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CX-GL Honda MCC

I Used To Have One Of Those

Andrew B

Euro rear suspension - solving the bush problem

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Apologies if this has been brought up before but whilst in the throes of working out what to do with my 650 swingarm - all the usual corrosion issues and a few more besides - it suddenly dawned on me that it would be very simple to just stick a shock mount on to the cross piece, source a shorter shock, and end up with something similar to what has been done to twin shock CXs many times before. I would probably plate (5mm ?) the top of the cross piece first for strength but as they all rot here it needs doing anyway.

 

rutbf4.jpg

(Not my pic - somebody else with too many projects)

 

This is of course what has become the standard configuration for most sports bikes.

 

The biggest benefit is that not only do you lose the excess weight and complexity of the two linkages and the stupidly heavy Showa shocker

 

ayuikk.jpg

(Not mine either)

 

but you also eliminate those pesky bushes and end caps that cause so much trouble. The time and cost of doing this mod would probably be less than the time, cost and aggro of doing a full bush refurb - and you get a better working and more serviceable suspension into the bargain.

 

The downsides ? Identifying and sourcing a suitable shock would be the hardest part but I'll bet a second hand Fireblade unit will be less than the £300 you need for a new Showa unit.

Only other issue I can think of is originality but if it's better and cheaper who cares ? It would be largely un-noticeable anyway unless you had your head jammed between the wheel and the engine. I do wonder why Honda went to all this trouble originally - perhaps they were just showing off ? (Have a look at the poncey linkages on some mountain (push) bikes these days). Or perhaps monoshocks were a new thing in '82 and less well understood ?

 

Any thoughts anyone ? It wouldn't take much to come up with a kit to do this. 5 minutes of CAD, 2 pieces of laser cut steel, and a shock to suit. Max of an hours prep and welding which needs to be done by a pro - too much heat and these swingarms distort quite easily. No mods to the bike frame - only the swingarm - and completely reversible apart from the reinforcing plate which you probably need to pass the MoT anyway.

 

I'm off to the shed..............

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Your logic stands up for me Andrew. A fsir amount of trial and error before its how you need it I reckon but worthwhile once completed. Maybe some slotted brackets on the prototype to allow for minor adjustments until you're happy with it? Hood luck and keep us posted.

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Guest

Great Post, it should attract a lot of interest.

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Hey, who cropped my watermark off that photo?

 

Most of the monoshock converted CXs you see are rather... pogo-like... due to the lack of linkage. Any modern bike from Ninja 250s or Hyosungs to super sports I have worked on has had a linkage to give the mechanical advantage and the linkages do work very well towards that purpose.

 

Fresh steel bushings with a grease spiral and grease nipples and you should be good for a long time.

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One of the reasons that the monoshock converted twinshock CXs don't perform as well as you might like is that while the rear shocks that are commonly used come from similarly heavy bikes, they are designed with the linkage used on that bike in mind and perform nowhere near as well when transferred to a bike where they are used as a straight shock with no linkage.

 

Can't disagree that the stock shock is rubbish. People have sent me various other shocks they have got to work with the stock linakge on a GL500:

 

https://motofaction.org/motorcycles/honda-cx-gl/pro-link-shock-absorber-alternatives-honda-cx500-gl500-cx650-gl650/" target="_blank

 

...but nobody has sent me any info on using a shock from another bike on a 650E... yet. I have seen no bad reviews of the Hagon/YSS/Wilbers new options when compared to the stock Showa.

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Oops - apologies JC. I came across your site for the first time quite recently and bookmarked it for future reference.

 

But at least I'm now talking to someone who knows - unlike me - what they're on about.

 

My question is then if it works on 'blades and myriad other bikes why is it pogoey (!) on converted CXs ? Is it a failure to match the shock characteristics to the bike and is it therefore solvable by using a better/different shock ?

 

My main motivation is that worn bushes appear to be almost un-serviceable because they can't be removed easily if at all. Happy to be corrected if this is wrong but the ones I'm looking at are not good.

 

Appreciated your advice ?

 

EDIT - your second reply came as I was writing mine. Thanks.

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There's a few good pages out there regarding the advantage of the linkage setup vs the old twin shock setup - I don't have any links to hand but you'd find some easily on Google. It allows the shock to be calibrated to produce a good, usable rising rate setup so that you get good cushioning over small bumps but won't bottom out over bigger ones. Best of all worlds. The shock absorber is designed to work in tandem with the linkage and taking it out of the equation messes the whole setup up.

