Suspension

[Stevo]

Has anyone ever meddled with the compression or rebound damping. My Mrs keeps complaining that her bike (ZX9R) is trying to buck her off and that the suspension is that hard that she gets a sore ass. Even that lip where you change road surface type hits really hard.

[DEATH_INC.]

Man,you're opening a can of worms with this one......
The basics.
First,remember the spring holds the bike up,and supports the load from bumps ect.The shock (damping)controls how fast the suspension moves.The compression is the bike going down,rebound up.
Set the sag first,measured with the bike off the ground,then with the rider aboard(with their feet on the pegs and in riding gear)Any half decent website relating to the bike should be able to tell you what works,but generally about 1/3 of the travel.If you can't acheive this with the preload adjusters then the spring is wrong(too soft/hard)
Set the compression so that you get no hard jolts when you hit those square edged bumps that are everywhere,but only just soft enough for this.(keep winding it up 'till you get too stiff,then back it off just enough to fix it)
The rebound needs to be stiff enough to stop the rear(front)from bouncing up too fast,but again,only just enough is what you want.back 'er off till it starts to feel too bouncy,then stiffen it up a little.

this is real basic,there are books and books on this stuff.We could be here all day.but it works.
(having said that,I've spent hours trying to get my missus bike to work and she's still not happy....)

[Stevo]

The spring has been backed off cos it needed to be lowered.......... I just suspected that the rebound was set so stiff and this is why when she hits bumps etc (esp when cornering) she feels like being bucked off. I know this species is hard to satisfy But cos I cannot ride her bike (like there is nooooo way in hell she will ever let me or anyone cept her stepdad ride it) I find it difficult to work on such things. We have the full Manual for the bike which tells you how to set these things to an 'average' position so maybe we start there.

Just wondered if anyone else had meddled there.....................

[DEATH_INC.]

That's prolly the prob,you're getting into the stiffer part of the progressive curve......
try making some lowering links,it keeps the suspension more supple

[scroter]

what death said. start with the sag first, this is usually a good way too tell if the springs are too soft or too stiff. do you know when the fork oil was last changed and was it measured correctly. from your description could be any of the following. wrong spring, too much preload, incorrect fork oil level(too much), too hard compression.
one thing too note is that if the spring is too soft or stiff than chances are the damping wont work too well no matter what your settings.

[mangell6]

Has anyone ever meddled with the compression or rebound damping. My Mrs keeps complaining that her bike (ZX9R) is trying to buck her off and that the suspension is that hard that she gets a sore ass. Even that lip where you change road surface type hits really hard.

I have attached a text file that has some interesting stuff on suspension. I would also check out the ZX9R forum as they would have messed with the suspension.

Mike

[Stevo]

Sorry to take so long, But thanks heaps for that file. Was a great read and the Mrs read it too so now at least we both think we know what we are doing. We'll see if it leads to divorce on the day (not that we are married) which won't be this weekend as we are heading south in the truck.

Cheers Matey

[aff-man]

Good you got it sorted. But i don't know if the suspension is anything like the zxr400 because they are pretty shocking . I bought this one off a lady owner and she had the rebound turned right down so it was a noice soft ride but when i pushed it a bit it loaded up in the corners (making it interesting when coming out). I then turned the damping up so she wouldn't load up. Now it sits fine but the back end jumps around like mad if anything but smooth tarmac is ridden on (makes for some pretty sore thighs). So i dunno if there is a common ground. (or maybe it's just my crappy shock)

[Hoon]

Yep its just a crappy shock....common problem with ZXR400's.

Your best bet is to find a 95-98 ZX6R shock and put that in. They have a remote reservoir with about 15 levels of rebound/compression adustment as well as preload.

I'm running an ohlins in mine and even doing 1:10's I still can't get the rear to skip or slide whereas the stock shock would skip out on even the smallest bumps.

[Antallica]

Hey guys, I've got the word from the pillion and the rear shock on my Bandit is soft. By the sounds/looks it's sagging maybe halfway and I'm told it bottoms out on those raised bits we all hate on driveways.

