ST1300 Rear Shock Rebuild

[oude geit]

Damn, at 147000 miles mine is way overdue a rebuild...lol

 

[dduelin]

Yeah, you're correct and I do weigh more than 175lbs (w/out gear LOL...) On my previous bikes I had to add spacers to forks for correct sag (and replaced sprinds with progressive wound), however the rear shocks preload adjustment had enough range for my weight. But that was then... not sure about this ST rear shock, eyeballing the coil diameter seems to be enough but his bike is a lot heavier as well... may end up replacing the spring??? More to come on this one.



That's pretty much why I bought this bike if I'm honest, my current Magna and Nighthawk had enough power but after a 300 mile ride my behind wasn't happy.

When you check rider sag vs static sag you will probably find that the amount of preload required for your weight will cause the shock to top out or nearly so when you remove your weight off the bike. When you can set an adequate amount of rider sag with sufficient preload and then if there is little to no static sag that is in your face too little spring. I think the OEM shock is amazingly long lived. Many riders are on their second, third or fourth 100,000 miles and still original. I also think when they replace it, even with a stock one, it will be apparent how much better controlled the rear suspension becomes.

 

[MidLife]

...... rebuilding the rear shock ...... (is it even rebuildable) ......

 

[draser]

For about $400 Traxxion Dynamics rebuilt, revalved, and resprung my stock shock.

Thank you, will give them a shout!!

Here you go:

Rebuilding the rear shock

Thanks, that's what prompted starting this thread.

It isn't clear to me by what you have written whether you are planning to rebuild the shock in its stock configuration or not. It seems to be an opinion held by several on this forum that the OEM shock, front springs are woefully under capacity for anyone who tips the scales at more than around 175 pounds.

Good point, my premise was - as with any other bikes I worked on - that, in stock condition, the suspension is set to handle average weight riders and luggage (any vehicle has a stated design load capacity). However, since in real life things may work differently, I'm tapping this forum's "riders knowledge base" to understand what others are experiencing.

So, I am unsure which direction to go (stock or higher sprung) and, as others suggested, I'll ride it as is (except for fork service) the first year to see what's what. My main fear, to be honest, is the high speed instability/wobble, so I'm trying to repair anything that has play/wear. I like to go three digits once in a while.

 

[draser]

I also think when they replace it, even with a stock one, it will be apparent how much better controlled the rear suspension becomes.

That's somewhat my problem, I don't know how the bike rode new, I can only compare to my previous bikes (all naked bikes, it's not really apples to apples). When I took my first ride the bike felt fine in straight line and corners, but I'll need more seat time.

 

[dduelin]

So, I am unsure which direction to go (stock or higher sprung) and, as others suggested, I'll ride it as is (except for fork service) the first year to see what's what. My main fear, to be honest, is the high speed instability/wobble, so I'm trying to repair anything that has play/wear. I like to go three digits once in a while.

If there is a good thing about the Pan weave is an oscillation that it starts out in magnitude slowly and only increases with further increases in speed. One can ride for extended periods just below or just above the onset speed which varies with load configuration and wind speed and direction. It's a weave, not a fork wobble or tank slapper, that can happen suddenly or rapidly increase in frequency until it is out of control.

 

[MidLife]

It's a weave....

Haven't experienced it on mine anymore since installing a stronger spring keeping the rear higher.

 

[TerryS]

Haven't experienced it on mine anymore since installing a stronger spring keeping the rear higher.

Nor me; my bike gets a little loose in truck vortices but is otherwise arrow-straight at all sensible speeds. I don't use the top-box and rarely carry much weight in the panniers.

 

[draser]

Haven't experienced it on mine anymore since installing a stronger spring keeping the rear higher.

How was it before? Any tips (bike loading, tire pressure, starting speed)?

 

[sirbike]

Haven't experienced it on mine anymore since installing a stronger spring keeping the rear higher.

How was it before? Any tips (bike loading, tire pressure, starting speed)?

I have always wondered if there is, particular to the ST1300, that as speed increases, a combination of aerodynamic downforce on the suspension combined with weight loading, weight distribution, spring rate, valving, a self limiting aerodynamic dynamic tendency to yaw, that is, tending yaw but only so far then swinging back the other way, combined with the suspension being compressed at the apex of each turn of the weave, suspension extending as the bike becomes upright then being compressed at the next apex resulting in a slow pitching oscillation that is mixed up with a slow yawing momentum and all these factors having a harmonic coupling.

Various accounts show that changing one of these factors raises the threshold of or negates the weave.

 

[Sadlsor]

I'm just glad to say I've never had that experience, and I run a Givi 45l top box nearly all the time.
But I guess it really doesn't count, as I seldom (SELDOM - like nearly never) toodle around over the ton, and it's usually just to pass, if I do. 100mph indicated is closer to 92 on my 1300.
Triple digits is where the insatiable instability demons lurk.

 

[MidLife]

How was it before? Any tips (bike loading, tire pressure, starting speed)?

No real tips. In general, the OEM setting had a "mushy" feel on the front. It goes approximately where you want it to but you are tight on the grips because you constantly have to make micro corrections (or think you need to!). No matter the speed. It is just a bit scarier and noticeable at higher speed as you have to react faster and overcorrection can result in weave amplification.

It is worse with some tires and best tire pressure varies also with the tires. Lots of good tires available now, and new ones coming along all the time, can only say the T32s are working well for me.

Was also worse for me with bar risers and reverted back to OEM.

......arrow-straight .......

Cannot describe the change to stronger spring better than that.

