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Old June 8th, 2019, 02:13 AM   #1
nocturncal
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Front Wheel Dragging Problems

So I'm out riding my 08 Ninja 250r and all of a sudden I felt my front brake lever "give" while coming to a stop.

Since then, my front wheel is dragging heavily. On a triple tree stand, if I try to spin my front wheel it'll barely spin 2 inches of travel (don't know how to phrase that better).

Brakes were flushes 2000 mi ago
Original brake pads, calipers, lines
Lines don't appear to be leaking

Squeezing the front brake does produce stoppage to the front wheel, only that when not applying front brakes the front is dragging.

Looking for ideas on where to start troubleshooting so I can get my front brakes functioning again ��
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Old June 8th, 2019, 06:01 AM   #2
Triple Jim
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It could be one or more of several things. The lever moving closer to the handlebar while you were stopping could indicate a leak somewhere. It could be a leaking seal inside the master cylinder or a leaking wheel cylinder. It could also be a leak at a fitting.

A dragging brake could be caused by the master cylinder not releasing pressure when you're not squeezing the lever, which may mean the small pressure relief hole in its bore is clogged. Dragging can also be caused by a corroded cylinder or piston in the front caliper that's not letting a piston move freely.

I've also seen brake hoses that get partially clogged and cause strange things to happen. A partially clogged hose could make it hard to squeeze the lever and get fluid to the brake caliper, and then once it's there, make it hard for the fluid to get back to the master cylinder, causing the brake to drag. This seems to fit your symptoms pretty well, so you might start by removing the hose and checking it for clogs.

If the hose is OK, the next step would be to get rebuild kits for the master cylinder and caliper and thoroughly clean and rebuild them.
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Old June 8th, 2019, 03:55 PM   #3
jkv45
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It sounds like the caliper needs servicing.

Cleaning and lubing will most likely cure the problem. The sliding pins can get gunked-up with crusty grease and not move freely.

Pads may need replacement also.

Here's some info - https://faq.ninja250.org/wiki/Brake_caliper_rebuild
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Old June 9th, 2019, 12:45 PM   #4
nocturncal
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Well everyone here was right... They definitely needed servicing!

I went to disassemble the calipers and low and behold, a piece of one of the brake pad cracked off. I couldn't see it from the outside.

Luckily i was near my house when I felt my brakes "give". And it doesn't look like the disc took any damage. I'm assuming when my brakes "gave" was when the brake pad cracked off.

Just ordered a rebuild kit and a trip to the auto parts store for some brake cleaner are in order!

Question reguarding lube... I've been watching videos about servicing them, and I see some videos using copper grease and others mention using permatex ultra disc grease.

What kind of grease should I use on the calipers?
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Old June 9th, 2019, 05:13 PM   #5
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I've used NAPA SylGlide and CRC Brake Grease on the sliding pins. Be sure to clean out all the old dry grease inside the opening.

I also have some Super Lube light synthetic grease (M1/M14 grease for you gun guys) that should work well also.

When pads get thin they have a tendency for the material to separate from the metal.

Best to try to keep an eye on the pad thickness, but notice that the inside pad (active side - against the pistons) will wear faster than the outside pad (on the non-active part of the caliper) on a simple single-sided caliper.

Last futzed with by jkv45; June 12th, 2019 at 10:04 AM. Reason: correction
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Old June 12th, 2019, 09:47 AM   #6
nocturncal
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Thanks for answering all my questions! Next one - what's the service limit on rotor thickness? I get that if the disc is warped, they need to be changed, but how long can I go on the thickness? My front roto is at 4.45mm thickness
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Old June 12th, 2019, 10:07 AM   #7
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This is all I found on rotor thickness - https://faq.ninja250.org/wiki/The_brake_disc

"The minimum thickness is stamped right on the rotor. You can get a good idea of your thickness by checking it with your hand. Once the rotor "lip" gets extremely pronounced, it's probably time for replacement."
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Old June 13th, 2019, 09:06 AM   #8
nocturncal
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Quote:
Originally Posted by jkv45 View Post
This is all I found on rotor thickness - https://faq.ninja250.org/wiki/The_brake_disc

"The minimum thickness is stamped right on the rotor. You can get a good idea of your thickness by checking it with your hand. Once the rotor "lip" gets extremely pronounced, it's probably time for replacement."
Took a look at the stock rotor and it says minimum thickness is 4mm, so I'm good to go 😁
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