If the left side had no damping, why would you even put oil in it?
MotorCyclist Customizes a '13
- Thread starter Redfish Hunter
- Start date
Help Support Yamaha FJR Motorcycle Forum:
I guess it's time I show my ignorance. I don't have a thorough understanding of how the shocks on my bike work beyond springs and oil, but I really don't understand how it's effective to have only one of the two shocks actually doing any work...which is what it seems I am reading. Again, I am probably waaaay off base, but how is it that this setup can actually work? Am I completely missing something (most likely)?
Old Guy
Well-known member
Pffft!!!To keep the seal moist?
Well, both fork legs would have springs, and work together to support the weight of the bike. However, technically if the fork legs are attached together securely enough at the triple clamps, you could have all of the work being done on one fork leg. In fact, if the axle was supported enough in that fork leg there would be no need for the second leg to even be there.I guess it's time I show my ignorance. I don't have a thorough understanding of how the shocks on my bike work beyond springs and oil, but I really don't understand how it's effective to have only one of the two shocks actually doing any work...which is what it seems I am reading. Again, I am probably waaaay off base, but how is it that this setup can actually work? Am I completely missing something (most likely)?
But the reality of the current design is that the bike is supported off of the front wheel by both fork legs to share the load. They do not need to supply a totally equal support of the bike as they are fastened together at the axle and at the triple clamps. Damping is only a relatively small force to vary the response of the springs over time. You could easily have the damping function in only one side or the other, but you would have to have a single damper that supplies twice the force of twin dampers.
Much more likely that they have a damper in both sides and just one side is adjustable. Not that it is a dud.
Old Guy
Well-known member
The service manual does show a "damper rod assembly" in the left fork but no adjustment bits.
ionbeam
2 FUN
In a previous post MCRIDER007 sez:
We have information, but I can't see any of it as facts yet. Words can be trickisy things to use well and what you think they mean may not be what I think they mean.
I will observe that both sides have damping rods going into the cartridges, if one side was just a spring and spacer with no guts in the cartridge there would be no need for a damping rod.
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MCRIDER007
Well-known member
I think the fork springs and bushings would get pretty hot without oil.
Just to clarify terms, before we had cartridge forks, we had forks with "damper rods" that bolted to the bottom of the forks and supported the springs as well as providing rebound and compression damping. Cartridge forks have cartridges that bolt to the bottom of the forks, support the springs, and also have a "damper rod assembly" which is a thin hollow tube that threads to the fork cap at the top, runs through the springs and into the top of the cartridge, and threads to the rebound damping piston (inside the cartridge) at the bottom end.
When you look at a parts list for the FJR fork you see a diagram of the cartridge with the damping rod assembly sticking out the top.
Damper rods and damping rod assembly are much different parts but easy to confuse when explaining fork suspension.
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No friction from the springs. Bushings you may have a point
Lauren_TK
Well-known member
That is my world. I am a Technical Writer. I produce only two or three hundred words a day, but I have to make sure those words mean one thing, and one thing only.
As a writer of repair manuals, albiet for electronic goods, it is extremely difficult to acheive that clarity. The deeper one gets into a project, the easier it is to overlook something because of "assumed knowledge."
I will now wait patiently for Fred to make his observation, and report back.
MCRIDER007
Well-known member
I totally agree re:the damping rod assembly, however until someone takes one apart there isn't any way to know of the parts diagram is correct. I would think that if the cartridge did not have any guts (damping pistons) the cost would be a lot less than the right fork cartridge.
ionbeam
2 FUN
Edited to remove inaccurate information. Replacement information about the cartridges from the Yamaha web site:
1MC-2315L-00-00 $182.49
1MC-2315K-00-00 $182.49
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Redfish Hunter
Gone Fishing
Fred! I thought we were friends! I am going to sit here and cry for a while...
I do seem to remember that the '13 was supposed to only have damping in one fork leg. If I remember, Yamaha said it was to shave weight, we all said it was to save money. I did a very small amount of digging and found this:
"The FJR now utilizes an independent damping fork, with new internals and springs. Three-way adjustment remains up front, but compression and rebound is handled in the right fork leg only. Yamaha says the fork has been firmed up, with the new configuration shaving weight. The rear shock is also stiffer, with revised settings. "
Oh and Fred? I also 100% agree with your assessment of Cook. I was never a fan of Editor Catterson. That was one reason I was hesitant to post this thread to begin with. It was Catterson who took the FJR to Colorado and he wrote the last page of the article.
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MCRIDER007
Well-known member
I think you are looking at an earlier model year, the 2013 fork cartridges have part numbers of 1MC-2315K-00-00 and 1MC-2315L-00-00.....at least at the fiche I have been able to find.Funny, when I try the Yamaha fiche both the R & L cartridges have the same P/N and both cost $186.95. I'm betting with the same P/N they are the same parts
ionbeam
2 FUN
From the Yamaha web site, definitely the 2013 fiche if only I had clicked on the correct partsI think you are looking at an earlier model year, the 2013 fork cartridges have part numbers of 1MC-2315K-00-00 and 1MC-2315L-00-00.....at least at the fiche I have been able to find.Funny, when I try the Yamaha fiche both the R & L cartridges have the same P/N and both cost $186.95. I'm betting with the same P/N they are the same parts
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MCRIDER007
Well-known member
Gee, I don't know if I can wait that long.....but having access to the internals will certainly end the speculation. Yamaha usually uses lock tight on the damping pistons and you will probably need heat and a 20mm cartridge holder to separate the pistons from the cartridge. Traxxion will probably do it for you if you ask in advance.
You can also pump the left fork manually when its off the bike and you will know immediately if it has any rebound damping.
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MCRIDER007
Well-known member
I received an email from Traxxion stating that the 2013 left fork does not do any damping and they modify the left fork cap to provide rebound adjustment in that fork with the AK-20. There is no compression damping in that fork. This confirms what was stated in the Motorcyclist article.
I also had asked if just installing a AK-20 in the right leg would be an improvement and the Traxxion response (as I expected) was that it would be a bad idea because the OEM damping on the right fork flows more oil through the high speed compression circuit than a single AK-20 (as designed for the older FJR models).
I'm not impressed with this option or the cost (Traxxion, shipping, and shipping insurance) and would rather spend another $150, buy a 2012 left fork, and install my AK-20s myself.
I also had asked if just installing a AK-20 in the right leg would be an improvement and the Traxxion response (as I expected) was that it would be a bad idea because the OEM damping on the right fork flows more oil through the high speed compression circuit than a single AK-20 (as designed for the older FJR models).
I'm not impressed with this option or the cost (Traxxion, shipping, and shipping insurance) and would rather spend another $150, buy a 2012 left fork, and install my AK-20s myself.
gixxerjasen
Well-known member
Aren't the outers the same as the 2012? You should only need to buy the cap(s) for the 2012 and then get the AK for the 2012, right?
MCRIDER007
Well-known member
The AK-20 will fit the 2013 right leg without modifications but it will take about $375 in parts to modify the left fork for a conventional AK-20 installation. I would rather spend $458 for an entire left fork assembly. It would be fully adjustable with the AK-20 and I could sell it later if I were to part out the AK-20s.
The new suspension is sounding more and more like a soup sandwich.
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