.

The 45 degree of the Harley motor cannot be balanced out for all rpms, but generally speaking only in a certain rpm range. My old Shovelhead is balanced for the 3000 to 3500 range which is it's most likely cruising rpm. This motor is also bolted to the frame without any means of rubber dampers. My newer '09 is a rubber mounted motor and it shakes like a bugger at idle and you do feel the motor a bit, but once under motion the rubber mounts smooth it out and you never feel anything while riding at any rpm.

My guess is that the 56 degree S&S, which some of the Japanese bikes use as well, is much more balance friendly.

I think we're all going to just keep on with what we're used to and cush drive or compensator, the results are the same.

My opinion is that the Centa unit is much more durable than the original modified Harley unit. We use couplings on lots of our equipment that we manufacture and the rubber, nylon, urethane etc spiders or inserts, last a VERY long time. I realize that the Centa unit is not very user friendly by placement and will require the removal of the motor to replace the rubber rods. But seriously we're probably talking 10's of thousands of miles on a set.

Although other bikes, British and Japanese have used rear wheel cush drive lugs with rubber inserts for many years, Harley just started using them in '08 on all touring bikes. They are holding up under extreme conditions 40k to 60k miles without any total disintegration so to speak. My bike has 15k miles and I inspected mine this summer and could not find any wear on them whatsoever. So I would not get too concerned about the need for new rubber rods in your Centa's anytime soon. I have no magic wand nor am I a psychic, but just an educated guess on my part.

So lets hear stories now about how well everyone is doing with the new Centa drives... Everyone so far has nothing but praise for the new units.

Aha! It's an American term. Two nations divided by a common language and all that.

Centa drives are a popular choice and maintain a good reputation in the canal boat world I'm familiar with. Typically fitted between gearbox output and propshaft, they can absorb minor shaft misalignment as well as shock loads.

From the point of evaluating second hand M3W's , is there an easy visual clue as to wether a Centa has been fitted or the original is still on ?

( That could easily have been any of us ! )
And still could be I guess when the Centa gives out

I've used that same saying before and it's truer than one might think...

I've been to way more car shows than I care to remember and the joke there is this, "Which one is your husband? He's the one over there with grey hair, beer belly, hot rod tee shirt and a ball cap." That's a bit too close to home for me.

As far as the pictures I've seen on the old and new "coupling devices", they are both enclosed in a metal housing and may look very similar on the outside if viewed through any gap in the coupling housing. As you guys know, a good grease packed old style doesn't sound any differently than the new Centa. But it's not hard to guess what's wrong when one is getting noisy.