Dr650 speed wobble at 110km/h [Archive]

Monstaman

14th July 2009, 14:05

So I lowered my bike on the rear spring bolt, reset my preload to my correct static sag with rider etc, and made it slightly firmer than the front for carrying shit, the shock bolt height dropped the bike 37 mm vertical from the wheel nut.

I dropped the forks through the clamps 20 mm to come closer to geometry however at 110 km/hr it does a little weave on the road, not bad but quite noticeable.

I put the forks back through the clamps level with the top triple again and this has settled it down a bit.

I am running full knobblies at present and wonder if this has a big influence, any input would be cool.

Signed Dr Jekyll or Hyde .... sure :laugh:

Squiggles

14th July 2009, 14:08

*watches with interest*

Monstaman

14th July 2009, 14:10

*watches with interest*

...I usually charge for that :shifty:

Crisis management

14th July 2009, 14:38

You've made a couple of erroneous supositions.
1. The suspension on a DR can be adjusted to make it work.
2. A DR will track straight on any surface.

Talk to Nordie or Bass if you want the suspension to actually work, the rest of us just assumed it was crap and carried on, by winding everything up tight mine worked ok but I'm only 70kgs....

Bass

14th July 2009, 15:42

I am running full knobblies at present and wonder if this has a big influence, any input would be cool.

Signed Dr Jekyll or Hyde .... sure :laugh:

What tyres are you running and what pressures are you using?

What do you mean by "firmer" - damping or preload?

GaZBur

14th July 2009, 15:53

I also dropped the back and left the front standard when I put 17inch rims on the front. No handling issues re wobbles and have been up to 179Kph. I put the 21inch wheel with full knobs back on without altering the suspension back and found it surprisingly good up to about 130 Kph but not had it any higher as mostly on gravel. My preload is very high - not much adjustment left. I would guess it is tyres as knobs on tar are really bouncing from knob to knob rather that having constant traction. With knobs on it is more a case of point and hope rather than steering for me anyway! I find full knobs on the DR quite un-nerving in low- med speed corners and find it best to lean the bike in over the first set of knobs before leaning your body into the turn.
Perhaps higher pressures will help? I dont know what you are meant to run but for memory I am 24 and 26psi. The adventure boys would have a better idea of correct pressures for knobs on the road.

Monstaman

14th July 2009, 16:07

What tyres are you running and what pressures are you using?

What do you mean by "firmer" - damping or preload?

Set both front and rear to 30PSI just to road test, the rear is Trak Master M760, the front is BFG Crossengo.

Firmer, slightly less static sag than the front, I also firmed up the damping a bit as well, not far off the firmest, rebound is still very fast, faster than I thought it would be nearly all the way in.

I would guess it is tyres as knobs on tar are really bouncing from knob to knob rather that having constant traction.

I wondered about this too, I will drop the static sag in the rear to suit the front and start with that.

I went out fo a quick skid to Motutapu and yeap around the twisties I was sliding all over the place.

Bass

14th July 2009, 16:53

Set both front and rear to 30PSI just to road test, the rear is Trak Master M760, the front is BFG Crossengo.

Firmer, slightly less static sag than the front, I also firmed up the damping a bit as well, not far off the firmest, rebound is still very fast, faster than I thought it would be nearly all the way in.

OK.......
The only time that I have encountered the dreaded weave was when I put some really agressive knobs on. I suspect that Gaz is right about the tyres being the cause, but that the problem is the knobs flexing. I played around a lot with pressures and found that lower pressures seemed to help. No, I can't explain that, cos it makes no sense to me either, but the front was definitely more stable when I got the pressure down to about 18 psi, which is as far as I was game to go on rough stuff with no rimlocks. Have been down to 15 in soft sand.
The back doesn't seem to matter much and I don't notice a lot of difference from 20 to 38 psi, unless it's soft or slippery when the usual low pressures are the way to go.
I'm sorry, but I don't recognise either of the tyre brands that you have mentioned and so can't comment further.
As far as suspension settings go, my riding mate in Oz also lowered the back of his DR, as you have done and dropped the forks through the clamps an appropriate amount.
He hated the result. He said the handling was of real concern and pushed the forks back to full height. His concern was the tracking too.
I can't explain that either. I would have thought that lowering both ends the same amount would be the correct thing to do, but it's not.
The only thing I can suggest is that lowering the back alters the geometry so that it needs more rake and trail and so wants the forks at full length.
If you went out in the gravel with 30 in the front, I would expect her to slide around a bit.

