Steering issues 99 sv650 s

[Danny Dickinson]

Right, for those who havent read the back end of my caliper overhaul thread, here's the issue:

Front brake calipers were overhauled, new pistons, seals and pads, along with new SS brake lines and fresh Wurth DOT4 brake fluid.

I took the bike on a test ride, about 40 miles or so, to market rasen and back, and on the way back, about 30 miles in, i developed a sudden issue with the steering. The easiest way to explain it, is that if you were going round a corner/bend, and you turned the wheel slightly to the left, the bike feels like it wants to push itself to full left lock, and fold in! As a result, i have to fight the bloody steering as i go down any road that isnt straight.

The tyres are fine, both michelin pilot powers, rear is pretty much new, front is about 2/3 worn. All bearings are fine, with no excessive play, and alignment is fine. There was NO issue BEFORE the caliper overhaul, so i think it has to be brake related.

Also, the pads aren't rubbing on the discs, the fluid is at the correct level, and there is no air in the system.

Sorry for the essay, but i want to eliminate things i know arent causing the problem before people suggest them.

Anyone local, if you want to ride the bike to get an idea of what im on about, feel free.

Any ideas are appreciated

Thanks!

[speedyandypandy]

Maybe something is misaligned, I've heard about people taking front apart, and had strange feelings first time out afterwards, been cured with loosening the front up and retightening everything. Check play on front wheel bearings while your at it. Did you use a torquewrench and the spesific torquesettings when refitting everything?
First thing might be to recheck all the bolts to check if your forgot one.

[Danny Dickinson]

Do you think it is possible that having incorrect torque settings could be causing the issue??? Generally the torque setting i use is 'my arm hurts', but this wouldnt explain why it didnt start until 30 miles after starting to ride, and the only bolts on there are the ones for mounting the calipers... would they be likely suspects for screwing steering up?

[monkey]

Brakes shouldn't affect the steering at all.

Did you have the forks out or have you had the yokes undone at all?

[Danny Dickinson]

Nope, the only thing that came apart were the calipers and brake lines. Nothing at all was touched.

[speedyandypandy]

No, if the caliper bolts where the only ones you touched, you wouldn't get that from just them. If something else isn't a bit loose, then you might have moved something when untightening or tightening.
Check wheel bearings atleast.

[svrich]

When you say that the tyre pressures are ok, what are they? And does it just happen when turning left?

[stevegr]

Somehow I think the brake hoses on the front end are being compressed a bit.

Have you routed them same as the OE ones?

Are the lines the same size as the OE?

It does sound to me you have some part of the bike coming to connection with the hoses when you go left.

If it was a problem outside of that, it would effect the whole bike.

Not just one side, routing and length has to be right.

I am not sure what the tire pressures have to do with this problem.

[monkey]

Please tell us what thinking has got you to the brake lines causing the problem?

[muzikill]

Take the weight of the front of the bike and do the steering lock to lock test also visually check the slack on the new lines with the weight off if the are tight that could be the issue under load.

Some pics of the routing?

[svrich]

In no way does brake binding etc effect seering (single disc bikes pull up in a straight line).
If the tyre pressure is low the tyre will be deforming once it reaches a certain angle of lean. If this happens the steering will become very unstable.... That's what tyre pressures have to do with this problem.
Does the same thing happen when turning right?

[stevegr]

Please tell us what thinking has got you to the brake lines causing the problem?

Please tell me why not!

Brake hoses that are not routed correctly can be compressed.

That can cause the effect here.

Cables are the same.

A brake cable needs to be uneffected by movement.

Let's see, he's made these changes and now it does not work correctly.

So the changes are the problem.

Simple, I am still at a loss on here why most of you can't see that sort of thing.

Anyway, I am off to fit GSXR front end an SV does not really need for road use and replace my stock rear shock after 32000 miles as it's shot.

I must tell the rear shock that, it does not know it does not work any more.

