Front disc brakes

[Shaggy]

OK im back again with this whole brake problem, I have the pads, now how do I change them, its confusing me, can I just take those pins out and slide new ones in or do I have to unbolt something.

 

[Scott-Westy]

pins out, retaining clip will then spring off, old pads and plates out, stick some copaslip on backs of new pads, then re-assemble everything again.

You may need to purseuade the new ones in by levering the pistons back into the calipers carefully.

Usually you will get new pins and retaining clip with the new pads :wink:

 

[Shaggy]

OOOOOOOOOOHHHHHHH! i am such an idiot!
I won't tell you why, but thank you dude thats so much help

 

[Shaggy]

whats the best way of purseuade the new ones in by levering the pistons back, as the pistons (which I assume are the round metal rings that push the pads to the disc, as I tried to push the back abit but they don't budge or am I just being a wuss

 

[Araon]

Be very gentle with them try a piece of soft wood, you may need to take the caliper off without removing the hose or anything, I find a hammer shaft rotated between the pistons works well to get them moving.

 

[Shaggy]

Araon you always come up with the answers, thank you very much I will go try that now

 

[slammedkustom]

you can get a tool to push them back but another trick is a big screwdriver between the disc and OLD pad, dont use the new ones as it will get damaged. you can normally get a bit more clearence buy forcing the piston back with the OLD pad.
good luck
:wink:

 

[Shaggy]

Thank you slammedkustom I tired all of those and still couldn't get the new pads in plus I couldn't take the calipars off as the bolts just don't move, but they didn't seem to bad, not that I know what bad would be, but its getting rubbish as every job I try and do I fail at

 

[Araon]

Spray the calipers liberally with brake cleaner (WD40 if you intend to thoroughly clean afterwards) the dust and heat has a tendancy to lock them up quite well so a little leverage will help. You'll probably find they'll go with a disconcerting CRACK.

You may try releasing a little fluid and then try prising the pistons again, but remember, to thoroughly bleed the brakes afterwards.

Hope you have luck...

 

[Shaggy]

ok how do i release the fluid, and also what happens if you don't bleed them and also how do you do that, I really am stupid when it comes to stuff like this

 

[Araon]

Do you have a Haynes manual? as it is easier than trying to explain or Ill have a look for an online version for you.. :lol:

Theres a nipple on the caliper (grease nipple) loosen that (use the tube from a bleed kit) lever the pistons of the brakes so the bakes so that some of the fluid is emptied into a jar. This should release a little pressure and you should see the pistonsmove easily.

If you've a bleed kit (few quid from any motor factors) the bleed principles are on them.

Basically yor removing old fluid and air and dirt from the system. This will give you optimum pressure.

 

[VWAIRCOOLED]

Before pushing pistons back,remove the reservoir cap check the reservoir is not filled right up too as when you push the piston back it could overflow and pour down inside.Remove some fluid with a syringe if neccasary.Leave the cap off until you've finished.
Next lever the piston back evenly with an old pad against the disc and a lever bar between the pad and caliper it might take a fair amount of force to start moving it.If it doesn't move you could try putting a bleed bottle connected to the nipple ,loosen the nipple and retry the levering.You could try using a g-clamp if you've got one and can get the access.Put an old pad against the piston and fit the g-clamp against the old pad and the back of the caliper then screw it in,put an extension bar on the g-clamp if neccasary to get it moving.If you can see the dust seal has split and can see rust in there the chances are the piston has seized.

If it just won't move then you have got a seized caliper and you will need to unseize it or replace it.
To do this is tricky but this is how I do it.firstly top the reservoir right up.Leave one caliper with brake pads in.The other one remove but leave pipe on.Get someone to pump the pedal up until piston comes right out,then clamp the rubber hose.Remove caliper completely check piston bore for scores etc.Clean up rust from the outside lip.Clean the piston lip of corrosion and check for scoring too.Put new rubber seal on piston.The dust seal is the tricky one,get the top lip on the piston first and pull it down to the bottom of the piston so that you have the larger diameter bottom end hanging down and the smaller end just on the bottom of the piston,then with plenty of brake fluid as lubricant hook the bottom of the dust seal into the caliper all the way around.Then carefuly slide the piston into the caliper whilst aligning the dust seal sliding it up the piston as you gnce the first bit is in it is easy.Push piston right in and away you go fit it all up then bleed it out.Got to be cheaper rebuilding it yourself than buying a rebuilt one.repair kit £14.95 rebuilt caliper $176.25!

 

[VWAIRCOOLED]

Whilst on the subject of brakes what is the best fluid to use? Is dot 5.1 ok to use in these?

 

[Araon]

First you need to ask what your running at the moment what you dont want is to mix dot 5 (silicon based) with dot 3/4/5.1 glycol based.. the dot rating refers to the boiling point and its moisture absorbtion capability.

On bikes its more critical as the heat (especially in hydraulic clutches) can cause the rubber hoses to break down adding another contaminant into the system and reducing efficiency.

What I will say is if your not sure flush it entirely, and check after say a month that the fluid is still clear and free of crap. the 5.1 has a higher boiling point and lower moisture absorbtion so "should" be fine, I know that on my Ducati it strips the lining from the hoses. But then the vw system will run cooler for sure.

Hope this helps

To be honest I stick to the dot 4 myself as thats the original rating.

Araon

 

[Guest]

shaggy i have 2 seized calipers, one on the bus and one off it on a spare set of spindles, ill be trying this at the weekend and taking some pics to help out i got the refurb kit but you need to make sure you replace the steel bolts with new ones. I believe early caliper bolts were M12 and later calipers M14.

If you cant shift the nutts use a release oil like 3 in 1, after you have liberally used WD 40. Leave the WD4o on for an hour or so then 3 in 1 over night. usually works on really stubbourn bolts for me, i also have a big ass breaker bar.

 

[Araon]

If you still have probs breaking it then blow torch WD40 brute strength and ignorance a good healthy mix of all should crack it

If you go the blow torch route then best to bleed the entire fluid from the system. As the fluid boils then turns to gas and turns your brakes to ****.

 

[lowblow]

If you piston does not move back and acts seized. Unbolt the caliper, with the pads all ready removed. Next get a pair of grips bigger the better, and grasp the piston sideways on, so you twist the piston around, yes its going to be tight but twisting back and forwards will slowly free it. Never use wd40 on brakes only if a overhaul is intended. Wd40 will expand, split and eat away at rubber. This is a true fact. I teach motor vehicle and I showed my students what wd40 did to a valve from a car. I placed the valve in glass and poured wd40 over it till it was coverd. I left the valve in there for one hour and in that time the rubber had expanded to make the valve three times the size. So think to what its doing to your seals in your calipers with all that pressure when your braking :?. Another quick tip is if you had to undo the bleed nipple, clamp that brake hose off with a hose clamp, do the work you need to do. When youve finshed leave the bleed nipple just undone, remove the hose clamp, place a container under the brake component and go and make yourself a cuppa. When you return you will notice brake fluid dripping into a container. lock of the nipple, top up the fluid and your brakes are bleed. :wink: