Speed Wobble with touratech panniers

[alex22]

Hi All,
I am new to this forum and looking for help!
I have just fitted a set of 41Liter touratech zega cases on to my R100GS (1989 Bumblebee) in preparation for a trip to Hungary. However i am having some really nasty speed wobble problems.

With the panniers heavily loaded (30kg each side!) the bike rides ok at slow speeds though feels pretty wallowy. However, if i try to go over 68mph she starts to wobble and snake from side to side, powering through this is not an option as it gets much worse very quickly.

I assumed this to be a weight related issue. However, even with empty boxes fitted the wobble is still apparent though doesn't kick in till around 80mph.

The bike seems to ride ok without the panniers on and have taken her over 90 without too much of a problem, though she does begin to feel a little unstable (but assume this as to be expected on an old airhead?).

Ive had the bike laden in the past with the original bmw boxes and don't remember feeling anything like this.

Is this kind of wobble normal with Touratech’s boxes? Its bloody scary.

the bike is pretty standard in terms of frame and suspension fitted as follows:

stock rear suspension

stock forks with Progressive springs

low front mudguard

Michelin anakee front tyre - 32 psi

Meltzer tourance rear - 34 psi


Any help or advice would be much appreciated.

cheers, Alex

 

[fayeslane]

Have you adjusted the pre load on your rear shock to allow for the extra weight. Do a search on setting the suspension sag it might help. Suspension and tyre pressure adjustments are a low cost place to start.

 

[g.s.john]

Could be the mix of tyres which are potentially unstable the extra weight will magnify the problem.

 

[flytoolow]

..You could slow down a bit.......see if that helps ??

 

[fayeslane]

..You could slow down a bit.......see if that helps ??

Lateral thinker

 

[judge]

Has the preload on the rear suspension been adjusted accordingly?

Tyre pressures for load 36 front 42 rear.

Even so mine was light over the front wheel so tank bag and tank panniers loaded helped.


Even so 68 moh is a nice cruising speed for an airhead on a trip

 

[Michael R1150GS Adventure]

yep my 1150 will kill me if i go over 85 with my zegas on

a few tips after 6 years of using these bloody boxes:

1. too much weight over the back of the bike - lighten up man!
2. you need more weight moving forwards - i always have my bike chain wrapped round the tankbag, bottles of wine in the bag etc
3. Try getting the particularly lardy items in your panniers packed LOW and FORWARD and on the INSIDE face of the panniers (if you must carry that much gear)
4. Preload rear, up. Makes an amazing difference


As we may as well tie two bungalow gable ends to either side of our bikes, we need to accept the sad reality that if you go any faster it will hurt you.
Dont even mention trying to overtake lorries on a cross wind day either.

The boxes make your bike very unstable, once you have given up trying to cure it you can enjoy trying to improve the set the best you can.

Its taken me years and I think I have it sussed now...

This is my bike tail heavy after an enduro weekend, wallowed like a bitch, shook her head and didnt steer. Not enough wine in the tank bag

 

[Shep]

Steering head bearings or perhaps worn tyres (either due to the knacked bearings or high milage)

 

[Voyager]

Make sure there is no play in the swing arm pivot bearings or the Paralever bearings. It doesn't take much play there to cause the bike to shake its head.

Bob.

 

[v4our]

Steering head bearings too tight.

 

[Loiq]

they all do that don't they?

I'm sure it give a do not exceed blah blah speed with panniers on... it what was blamed for the big police crash on the A3 20 years ago. 6+ police all came off at the same bend on a training ride total carnage...!

 

[David Nimrod]

60kg in your panniers...

Why..?

Lighten up, slow down, enjoy the ride

 

[flytoolow]

they all do that don't they?

On a similar note, the last time I was in the UK (about 3 weeks ago) I spent the afternoon with my Father & an old work collegue of his (both now in their 80's)..

His old work collegue was/is a real BMW fan... He rode BMW's back in the 50's or 60's (Thats why my father thought it would be a good idea for us to meet), and was riding until very recently...old age and all that

He showed me a photo of a bike that he had "modified" (Professional controls engineer by trade) the front end on a R50/? I think. He stated that the reason that the "old" BMW's wobbled at high speed (...I believe they all do it as well to a limited degree...I did notice that my new/old R80GSPD certainly has a small low frequency occillation around the 120Km mark..something that my 1150GSA does not) was due to the location of the unsprung mass of the the front wheel being behind(?) the main fork mass..(or something to that effect...)

His modification was another sprung pivoting arm at the bottom of the front fork that moved the front wheel mass forward of the original fork bottom by about 10cm. He said it cured the high speed occillation. He sold the bike and asked that if it was ever sold on, if he could have the modification back...He never did get it back...

Apparently the low speed occillation is caused (according to him...dont quote me) by "...the angle of the rear arm being directed to the front head stock of the bikes...."

He quickly showed me a book...by some german engineer that explained it all on a mathamatical basis (something that Ive not done since my varsity days...)...But I'm hoping to get the ISBN number or at least a look through to see what its all about...and next time Im back home (Manchester) I mean to stop by again and discuss it in more detail...He showed me this just as we were leaving...

...Slightly long winded response I know...

 

[alex22]

Thanks for all of your help guys.

Yea am happy to ride it slow when loaded, am just worried that it is something more serious exasperated by adding panniers / weight.

My main worry is that the bike still does it unloaded (just at higher speed) and with unloaded panniers. for example: at 75 / 80 with no panniers if i nudge the bars she goes in to a wobble, a kind of slow snaking that gets faster if you go faster. Im sure i remember that in the past she would just shake her head and straighten up.

My brother reminded me that this is actually the first time ive taken her anywhere loaded since a low speed off i had (25 / 30mph). This was bad enough to bend the fork stanchions as the bike went headlong in to the side of a van...with a lot of help from a private taxi that turned in to me......Nice.
Anyway, the stanchions were replaced and the bike has only been city riding round London since!!

Am going to strip the forks and check the front yolks for straightness, as these weren't changed.
Also, ill check the paralever and swing arm bearings with a torque wrench while i’m at it but cant feel any play by hand.

I have already adjusted the steering head bearings, re torqued etc... doesn't seem to help. And played with the tyre pressures, they don't seem to make much if any difference either?!

However, pretty sure the stock rear shock has no damping what so ever had a few comments about that today at a local bike shop (though they only really do bikes of the super fast variety), proper springy. Though the front forks aren't much better, currently 10 weight oil in either side and progressive springs, (these were swapped at the time too for a different set of progressives which i’m now regretting as I’m sure the ones I had in there were newer and better!) Damn so many variables, that will tech me for changing tones of stuff in one go!

Final thing to mention about the panniers is that there a bit custom too, reinforced zega cases (were a bit cracked when I bought them) mounted on the original but heavily reinforced BMW pannier frame... Maybe there mounted a bit far back??

Will report back after ive checked my yolks etc...

Thanks again y'all,

Alex

Pic of bike.

 

[Sunny Jim]

An early ride on my '91 GS (with luggage) many years ago nearly ended in tears when riding through traffic at about 20mph - took my left hand off to have a stretch only to find this amazing wabble developing

When you have a good look at the length of the forks and the distances involved from yoke to brace at mudguard (the weakest point IMHO)to spindle it's not surprising the forks 'twist' and generate a wobble.

Time someone fabricated a substantial mudguard brace

 

[Beemerboff]

Torquing up the swinging arm and paralever bearings doesnt always make a difference, as the bearings can turn on the pins , and no amount of adjustment will fix that.

I dont like the way the GS handles even with OEM panniers with clothes, towels and sleeping bag in them, so I stuff what would be in the boxes into a large Ortlieb roll bag and bungy it to the back seat, and leave the panniers at home.

Tyre profile makes a big difference too - I like a tyre with a good rounded profile , the flatter the tread the less stable they are.

But if you pack around twice the recommended load too far back and out too wide you are just going to have to risk your life every time you ride it, its your choice!

 

[Shurv]

Never been a fan of bloody great ally boxes on a bike.Encourages folk to fill them full of heavy stuff and feck up the handling.Those boxes look huge,and i'm not surprised it doesn't like them.Get some nice plastic OE ones,smaller, more aerodynamic and less likely to turn your bike into a death trap.

 

[litelfun]

Hi All,
I am new to this forum and looking for help!
I have just fitted a set of 41Liter touratech zega cases on to my R100GS (1989 Bumblebee) in preparation for a trip to Hungary. However i am having some really nasty speed wobble problems.

With the panniers heavily loaded (30kg each side!) the bike rides ok at slow speeds though feels pretty wallowy. However, if i try to go over 68mph she starts to wobble and snake from side to side, powering through this is not an option as it gets much worse very quickly.

I assumed this to be a weight related issue. However, even with empty boxes fitted the wobble is still apparent though doesn't kick in till around 80mph.

The bike seems to ride ok without the panniers on and have taken her over 90 without too much of a problem, though she does begin to feel a little unstable (but assume this as to be expected on an old airhead?).

Ive had the bike laden in the past with the original bmw boxes and don't remember feeling anything like this.

Is this kind of wobble normal with Touratech’s boxes? Its bloody scary.

the bike is pretty standard in terms of frame and suspension fitted as follows:

stock rear suspension

stock forks with Progressive springs

low front mudguard

Michelin anakee front tyre - 32 psi

Meltzer tourance rear - 34 psi


Any help or advice would be much appreciated.

cheers, Alex

I had some touretek on my GS1150 I allso expeanced some badhandling that allmost killed me several times on one toure so I would only ever use a tube bag now a lot cheeper to

 

[Paul Rochdale]

So Alex, did you ever discover the cause of your bike's speed wobble? I'm interested as my own bike does the same, and is often brought on when the road surface has been scraped into ridges. I did discover my tyre pressure gauge was faulty and my front tyre incorrectly inflated. There is an annoying rattle in the front forks which is noticeable when riding on uneven roads and can be felt through the handlebars. Almost like loose head bearings but they are OK, perhaps even too tight.

 

[Wrigsby1]

So Alex, did you ever discover the cause of your bike's speed wobble? I'm interested as my own bike does the same, and is often brought on when the road surface has been scraped into ridges. I did discover my tyre pressure gauge was faulty and my front tyre incorrectly inflated. There is an annoying rattle in the front forks which is noticeable when riding on uneven roads and can be felt through the handlebars. Almost like loose head bearings but they are OK, perhaps even too tight.

Virtually all of the things you mention can get the bike wobbling... Worn H/B's or too tight is an obvious as is tyre pressures being "incorrect" even though this implies you know what is correct... A bit of trial and error for tyre pressures especially on different tyre makes... big boxes can make a modern bike a handful and so Airheads are going ot get a much harder time... Tired shocks, shagged fornt fork springs, oil, etc...

The main thing is pack sensibly with as much of your weight forward and lower... So panniers OK if they are not mounted way back, loads of stuff high up will make the bike fall in to turns especially when going slowly... Top boxes and worn tyres are major causes on the slow tank slapper... The other bit is don't keep letting go of the bars if it goes into a wobble when you do...

My 100 RT does it around 30mph as its all round worn... My V Strom thou can be a bit the same since I changed the tyre... Or is the wheel out... Or the top box too big etc etc etc...