NordieBoy

14th July 2009, 17:42

Technically dropping the rear with the boltand dropping the front 4cm is the same as doing it properly.

UNLESS you bottom out the suspension whereupon you will get launched over the bars as either wheel hits the guard and stops suddenly.

If you drop the back 4cm then to keep the exact same rake/trail you'd need to drop the front slightly more than 4cm through the clamps.

It should handle fine.

But....

Taz

14th July 2009, 17:47

Every bike moves around on K760's.

Squiggles

14th July 2009, 19:23

What pressures are you running? I've been at 28/32 with the trailwings on the road... interested to hear what others are at

johannvr

14th July 2009, 19:43

Every bike moves around on K760's.

I tend to concur. Those Kenda's look fairly "rough" for tarseal, even tho they are DOT approved.

I used to have as stable a ride as the DR could do on Pirelli MT21's - now less so on Michelin T-63's which have a similar-ish pattern & I have also noticed a slight weave on the front from a little :shutup: above the legal limit, that was not there before.

Not sure exactly why either ... in the past with roadbikes we used to have a common belief that a weave in the front actually caused by something from the back wheel (ie not tracking true to frame, etc etc) - not sure if it was anything more than urban legend & if it applies equally to ADV bike or not ...

Woodman

14th July 2009, 21:52

junkmanjoe

14th July 2009, 22:35

hey any other DR riders out there notice that the factory speedo runs at 10km slower than what its reading...

johannvr

14th July 2009, 22:41

Mine runs true according to GPS, at least to my memory. Can vouch that the odo is spot-on, but will have to confirm the speedo again just to be absolutely sure.

johannvr

14th July 2009, 22:46

not a Dr but a klr, but I think your problem is tyre combination. when I had
e09 front and rear she tracked true as, but when I replaced the rear only with a t63 the front now weaves and wobbles on the road.
My advice is to ride through it.:blink:

Entirely possible. Mine now both T63's though, so not the cause in my case. Have however got one size fatter (130) on the back & not the stock 120 anymore -have wondered before if that may have any side effects.

Woodman

14th July 2009, 22:52

Entirely possible. Mine now both T63's though, so not the cause in my case. Have however got one size fatter (130) on the back & not the stock 120 anymore -have wondered before if that may have any side effects.

i went from a 140(e09) to a 130 (t63), but there are way too many variables to be sure.

johannvr

14th July 2009, 23:01

's true. Like you said - just ride through it. :Punk:

warewolf

14th July 2009, 23:26

A couple of thoughts:

Lowering both ends will slightly reduce the wheelbase and possibly the trail. Both of those make the bike less stable.

Stiffening the suspension (through damping clicker adjustment or raising tyre pressure - the tyre sidewalls act as the first part of the suspension) will reduce the bike's ability to damp out oscillations before they get carried away. Static push-tests on the suspension don't tell you much if anything about how you've affected the bike at road-speed suspension loads. Too much front rebound or too little rear rebound damping is a cause. More preload usually needs more rebound damping to counteract the stronger spring return force - aren't the DR650's notorious for insufficient rear rebound? Google "motorcycle suspension weave (http://www.google.co.nz/search?hl=en&q=motorcycle+suspension+weave)".

Knobby tyres are not known for even wear, in any dimension. Worn tyres in combination with the aforementioned could be enough to tip the balance.

So I would suggest back off your tyre pressures and suspension clickers as a first test.

