Front brake dragging or bearings or both?
 

My front end has handled poorly since I got the bike. Not stable under braking or entering a rut, and also wants to over steer in corners. I've been clicking away making suspension adjustments, sliding forks all the way down, playing with sag, and while making improvements, it still feels strange and unruly. Kind of felt like there was some drag coming front the front wheel. I'm looking at three areas that don't feel right to me.

1. My front brake feels strange at the lever. The lever, when pulled in doesn't feel smooth, feels sort of sticky. If pulled 3 or 4 times repeatedly, it actually vibrates and makes a binding noise. The pull seems short too. It was squealing yesterday in the OKC National Enduro. I've never had that happen before. Consequently, I've never had to rebuild a front brake master cylinder before, I'm thinking that is one of the culprits.

2. Also, I'm noticing I can give the front wheel a good spin on the stand, but it only goes around 2 1/2 times before stopping. My WR right next to it spins around like 10-12 times before stopping, then it will rock back and for before settling at a stop. The 300 isn't free like that at all. The side to side play is good, with no play or slop at all. I cleaned up the axle and lightly greased it before installation. It also isn't binding at the axle clamps either, I checked that. It also sounds quiet, no grinding or crunching noise when spinning. Doesn't seem like but could the bearings be going bad?

3. Also noticed that the PO left the stock chain on after going to a 50t rear sprocket. The rear axle is so far forward, the tire is hitting the mud flap wearing holes through it. I imagine getting that axle back with a 114 link chain would help the front end weirdness as well.

2012 R model. 48mm CC Zokes. Have they been serviced? Multiple reports of the inner chamber not being bled correctly and clunking on full extension. If they haven't been serviced, plan on it.

Sounds like the brake caliper could use some love too. Either just a pull down and clean up, or maybe a full rebuild.

The front wheel sounds like a combination of the front brake dragging and possibly some stiction of the seals. Removing the front brake caliper should let you know more quickly for your 'spin test'.

Has the bike been resprung? Hows the sag figures? Are the forks through the triples some or flush with caps?

Yeah, forks and shock just got rebuilt. .48 front and 6.2 rear and PFP full out. I'm 235 with no gear. Fast B/Slow A rider. I haven't noticed any clunking. Forks are at the upper limit in clamps. Sag is at 35mm static. I haven't been around a few people to help with the race sag. Been solo lately. Maybe it's time to train the wife and 6 year old boy on setting sag. I've been adjusting it from 30mm static to 39mm static. Feels best at 35mm. I guessing it will be around 105mm. We shall see tomorrow.

Removing the caliper and spinning was great advice. I just removed it and the wheel spins freely now like it should. Looks like a caliper/MC rebuild.

I'm excited bc I think now my handling issues will be solved. I was starting to get annoyed with this thing.

Sometimes just pulling the brake pads and cleaning up the pins and pistons will make a big difference. Probably worth a try before you go the whole hog.

The rest sounds like its on the right page.

Going with new pads and pin. How do I get the pistons out? It has been a while and I have no manual.

*shrugs*

I've never had to rebuild a caliper either. While we're on it.. Where can I buy service kits? The guide pins (for the caliper, not the pads) are getting a bit slop on mine. I've replaced the pad pins once. Too much riding is wearing my bike out! :o

Use compressed air, put the nozzel where the breakhose would be. Watch your fingers!:)

I have bought rebuild kits on Ebay. Here in the US. I like to buy a lot of OEM parts from ServiceHonda.com. They stock most OEM (Japan Bikes) parts. The front and rear caliper are the same as what is on a YZ250/450 bike, just can't remember what years.

As for brake pins I would recommend finding the Stainless steel aftermarket ones as they don't rust or wear as fast. If I recall Zeta Racing makes them and so does Moose Racing. Plus the aftermarket ones eliminate that stupid little cap/cover and are a bolt head instead of the allen head type pin.