Possibly an adjustable fix or the rear shock had-it?

[vifferman]

Hey guys, I've got the word from the pillion and the rear shock on my Bandit is soft. By the sounds/looks it's sagging maybe halfway and I'm told it bottoms out on those raised bits we all hate on driveways.

Possibly an adjustable fix or the rear shock had-it?

Maybe I've missed some posts somewhere - when did the Bandit materialise?

Sounds like it needs a stiffer spring. If it has a preload adjustment, that would help a little, but not enough to stop it bottoming out.

[F5 Dave]

Yeah a stiffer spring will work wonders here. The problem is to find one & correctly fit it.

2 options: Get one made (give someone the old spring & say make it say 20% stiffer, or 30% if it is that soft & you take a pillion regularly)
2nd is find another from a wrecker. This requires a friendly wrecker who has a bunch of springs & is prepared to find you the right one.

This also means you have to be a bit lucky finding the stiffer one that is the same length & ID so it fits on the old shock. If it is close you will have to make adaptors that won’t buckle under the not inconsiderable forces. Also the Preload should be somewhere near the same when mounted back on & the spring shouldn’t coilbind.

Also you have to take the old spring off. They are pretty dangerous if treated without respect. The safest way is probably to use 3 large hose clamps & feed them around 3-4 coils at 120degree spaces & progressively do them up (car spring compressors are too big mostly). Then you should be able to take the retainers out & free the spring. Measure the spring mounted & free so you can compare to another spring. I also have a way of measuring the spring rate using a bathroom scale if you want to do some comparisons.

Oh the ZX9, well they are known for that. The problem is largely in the linkage & the shock design & the sw angle. It’s the compression damping that is too hard, but likely the high speed compression that can’t be adjusted with the clicker. To lower the bike some longer suspension links are required + you can drop the forks in the clamps a little, spacers in the forks to limit return, trim the seat padding (but would affect comfort) or get her boots built up by a decent cobbler.

[vifferman]

Check this page out:

http://www.sportrider.com/tech/suspension/

It also has a section with the 'best' suspension settings for all bike models. I don't know how they arrive at these, but at least it's a starting point when setting your bike up.

[Antallica]

Maybe I've missed some posts somewhere - when did the Bandit materialise?

Got it on the weekend. Check out the 'Bandit 250 for sale' thread.

I imagine the spring has just had it's day. I'll have both front and rear checked out, front left needs a seal anyway.

[TonyB]

I've got a question- can rear rebound settings have a major effect on tyre wear?
I went for a ride to Murchison and back on Saturday, tagging along with some guys who were going to a rally in Nelson. When we got to Murch' my rear tyre was looking fairly chewed up. The tyres on the three bikes I was with looked good. One of the bikes was a GSXR1100 which would have similar power and weight to mine.
On the way back to Chch I decided the backend was a bit bouncy, so I stopped and added one click of rebound (except I turned it the wrong way-Du-oh!), the adjuster was hot enough to hurt my fingers, but then the last 10k's had been quick and bumpy. Before I got to Springs Junction the rear end started feeling a little loose, and I thought about adding some more air but decided against it. Going up the Lewis Pass it started getting really loose, so I backed off a bit. At the top I stopped and checked the tyre- the wear was heaps worse than I managed at the track, with large balls and ropes of rubber all over the tyre. By then I realised I'd turned the adjuster the wrong way so I gave it 3 clicks in the right direction and carried on. After about 15mins the tyre stopped drifting and felt pretty good. I think my corner speed came up a bit and I was leaning further than I had managed at the track. I stopped at Culverden and checked the tyre and it looked pretty good, with a rough orange peel appearance.
So it seems to me that the rebound settings can have a big effect on tyre wear- is that right?

And if the bloke on the RVF400 is reading this: sorry about tripping you up in the corners mate- I think my corner entry speed has come up a bit now