Front brake dragging or bearings or both?

[Bandit9]

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.

 

[Jakobi]

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?

 

[Bandit9]

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.

 

[Jakobi]

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.

 

[Bandit9]

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.

 

[Jakobi]

*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!

 

[Wimpy525]

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

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

 

[StuJohnson]

*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!

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.

 

[StuJohnson]

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

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.

 

[Bandit9]

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.

 

[Fred1956]

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....

 

[PEB]

+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.

 

[Bandit9]

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.

 

[Bandit9]

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.

 

[twowheels]

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.

 

[Bandit9]

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?

 

[twowheels]

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.

 

[Bandit9]

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

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

 

[Bandit9]

So are all the Japanese Nissin MC the same size?

 

[noobi]

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.