(Personally I haven't noticed any instability with the T63, in fact possibly the opposite. A sample of one is not statistically significant though.)

junkmanjoe

14th July 2009, 23:42

i check it next to another bike, got him to sit on 100km. i read 110km.

also on the speed readings on some speed check poles around town, doing 60km on my speedo read 52km on the readout..???

NordieBoy

15th July 2009, 07:54

hey any other DR riders out there notice that the factory speedo runs at 10km slower than what its reading...

99% of DR650's read 10% high.

The odo is accurate however.

Transalper

15th July 2009, 09:09

99% of DR650's read 10% high.

The odo is accurate however.I ride with GPS and agree, on straight roads at about 55 on the speedo im doing 50 on the gps and 110 speedo is about 100 on the gps. Helps keep ya ticket free aye.
The faster you go the bigger the difference.

Haven't checked the odo. The GPS cuts corners.

junkmanjoe

15th July 2009, 09:10

oh well at least i should never get a speeding ticket.

Monstaman

15th July 2009, 09:46

Well that means I am weaving at 100k, tried riding through it and results weren't good.

Will piss around with tyre pressures etc, will back off the damping slightly at the rear and will also set the static sag with rider and gear to the same as the rear is slightly firmer.

I will do these in small increments and note the difference, unfortunately with budget suspension there is only so much one can adjust but by all accounts it still works ok, just a matter of fine tuning it to the best I can get.

It's good fun playing anyway :headbang:

Crazy Steve

15th July 2009, 10:45

Transalper

15th July 2009, 12:36

I have an agressive front knobble tyre (Trelleberg? from memory) that does it to my bike. It was annoying but fairly predictable.
Not so bad with a fork brace installed but then that's an overpriced mission on its own which severley limits suspension clearances up front.
I run the rear lowered as per the book and am back to full height on the front.

With a good and stable front tyre on I have also experienced what felt like a front end wobble for the first 300ish km running in the new rear tyre. Obviously it was the rear doing it that time. It was the C02 Mitas? which settled down eventually and become a new favourite agressive rear.
Only had it happen with knobbly tyres.
I have balanced my rims to off-set the rim locks when I installed them, but not the whole deal including tyre, not recently anyway.

clint640

15th July 2009, 12:47

Nice big effective front mudguards like the DR has can also cause a wobble at higher speeds, I wouldn't expect much at 100 but checking it is bolted on straight would be a good idea.

Clint

Paladin

15th July 2009, 19:25

My Dr has had the same speed wobble since putting D606's on it!

But... that same weekend was when I decided to crash the hell outta the bike on Orongorongo on Easter Sunday, so......

might actually not be the tyres!

;)

Transalper

15th July 2009, 19:50

My DR likes the D606s.

junkmanjoe

15th July 2009, 19:59

with eather trail wings and E-07, E-09, tires, bikes been stright and true..

johannvr

15th July 2009, 20:06

sounds like you've got a good 'un - hang on to it aye ...

avgas

15th July 2009, 20:11

i found that most bikes hit a harmonic wobble at about 150kph when they have a big bloody mudguard - remove that and it seems to be fine.

junkmanjoe

15th July 2009, 20:11

i just try not to crash as much as others....

warewolf

15th July 2009, 21:54

hey any other DR riders out there notice that the factory speedo runs at 10km slower than what its reading...Most bikes over-read by 5-10%, it's nothing peculiar to DRs or your specific bike.

junkmanjoe

15th July 2009, 21:56

okies, just wanted to put tit out there...sweet.

warewolf

15th July 2009, 22:03

There's a few threads on here about it, IIRC.

