Author Topic: Disc brake info on the C5 (Read 6696 times)

wildbill · **on:** January 29, 2012, 01:37:11 am

Hi all
Just wondering if this is the norm for an Enfield. Every time I apply or attempt to apply the front disc drake it appears to bite savagely. Not a lock up but you see the front forks move up and down briskly.
No difference if its 50 klm or 5klm per hour. Just a savage grab. Tried the fingers further up the brake lever but to no avail.
Thought all this would have been picked up prior to the delivery. Same with the clutch. It too was savage. Release the nut near the engine a couple of turns -now its fine.
Any thoughts? and regards

Ducati Scotty · **Reply #1 on:** January 29, 2012, 03:05:43 am

I've had this with brakes on a few bikes, some new some not.

First, make sure there's not obvious binding or problems.

Open it up. Sand the pads to break the glaze. Use something like 220 paper on a flat glass plate to make sure it's flat.

Get a genuine green 3M Scotch Brite pad (iimitations will not do) and some brake cleaner. Scrub the hell out of both sides of the rotor. Lots of pressure. Watch the fluid, it will eat paint.

Put it back together and see how it feels. Pads get old and glazed and a bad layer of material can collect on the rotor. Now got out and so some long stops from about 40 mph down to 2mph one after the other. No stopping, keep the bike moving so the rotor cools evenly. Then go for a nice long spin with no stop at all to cool it completely.

It takes a little time but costs very little money. I've seen this transform very grabby brakes into smooth as glass operators. I'm due for this myself on my bike.

Scott

GlennF · **Reply #2 on:** January 29, 2012, 04:03:30 am

Quote from: Ducati Scotty on January 29, 2012, 03:05:43 am

I've had this with brakes on a few bikes, some new some not.

First, make sure there's not obvious binding or problems.

Open it up. Sand the pads to break the glaze. Use something like 220 paper on a flat glass plate to make sure it's flat.

Get a genuine green 3M Scotch Brite pad (iimitations will not do) and some brake cleaner. Scrub the hell out of both sides of the rotor. Lots of pressure. Watch the fluid, it will eat paint.

Put it back together and see how it feels. Pads get old and glazed and a bad layer of material can collect on the rotor. Now got out and so some long stops from about 40 mph down to 2mph one after the other. No stopping, keep the bike moving so the rotor cools evenly. Then go for a nice long spin with no stop at all to cool it completely.

It takes a little time but costs very little money. I've seen this transform very grabby brakes into smooth as glass operators. I'm due for this myself on my bike.

Scott

If I recall correctly this is a brand new C5.

Wild .... have you ridden hydraulic front disk bikes before ? They require a lot less strength in the "grab" than cable/drum brakes. How sudden is teh fork compression ? A good dual disk sports bike can have you lifting the rear wheel off the ground if you squeeze hard enough.

wildbill · **Reply #3 on:** January 29, 2012, 08:52:39 am

Scott
I might give this a try. Once i remove the caliper from the front fork -how hard is it to get the the pads out and back in. Class this brake problem a bit on the dangerous side.
Don't fancy the idea of a 8 hour drive to the dealer when i might be able to solve it.
Bikes running fine and have 130 klm or 80 mile on it.

Glenn
Very little pressure is enough to grab the front discs. Wouldn't like to run into a wet road with this problem. Although it was 40 years ago - the 750 Suzuki i bought new had double disc brakes and I recall not a problem.

Ducati Scotty · **Reply #4 on:** January 29, 2012, 09:19:00 am

It comes apart pretty easily, you should have no problems.

Scott

wildbill · **Reply #5 on:** January 29, 2012, 09:38:09 am

Scott
220 dry rub or wet/dry and thanks for the help

BRADEY · **Reply #6 on:** January 29, 2012, 09:50:31 am

I think the first thing you need to check is the disk.
This in my experience happens if the disk is bent even slightly.
I had this issue, and the bike would wiggle under braking, but
changing the brake disk, changed that !

barenekd · **Reply #7 on:** January 29, 2012, 05:08:12 pm

My brake is very smooth and progressive. It also will lock up the front tire. No stoppies on these skinny tires! BUT, locking up the front tire can put you on your butt...be careful
I'd go with the warped disk idea on your bike.
Bare

Arizoni · **Reply #8 on:** January 29, 2012, 08:49:36 pm

Doesn't a warped disk usually cause a pulsing in the feel of the braking? I know it does in a car.

