Too much F/ brake lever travel

[johny brando]

Long story "not so" short !
Front brake system bled every which way & NO air present , yet I have 50mm of lever travel until it's firm & it should be only about 25mm !
Both Calipers have just been rebuilt with new S/steel pistons & all new seals & new Pads. Master Cylinder rebuilt with a ( Japanesse make) 'Tour Max' rebuild kit label # 280069 , underneth this label could be seen another label numbered 08-0217 ....I found this strange but all internal M/cylinder parts appeared to be the same as OEM so I continued.
Also I installed all new Copper banjo bolt sealing washers throughout complete system, & used new Dot 4 Oil .
I was very careful in my assembly proceedures not to nick/damage any seals ..... I inverted the M/cylinder 90 degrees to bleed that & also released the hose splitter unit so I could swing it during bleeding to vent any possible air entrapment there . I used a clear hose connected at one end to an elivated catch jar this hanging 250mm above the calipers with it's upper end emmersed in oil within that jar the other end of the hose connected to an inline vertical mini Non-return valve ...the hose (which is now pre-filled with oil ) continuing down to the 12 o/clock positioned Caliper Bleed Nipples which had each been prior wrapped with 4 turns of PTFE tape to prevent any possible air ingress there.These then bleed in the conventional fashion .
When I then couldn't seem to get the lever firm enough I tried my other method of "reverse pressure bleeding the system" i.e. pushing fluid back up into the Master Cylinder this via the pressure release vent hole ...I do this by using a very large 75 ml Syringe ( 3 times M/cylinder volume ) this is filled & connected directly to each bleed nipple. I did this a few time via each Caliper & did not see any air exit into the Master Cylinder. I could & did during this process, swing the hose splitter to & fro & continually move & tap all lines to aid in moving any lodged air bubbles . I also pushed & pulled brake fluid both back and forward in the system trying to move any trapped air that way too.
With either method I could not get or find any additional trapped air after the initial bleeding. The crazy thing is.... if I cable tie up the lever in a compressed state for several hours then release the held pressure.... it then feels great ...as it should feel ! but within 5 minutes it magically reverts back to the 50 mm travel.....
I think the problems is most likey in the Master Cylinder but what it is within....I now have no idea ( has anyone here used the same Tour Max kit with the same numbers ???? ) I would very much value any input or idea's you may have. THANKYOU , Johny Brando.

[ADE]

If you have access to another master cylinder.off any motorcycle and try again.This may confirm if it is the master cylinder or not.
Ade

[Gavin]

If you have access to another master cylinder.off any motorcycle and try again.This may confirm if it is the master cylinder or not.
Ade

After all you have done, it sounds like it may be the master cylinder

[Tonka]

Master cylinder IMHO

[johny brando]

If you have access to another master cylinder.off any motorcycle and try again.This may confirm if it is the master cylinder or not.
Ade

Yeh ...thankyou, thats a good point ! I'm a bit louthed to pull my Master Cylinder of my Speed Triple but your right ....that would be a sound means of identifying the source area of the problem.
Thanks for your valid input. Johny

[johny brando]

Master cylinder IMHO

Mmmm ......... thats what I think too & thats why I'm enquiring if any one else has info or tails of Wo on these Tour Max kits & the Kit Part # too.. as there seems an issue there due to the covering up of the original Tour Max Part # .
These kits are commonly sold on the 900 Kawa site on Ebay & I bought mine on line from Ebay UK. Maybe I was unlucky & mine was a Dud with a manufacturing floor but hey ...it's Japanesse not Chinese made & we all know & accept that normally that equals fair to good quality aye.
Thankyou . Johny B

[lta01]

are you sure that you are not suffering with slightly more seal stiction than usual in the calipers, especially with the pistons being stainless rather than chromed finish ?

I have experienced this before with stainless pistons. It can show up as the calipers having slack on the discs which you can feel by rattling them on the sliding bolts.

Quick way to rule this out....remove the calipers one at a time from their mounts, pump lever very gently until piston moves out and just stays out..put back on disc carefully...should now be a tighter fit. Do this on both sides, then try lever again.

No improvement, I would say master cylinder problem, if it has improved, either leave as is if drag is not bad, otherwise disassemble calipers, remove seal, clean groove carefully and rebuild with plenty of lubrication around the seal.