 

I bought a 20 tonne press mostly for pressing Pro Link bushings out... I use it for plenty of other stuff these days but it started out just for those. Works a treat. Often couldn't get them with a 1kg hammer and drift...!

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Isn't it odd how everything turns out to be more complicated than you thought ?

 

I've had a quick look at rising rate suspensions - and regretted it - so now I'm trying to find OE installations that don't have links and - as JC has suggested - there don't seem to be any.

 

Plan B is to investigate spring/damper assys with rising rate springs - which I'm hoping will turn out to do what a linkage system does but perhaps not quite as well. The other part of plan B is that because I can fab and attach a bracket to my own swingarm I can then experiment with different shocks but still return to stock if/when it all goes pear shaped. Adjustment as suggested by Marty will be included.

 

This is the stock set up if you're not familiar

 

2pzwhw0.jpg

 

and what I'm thinking of is this but with less cardboard - the top mount remains the same.

 

2hztoat.jpg

 

I think the airbox may need modding slightly as I'm anticipating a spring which is a bit fatter than the cardboard tube

 

2czq5wh.jpg

 

..........but that's ok - I have spare ones to butcher. At least I have an idea of the size of shock I'm looking for.

 

I'm not ignoring your advice JC - just looking for ways to avoid sorting those bushes.

 

BTW - in looking around I came across this complete (American) rebuttal of monoshock/linkage suspension systems https://motocrossactionmag.com/death-of-the-rising-rate/" target="_blank which I only link to because it includes the line:

 

' you can’t stuff a large pig through a hole in the fence as fast as you can a small one ' ?!?

 

Which seems an odd analogy but I guess if you're all alone (apart from two pigs) and far out in the mid-west (and I don't mean Gloucestershire ) then odd things come to mind.

Edited by Guest

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dont we have a member in poland that makes new bushes ?

mad max put a new hagon on is gl/indian project and is pleased with it

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dont we have a member in poland that makes new bushes ?

 

Yes there is and it looks like he does a very nice job but it's the rebushing - with 20 tonne presses - and those problem prone bushes with the hard to get end caps that I want to avoid.

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of all the gl i have had i when i stripped them i could nearly push the pins out with my fingers but they were interstates the only one i had problems with was a british 2DE soon got shut of that one

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original honda shock linkages gave a very progressive rising rate damping which is what you ideally want for comfort etc, modern suspension systems can now offer both high and low speed damping(adjustable on top end versions) so simple mono shock systems are now the norm( a good example of this new technology is when people ask me why honda did not fit dump valves to their turbo bikes? the answer is simple, they were not invented then!) original honda prolink systems work well and are cheap and very simple to rebuild more so if you use ptfe bushes which are lubricated by water( plenty of that in england so i have heard)

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Something else which may interest you... pulling apart a few modern monoshock setups reveals greased needle bearings around the bushings rather than the dimpled metal surround of the CX-era Pro Link. If I had a spare frame and suspension I’d play around with using different sized shafts to make use of bearings instead as an interesting exercise...

 

With the linkages and positioning close to the swing arm pivot the single shock gets to move only a little as opposed to twin shocks at the back wheel, which move a great deal more over the same series of bumps... which results in a lot more agitation of the damping oil and if that gets too agitated performance suffers. I think most modern bikes you see with twin shocks are sporting those for either style or cost reasons.

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Oh, and I’d be very interested to see the results of this experiment!

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dont we have a member in poland that makes new bushes ?

 

Yes there is and it looks like he does a very nice job but it's the rebushing - with 20 tonne presses - and those problem prone bushes with the hard to get end caps that I want to avoid.

 

 

Yes, Pavel (user BC030??) has chatted lots about this, and I plan, eventually, to send my 500ec unit to him for a refurb. At the moment, it is so completely bu@@ered that I can't get it off the bike, and gave up for summer/new job/FT500 getting registered.

 

But I will, it seems a reasonable price!

 

 

Everyone moans about this, but to be honest, I ran mine for 15 years after oaying £400 for a 30K miles bike, pretty good value, now 75k. After 35 years, SOMETHING is gonna be a weak point!

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Some interesting points there.

 

Firstly two nice engineering solutions but both probably having the drawback of needing some quite expensive machining time to modify the linkages etc.

 

Mike mentioned PTFE bushes - I'd not thought of that. I probably know someone who could make them - unless you know a source already ? Some reaming might also be required to clean things up before pushing the bushes in ? I wouldn't know where to start on speccing bore diameters and tolerances etc ?