Just like Wimpy said.
But I would recommend you put a thick (say 1/4") wood shim in between where the pistons come out and what holds the opposing brake pads in. This way when the compressed air POPS (you may jump when this happens) the piston out it does not go flying across the floor and also with the wood shim the pistons will not get damaged and prevent you from spending more $$$ to rebuild your caliper.

I will use the WR manual. I'll bet it is very close to being the same. Yamaha puts out a very good owner's manual.

I'm running short on time this week, I may have someone do it if it doesn't cost a bunch. I really need to ride this weekend. Preferrably on this 300 w/o a dragging front wheel.

Also check for a bent rotor in the front as well, if the piston pushes back in cleanly/easily you shouldn't need a rebuild Take the caliper off and then spin the wheel to isolate the brakes from the bearings

& just my opinion-a 6.2 on the back is waaaay to big a spring, I saw you and you aren't that big i.e. I'm 195# and run a 5.4....

+1 on the bent rotor, if it isn't bent to badly you can bend it back. A big crescent wrench should do the job.

The rotor isn't bent. There is no pulsing. It is a constant drag. I think the pistons are sticking the more I look at it.

Thanks for the compliment Fred, but the scale don't lie. 238 lbs this morning. I'm 6'1", so it spreads out.

As soon as I get the brake issue and a longer chain, then the process can be resumed. I too felt like 6.2 was too big, especially when paired with .48 forks. Would expect to see .50 with a 6.2. However, that was what my guy recommended. So we will do further testing to find out.

Well the pistons were not stuck. I can move them in and out with my thumbs. I put a little lube on them and worked them in and out a few times. Pins were clean and greased. Pad pin isn't grooved or anything. Cleaned and reassembled and it is better and spins more freely. Still not as free as my WR next to it. The lever still feels crunchy and sticky. I'm thinking the MC needs to be rebuilt.

You'd be surprised what a little love applied to the pivot and anvil/cup of the lever will do. Disassemble, clean, grease and reassemble. Remove the brake light switch if you haven't already. Run three times as much fluid as you think you need to through it while you're bleeding it. Revel in your new-found brake goodness.

I removed the lever and cleaned and greased. While it is a little better, there is still a binding feeling when the lever is pulled all the way in.

There is a KTM shop in town. I'm guessing the Brembo parts crossover? How do I know what size MC I have?

You should be travelling to your local Japanese dealer if anything - your bike *should* have Nissin brake components.

Aaahhhhh! Not only that, but it's Magura not Brembo.

Trying to do too many things at one time.....

So are all the Japanese Nissin MC the same size?

No, they are not. Well, they might be the same piston size, but the rebuild kits for them are not all the same.
The part number of the genuine GasGas rebuild kit is BC25922219

As for the Magura clutch master, KTM did use Magura stuff on their earlier models, and the levers and rebuild kits should cross over. A few members have scrapped the stock AJP master in favour of a Magura master of similar or slightly larger diameter.

Really? I loved the AJP on my 05. Couldn't imagine swapping it out.

This Magura on my 12 is a little stiffer.

Happy to report front end issues are over. Took the caliper/MC apart and cleaned everything. Replaced fluid and bleed it. Spins free and the dragging has gone away. I also replaced the chain with a 114 link for the 50t sprocket. I estimate that the rear axle moved back about 15mm. Which is a lot. Man, that was what the bike needed. Finally the front end was planted. The front brake worked. I was able to lower my pegs. Much better position. I could stand up! Yeh!

About the spring, I was finally able to set the sag today at 106mm. Unfortunately, I only had 10mm of static. So I think I actually need a 6.4!

Sorry to dig up an OLD thread: But is a caliper rebuild kit from a YZ250 / 450 going to work on my 2006 EC 250 ????? (Front end im looking for - 2 piston Nissin caliper on right now).

Front brake was 'ok' - thats all. I flushed through new fluid and bled it - then noticed pads were a little low.

So ive just fitted new pads, cleaned up the pistons and caliper pins before applying some copper-slip and pushing everything backtogether again. And now the brake is binding quite badly.

