Sean C. What's the latest?

[petevtwin650]

Sean, any updates on your front wheel/ discs/ brakes problems.?

[plowsie]

Yeah c'mon whats going down, i have the SV sitting in the garage atm and looking like it will be fore a considerable amount of time, I'm trying to gauge whether time wise we might be able to sort summit out to get you back on the road...

[Sean_C]

Too cold for me to be arsed with it to be honest fellas, thanks for asking though.

I will get the front wheel off over the weekend though, some wet and dry on a block and try to make sure that it's flat behind the discs. Need to pick up some loan discs and get some rear pads.

Just too damn cold at the moment!

Disheartened with the whole thing still- its not that a lot needs doing, I'm just so ****ed off with it. :(

[petevtwin650]

Sean, I know it's not much fun for you at the moment and it's frustrating to boot.

Just don't do anything hasty.

Hope to catch up with you soon.

Best to you and Izzy. :)

[Sean_C]

Well well. I cant get the horn not to work. Strange.

I did everything Tilt suggested. There's no problem with the forks, they're sound. The discs don't look unevenly worn to me, and there's less movement in the LHS disc than I thought. There's less than 1mm of rotational movement, and they're sound regarding sideways movement. I didnt take the discs off to check behind, I'll do that over the weekend.

Rear pads were very unevenly worn, one had loads of life left, other was dead thin and wedge shaped. Cleaned and greased the pistons, only for one to pop out, so I need to bleed them now. Oops!

So.. new mot station I think.

I had an advisory that more braking efficiency should be easily obtainable.. Perhaps the seals on the master cylinder are tired, does that happen?

[petevtwin650]

So looks like you were stitched up again Sean. :mad:

Whenever the bike has a MOT I always watch to ensure that the treat the bike right. Also gives you a chance to fiddle with a recalcitrant switch or bulb then.

Dunno about the seals on the M/C. Maybe the wrong ratio, or the guy doesn't really know his bikes. How did it feel to you?

Good to see you've fired up some enthusiasm for your beautiful baby. :cheers:

[Sean_C]

It's always felt like it'll stop no problems but I haven't been amazed by them at all.

I dropped it off after work and picked up the next day, so didnt watch, just got the surprise the day after.

MC rebuild kit is 20 quid from wemoto so it might be worth doing. Though that means bleeding brakes yet again!!

Yes, a bit of enthusiasm.. I've been lacking it in everything recently :(

[Tilt]

Sorry to hear that Sean. I cant think of much else to check...........

MC seals may help but you would be seeing oil before they caused you to fail an MOT just after you have bled the brakes.

Is the MC on the front off the sv?

I have assumed that the MOT garage failed with respect to front disc's did they specify the front on the report?

[Sean_C]

There's nothing leaking the master cylinder end of the brakes (or anywhere else for that matter. I rebuilt the calipers, they're newish pads, braided hoses, so I can't really see why they aren't as strong as the advisory suggests they should be. Unless air is getting into the system somehow..

Yes, they specified front brakes. Its a naked SV master cylinder and reservoir with gsxr 4 pots.

[Tilt]

I wonder if the swept volume of the master is enough for the gsxr pots? what diameter are the gsxr pots compared to the old sv pots?



EDIT not according to this fella............

http://www.gregoryli.com/2007/05/ask-me-about-my-gsx-r-front-end.html

only difference is that he has a pointy.

FURTHER EDIT seems that some gsxrs shared the same MC as some SV's.

[Sean_C]

I think the o/d is 27 and 30mm for the 4 pots. They're not radials, from the SRAD era.
I'm not sure what the SV pots are, I think they're 27mm.

I have a very firm lever that doesn't pull back very far, but apparently not as much braking power as expected/I should have. Would that suggest I need a smaller piston? I don't know anything about brakes really.

[Tilt]

All your MC piston has to have is the ability to move sufficient oil to pump (in one stroke or part there of) the slave cylinders out to clamp the disc.

If you want more oil per MC stroke then you want a bigger MC with either a wider piston or a longer stroke. (or both)

If you go for a wider diameter cylinder then the lever stroke is shorter and you actually lose a bit of mechanical advantage. (most of which is generated by the lever ratio itsself)

But you say your lever is firm. Infact you say it is very firm.
From this we would expect the MC seals to be good (A test is to grab the front brake hold it on tight and see if the lever slowly moves over a period of time [a minute])
We would also expect the system to be well bled.


