offering advice on brakes

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

Hello all

My mechanical forte is brakes, how they work what they do and how to fix em properly!!!

any questions post a note

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mr.z · World Chat Champion Joined: 04 Feb 2004 Karma :

okeydokey, you asked for it Razz

Do you know allot about drum brakes? the other night i noticed the rear brake is not totaly constant, it dosent pulse noticably i could only really feel the effect when drifting allong, i'd been exprianceing some wobbleings arround country lanes recently and put it down to bushes being worn or something...

So apparently this means the drum is warped slightly? do you know of anywhere who would be able to skim it back into shape? its a pritty specialist job i'd imagine?

Just wondering really, its not major but i'd like to sort it next time the wheels are off, also i dont buying a new drum would cost alltot anyways Very Happy

How much of a jolt would it need to cause damage to the drum?

Thanks for reading Wink

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Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

o.k first you say it wobbles around country roads

is this whilst braking Question

I'm not convinced this is entirely a brake issue first check all wheel/suspension fixings for tightness check all bushs for play

If it is a brake issue you can first try to buff up the shoe surface evenly using sandpaper.

whilst shoes are out, inspect friction surface of drum for signs of heavy or non contact this may show itself as areas of blueing or darkened areas(corrosion).
also inspect exterior of drum for cracks/ pieces missing, a lot of drums have cooling fins if any of these are broken /missing then drum may have warped due to overheating.

brake drums will also have a max amount of wear, this is difficult to measure without the correct device but as a generale rule of thumb if the drum has a ridge/lip around the edge of over 1mm the drum is worn out..

as to re machining I would not advise it as if warped the amount needing to be machined off will without doubt make the drum to thin.. as such it wont dissipate the heat generated by braking(frictional heat) and you will be in a worse situation within several miles.... it will work out cheaper to buy a new drum... note also change shoes at same time if changing drum is required.

hope this helps Thumbs Up

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binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Ive got a question!
On my speedfight the rear brake keeps locking on, pretty tight too.
It is a disk brake, and there are no score marks on the disk, and the pads are not worn out, theres a lot left on them.
The brake will be fine for ages, then all of a sudden, it will tighten right up and the bike wont goe very fast...

Any ideas?

Thanks... Ben

mchaggis · World Chat Champion Joined: 09 May 2004 Karma :

Here's a classic... Squeaky front drum brakes on a CG125. Squeak at low speed to start with, but squeaking dies down after time and higher speed. Dust in the drum, moisture in the drum? Or perhaps a leading edge of the shoe needing chamfered? Any ideas?

Thinking

:editted for grammar.

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

binge

sounds like the pads are jamming in the carrier a removal clean and refit should fix also check free movement of caliper pistons
Idea

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Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

mchaggis

all of the above plus possible glazing of the shoe friction material, easily sorted with a piece of sandpaper.... Idea

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steve09 · Scooby Slapper Joined: 25 Jul 2004 Karma :

I got a piaggio typhoon.
drum brakes at the back some times when ive stoped at the lights i accelrate off the lights and i can feel the back sticking and i have to revf it alot then it sorta comes unstuck and jumps forward

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

steve
I take it this drum brake is operated by a cable/rod assembly
first make sure cable is oiled and is releasing correctly same goes for the rod attached to the drum arm if fitted..

if all the linkages are free moving and well lubed then you probably need to strip out the shoes for inspection, clean refit and adjust.

hope this helps pm me if detailed help is required Thumbs Up

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steve09 · Scooby Slapper Joined: 25 Jul 2004 Karma :

thanks ill try that today let ya know how i get on

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

no worries m8 Thumbs Up

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ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Ok, heres one:
I was pulling apart the rear end on my '64 Galaxie 500XL on Friday & when I removed the right brake drum the linings fell out leaving the actual metal part of the shoes where they should be... The brake linings had just separated from the shoes.
What glue can I use to re-attach the linings to the shoes? Wink

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

fuck no

do not reattach linings

new linings required

the original means of attaching friction lining to shoe plate may be either very specialist rivets or specialist adhesive

I suspect the reason for them coming off is that they are almost worn to the metal or very old

worn brake shoes are easy as they have the same general limit as car tyres 1.6mm of material. specific bikes may vary depending on spec but 1.6mm is a good rule of thumb
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ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Claud 14.7 to 1 · World Chat Champion Joined: 06 May 2004 Karma :

How much meat should there be on my pads before i change them?

And because my calipers are not opposed pistion. Its a 2 piston sliding caliper, does this mean that the meat on the "piston side" will wear faster then the other side. I cannot see the wear on the piston side... Rolling Eyes

. So i kinda need to guess by looking on the other side. Rolling Eyes

Cbr400 '92

Thank you!

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Most brake pads have grooves in them, ya supposed to change em when they are worn down to the groove.....

However.. some pads don't have grooves in them (Kawasaki Z1/Z900 etc) They have a red line painted on the edge of the pad material instead Smile

Claud, just pop the caliper off & have a look, only takes a couple of minutes.....

Claud 14.7 to 1 · World Chat Champion Joined: 06 May 2004 Karma :

Thanks. The pads dont have any wear indicators, but if you get underneath the bike and look "up" the caliper you can see the meat left.

The side nearer the piston looks like it wears slightly faster, but its hardly noticable, both pretty much the same. Ive got a few mm left so it'll be alright but i'll keep an eye on them. Thumbs Up

gsxrboy · Scooby Slapper Joined: 29 Jun 2004 Karma :

I have a crappy bike i bought just to sell again from ebay, cb350s, unless anyone wants it then its a minter!! the front discs are shot in a big way and need replacing. I can machine pretty much anything and don't wish to pay £90 each.

what the hell are they made of??

Cheers chief Mr. Green

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

don't even think about it...
tolerances are minimal any more than 0.015mm warpage will result in brake vibration...
skimming the discs below minimum thickness will result in poor frictional heat dissipation resulting in brake vibration

sorry if thats not what you want to hear

material depends on make but will have a high content of steel
Thumbs Up

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Big Pete · Spanner Monkey Joined: 18 Jul 2004 Karma :

jay12329 · Dr. Evil Joined: 02 May 2003 Karma :

Towards the end of the silverstone track day my brakes became spongy, the bike was then sat for about an hour and they were nice and responcive which lasted all of 10mins. What is going on?
Bike is a hornet 6.
J

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

you are suffering from classic brake fade, as brake fluid ages it absorbs moisture this property is refered to as the fluid being hygroscopic..

all you need is fresh brake fluid

brake fluid has a boiling point somewhere around 160 degrees centigrade
1% of water redusces this point by 20 degrees

when the brakes get hot after thrashing round the track all day the fluid boils and turns to gas, gas is compresssable fluid is not.
change the fluid
remove the problem
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jay12329 · Dr. Evil Joined: 02 May 2003 Karma :

But the bike is only 5000miles and 12months old. Honda advise that brake fluid and lines will last at least 4 years.
J

Retro-Man · Traffic Copper Joined: 21 Aug 2004 Karma :

theres always one clever dick
did you tell me this the first time round ....NO......

where is the bike kept, brake fluid will seek out moisture wherever it can find it.
are all those miles dry miles Question

and I dont care what honda say brake fluid has maximum life of two years Thumbs Up

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ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Picked up my new Galaxie brake shoes this morning, $16.00 for the rears & the shop had the parts (for a 40 year old Ford) sitting right on the shelf.