Brake pad change

[PT1984]

I’m fitting some HH pads to my Ducati Scrambler 800. I’m going to give everything a good clean while I’m in there.

I’m good with the rear caliper as it’s a single piston sliding jobby. The front uses a single Brembo 4 piston fixed caliper.

When I come to mounting everything up, do you just torque up the caliper, then slide in the pads and clips (after pushing the pistons back in). My thoughts is that the caliper may not be centred?

So loosely do up the bolts, pump the brake a few times to get the pistons and pads seated, keep the lever squeezed, then finally torque the bolts? Or as usual am I overthinking things……

Also, I assume you have to crack both master cylinder covers when pushing the pistons in?

Appreciated.

[OutInTheShed]

A four piston caliper (or any opposed piston caliper) does not need to be exactly 'centred'.
The pistons should self-adjust to get the pads in the right place.
If it doesn't, you may have a piston sticking due to dirt or corrosion.

[KTMsm]

You're overthinking things

However, it's always best to check with brakes

I think you'll find if you do a quick Google, you'll find the owner's manual and probably a YouTube guide too

If it hasn't been done recently, whilst you're in the area... a brake fluid change can make a massive difference too

[PT1984]

Cheers! I will be doing the fluid too as the front is rather spongy. My CB125r has a better feeling front!

[PT1984]

Found a manual. Excellent.

[mikey_b]

Push the pistons back in, then mount the caliper solidly. Once the caliper is firmly in place, slide the pads in and then fit the spring clip and retaining pin. Torque everything up, then pull the lever several times to get everything settled in the right place. Since there are pistons both sides, they sort of find their own level as it's only one lot of fluid behind them.

[Krikkit]

PT1984 said:

Found a manual. Excellent.

What's the procedure?

On the monster with the same calipers the procedure is push out the pistons, fit the new pads with clips etc, put them back on the discs with the bolts very lightly torqued (5Nm iirc), pump and hold the lever to hold the pads, undo the bolts then torque them to full tightness

[PT1984]

There was no real detail or torque settings!



What you have advised for the Monster is along the lines of what I was thinking.

[the cueball]

Put your pads in the caliper before putting back on the bike.

With the front wheel in the air, put caliper on and bolt up finger tight.

Spin the wheel and pump the brakes a few times.

Keeping doing the above until everything has seated properly and the brake is stopping the front wheel as it should and on the LAST go, keep holding the brake lever in and torque up the caliper to spec.

[trickywoo]

the cueball said:

Put your pads in the caliper before putting back on the bike.

With the front wheel in the air, put caliper on and bolt up finger tight.

Spin the wheel and pump the brakes a few times.

Keeping doing the above until everything has seated properly and the brake is stopping the front wheel as it should and on the LAST go, keep holding the brake lever in and torque up the caliper to spec.

Is the right answer. I’m not sure the spin adds anything though.

You aren’t going to crash and die if you don’t centre the pistons with the calliper bolts loose but it’s definitely good practice.

[Drawweight]

Don’t forget to pump the lever a few times when it’s off the stand and back on the ground, and even a few slow speed stops. Pumping the lever after tightening everything up is fine but you need the final test.

Many a brake lever has been grabbed only to go back to the bars.

[RizzoTheRat]

the cueball said:

Put your pads in the caliper before putting back on the bike.

With the front wheel in the air, put caliper on and bolt up finger tight.

Spin the wheel and pump the brakes a few times.

Keeping doing the above until everything has seated properly and the brake is stopping the front wheel as it should and on the LAST go, keep holding the brake lever in and torque up the caliper to spec.

I always do the first part of that, but what's the reason for keeping the lever in while torquing up the caliper? Shouldn't the pistons mean it all ends up centered properly anyway?

[trickywoo]

RizzoTheRat said:

I always do the first part of that, but what's the reason for keeping the lever in while torquing up the caliper? Shouldn't the pistons mean it all ends up centered properly anyway?

In theory the pistons could move while you tighten the caliper if not under pressure.

[RizzoTheRat]

Is that a problem? Surely they're supposed to move? Or do you mean it could move to fully depress one sides pistons and the other side over extends?

(genuine question, wondering if I'm doing something wrong)

[trickywoo]

RizzoTheRat said:

Is that a problem? Surely they're supposed to move? Or do you mean it could move to fully depress one sides pistons and the other side over extends?

(genuine question, wondering if I'm doing something wrong)

I should have said become out of alignment.

[Krikkit]

The way the Ducati manual describes it, it's to keep the pad parallel and pistons perfectly perpendicular to the disc so you don't get uneven pad contact and worn piston seals.

[PT1984]

Thanks all. It seems it’s as I thought.

Called the dealer and they did the fluid change during the service when it was sold. Bonus!

I do love this little bike.

[richhead]

From reading what the bit from the manual yo posted, it seems yo dont need to touch the caliper bolts to get the pads out, dont know the calipers in question, but pads often just slide out the top of the capiler while its in place, its often only the pins holding them in. If im right just push the pistons back on one pad at a time, best if you open the bleed nipple to allow the old caliper fluid out and leave the nipple open for a sec after pushing them back until fluid dribbles out, fit new pads fit pins job done.
If the pistons are all moving free, no need to do anything other than pump up the leaver after, bare in mind new pads will feel spongey until they bed in, so take alittle care in the first hundred or so miles.

[PT1984]

You are correct. But I wanted to give the calipers a good clean before the new pads are put in. The front just feels a little spongy. Given the fluid was changed by Ducati 4 months ago, just want to make sure the pas are moving freely.

The rear looks a bit of a faff to remove the caliper for cleaning, so I may just do the pads in that.

[KTMsm]

If it feels spongy just check if there are any bubbles in it

It's usually the apprentice doing these things so you probably know more than he does

That's if it was done at all