Rear shock woes

[RiderX]

Yeah and you can still get 20% off a stock rebuild with a stiffer spring with the Race Tech Forum discount.

 

[900gc]

Definitely load, the pace of riding and where (twisties, superslab, etc.), has a lot to do with whats required of the suspension. I've been on rides (if you could even call it that) with folks that couldn't keep pace with a turnip truck. I could have been on a hard tail or had marshmallows for suspension and it wouldn't have mattered much. On the other hand, I wish I had the Penske from my race bike when blasting through the mountains with my fast friends.

Please Santa, I'll be good this year

 

[Sno Cat]

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

 

[LAF]

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

Put on the Pensky, order 1.1 Omni Springs and spring buffers all from Lee at Traxxion. Get their oil too! Will be in the 1200.00 mark and will improve the bike more then you can imagine. Not bad to do as I did it with a broken neck! It will come all set up including the spacers for the front forks, the rear dialed in for your weight and is a very good compromise from doing the full Monty with AK's. It has passified me for 3 years but I will get the AK,s next winter. The good thing is you already have the springs and buffers so that comes off the price of the AK,s.

Lee is the man on FJR's and everything coming set up for you. Just install and ride.

 

[J Paul]

I just installed a Nitron with hydraulic preload and got the full RaceTech fork rebuild with Gold valving for right at 2000$. My 08 has 29500mi and a fork seal went so I went ahead with the full upgrade. It definatly helps in corners as I can pick a line and it holds it without constant minor corrections. Jeff

 

[Fred W]

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

At a minimum, in addition to an aftermarket shock, be sure to service the forks and replace the suspension fluid (fork oil) if you haven't already, with something just tad heavier, but NOT TOO MUCH, and replace the fork springs with something more appropriate to your size. This is a low cost thing you can do that will restore a lot of the damping you once had when the bike was new, but with better springs.

 

[MCRIDER007]

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

At a minimum, in addition to an aftermarket shock, be sure to service the forks and replace the suspension fluid (fork oil) if you haven't already, with something just tad heavier, but NOT TOO MUCH, and replace the fork springs with something more appropriate to your size. This is a low cost thing you can do that will restore a lot of the damping you once had when the bike was new, but with better springs.

Why would using heavier oil improve damping? The biggest deficiency in the forks damping is insufficient oil flow through the high speed compression circuit, heavier oil just decreases oil flow and restricts the forks ability to compress over bumps.

 

[Fred W]

Not sure where you got that info. I've never heard that theory before.

What you described is an over-damped condition. And you are right, the way to improve that would be the use of thinner oil. The stock Yamaha fork oil is just about the thinnest oil on the planet when new from the bottle and like any fork oil it thins out with continued use. Based on your assertion the suspension's performance should improve as the stock oil thins out with age.

Most folks believe that the deficiency of the stock forks is that they are under damped in areas that cannot be adjusted with the clickers, especially so as the oil ages. Just about anyone who changes their fork oil ends up putting in an oil that is (at least slightly) heavier than stock, and is considerably heavier than the old used oil. If what you say is true then every one of them is doing exactly the wrong thing.

 

[MCRIDER007]

Not sure where you got that info. I've never heard that theory before.
What you described is an over-damped condition. And you are right, the way to improve that would be the use of thinner oil. The stock Yamaha fork oil is just about the thinnest oil on the planet when new from the bottle and like any fork oil it thins out with continued use. Based on your assertion the suspension's performance should improve as the stock oil thins out with age.

Most folks believe that the deficiency of the stock forks is that they are under damped in areas that cannot be adjusted with the clickers, especially so as the oil ages. Just about anyone who changes their fork oil ends up putting in an oil that is (at least slightly) heavier than stock, and is considerably heavier than the old used oil. If what you say is true then every one of them is doing exactly the wrong thing.

Yep......if going to thicker oil solved the damping problems then there wouldn't be any reason to have the forks re-valved. If you want to see what is wrong with the OEM damping then you need to look at what the suspension gurus change when they re-valve the forks. They replace Yamaha's one shim spring loaded (very cheap to build) high speed compression damping valves with valves that use stacked shims that flow a variable amount of oil under varying internal pressures. The stacked shims flow more oil, not less, which allow the forks to compress quicker when you hit a large bump. The deficiency in the stock forks is that they are over damped in the high speed compression circuit, using lighter oil could help that circuit but lighter oil decreases rebound damping. When you increase the spring rate you need to decrease compression damping, especially in the non-adjustable high speed circuit, but increase rebound damping. Since all circuits use the same oil, something needs to be re-valved to keep the damping system in balance and that is the non-adjustable circuit. Fork oil viscosity changes with use but the variance due to temperature is usually greater than the change due to use.