 

JC suggested needle bearings - I'd still have reservations about being able to keep the water out. Which is of course exactly the problem we have with the OE bushes. The 'caps' with the bonded rubber inserts just aren't up to it.

 

Which brings us to the other problem which Brendan has - you can't even get the bloody thing apart to do a service/upgrade/modification. Which is probably what happened to my swingarm and which is why the previous owner hacked it off and then repaired it - sort of - to end up with this.

 

2rxaed4.jpg

 

That's a 'replacement' washer and note the grinder cuts in the bracket.

 

Originally I was going to grind off the 'new' washer and make a tidier job of welding another one on. But I'm not certain that the hole is where it should be - or that it's even round ! - and the other side of the same bracket has similar issues. I could replace the whole bracket with one from another (scrap) swingarm. This dilemma was partly what set me off thinking about junking the linkages altogether.

 

Why oh why didn't Honda fit grease nipples ? (and there is another retro fit possibility - IF you can get them apart and IF they're not shagged already)

 

Finally JC - you're looking forward to seeing the results ! Me too !! This is part of a complete resto (with significant upgrades see my thread in the shed/garage section) so I'm currently working out how to re-schedule things to give quicker results.

 

Thanks for the inputs - keep 'em coming.

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Grease nipples are a pretty common upgrade once people get them apart, it's a good idea... making more of those bushings is one reason I always wanted to get a lathe, the local machinists wanted $700 for a set which is nuts... I eventually found a guy locally who would make a set for $75 after I provided the metal for it ($15 of rod) but it took him five and a half months to get around to it so it wasn't exactly a wonderful alternative, though the bushings he provided did work just fine.

 

I tend to think of pulling the bushings and cleaning/re-greasing as being a necessary part of annual maintenance... which of course only helps once you have them able to be removed!

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I've not given up on this yet...............but I am struggling.

Excuses:   1.  Major project at a critical phase on at work so no spare time or brain power.

                   2. Can't find a shock short enough to fit in the gap available.

                   3. Biggest problem though - when I do find the time - it understanding the existing set-up.  Always a good principle to follow when you're trying to improve something - but boy is it doing my head in.  As you can see on the parts finder - there are half a dozen different configurations of bush/cap/sleeve/pin etc in the Euro suspension and when what you're working on is 35 years old, rusty, dirty, incomplete, worn out and bodged it can be quite hard to work out what's going on. 

image.thumb.png.c1bd0c95acbf6c53d227ed9d7bbf640c.png

 

At the moment my thinking is to forget the original plan for a new spring in a new place and just stick to refurbing the original set up - with the addition of grease nipples.

After that it will be a strict regime of regular greasing to combat all the water and muck trying to get in.

One challenge on the way is what to do about the holes in the swingarm that take the bolts to mount the large of the two linkages.

These holes take a 10mm bolt (No 21 above).  If you look at the last pic in my previous post you'll see that there should be what I assume to be a hardened washer spot welded onto the mild steel of the swingarm. Obviously over time - and with a lack of maintenance - the bolt wears this away with the result that on my swingarm 2 of the 4 holes are over 11mm diameter.  Imagine how that's going to feel if the clamping forces aren't holding everything still.  Apart from which you probably wouldn't have clamped the bush up in the 'correct' central position anyway which could make the suspension stiff - or solid.

Grinding what's left of the old washers off and welding new ones on seems fairly simple - getting them in the right place could be a bit fiddly.  I'll probably use the cast iron linkage and a long 10mm bolt as a jig.

One thing I've realised -  all of this has been bloody difficult with the bike stripped to a bare frame and upside down on the bench.  If you're doing this on an old un-restored bike, the right way up - even on a bike lift - understanding how everything works, assessing any wear, and the right order to assemble and tighten everything would be nigh on impossible. Especially if you want to have confidence that you're doing it right and won't have to go back in there again in 6 months time.

Excuse No 4 is that I'm just having a rest.  You could say I'm bushed.😁

 

 

 

 

Edited by Andrew B

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On Bike Exif today, a monoshocked CX with an interesting swingarm which sill divide opinion!  I liked it, in fact I liked the whole bike, but am too practical to own stuff where you can't put a lock, waterproofs, and plus 1.  And the cleaning....

 

https://rocket-garage.blogspot.com/2018/09/radical-cx-500-luuc-muis-creations.html

Edited by BrendanO

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