Hope this helps

[needaz1100r]

are you sure that you are not suffering with slightly more seal stiction than usual in the calipers, especially with the pistons being stainless rather than chromed finish ?

I have experienced this before with stainless pistons. It can show up as the calipers having slack on the discs which you can feel by rattling them on the sliding bolts.

Quick way to rule this out....remove the calipers one at a time from their mounts, pump lever very gently until piston moves out and just stays out..put back on disc carefully...should now be a tighter fit. Do this on both sides, then try lever again.

No improvement, I would say master cylinder problem, if it has improved, either leave as is if drag is not bad, otherwise disassemble calipers, remove seal, clean groove carefully and rebuild with plenty of lubrication around the seal.

Hope this helps

+1

[johny brando]

are you sure that you are not suffering with slightly more seal stiction than usual in the calipers, especially with the pistons being stainless rather than chromed finish ?

I have experienced this before with stainless pistons. It can show up as the calipers having slack on the discs which you can feel by rattling them on the sliding bolts.

Quick way to rule this out....remove the calipers one at a time from their mounts, pump lever very gently until piston moves out and just stays out..put back on disc carefully...should now be a tighter fit. Do this on both sides, then try lever again.

No improvement, I would say master cylinder problem, if it has improved, either leave as is if drag is not bad, otherwise disassemble calipers, remove seal, clean groove carefully and rebuild with plenty of lubrication around the seal.

Hope this helps

Thanks Mark ....good points ! & I'll try what you suggest re- calipers off & pump each piston out a tiny ammount as I see where your coming from here - but I've never experienced that before. Everything inside the Caliper bodies is BRAND NEW & I did oil the seals faces (brake fluid ) when assembling... all the piston seal groves were cleaned very thoroughly too. Thanks again . Johny B

+1

[jimmock]

I'd try SPLIT BLEEDING before I start stripping MC again.

[needaz1100r]

are you sure that you are not suffering with slightly more seal stiction than usual in the calipers, especially with the pistons being stainless rather than chromed finish ?

I have experienced this before with stainless pistons. It can show up as the calipers having slack on the discs which you can feel by rattling them on the sliding bolts.

Quick way to rule this out....remove the calipers one at a time from their mounts, pump lever very gently until piston moves out and just stays out..put back on disc carefully...should now be a tighter fit. Do this on both sides, then try lever again.

No improvement, I would say master cylinder problem, if it has improved, either leave as is if drag is not bad, otherwise disassemble calipers, remove seal, clean groove carefully and rebuild with plenty of lubrication around the seal.

Hope this helps

Thanks Mark ....good points ! & I'll try what you suggest re- calipers off & pump each piston out a tiny ammount as I see where your coming from here - but I've never experienced that before. Everything inside the Caliper bodies is BRAND NEW & I did oil the seals faces (brake fluid ) when assembling... all the piston seal groves were cleaned very thoroughly too. Thanks again . Johny B

+1

Hi Johny,

I agree with what Ita01 wrote, but it was he that posted the suggestions.

One other thing to be really sure of is that the seal grooves in the caliper are REALLY well cleaned out, I bent an electrical screwdriver to use as a scraper. Then I fill the groove with copper slip and fit the seals, leave the copper slip all over the new seals and push the pistons in. Brake fluid on the face of the seals can have a sticky effect.

[kawasakichris]

have you tried the zippy the lever to the handlebars and leave overnight i was sceptical but it worked for me

[johny brando]

have you tried the zippy the lever to the handlebars and leave overnight i was sceptical but it worked for me

Hi Chris , thanks & yes I did state I'd done that too in my original (it's near the bottom of it ! ) Cheers

[johny brando]

I'd try SPLIT BLEEDING before I start stripping MC again.

Thanks Jim , I hear what you say but I was / am confident it's not a trapped air issue as with the methods I've used I'd definately would have moved it mate. I like the idea of your split bleeding though & THANKYOU.

[jimmock]

I'd try SPLIT BLEEDING before I start stripping MC again.

Thanks Jim , I hear what you say but I was / am confident it's not a trapped air issue as with the methods I've used I'd definately would have moved it mate. I like the idea of your split bleeding though & THANKYOU.

You are more than welcome Johny.

I find the split bleeding method works EVERY time!!