But like most are saying, ride it first the way it is, set the sag (preload) as well as you can and don't forget rebound adjustment. You won't appreciate the improvement of a better shock if you have nothing to compare it with! And some people are happy with the OEM set up anyway.

As @sirbike said there are many factors involved. So you may find a set up that works for you with what you have.

Various accounts show that changing one of these factors raises the threshold of or negates the weave.

The high speed wobble can be a bit scary, but you can feel it coming. And with time you'll learn how to tame it. Sometimes, if you have some reserve left, accelerating works better than slowing down.

 

[draser]

In general, the OEM setting had a "mushy" feel on the front.

That's how my Magna was with original linear springs. The front was somewhat floating/unplanted with easy bottoming out. That changed with progressive wound springs and sag adjustment. By comparison, my Nighthawk was stiffer/sportier and it took less preload in front to adjust for my weight.

but you are tight on the grips because you constantly have to make micro corrections (or think you need to!)

I normally have a relaxed grip allowing the bike to correct itself. So, I may be in for a surprise...

 

[dduelin]

It’s my opinion that even the best sorted ST1300 will have a nervous feel in dirty air at highway speeds. I called it ‘happy feet’. The forks don’t have a lot of rake, it has a shortish wheel base, and a large broad-in-the nose fairing. I do not think it is inherently unstable it’s just not as stable as many other motorcycles are in the same conditions.

Things that help minimize happy feet are sag as good as you can get it - get it and keep it out of the lower third of suspension travel, 42/42 psi, windshield not excessively high, respecting payload limits of ~under 395 lbs, cargo weight low and out of the top box.

And know that this nervous trait is not the same as the Pan Weave at 115 to 130 mph. Don’t be scared yours is going to suddenly go into a wild fork wobbling tank slapper. The weave oscillation starts out slow in frequency and magnitude and in my experience only increases with speed. I confess to have ridden a lot in the weave exploring it. Deserted empty roads don’t try this at home etc.. It’s just not going to show under supra legal speeds and if and when it does it’s gradual in onset. The ST1300 under WOT is starting to lose its best rapid acceleration rate by 120 or so and we just don’t pass some triple digit speed weave threshold so fast we can’t back out of it.

 

[DeanR]

It’s my opinion that even the best sorted ST1300 will have a nervous feel in dirty air at highway speeds.

My 1100 never feels like that. Another thing to add to the better things about the 'old' 1100's.

 

[Sadlsor]

My 1100 never feels like that. Another thing to add to the better things about the 'old' 1100's.

It varies. In nearly all circumstances, my 1300 is steady and stable. I ride in a sporting manner, but stay under the ton.
Probably the most fluttering or lightness I experience is when following the big trucks when they're passing each other, with all lanes blocked by the slower vehicles in front of me.
Giving them space reduces the effect, until a lane opens.

 

[motornut]

It varies. In nearly all circumstances, my 1300 is steady and stable. I ride in a sporting manner, but stay under the ton.
Probably the most fluttering or lightness I experience is when following the big trucks when they're passing each other, with all lanes blocked by the slower vehicles in front of me.
Giving them space reduces the effect, until a lane opens.

You hit the nail with a big hammer, since I prefer a more softer suspension setting my rake less steeper than if I jacked up the rear preload. It is more stable in my opinion which requires more body english and more purposeful but delicate inputs from throttle and brakes to ride with a little spirit.
I also use a more neutral tire profile , more round than the aggressive pointed style which tend to drop into corners easily and react quicker to negative inputs.
With large frontal fairing it will give a less than comfortable following zone than others. Try sometimes raising the windshield behind a truck, it becomes a wonderful sail and you will tack like a sailboat. My advice is to let it buffet if that is the zone you wish to ride in.
I have tried dirt riding and can't get by the idea that the back tire will do things and that I should let do it. It is not going to do me any harm, The buffeting behind a truck is very similar, let it and don't worry. If it is a bother, back off a bit and get to a comfortable zone like Sadlsor said.

That said, without more engineering and racing experience this is a opinion which I cannot base in facts because everybody has different comfort areas.

 

[draser]

the back tire will do things and that I should let do it

That's something that I've learned myself, my first exposure to this were the MotoJitsu learning videos, he's stating that the rider needs to expose himself to uncomfortable conditions as part of one's (parking lot) training. He's recommending dirt track time as well, to get familiar/comfortable with unstable bike situations. Same for front wheel and loose arms on the handlebars to allow the bike to correct itself.

My advice is to let it buffet if that is the zone you wish to ride in

I normally ride "in an open window" on the highway, as I'm trying to "acquire" open (reaction) space all around me.

 

[motornut]

You are so right and you put it clear draser, I think of it as a option zone where you have directions to go in avoidance ie right, left, brake or accelerate. The committed zone where you only have limited routes of "escape". Like to close at a light or stopping close and being in the center of the car in front of you, to close at speed. I still examine what I do on the road and try to adjust. I still appreciate "clean air on the freeway.

 

[Sadlsor]

I still appreciate "clean air on the freeway.

As well as ALL the view I can get. So I try to leave distance, or change lanes for a view farther ahead.
Just today, going to church, I was in the middle lane, being passed by an Escalade in the lane to my left.
I saw a 3ft long road Gator (remnant of a truck tire) in his lane ahead of him, which he should have seen as well, but he wasn't looking and ran right over it. It flew up into the air, about head high to me... if I was behind him, it could easily have hit me. Guessing that size piece of rubber weighed 10-12lbs, maybe more.
Yikes!
I just "knew" he'd see it, the lane was entirely clear in front of him, but I should have anticipated what "could" happen, even though I was in a different lane.