*Cough* Rideout Planning *Cough*

[Lissa]

Originally Posted by Sean_C

The pads were less than 200 miles old so I didn't bother.

I've just remembered my mate has a set of srad 600 discs that he offered me to borrow when I was without mine. Perhaps get it through mot and trade it in.....

Oh dear

What else do i do- keep throwing money at it?

Lozzo's cheap 7r looks attractive.

[Mr Speirs]

So what would be causing flucuations?

[Lissa]

Originally Posted by Sean_C

What else do i do- keep throwing money at it?

Lozzo's cheap 7r looks attractive.

It's silver

Maybe it's a slightly dodgy wheel? I'm going to check behind the discs and try an make sure it's perfectly flat where they mount.
Dodgy horn, got to see where there's a loose connection.
And need new pads on the rear.


All kind of ironic, considering I finally paid for the bike today..

[Lissa]

Originally Posted by Sean_C

Maybe it's a slightly dodgy wheel? I'm going to check behind the discs and try an make sure it's perfectly flat where they mount.
Dodgy horn, got to see where there's a loose connection.
And need new pads on the rear.


All kind of ironic, considering I finally paid for the bike today..

That was always the thing that stopped us doing the gixer conversion.............not being able to be 100% sure the bits we were getting were 100% ok.

How loose are the "buttons" on the disks Sean?

1. Solid. will not rotate under any circumstances
2. Tight but will move a little
3. Free moving / loose
4. Differing combinations of the above

measure (accurately) the distance between the outside centre of the wheel spindle and the under side of the bottom yoke on the out side of each fork.

1. when its free standing (vertically)
2. when some one is sitting on it (still vertically)

get the front wheel off the ground and spin it and watch the disks as they enter and leave the calipers.......... is there any movement?

One the RHS disc they're good as gold. On the LHS, there's slight rotational movement, I haven't measured- you can hear it if you roll forwards, brake, roll backwards brake. I knew the discs weren't perfect but I hadn't expected them to fail the MOT. On the LHS there's a tiny bit of play in the discs side to side, a mm or so. I haven't measured any of that, just guestemates from what I've observed.

I'll have a look at the rest tomorrow night. The tops of the forks are flush with the top yoke, so I'd assume they're both alright, but that doesn't account for some kind of spring problem I suppose. With the front in the air it spins freely, I will do what you say tomorrow when I get in from work. I would be surprised if they're warped though.

Like the last time, I've barely used the brakes..

This is all infuriating. For the amount of money I've spent I could have a lovely bike that just works....

Infuriating but not the end of the world.

As long as the forks are true and sprung/damped evenly then it will probably sit with the disc's somewhere.

The wheel has to be a long way off to cause pulsing at the brake. bearing collapse would usually have had to occiurred and that would be obvious to you the moment you try to push the bike out the garage.

You should not be able to move the disk on the bobbins/buttons at all (between two fingers) when cold but you should get the feeling of some "micro" movement when messing with the bobbins directly

Under heavy braking tight bobbins will cause the front to judder as it slows down. The bobbin allows the disK to move by a small amount side to side without pumping the slave cylinders. They actually take up the mico wavyness that may be within tolerance on the disk (Its the pumping that you can feel at the brake lever)

Uneven disk wear/deposition cannot be over come by bobbins. This is where the disk is actually thicker for part of its circumference than it is in other parts. This will also cause judder at the brake lever but serious casses can get the whole front shaking (particularly if the T point is at the wheel). If its on both disks then it may be amplified (at the brake lever) particularly if the wear is "in sync" across the disks.

Very loose bobbins can cause the whole front to judder particularly if associated with normally harmless brake squeal. (micro friction pad oscilation). The sensation is almost as if the brakes are on off (like a poorly set up ABS).

You do have brake shims in dont you? are they dry or copper slipped?

What ever the "fluctuation" the MOT guy has failed it on you should be able to feel when braking hard........ so what does it feel like?

Thats the thing. I havent braked hard, at all. The braking perhaps hasnt been as strong as I'd been expecting, but stops the bike with ease. I havent felt any pulsing at the lever or any juddering. I cannot say I've had much confidence in the bike since doing all this work and as such havent even approached "pushing it".

Brake shims. You mean the things behind the buttons/bobbins? Yes they are in, and dry.