Broken RMA Adjuster

This is very troubling.
I too have the RMA cam chain tensioner, in place for the past eight years.
The advantage of it, I was told, it that the timing is held constant, or better, than without it.

I now have the engine part for a rebuild. I think I am going to throw it away and go back to stock set up.
So what if I have to pull timing cover every 5000 miles and check/re tension the chain.
I did talk about the RMA this past week with Matt at Colorado Norton Works.
He said that he sets his Commandos up with the stock setup, not that he has anything strongly against the spring loaded device.

highdesert said:

This is very troubling.
I too have the RMA cam chain tensioner, in place for the past eight years.
The advantage of it, I was told, it that the timing is held constant, or better, than without it.

I now have the engine part for a rebuild. I think I am going to throw it away and go back to stock set up.
So what if I have to pull timing cover every 5000 miles and check/re tension the chain.
I did talk about the RMA this past week with Matt at Colorado Norton Works.
He said that he sets his Commandos up with the stock setup, not that he has anything strongly against the spring loaded device.

Click to expand...

You can throw it my way. :mrgreen:

hobot
I don't see how a bent crankshaft would have ANY effect on the cam chain tensioner. the way I see it is it all revolves around how concentric the two sprockets run on there shaft's.if one is out a fair amount or both are out a little it will have a VERY tight spot in rotation, as the RMA self adjusts at the point of the MOST slack and WILL NOT slacken off as it approach's the tightest portion therefor puts a LOT of strain on the chain, cam bush and tensioner. after the failures I have seen the tensioner is not worth the cost or trouble's it can cause and more reason for Jim's gear drive set.

IMHO the BEST place to through it is the TRASH CAN.

I have been blissfully ignorant, running an RMA timing chain adjuster for about 15 (? I can't find my reciept) years. I don't remember, and the instructions don't show, any flimsy circlip. Maybe I should remove the timiong cover and have a look...

Greg

Bill, till I stumbled on this thread I thought I was the only one
to screw up a slick RMA device. The injury mechanism should lie
in the common denominators of Kieth's and mine. I liked
the quality and concept of RMA device.

I'd love another for ordinary usage myself But it ain't pure factory
issue for my plane Jane Trixie Combat and it ain't up to rpm strains
planned for Ms Peel special.

I agree something or somethings sure got eccentric in Peels
case, Especially in the first event, 2nd event may be as
you stated a number of now tweak items all bent to some degree
adding up too much to take regardless of rpms.

In defense of RMA, Ms Peel did 5000+ mile extreme tests
some 7600 in 2nd skiing chicanes more that streering them.
plus 1000 mile out of state travel w/o a RMA issue and which
looked finely worn in till spun into the trash zone.

I suspect that something else must go wrong before the
RMA does but that a factory tensioner may be able
to tolerate it better?
How much can RMA tolerate long term?

hobot

gjr said:

I have been blissfully ignorant, running an RMA timing chain adjuster for about 15 (? I can't find my reciept) years. I don't remember, and the instructions don't show, any flimsy circlip. Maybe I should remove the timiong cover and have a look...

Greg

Click to expand...

Yes indeed you should, and like Bill suggested throw it in the trash can before it falls apart INSIDE your timingcase.

OK, but which tensioner? The original steel one or the one with the rubber buffer on it that appeared in 71? Or is there one with a delrin or better slide against the chain?

Dave
69S

Only the vintage all steel ones, especially those the links have
worn proper grooves in to allow the rollers to glide on oil film.

A what ever rpm Peel's event reached,it was at least
double what was measured at rest.
What else to undo RMA tensions as its been raced w/o
reports I've heard of.

hobot

This is semi-upsetting - the semi, because I haven't installed mine yet, but have had an RMA adjuster in my "to do" parts bucket for a while now - this winter was gonna be THE ONE!

How important is the cam chain adjustment, anyway - I mean, what's your experience with checking it and finding it out of whack? I've put 5K on my bike since getting it, used, with an unknown provenance. Starts first kick (if one abides by its likes and dislikes in this regard) and runs like a little stinker, but I don't think I've ever checked the timing for ghost marks (is that even the sign one looks for for this?). Other "symptoms" of poor cam chain adjustment?

Thanks all

Hmm, manual says check 5000 miles, but hardly anyone does
for 10's of 1000's of miles for decades now.

Extra chain noise and more drifting-jerking of timing marks
would be about only way to tell from outside. I have
to remind myself to check chain a number of times
as engine turned to account for any sprocket run out I guess.
I will have to check when hot some day to make sure
like the primary chain.

hobot

Thanks Hobot. - Brian

Thanks Ludwig; I'll try that.

This is a post Rick sent Alan Goldwaite [sp] in 2003,
about a year before Ms Peel over rev'd apart his device. hobot >


With regards to the long term wear of my chain tensioners and related
components:

While it is true that I have many thousands (about 22,000) of miles on my own
tensioner, it is indeed only a sample of one, and we all know that the
scientific method would never accept conclusions made from a sample of one.

To be perfectly honest with you, I do not know how long my automatic cam chain
tensioners will last, but things are looking mighty encouraging. I can tell you
that of the 300+ units sold since it’s introduction in 1989, not ONE person has
ever requested a replacement shoe, nor have I ever heard of any problems with
the cam chain or the camshaft bushings.

Here is what I have learned, and what I suspect is happening inside those
timing cases:

During reassembly, most installers will notice a tightness in the chain, which gets even
tighter as you line up the idler gear/sprocket shaft with the cover bushing.
People should not be concerned by this. The side plates of the chain will wear two guide
grooves into the wear shoe as the chain finds it's running alignment. As the
chain rollers settle down on the top of the wear shoe, two very cool things
happen: 1) The tension in the chain relaxes, and settles in to the correct
running condition. 2) The rollers go into a hydrodynamic condition with the oil
film between the round rollers moving across the relatively straight wear
shoe. All wear appears to stop at this point. My own wear shoes, (and I have
tried this on 3 separate occasions), show a small patch in between the chain
side plates and in the middle of the wear shoe, about ½” long. This I have
determined takes place in only a few hundred miles of running. Subsequent peeks
into the timing chest at 1000, 6500, and then later 15000 miles showed that the
wear patch had not changed in size.

This evidence, combined with the fact that in 14 years, no one has ever ordered
a replacement wear shoe, leads me to believe that the hydrodynamic condition is
indeed being established here, just as it between the camshaft and big-end cam
bushing, or your crank journals and connecting rods.

I will not make the claim that my cam chain tensioner will last forever, but it
appears to be well on its way to lasting at least as long as any of the
other “wear susceptible” components in the engine

Regards,
Rick Avidano, Owner RMA Engineering