[Sid Squid]

Brake hoses that are not routed correctly can be compressed.
Indeed they can, this would add some braking force, which would slow the wheel, this drag - if sufficient - could only add trail effect and self steering - straight. It could not add off centre steering torque.

That can cause the effect here.
That'll be no.
Cables are the same.
And would only do the same thing - add force to self steer effect/trail.

Let's see, he's made these changes and now it does not work correctly.

So the changes are the problem.
An unfortunately rigid assumption, any work recently done should immediately be suspect of course, but the effect is the opposite of that which a brake problem would cause.

Simple, I am still at a loss on here why most of you can't see that sort of thing.Perhaps because one or two people actually understand how this works, rather than the dogmatic assumption that the brakes are causing a problem opposite to which a deficiency in them would assert.

[monkey]

For the reasons mentioned in the post above yours.

It is possible (imo very unlikely) that the brakes are coming on causing the steering to feel different to the OP but given the fact the he has fitted braided lines I find that even less likely. Also the fact that the bars hardly move when steering whilst going along at at any sort of reasonable speed suggests it's unlikely.

The only way I can see brakes being involved are if they had started binding causing the front to be more weighted and cause an odd steering feeling, just like low tyre pressures could.

[monkey]

Indeed they can, this would add some braking force, which would slow the wheel, this drag - if sufficient - could only add trail effect and self steering - straight.

Very true.

[svrich]

Pass the popcorn for this one...

[NedSVS]

. The easiest way to explain it, is that if you were going round a corner/bend, and you turned the wheel slightly to the left, the bike feels like it wants to push itself to full left lock, and fold in! As a result, i have to fight the bloody steering as i go down any road that isnt straight.

Thanks!

Sounds like the brakes are on, usually binding, but assuming the overhaul went OK it must be something else. Have you inadvertently over filled the reservoir? Is the rubber expansion contraction diaphram fitted OK. And, any sign your brakes got very hot.

[andrewsmith]

That is not a brake related.

As Sid says the theory posted is valid but not for this, one of the hoses on my front is at a different angle to the other and its knocks the subframe on full lock only. Its been like that for about 4k

Could be tyres if your front is the way, quite a few of the current gen touring tyres don't work well mismatched (Dunlop design the Road and sportsmart to ware out at the same time by making the front quite a soft compound compared to the rear).

I would also get the front up on a headstock, strip the wheel and mudguard out and forks and reassemble it (check all the bolts in the yokes for the forks and clean them and but them back in with a mix of copper grease and high strength threadlock). Don't worry about the handlebars as they're attached to the yokes.

When you reassemble the front, get the forks in and lightly nip the bolts and but the axle through (it will but them into alignment) and tighten all the yoke bolts and rebuild the front

PS check the headstock aint too tight

[Biker Biggles]

You say you have a 2/3s worn front tyre and a new rear.Id start by getting a new front(you will need one soon anyway) as carp tyres can cause your problem.
As can naff steering head bearings.Id have a second look at that as well.

[johnnyrod]

Double check the rear wheel aligment, it's easy and rules it out. 30mph, close throttle, hands off, look for a consistent drift to one side. Even with wonky forks it'll go straight if the back wheel is in line. If it's out then it feels different going round lefts and rights (can drop in too quickly one way). No idea if you've touched the back but then there are lots of things I don't know!

[Danny Dickinson]

Right, after staying up late last night, i have taken the calipers off, re-routed the brake lines (not that you can really tell), re-greased everything and put it back on. One of the fluid seals on the left hand caliper had decided it prefers to let fluid out, but this is now corrected.

Took it for a good ride this morning while the roads were quiet and it was behaving perfectly normal.....???

Im at an utter loss as to what was going on, because im almost 100% sure, a leaky seal and perhaps not perfectly routed brake lines could have caused this issue.

However, thankyou very much for all of your feedback, shows off how much you lot bloody know! Perhaps one day i will know it too eh?!