I think with only 80 miles on the clock the brake shoes aren't even scuffed up yet.
I also think with only 80 miles on the bike wildbill hasn't developed the "feeling" for the bike and its quirks that can only come with time and mileage.

I recall reading of another forum member who was used to the brakes on his bicycle and thought the RE's front brake was way too powerful.
I haven't seen him post lately but hopefully some familiarization with his bike has taught him how to use his front brake.

GlennF · **Reply #9 on:** January 29, 2012, 10:06:46 pm

Quote from: barenekd on January 29, 2012, 05:08:12 pm

My brake is very smooth and progressive. It also will lock up the front tire. No stoppies on these skinny tires! BUT, locking up the front tire can put you on your butt...be careful
I'd go with the warped disk idea on your bike.
Bare

Yeah especially on dirt. I am considering swapping out the stock Avon for a K70 on my B5, once it gets a bit more worn.

I presume a warped disk should not be hard to spot.

wildbill · **Reply #10 on:** January 30, 2012, 01:39:19 am

Sat on the bike today whilst the wife attempted to spin the wheel. Said it was hard to move. Sat her on the bike and had a go myself.
Wheel does not spin freely at all. On a good hard spin it rotates just a few times and stops fairly quick.
As an example -nothing like a pushbike wheel spinning..
Couldn't see any buckle on the disc whilst spinning the wheel but I could hear the odd scraping sound.
Just wondering if the piston in the disc is working properly.......Could it be jammed etc and not moving freely

Arizoni · **Reply #11 on:** January 30, 2012, 02:02:48 am

bill
Since you've had this problem from the start on your bike you might want to check the fluid level in the master cylinder.

When I first got my bike I noticed that I couldn't see any fluid in the sight glass so I removed the cover.
Lo and behold! There was not only fluid in there but it will filled to the brim!

After this discovery I can see how this could be your problem.

If some idiot who filled your master cylinder filled it to over the brim and then screwed the cap on it is possible that the fluid pressure is always applying your brakes. That would cause the drag you are seeing on your front disk.

If the fluid level is too high you can probably lower it just a little bit and fix the problem?

As I'm sure you know, brake fluid will instantly dissolve paint so if you decide to remove that master cylinder cover be sure to protect your painted parts.

edit:

An alternate fix would be to slightly loosen the wheel cylinder bleed screw just enough to allow some fluid to run out of the end.
This should release any pressure that may be in the system.

If some fluid squirts out then I suggest that you apply a little side pressure to the outside of the caliper to force the pistons against the disk. You should be able to move it just slightly so it releases its grip on the disk when you remove the side pressure.

I suspect that this will fix your brake problem without doing anything drastic like disassembling the whole caliper.

wildbill · **Reply #12 on:** January 30, 2012, 05:07:34 am

hi Jim

did what you said to - master cylinder was filled to the brim. quick questionnaire is a min mark on the site glass could i drop the level to just above that.
thought i would position the bike off the side stand. rider on and then view the fluid level in the glass
how that
regards

Thanks to all those members who have commented on this fix

Arizoni · **Reply #13 on:** January 30, 2012, 05:20:41 am

It really doesn't matter if the resivour is filled higher than the sight glass as long as it is not totally filled.
I wouldn't lower it to the bottom of the sight glass though. Your brake will need the extra fluid as the pads wear.

When I mentioned trying to push the brake caliper against the disk I forgot to mention that an even easier way of lowering the fluid level and allowing the pistons to move back into the bores would be this:

Get a helper to help with this. Your wife will be fine.

Remove the little rubber cap on the caliper bleed valve.

Then turn the bleed valve on the caliper 1/4-1/2 turn CCW until some fluid starts to drip out.

Put a piece of expendable cloth over the end of the valve and grab the front brake lever.

Squeeze the brake lever about half way back towards the throttle and hold it in this position while your helper turns the bleed valve clockwise to tighten it.
Then, release the brake lever.

Check to make sure the valve is lightly tightened and replace the rubber cap.

Now, try to turn your front wheel. It will start to drag but before it has gone a full revolution it should turn quite freely.

