thundercat brakes

[el_oso]

having a bit of a problem with the brakes on my thundercat. the winter period really clogged them up. so i popped the pistons out to clean the calipers thoroughly. some of the dust seals were cracking and split so put them back together and without dust seals temporarily so i could use the bike for the week while i ordered a new set.
got the new seals and assembled everything but the brakes still seem stiff. can also pull the lever to the handlebar when the adjuster is in the shortest and second shortest position. have bled the system several times on several days and there is no more air coming out. when i have rebuilt brakes before i was able to push the pistons all the way back by hand. i can't do this with these calipers, i struggle pushing the pistons back using leverage as well.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[iooi]

Sounds like you still have air still trapped in there.

Tape the brake lever back to the bars overnight.
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Just because my bike was A DIVVY, does not mean i am......

[Blue_SV650S]

You need to scrape the crud out of the seal recesses! that is all it is*

*When you said 'thoroughly' did you get all scrapy on its behind if not then above is true!!??
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The purpose of life is to fight maturity.

[el_oso]

i did scrape in the seal recesses. there was a hell of a lot of crap that i scraped out. white crystally crap. it was then cleaned with brake fluid, then rinsed under the hose, then put in the oven on the lowest heat to dry out properly. didn't fancy any water in the brake lines.
i think i may take it all apart again tomorrow and give it another clean.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[0l0dom0l0]

Start from the beginning again.

The pistons should go back in without much persuasion at all. Mine do anyway!

Remember to lube the pistons with red rubber grease that will help.

Also, just as a word of warning the blue spots are all most impossible to bleed using the old fashioned method. The best thing I got for mine was a set of 'speed bleed' nipples. Just means you can pump the lever without having to keep shutting the nipple at the end of the travel and starting again.

I remember running about 5 complete resoviours through before they were stiff, if not more. If you can bring the bar back to the handlebars then you have air in the system.

I found the blue spots pretty nice to work on. Just bleeding them that's impossible!
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CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.

[weasley]

^^^What he said^^^

The Cat's brakes are notoriously difficult to bleed. Might be worth trying to reverse bleed them if you can - pump fluid into the bleed nipple to 'back-flush' the system.

One area that is, apparently, part of the problem is the tiny little link pipe that goes from one side of the caliper to the other.
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[el_oso]

i wanted to try reverse bleeding them, however i cannot find a syringe the same size as the hose. tried using one from a print cartridge refiller but still not big enough.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[totalllama82]

Mine are the same unfortunetly, i've bled and bled and I just cant get them firm. I've rebuilt the Master Cylinder components. The next stop was going to be new seals and a clean out of all the calipers and perhaps some braided hoses (I wasnt sure what was causing the problem).

Does reverse bleeding make things much easier? Are there any tips on getting the air out of the link pipe?
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Gone: Haotian HT125-8 / Yamaha YZF 600R Thundercat / Kawasaki ZX9R C2
Current: Kawasaki ZZR 1400 A7F

[el_oso]

you could try turning the caliper upside down and bleeding them
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[MarkJ]

Godfather, when you're bleeding the brakes (whether forwards or backwards) turn the handlebars to the left and put it on the sidestand. Should keep the inlet hole for the master cylinder higher than the m/c banjo bolts which can hold a bit of air if the inlet hole is below them.

With the reverse bleeding, my syringe doesn't fit on the rubber tubing I use - the syringe tip is probably only half the diameter of the inside of my rubber tubing. I just press the syringe into the tube pretty hard and inject the fluid whilst doing this. I get a dribble of brake fluid but not much.

[el_oso]

just an update. rebuilt and re-bled today. still no change.
tried the classic tried and tested method of bleeding. looks like the master cylinder is hardly pushing any fluid through. after pumping the lever 20-30 times then holding the lever to the bar and cracking the nipple virtually no air or fluid moves out the nipple connected hose.
time for a master cylinder rebuild methinks.
while i have everything off i think i'm going to change the pads and get some HEL/goodridge braided lines.
looks like I'm going to be cycling to work for while now.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[0l0dom0l0]

[el_oso]

sorry if i didn't make that clear, but what i meant was that i tried the method of reverse bleeding by forcing fluid through the calipers. after that didn't work i then tried the method of pumping the brake lever, hold the lever to the bar, crack the nipple etc.
now that i have the lever off the bike i tried pumping out the remaining fluid in the reservoir. the fluid didn't spit out everywhere. just dribbled out the end. when i had the hoses off the master cylinder on a GPZ i grabbed the lever and spit brake fluid across the garage.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[evoboy]

Have you bled the master cylinder?

I have Thundercat calipers on my TRX, dead easy to bleed using the old style method. Solid feel at the lever.
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Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[totalllama82]

I find to get any feel when (failing to) bleed my brakes, I need to crack the banjo nut up at the master cylinder to get the fluid down through the hoses. You only need to do the pump, hold, crack open, shut, release a few times at the top before it will give up all of the air.

Another thing i've tried is clamping the brake line at one side and bleeding the opposite then swapping around when the lines are empty... not sure if it helps though.
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Gone: Haotian HT125-8 / Yamaha YZF 600R Thundercat / Kawasaki ZX9R C2
Current: Kawasaki ZZR 1400 A7F

[el_oso]

didn't know you could bleed the mc on the thundercat. i will have another look at them

i did try cracking the banjo at the top where the mc is. i did that when i have to re fill up the lines. gives the air in the lines somewhere to escape
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L