I think everyone is familiar with GP Suspension's re-valving kits. They do not change the FJR's low speed compression at all and looking at the damping pistons it appears that the rebound circuits are also the same (they do re-design the rebound adjustment needles to give more precise adjustments), all of the real valving changes are in the high speed compression circuits.....and those circuits are designed to be used with a specific viscosity of oil and work best between 65-85 degrees F. Anyone who consistently rides outside that temperature range should change the oil viscosity to compensate.

 

[Bounce]

But they're also including stiffer springs in the rebuild. For those not doing a rebuild, thicker oil is a poor man's way to stiffen the overly-soft stock front end.

Given that so many FJR riders putting large miles on their bikes live (or ride) in west of the Mississippi, the bulk of those miles are probably not in that range... personally I seldom see below 32 and often (down on the road in the summer) see temps for months in the 100+ range.

 

[MCRIDER007]

But they're also including stiffer springs in the rebuild. For those not doing a rebuild, thicker oil is a poor man's way to stiffen the overly-soft stock front end.

You're right, the suspension shops are putting in stiffer springs with the re-valve and getting the best of both worlds, a firmer ride that actually feels softer over bumps (the most description is that small bumps disappear and large bumps feel like small bumps).

The problem with using heavier oil to stiffen a weak spring is that you will feel the bumps more. I think a better solution is to raise the oil level in the forks and let the lower air volume make the springs more progressive.

 

[John d]

But they're also including stiffer springs in the rebuild. For those not doing a rebuild, thicker oil is a poor man's way to stiffen the overly-soft stock front end.

You're right, the suspension shops are putting in stiffer springs with the re-valve and getting the best of both worlds, a firmer ride that actually feels softer over bumps (the most description is that small bumps disappear and large bumps feel like small bumps).

The problem with using heavier oil to stiffen a weak spring is that you will feel the bumps more. I think a better solution is to raise the oil level in the forks and let the lower air volume make the springs more progressive.

How far could you, or would you, raise the oil level?

 

[Sno Cat]

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

Put on the Pensky, order 1.1 Omni Springs and spring buffers all from Lee at Traxxion. Get their oil too! Will be in the 1200.00 mark and will improve the bike more then you can imagine. Not bad to do as I did it with a broken neck! It will come all set up including the spacers for the front forks, the rear dialed in for your weight and is a very good compromise from doing the full Monty with AK's. It has passified me for 3 years but I will get the AK,s next winter. The good thing is you already have the springs and buffers so that comes off the price of the AK,s.

Lee is the man on FJR's and everything coming set up for you. Just install and ride.

My shock & forks are toast @ 13,000mi, the bike is mushy / wobbly in the turns. She's a prime candidate for a fork kit & Penske but that looks to be $2,500-$3K. Trying to figure out a solution for <$2K - ideas?

At a minimum, in addition to an aftermarket shock, be sure to service the forks and replace the suspension fluid (fork oil) if you haven't already, with something just tad heavier, but NOT TOO MUCH, and replace the fork springs with something more appropriate to your size. This is a low cost thing you can do that will restore a lot of the damping you once had when the bike was new, but with better springs.

As always gentlemen, thanks for the excellent info., I'll be moving on to the next step!

 

[MCRIDER007]

But they're also including stiffer springs in the rebuild. For those not doing a rebuild, thicker oil is a poor man's way to stiffen the overly-soft stock front end.

You're right, the suspension shops are putting in stiffer springs with the re-valve and getting the best of both worlds, a firmer ride that actually feels softer over bumps (the most description is that small bumps disappear and large bumps feel like small bumps).

The problem with using heavier oil to stiffen a weak spring is that you will feel the bumps more. I think a better solution is to raise the oil level in the forks and let the lower air volume make the springs more progressive.

How far could you, or would you, raise the oil level?

I would raise the oil level 10 mm.