Old GS handling limitations

[glib]

I think your math is probably off. There's more to it than just the ratio of swingarm pivot-shock mount distance to swingarm pivot-axle distance.

That said, could they be the wrong shocks for your bike?

Actually you are right. The forward angle of the shocks adds travel to the axle and would bring the numbers pretty close to stock with the Progressives. The Ohlins do have shorter travel. Would that justify less sag? Otherwise there is significantly less travel before bottoming. Would that be a spring stiffness issue? I believe they are SU 142s. Should be correct for the bike but maybe for a lighter pilot.

 

[RichDesmond]

Actually you are right. The forward angle of the shocks adds travel to the axle and would bring the numbers pretty close to stock with the Progressives. The Ohlins do have shorter travel. Would that justify less sag? Otherwise there is significantly less travel before bottoming. Would that be a spring stiffness issue? I believe they are SU 142s. Should be correct for the bike but maybe for a lighter pilot.

All of the above. If you have less actual axle travel then you need both less sag and stiffer springs.
It's important to work from axle travel, not shock travel. Depending on the mounting points dual shock setups can have either (slightly) rising rate geometry, falling rate, or be almost linear.
If you pull the springs off the shocks and then reinstall them you can measure axle travel, having that number would help. I typically use 28-31% of travel when setting total sag.

 

[glib]

All of the above. If you have less actual axle travel then you need both less sag and stiffer springs.
It's important to work from axle travel, not shock travel. Depending on the mounting points dual shock setups can have either (slightly) rising rate geometry, falling rate, or be almost linear.
If you pull the springs off the shocks and then reinstall them you can measure axle travel, having that number would help. I typically use 28-31% of travel when setting total sag.

Perfect timing for that suggestion because last night I decided I'd go today and get my Works shocks charged with nitrogen (hard to find someone to trust even with such a simple task), so I took off the springs. I just went out and mounted one with no springs and measured travel several times. The axle travel from extended shock to bump is 101mm (Works shock travel is 70mm--just 2mm less than the Ohlins). So I need 28-31mm of sag.

What is the consequence of too little sag? I don't think I've seen that addressed.

 

[RichDesmond]

Perfect timing for that suggestion because last night I decided I'd go today and get my Works shocks charged with nitrogen (hard to find someone to trust even with such a simple task), so I took off the springs. I just went out and mounted one with no springs and measured travel several times. The axle travel from extended shock to bump is 101mm (Works shock travel is 70mm--just 2mm less than the Ohlins). So I need 28-31mm of sag.

What is the consequence of too little sag? I don't think I've seen that addressed.

Depends on what's causing it. If it's springs that are too stiff then you have restricted travel and forces larger than they need to be being fed into the chassis. If it's due to excess preload then you'll get harshness at the top of the stroke, as it takes more force to get the suspension moving again after it's topped out.
Either situation compromises ride quality and traction.

 

[glib]

Depends on what's causing it. If it's springs that are too stiff then you have restricted travel and forces larger than they need to be being fed into the chassis. If it's due to excess preload then you'll get harshness at the top of the stroke, as it takes more force to get the suspension moving again after it's topped out.
Either situation compromises ride quality and traction.

I guess it's just a hazard of setting up used parts but I have to guess at the initial preload setting (the wire clip) and it's not an easy adjustment once installed.

 

[RichDesmond]

I guess it's just a hazard of setting up used parts but I have to guess at the initial preload setting (the wire clip) and it's not an easy adjustment once installed.

If you have to redo it you can work from the ratio of shock travel to axle travel to figure out how to change preload to get the sag you need. That way you only have to do it once.

 

[Guest]

I was about to go out and move the forks but the tubes have holes that will leak once moved out of the fittings that trap the air. Even ten mm will move them out from under the seal. Not sure what to do now. I'd have to find a way to seal the holes.

I just use some JB weld on mine, then lightly sand and buff it smooth.

 

[limeex2]

Nice to know on the JB weld. I would like to seal mine up. I would like to get rid of the equalizer as it makes fork removal easier even when the rubber seals are plenty lubed up.

 

[Guest]

Nice to know on the JB weld. I would like to seal mine up. I would like to get rid of the equalizer as it makes fork removal easier even when the rubber seals are plenty lubed up.

I want to get rid of that equalizer tube as well, been thinking of taking it to a machine shop and have two spacers made.

 

[glib]

I want to get rid of that equalizer tube as well, been thinking of taking it to a machine shop and have two spacers made.

Is there any reason the equalizer should not be removed altogether if it's not going to be used and the tubes moved up?

 

[glib]

If you have to redo it you can work from the ratio of shock travel to axle travel to figure out how to change preload to get the sag you need. That way you only have to do it once.

Well I overshot adjusting the (rear Works shocks) and ended up at 23mm. If total wheel travel is 101 then it is also 23%. The next step back down in preload should put me at 30%. I think I'll go for a ride just to see how it feels before the next adjustment. I want to drop the front a bit too but I think one change at a time between rides is best to see if I can feel anything.

 

[salty_monk]

Is there any reason the equalizer should not be removed altogether if it's not going to be used and the tubes moved up?

there are small holes in the fork legs... Some have jb welded. Some have really welded. I removed the centre hose and blocked all parts with correct size bolts and sealant. Left the collars in place.

 

[glib]

there are small holes in the fork legs... Some have jb welded. Some have really welded. I removed the centre hose and blocked all parts with correct size bolts and sealant. Left the collars in place.

Yes I am thinking about which way to go with the holes. I was thinking a strong sealant would work if raising the fork legs put the holes under the upper clamps but haven't tried yet. The wire clip will have to go. (EDIT: Decided not to do this)

 

[Guest]

If you did the race tech emulators and heavier springs , why are you still using the air? Generally you braze the holes closed.

 

[glib]

If you did the race tech emulators and heavier springs , why are you still using the air? Generally you braze the holes closed.

I'm glad you asked because I just raised my forks 10mm and by removing the cushions between the air collars and the top clamp I was able to keep the air sealed but without the extra air pressure my sag increased. Did you have to re-adjust pre-load after closing the holes?

 

[Steve]

If you did the race tech emulators and heavier springs , why are you still using the air? Generally you braze the holes closed.

It's not that he is "using the air". There is ALWAYS air involved in the front suspension, it's a matter of ADDITIONAL air. The fork tubes on the 1100s have a small hole on the side of the tube that lines up with a collar that has a couple of o-rings that go around the fork tubes. Between the two collars is a small tube that equalizes the pressure between the two tubes. Not only does that ensure perfectly equal pressure in the two tubes, it allows the use of just one inflation valve, making it easier.

With the addition of proper springs (and emulators), you do not need any additional air, just whatever is trapped in the tubes when you put the cap on. Since he is moving the tubes in the clamps, those equalizer holes are now open to the atmosphere. There will be NO air trapped in the tubes that will be compressed along with the springs. Not only does that reduce the overall spring rate, it will also allow fork oil to be spit out.

If you don't move the tubes in the clamps, you can leave the holes open, but if you slide them past the equalizer collars, you MUST close them off, one way or another.

.

 

[glib]

It's not that he is "using the air". There is ALWAYS air involved in the front suspension, it's a matter of ADDITIONAL air. The fork tubes on the 1100s have a small hole on the side of the tube that lines up with a collar that has a couple of o-rings that go around the fork tubes. Between the two collars is a small tube that equalizes the pressure between the two tubes. Not only does that ensure perfectly equal pressure in the two tubes, it allows the use of just one inflation valve, making it easier.

With the addition of proper springs (and emulators), you do not need any additional air, just whatever is trapped in the tubes when you put the cap on. Since he is moving the tubes in the clamps, those equalizer holes are now open to the atmosphere. There will be NO air trapped in the tubes that will be compressed along with the springs. Not only does that reduce the overall spring rate, it will also allow fork oil to be spit out.

If you don't move the tubes in the clamps, you can leave the holes open, but if you slide them past the equalizer collars, you MUST close them off, one way or another.

.

Thanks Steve. I actually did move them back down so that they are only raised by the amount equal to the rubber cushion (which I removed) between the top triple clamp and the air collars so that I could keep the wire snap ring in place and the holes inside the air collar. So now the air equalizer is still secure and functioning. I feel more comfortable with that--especially since if I want to drop the front down (which I know has consequences), I can just reduce the air pressure.

 

[RichDesmond]

What springs do you have?

 

[glib]

What springs do you have?

1.0 (Based on calculator recommendation) And I like them...

I think I confused the different terms in the RaceTech instructions, free, static, race etc. and though using Sonic instructions, ended up measuring incorrectly in the front. I think I had too little sag on the ride last weekend and now, without added air, I have too much actually. After correcting this, the final result will be a lower front, smaller rake angle--maybe two degrees. Maybe that will help.

 

[Guest]

Is there any reason the equalizer should not be removed altogether if it's not going to be used and the tubes moved up?

If you are talking about the complete set up, you'll need two spacers in the place of the units...at least on mine I do. Look at yours, mine support the bottom of the headlite mounts.