PITA if you ask me, I'd rather they were only a couple of % out. My car is appalling, at an indicated 65km/h the roadside radar display says 47km/h !! No wonder I get tailgated at an indicated 50.

btw I had the speed wobble with an old (hard) part-worn TR8 front and well worn MT90 A/T rear. That was with lowering links, forks pulled through, and probably poor suspension clicker settings. Seemed to go away with chunkier tyres and some suspension fettling, despite notched steering head bearings. Haven't noticed it at all with the lowering links removed and forks pushed back flat with the clamps.

junkmanjoe

15th July 2009, 22:10

onsitly i have to say ive never had the speed wobbles on my dr.
and i have pushed it to 160 on the clock,, but was only realy doing 150km..
and thats fast enough on this bike.
i have pushed my road bkes up to the 180-90 mark...scary..
pushed my Rx7 up to 200kms one night on foxton strights...and that didnt get the wobbles.....not that i wanted them...
young and silly back then,,, now old and slow....:shifty:

merv

15th July 2009, 22:14

We're still running our DR on OEM road/trail tyres with it lowered and its never had any wobble problems. With it lowered at the back and I thought a similar amount at the front the only thing I find with it is it really understeers (squealing the front tyre) on the road as if it has far too much trail as the forks are kicked out at quite an angle compared to our other trail bikes. I've seen 152km/hr on my GPS on gravel on this bike with no stability problems at all (on closed roads under controlled conditions of course :laugh:).

I'd say its your tyres - have they been put on absolutely true for a start? Usually knobblies on the road are fine provided they are put on nice and straight with the beads all even.

junkmanjoe

15th July 2009, 22:17

thats a point i get my wheels balanced, with new tires..

Monstaman

15th July 2009, 22:48

Yeah my wheel are nice and true, balanced and fitted nicely, reduced the rear preload to match the front so it has bought teh back down by 14mm.

Will head out tomorrow for another skid, I will let the tyres down a smige on the way back to see how it changes the handling.

junkmanjoe

15th July 2009, 22:56

hey did ya feel the shake mate....rattle and roll aye

Monstaman

16th July 2009, 08:04

hey did ya feel the shake mate....rattle and roll aye

Dude it rocked the house, checked on all the girls but none fell over thankfully.

Few cracks have form but noting to bad, it went one for about 1 1/2 - 2 minutes, probably the longest quake I have ever felt.

junkmanjoe

16th July 2009, 09:53

fuk i miss all the good stuff...
5km deep shallow mate...be on ya door step next time..
its a coming...

Monstaman

16th July 2009, 10:31

junkmanjoe

16th July 2009, 10:40

oh not not suzy...better tie here down mate..
we had a good one a little while ago...me i ran for the 50inch,,,, noooo my telly....:gob:

cooneyr

16th July 2009, 12:10

Our biggie which we are statistically 280 years overdue they are saying at least mag 9.2/3/4 ish which is very destructive.

The area between Haast and Murchison has not moved in a long time, at the Geonet conference they held here in Wanaka they said we can expect a 4 meter split in height and a 40 meter shift horizontal :shit:

Think that will wreck our home and prolly knock Suzy over too.

Bye bye almost all buildings in SI. Last I'd heard (some years ago) we were waiting for a magnitude 8 but either way (I know there is a 100 fold increase in energy from 8 to 9) we are screwed. Just hope I'm not at work, 6th story (of 7) of a building in the CBD of Chch, with the high probability of liqufaction in the area it aint gonna be pretty.

Monstaman

16th July 2009, 12:16

with the high probability of liqufaction in the area it aint gonna be pretty.

You'll be sweet, when it has stopped shaking and liquafying you will probably be able to step straight out onto the ground :shit:

It will bring us out of recession, a good natural disaster, rebuild on the insurance companies ... beats a war.

It is a scary thought of the grunt we will have thrust upon us and we will get thrown around like rag dolls at that.

Taz

16th July 2009, 19:57

I tend to concur. Those Kenda's look fairly "rough" for tarseal, even tho they are DOT approved.

Not only that, they also use a very soft rubber compound which allows them to squirm.... Were even quite scary on my KX125 while riding the real Desert Storm trail ride way back in the day (you know the original one following the tank tracks not too many months after the LaHaar....). Also had to change the air filter after day 1 because of all the ash, Luckily I took a spare one pre oiled.