Im guessing new piston seals would be my first point of call and at first glance theres not much available in the UK. So any other makes these calipers are fitted to, along with the year would widen my options !!!!

Or does anyone know the exact piston size - maybe this place in the UK can supply me with the seals: http://www.ebay.co.uk/itm/Honda-Kawa...item258096efdb

Ok, been back out into the garage - took off the cap from the master-cyclinder to check fluid wasnt stupidy high (As i bled brake using new fluid; before i realised the pads were low).

And it was a touch high, so i dropped a little out, so its at the top of the sight-glass with bike sitting level.



Then took off caliper again, pumped brakes a few times till pads almost touched, then pushed pistons back in again (Pretty easily and with no fuss) and then re-attatched the caliper to fork leg. I checked the wheel spun fine without the caliper fitted and indeed it did ;)

Pumped brakes a few times, to get pads out,and brakes still binding :( If i spin the wheel hard as i can by hand - i can barely get one revolution before it stops.

So: No leaks, new fluid, new pads, brakes working ok, but binding slightly ?

Im no brake expert at-all, but i can only think seals were ok where they were with old pads fitted, but having disturbed them in fitting fresh pads the piston / pistons are now sticking slightly.

Plausable ?

If the pistons have been exposed for some time due to having very little pad they could be a bit rough. Did you pop them right up and clean them well really well?

Pads were really low, with just a couple of mm left - so the pistons were well out.......

I got a few q-tips / cotton-buds and dipped in some WD40 and wiped and cleaned right around the sides of the piston, and cleaned up the face of the caliper where the piston enters / exits the caliper so it didnt drag any in crap that way either.

Bearing in mind it seemed ok before - id say i cleaned it up pretty good. Suppose i spent a good 20 minutes just cleaning.

Maybe like you say - i should get up early before work and remove the pads. Pop the pistons right out and double check all is smooth and well...........

It can't hurt. I'd probably give them a light touch up with some steel wool or wet and dry. Nothing abrasive enough that it will damage the actual piston, but that will remove any build up on it.

Clean and re grease the pines it slides on check that your disk is not bent.

:eek:yikes! My is bent to the left!

LOL

oops:o but that's funny:D

Try using your other hand.:rolleyes:

Well; I got up at 5am before work to sort this once and for all !

Removed caliper again, took pads out and fully exposed the pistons.

Cleaned them up good and proper and pushed them back in again......

Squeezed the lever a few times and only one piston came back out again. Had a good look and i could see bits of seal trying to come back out with the piston.... :(

So, decided to remove both front and rear caliper while im doing the front, and have sent both off them off for refurbishment. (If you click the link uptop in orange - theres a huge article about what exactly they do) For this price its not worth me messing around with them myself - its easier and less painfull to do a couple of hours overtime at work ! Plus a 2 day turnaround means i'll be back riding next weekend. Just another problem that hopefully wont ever return !

http://www.powerhouseautomotive.co.u...yorkshire.html

Very unhappy to report my front brake problems are back and even worse now. The lever will barely move. The pistons in the caliper move freely. It has to be the MC, but we took it apart last weekend and it looked fine. No torn seals or anything. So I don't know. I'm rebuilding the MC, if that doesn't work, I will send it off somewhere.

There may be a restriction in the hose.
It may have delaminated internally, possibly impact damagefrom trail debris.

We thought about that too, but we can back bleed fluid through the hose with no problem, it would squirt out in a nice little stream. So it appears the hose is fine.

We took the front brake MC off Paul's KTM and put it on my 300. Hoping to see if the MC was surely the problem. Hooked it all up and could not get the lever to firm up. We back bled it, front bled it, etc for 1.5 hrs before giving up.

I may send the whole assembly to my main GasGas guy in Houston. He is pretty good at fixing stuff I hear......;)

I may have my OEM caliper in the garage.
Lemme check.

Gots it.
What cha wanna do?

Sent PM. Thanks Girard.