Let us know if it doesn't.

wildbill · **Reply #14 on:** January 30, 2012, 05:37:49 am

sounds easy..........will give it a go
thanks

jartist · **Reply #15 on:** January 30, 2012, 06:41:27 am

Be sure to let us know when you get the issue solved and what it was that did the trick!

wildbill · **Reply #16 on:** January 30, 2012, 08:08:06 am

Will do. Just bleed the brakes but too wet to risk a run to try it out.

Might try in the morning. What i noticed immediately - Once up on the stand i now require much more pressure on the lever to stop the front wheel spinning

.
Prior to the bleed - just touch the brake lever gently and the brakes were full on!

uRban-x · **Reply #17 on:** January 30, 2012, 10:44:51 am

Make sure that the break fluid does'nt come in contact with paint, and if possible attatch a small length of tubing to the bleeder nipple.

There is a video on youtube by forum member singh5g on removal and replacement of break pads and shoes, it should help a lot.

Cheers,
Urbanx.

barenekd · **Reply #18 on:** January 30, 2012, 04:54:50 pm

Are you sure it's the brake dragging? If it is, you have a malfunction in hte calipers. They shouldn't be dragging when the brake is released. If you're sure that's what it is, take the Breke off the fork and push the calipers back into the body, then replace the brake and pump the brakes back up. By the way, while the brake is off, spin the wheel and see if it's free. The wheel should spin easily. If not you probably have a spacer on the axle installed wrong or missing.
Bare

tooseevee · **Reply #19 on:** January 30, 2012, 05:01:42 pm

Quote from: uRban-x on January 30, 2012, 10:44:51 am

Make sure that the break fluid does'nt come in contact with paint, and if possible attatch a small length of tubing to the bleeder nipple.

There is a video on youtube by forum member singh5g on removal and replacement of break pads and shoes, it should help a lot.

Cheers,
Urbanx.

C'mon. They're brakes, not breaks.

wildbill · **Reply #20 on:** January 31, 2012, 12:27:14 am

Latest update on the front disc. Took the bike for another run. Better on the brakes but still a bit touchy. Took the calliper off - spun the wheel. Wheel spun freely. Notice both pistons were sitting well out so i used a flat bar to roseate them back into the cavity.
Put the disc calliper back on and got the wife to spin the wheel. Free spinning!
As instructed pumped up the lever till i got good pressure on the lever. Got the wife on the bike while i spun the wheel
wheel spin had improve by several revolutions but I could still hear the disc scraping on the pad or pads.

wildbill · **Reply #21 on:** January 31, 2012, 12:30:07 am

Forgot to mention. One piston was harder to push back in than the other one.

Arizoni · **Reply #22 on:** January 31, 2012, 04:28:55 am

Just my opinion but there is nothing to cause the brake pads to move away from the disk except the runout or wobble of the disk as the wheel rotates.

If the disk is properly made this runout will be almost zero causing the pads to move a very small amount away from the disk.
That will always result in some slight touching between the pads and the disk which will cause a slight scraping sound.

If your car has disk brakes it is doing the same thing.
With the tire on a car pretty much surrounded by the wheel enclosure plus with the tire noise on the road and wind noise this rubbing sound usually goes unnoticed.

On your bike, with the disk standing proud out there in the air the sound is easier to hear. That is, it is easier to hear if the engine is not running.
Just start your engine and like magic, the slight scraping sound will vanish.

wildbill · **Reply #23 on:** January 31, 2012, 05:01:03 am

Thanks Jim.
I will give it another try tomorrow. Definitely some improvement. Just gave the wheel a quick spin - When compared prior to the bleed etc it's now spinning many more revolutions.
Just ready to take my miata out for a photo shoot. Not long ago sprayed it white and a few on the Mazdaspeed forum are keen to see the results Your help was greatly appreciated and I've found that for results Forums beat dealer anytime
Regards Graham

uRban-x · **Reply #24 on:** January 31, 2012, 08:20:22 am

Quote from: tooseevee on January 30, 2012, 05:01:42 pm

C'mon. They're brakes, not breaks.

Oops sorry..

Arizoni · **Reply #25 on:** January 31, 2012, 10:57:55 pm

Bill
Sounds like you may have fixed it.

(I know its not a RE but here's a picture of my '99 10th Anniversary