You get some braking but its not the awsome braking you expect and indeed your MOT garage agrees with you.
Your discs are not worn and the bobbins seem OK.
Your discs are not warped.
You have new pads.

Basically then the force being applied at your MC is not getting thru to your slave cylinders.

Lets check this.

Remove a caliper off the disc on one side. Take the pads out

get a flat piece of bar (about 3-5mm) put it between two of the pots with a flat spanner between the other two. (it is a 4 pot isnt it?).

Now operate the brake. See if the slaves extend smoothly to clamp both the spanner and the thinner bar.

Did both sides extend the same distance? (either side of the flat)
Is the flat firmly clamped? (when you have the lever depressed)

Ease the pots apart.

Now reverse the flat and the spanner and do the same test again.

Same questions as above. Particularly note if pistons extend differently.

Replace the caliper and repeat for the other side.

What are we looking for here?

You stated that the lever stroke was short. Actually it should be no shorter than on your old SV slave pots indeed it should be longer! (as some of your pots are a bigger diameter)

This implies that the pots are not (all) moving (to clamp the discs) as they should.

The fact that you have some braking force implies that the MC is OK Unless there is some thing jamming it mechanically (ie the firmness is a mechanical corruption of the lever/MC set up) ignoring this the above checks ensure that we do not have a blockage or siezure with respect to some of the slave pots.

[Sean_C]

No seizure in the brake pistons. One of the bottom pots didn't come out at the same rate as the top, it was a bit gunked up (already :o ) so I cleaned it and now works as it should. When the lever is let off the pistons go back slightly. All looks ok to me.
****ed if I know what's going on here. According to your test, the MC seals appear to be fine.
I'm going to bleed the brakes again. Empty all fluid out, bleed them from dry, get the lever nice and solid again. Start from the ground up.
Under the loose disc it wasn't perfect, but it was bad by any means. There's no paint under there from when I sprayed the wheel, it just wasn't shiny clean. So that's clean now.

With the disc off the wheel the movement is more apparent, but still less than a mm. I can spin two brake rivets around easily, the rest are good. Would this suggest that there's a particular part of the wheel that the disc mounts to that isn't quite flat? I've gone round with 1200 wet and dry, but it's hard to make sure you're doing it right because you can't put a block over the whole lot. Grrrrr.
Put the disc back on and wheel back in. Spins nicely, I can't see any change in disc thickness or any visible warping.


And I've started spending again...!
I've bought some footrest jack up plates, which I will turn upside down to get my gangly legs on the bike comfortably. At the moment, they touch the crash bungs which is a pain.
And I have my eye on a gel seat.

Here we go again!

[Seggons]

Sounds like your bike is more of a emotional roller-coaster. Good luck with it and I hope to see you on it soon. :D

[Sean_C]

If I had the money to spare I'd get a naked curvy straight away, but I don't, so that's that :p
To be honest, I've been constantly bored lately, and it's giving me something to do again. I'm horrible when I'm bored :p

I'm looking forward to being on the road over the summer, which I didn't get last year, because I was a twot and rode over a ditch. :p

[Lissa]

If I had the money to spare I'd get a naked curvy straight away, but I don't, so that's that :p
To be honest, I've been constantly bored lately, and it's giving me something to do again. I'm horrible when I'm bored :p

Only then?:D

I'm looking forward to being on the road over the summer, which I didn't get last year, because I was a twot and rode over a ditch. :p

Yeah, but at least you went over it, not into it! Anyone can go into one!;)

[Sean_C]

Yeah, but at least you went over it, not into it! Anyone can go into one!;)


All the same, it's not something I wish to repeat :mrgreen::rolleyes:

Just need to get an MOT on it, then I can try and get comfortable again.

I think I'll undo the locating bolt on the clip ons and rotate them out a bit, that should make it comfier on the wrists. I could put a posh top yoke and flat bars but they wouldn't look near as good as clip ons..

I still need to adjust the shock ride height. It's on max (I had a look), which makes for unpleasant handling with short forks!

[Lissa]

I still need to adjust the shock ride height. It's on max (I had a look), which makes for unpleasant handling with short forks!

Yes, that would make it very pointy (steering-wise), and if you're not used to that it could be a bit nerve-wracking.:)