Front Brakes

[gstallons]

Cash , you have solved your problem . The piston has to retract enough to allow fluid to return to the reservoir . If not , you will be using the master cylinder to jack to clamp the caliper and not release the pressure .  

 Adjust the screw as I recommended earlier and you will correct your problem . As far as the front brake lever adjustment you need to do this with the knob on the lever .

[cash1000]

Backed of screw until only just touching the plunger. Had to use all adjustment on lever. Will need to bleed brakes again. I've fitted speed bleeders so should be easy.

[Cabernet]

 

Where is this "hot expanding fluid" master cylinder screw adjustment?

I think this is referring to the adjustment screw on the lever, which actuates the plunger. If you screw it in too much, you reduce the free-play, and can end up not allowing fluid back in. I had that problem on the clutch side a while ago. The lever went rock hard and the clutch started slipping - then I backed that screw out and got some free-play back. Same principle with the brakes - but worse potential consequences (lock-up brakes vs slipping clutch).

 

If that's not what it is, then there's an adjustment I don't know about yet.

Did the same thing on the back brake and wrecked the slave cylinder seals.

 

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[shiloh]

Why so much bleeding, is there air getting into the system, that would make the brake action feel soft or spongy.

[68C]

I once spent hours trying to bleed a brake, turned out the seal was stuck to the piston after I had pushed it back to fit new pads. The piston could not slide through the seal to take up the adjustment.  Instead it just moved back and forth as I pumped the lever, as it returned back it left a gap between the pad and the disc so when I pulled the lever it only moved up to touch the disc then when I released the lever the seal pulled the piston back again.  You could actually see the piston and pad moving to and fro.  I had some braking and a very spongy lever which felt like air but was just the piston taking up the gap.  Of course don't forget there should be a little retraction of the piston just not so much as I had.

[gstallons]

Mmmmmmmm. I think you need to fix this ( rebuild ) for best results

[Kiwi_Roy]

Sometimes if you look into the brake reservoir as you let the lever out you will see a little swirl in the fluid as the tiny hole is uncovered by the piston.

 

 

Sent from my shoe phone!

[Kiwi_Roy]

This should happen right at the end of travel.

 

 

Sent from my shoe phone!

[Scud]

If you are extending / cleaning the caliper pistons and pushing them back into their bores , good . Reinstall everything and bleed the brakes . Then , raise the front wheel and pull the front brake lever and release . the front wheel should spin with no drag .  

 If it does not spin , break one bleeder screw and see if the wheel turns . If not , do this to the other caliper and see what happens. If there is still drag or no change , the calipers are sticking.  

 If the front wheel spins after releasing one or both caliper bleed screws , either the front brake hose is bad or the front brake master cylinder is bad . 

 

Thanks again for describing this test. After cleaning the pistons and performing the above test, the brakes are still dragging - not spinning freely. So I guess that means it's time for a rebuild kit... 

 

It's not easy to find seals for these Brembo P4 30/34mm 4-piston calipers. I found a kit on eBay in the UK that fits a 1995 Ducati 900SS (same brakes as V11). http://www.ebay.com/itm/Ducati-Supersport-900-900SS-Superlight-1995-Brembo-front-brake-caliper-seal-kit-/161086784313?hash=item2581854339:g:1gwAAMXQAEFSC8nk&vxp=mtr

 

That's gonna cost $70 and take 3 weeks. Anybody know a US-source?

[docc]

 

If you are extending / cleaning the caliper pistons and pushing them back into their bores , good . Reinstall everything and bleed the brakes . Then , raise the front wheel and pull the front brake lever and release . the front wheel should spin with no drag .  

 If it does not spin , break one bleeder screw and see if the wheel turns . If not , do this to the other caliper and see what happens. If there is still drag or no change , the calipers are sticking.  

 If the front wheel spins after releasing one or both caliper bleed screws , either the front brake hose is bad or the front brake master cylinder is bad . 

 

Thanks again for describing this test. After cleaning the pistons and performing the above test, the brakes are still dragging - not spinning freely. So I guess that means it's time for a rebuild kit... 

 

It's not easy to find seals for these Brembo P4 30/34mm 4-piston calipers. I found a kit on eBay in the UK that fits a 1995 Ducati 900SS (same brakes as V11). http://www.ebay.com/itm/Ducati-Supersport-900-900SS-Superlight-1995-Brembo-front-brake-caliper-seal-kit-/161086784313?hash=item2581854339:g:1gwAAMXQAEFSC8nk&vxp=mtr

 

That's gonna cost $70 and take 3 weeks. Anybody know a US-source?

 

I linked this in the "Wheels Off maintenance Checklist"

[Scud]

I've been struggling with my LeMans' dragging brakes for a little while. A week ago, I swapped the calipers for a used set I had - but they were dragging too.

 

So I figured I'd pop the pistons out and do a serious cleaning. I made this little tool out of a block of wood block so I could pop out one piston at a time with compressed air.

 

 

Here's what I did:

• Piston in Ultrasonic cleaner with Simple Green for a couple minutes.
• Wipe out open cylinder and seal with paper towel.
• Reinstall piston (using just a bit of brake fluid as lube)
• Repeat for other three pistons.

 

Six of the eight cylinders had visible debris in them. All the seals released a bit of dirt when I wiped them with the paper towel.

 

Now the wheel turns freely and the feel is vastly improved.

 

[Cabernet]

I've been struggling with my LeMans' dragging brakes for a little while. A week ago, I swapped the calipers for a used set I had - but they were dragging too.

 

So I figured I'd pop the pistons out and do a serious cleaning. I made this little tool out of a block of wood block so I could pop out one piston at a time with compressed air.

 

 

Here's what I did:

• Piston in Ultrasonic cleaner with Simple Green for a couple minutes.
• Wipe out open cylinder and seal with paper towel.
• Reinstall piston (using just a bit of brake fluid as lube)
• Repeat for other three pistons.

Six of the eight cylinders had visible debris in them. All the seals released a bit of dirt when I wiped them with the paper towel.

 

Now the wheel turns freely and the feel is vastly improved.

May only be a short term fix. I have had an issue on my Breva 750 rear brake. I would extend the pisiton and clean, exercise and reinstall, but after a few months it would bind again.

I got serous and had it all apart last week. The wiper seal had perished, disintegrated and gone bar some residue. Thoroughly cleaned and a new seal kit installed and all is well.

Why oh why Breva 750 rear seal kits are available, but V11 rear are not illudes me.

 

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[gstallons]

This wooden block looks great . Can you post specs on the dimensions ?

[luhbo]

Isn't the idea well enough?

[Scud]

The exact dimensions are not essential, I just started with whatever block I had that seemed close enough and cut it without measuring. But here are the measurements of the final product:

 

70mm x 37mm x 20mm.  The step thickness is 7mm (13mm cut away from the 20mm side) to allow one piston out.

 

After measuring, I "promoted" it from the wood block box to the tool box. I think it will be handy for simple cleaning too - to work one piston at a time.