Getting a GS 1000 S to handle

[bwringer]

The first thing I thought of was steering stem bearings. A couple of other people have mentioned steering stem bearings, but I haven't seen any info verifying that the PO has replaced these.

Of course, the problem could certainly be aerodynamic instability of the fork-mounted fairing. Even very small changes or misalignments can cause problems.

[GregT]

All the race GS1000's I've seen with the small fairing fitted have converted to frame mount to avoid the instability problems discussed here....

Even a small spotlight fitted as an extra headlight can add enough extra mass forward of the steering head to cause problems.

[salty_monk]

I've ridden a 1000S stock with none of those issues.... My 1000E is solid at any speed with a Maier fairing (similar to the S) fitted.

[TheCafeKid]

I've ridden a 1000S stock with none of those issues.... My 1000E is solid at any speed with a Maier fairing (similar to the S) fitted.

Never had a problem with the one on my 1000G either

[John Kat]

I'm not sure I understand your point CaféKid?
[PHP]Again I will ask, did you assure that the squish in the swingarm was adequate to sandwich everything together?? While the hub on your "new" rear wheel may look the same, it may not be the same depth as the original. This is actually pretty common in the GS line from model to model. A lot of the bikes rear spacers are not the same width. I misjudged that myself and had as little as .075" of play left on the axle, side to side, and it made the bike VERY squirelly. If you run out of threads before the axle nut can compress the swingarm, the rear wheel may walk on the axle. [/PHP]I replaced the original 18" GS 1000 ST wheel with a GSX 1100 17" wheel complete with it's axle and spacers.
There was no need to change any spacer as the width of the steel swinging arm is exactly the same as the aluminum one ( to the nearest mm).
I torqued the rear axle to the recommended value and there is no play whatsoever.
Where do you measure the .075" play?

[Roger P.]

The fork mounted fairing on the 900 Seca was responsible for more than a few brown trouser moments as well. The switch to a new frame mounted unit apparently solved the issue.

[gs58]

I have ridden my '79 GS 1000S at 210 kph without any noticable weave or other issues. The fairing would be the same as yours and mounted to the triple clamps as your is. I think that your problem is somewhere else, but it may be exaggerated by the fairing.

[TheCafeKid]

I'm not sure I understand your point CaféKid?
[PHP]Again I will ask, did you assure that the squish in the swingarm was adequate to sandwich everything together?? While the hub on your "new" rear wheel may look the same, it may not be the same depth as the original. This is actually pretty common in the GS line from model to model. A lot of the bikes rear spacers are not the same width. I misjudged that myself and had as little as .075" of play left on the axle, side to side, and it made the bike VERY squirelly. If you run out of threads before the axle nut can compress the swingarm, the rear wheel may walk on the axle. [/PHP]I replaced the original 18" GS 1000 ST wheel with a GSX 1100 17" wheel complete with it's axle and spacers.
There was no need to change any spacer as the width of the steel swinging arm is exactly the same as the aluminum one ( to the nearest mm).
I torqued the rear axle to the recommended value and there is no play whatsoever.
Where do you measure the .075" play?

I wasn't sure if you'd used the matching axle and spacers.

Like I said I did an 1150 3.5" wheel conversion on my 1100ES. The wheels were the same appearance wise aside from the rim being wider and the Hun being narrower than the OEM wheel. I didn't have the 1150 spacers etc so I had to use the 1100 stuff. The axle was too long for the hub of the rim, and with the OEM spacers you ran out of thread on the axle to sufficiently tighten the swingarm, thus a near invisible amount of slop. It became quite apparent while cornering hard and at high speed and was downright scary under heavy rear brake. I ended up having to add 25 thousandths inboard of the caliper hanger and fifty thou outboard and she was all good. That's all inwas talking about. But obviously that's probably not your issue here

[John Kat]

I have ridden my '79 GS 1000S at 210 kph without any noticable weave or other issues. The fairing would be the same as yours and mounted to the triple clamps as your is. I think that your problem is somewhere else, but it may be exaggerated by the fairing.

I agree.
My next test will be with Racetech .95kg/mm springs in the front forks.
Interestingly enough, the GS 1000 ST springs are not the same as those mounted in the original GS 1000 S.
In fact when I bought the bike there was one fork leg with one type of spring and the other with the longer ST type.
I suppose this was done after a crash?
This has been corrected of course!
The question is: are the hydraulics the same on the two legs?
I compared the "fork cylinders" ( PN 51146-49000) and there were identical but what about the fork tubes themselves?
As far as I understand the compression damping is controlled by the holes in the "fork cylinders" and the rebound damping by the valves at the bottom of the fork tubes?
By the way, I also use a fork brace that should (?) minimize any unbalance between the fork legs.
Next update following the test with the Racetech springs.

[sharpy]

How bad was the crash? And did u get my pm? Inner fork tubs are the same. whats the codition of your tyres? Worn tyres wont help one bit.

[John Kat]

An update on my roadholding problems on my GS 1000 ST.
The problem seemed to be due to the bikini fairing but following a new test with another front tire I discovered that the weaving was still there in long sweeping turns allthough I was riding without the fairing
The current front tire is a BT 45 F 100/90*19 V rating.
I still plan to test the bike with RaceTech springs upfront but the french importer isn't responding since I placed my order 6 weeks ago
The problem is really puzzling me as my two other GS 1000's don't have the issue.
Until I get the front springs, I'm going to go back to the OEM rear shocks instead of the Konis that are fitted currently.
I get the feeling that as soon as the rear goes over a bump in a fast corner, the weave starts?

[posplayr]

An update on my roadholding problems on my GS 1000 ST.
The problem seemed to be due to the bikini fairing but following a new test with another front tire I discovered that the weaving was still there in long sweeping turns allthough I was riding without the fairing
The current front tire is a BT 45 F 100/90*19 V rating.
I still plan to test the bike with RaceTech springs upfront but the french importer isn't responding since I placed my order 6 weeks ago
The problem is really puzzling me as my two other GS 1000's don't have the issue.
Until I get the front springs, I'm going to go back to the OEM rear shocks instead of the Konis that are fitted currently.
I get the feeling that as soon as the rear goes over a bump in a fast corner, the weave starts?

I have issues when the rear shocks are undersprung that sound similar to yours.

[John Kat]

It's good to hear that someone has the same issue !
I noticed that your bike is fitted with Ohlins shocks?
Are you able to adjust the compression and rebound damping separately?
Do you believe the issue is related to too much compression damping or too little rebound damping?
In the 80's the engineers used shocks with very little compression damping and harder springs that in turn required more rebound damping.
Not a good idea, compounded by the fact that the first "mag" wheels were massively heavy thus making it more difficult for the suspension to control all this unsprung mass !

[bonanzadave]

It's good to hear that someone has the same issue !

Search Wobble or Weave. You are not alone. I cant find my thread. I think 2008 got purged... ??...anyway yes, my bike has the the weave disease too.

have I tried.......YES ! I have tried everything. My easy solution is to not go 100+ mph .

Edit: OK one thing I haven't tried that Ive been thinking about.....I want to check the compression force on EACH fork with a scale to see if there is any difference. Im thinking a digital scale and a jack....or something.....

[posplayr]

It's good to hear that someone has the same issue !
I noticed that your bike is fitted with Ohlins shocks?
Are you able to adjust the compression and rebound damping separately?
Do you believe the issue is related to too much compression damping or too little rebound damping?
In the 80's the engineers used shocks with very little compression damping and harder springs that in turn required more rebound damping.
Not a good idea, compounded by the fact that the first "mag" wheels were massively heavy thus making it more difficult for the suspension to control all this unsprung mass !

I have a theory and it seems to be confirmed by other riders I have spoke to. With a high profile rear tire (relatively flexible sidewall), you can develop a weave in a sweeping curve when there are undulations in the road.

As you are going through the turn, and you go over an undulation when the rear compresses there is a tendency for the bike to lay over into the direction of the sweeping turn. Each undulation and another laydown. When the rear uncompresses the bike stands back up.

I attributed the compression to an increased rear tire sidewall flex causing the bike to weave. A stiffer rear spring and stiffer side walls made it go away. Of course this was in the course of doing an 88 Gixxer upgrade.

I don't think it really has anything to do with the damping. It only happened to me when I had the SU-143 Ohlins which did not have any adjust-ability but did have an under sprung spring for my weight and load. It was really noticeable with 100 lbs of camping weight on the rear.

I later got some SU-145's fully adjustable (the ones you see on the bike) and bumped up the spring stiffness as well.


Part of the discussion was here. After rereading I realize that part of the issue was overly stiff front and under stiff rear making it worse. It is really all about getting the sag correct both front and back.

http://www.thegsresources.com/_forum/showthread.php?t=140521&highlight=Ohlins+preload&page=2