Help needed- in the middle of Brake Disc change

[Albert27]

Hi guys,

working on the car right now.  Have got the wheel, caliper & caliper bracket off the disc but the disc seems stuck on.  I've hit a few times with a hammer and have just stuck some plus gas in behind it but no joy so far.  Any advice would be appreciated!

 

[dezwez]

Are you renewing the disk if so you will need a big hammer and belt it from the back

also some disk have a small Philips Screw on the front of them you have to remove first

[Albert27]

Just now, dezwez said:

Are you renewing the disk if so you will need a big hammer and belt it from the back

also some disk have a small Philips Screw on the front of them you have to remove first

Cheers Dez.  I'm pretty sure there is no screw.  Where exactly would it be if there was?  Would it be obvious?

[dezwez]

yes it would be on the front face some times they just need a good few heavy hits to come off

[Albert27]

7 minutes ago, dezwez said:

yes it would be on the front face some times they just need a good few heavy hits to come off

There is no screw anywhere near the wheel nuts but there is a screw in the centre (not part of the rotor).  Is that for something else?

[dezwez]

The screw in the centre is (not part of the rotor).on the studs that come though the disk are there any retaining clips if so remove them it should

come off with a few good hits

[stef123]

Hit it harder with a bigger hammer it'll come off eventually. They can be well stuck on! 

[Albert27]

9 minutes ago, dezwez said:

The screw in the centre is (not part of the rotor

Just to check, I shouldn't need to touch that screw?

[dezwez]

no just whack it off

[isetta]

If you keep hitting from one side on the back it can cause it wedge at an angle. you need to whack it on the back, and then whack it 180 degrees around the disc alternately to stop it wedging.

from an access point of view it is probably easier to trun the disc half a turn between each whack rather than trying to get the hammer in a different place. a normal hammer probably won't do much, heavy club hammer or sledge hammer is needed

[Albert27]

She's off guys after a few hits either side with two hammers.  On to the next disc after lunch!! Thanks for all the help - got there in the end!

[dezwez]

your welcome

[Albert27]

The job is done and the car is road tested - all is working fine!  I've wrecked a 3/8" ratchet through my own stupidity - it was a very basic cheap one one though so not too bothered and discovered a 1/2" breaker bar might come in handy in future.  I've got two questions now that I've done the job.

Do any of you open the bleed nipple when pushing back the piston?  I didn't bother as it was just another thing to do when I was already hitting problems (literally).  According to haynes there is a danger you can 'flip' the seals.  Just wondered what the general consensus was.

When refitting the caliper bracket, at one point it was making contact with the disc surface.  I shuffled it a bit and the disc and got it so it wasn't touching.  If I hadn't bothered, will the tightening of the other bolts like the guide bolts and wheel nuts make everything snug by the end?

[mrmetallica]

9 minutes ago, Albert27 said:

The job is done and the car is road tested - all is working fine!  I've wrecked a 3/8" ratchet through my own stupidity - it was a very basic cheap one one though so not too bothered and discovered a 1/2" breaker bar might come in handy in future.  I've got two questions now that I've done the job.

Do any of you open the bleed nipple when pushing back the piston?  I didn't bother as it was just another thing to do when I was already hitting problems (literally).  According to haynes there is a danger you can 'flip' the seals.  Just wondered what the general consensus was.

When refitting the caliper bracket, at one point it was making contact with the disc surface.  I shuffled it a bit and the disc and got it so it wasn't touching.  If I hadn't bothered, will the tightening of the other bolts like the guide bolts and wheel nuts make everything snug by the end?

i dont bother with the nipples .good idea to put some copper slip on back of disc so it comes of easier if need be

[dezwez]

I all ways take the brake fluid top off the master cylinder  and push the piston back very slow as for the bolts they will pull ever thing up to where they should be

when you tighten them

[Albert27]

42 minutes ago, mrmetallica said:

i dont bother with the nipples .good idea to put some copper slip on back of disc so it comes of easier if need be

I did this so all good there !

 

35 minutes ago, dezwez said:

I all ways take the brake fluid top off the master cylinder  and push the piston back very slow as for the bolts they will pull ever thing up to where they should be

when you tighten them

Cheers Dez.  I did the same with the MC and then used a baster to get the excess fluid out.  My only other screw up was the caliper dropped off the disc twice - not good for the brake lines i understand but i got there quickly and secured it with a bungee cord to that giant spring by the wheel arch.  Doesn't appear any damage is done so got away with it!

[isetta]

it's best to tie the calipers up at the start. however sure you think you have it resting/balancing on something you will accidentally knock it off.

I never undo bleed screw unless absolutely neccessary in case they snap or the thread strips. I have had ones that have snapped when I have replaced hose etc and then have to try to bleed air out of the pipe/hose connection which it not easy and would normally mean removing the caliper to get it at a certain angle

[Rockhopper]

Presumably you need a wind back tool to do this job?  Does it need to be the type that goes both ways?

[Albert27]

3 hours ago, Rockhopper said:

Presumably you need a wind back tool to do this job?  Does it need to be the type that goes both ways?

Yes you do.  They're different sizes for the front and back though.  The dual laser tool just about fits the front (£11 from amazon).  For the rears I bought a wind back set from eBay for £11 with lots of different adaptors and a clockwise/anti clockwise tool.  I think the latter would do front and back but I made the mistake of buying the laser tool first and then getting stuck in the middle of doing the rear pads!  Thankful for good neighbours who lent me a set 

[madmole]

Open the nipples and then you can just put a screwdriver between the old pads and twist. quick and easy and has the advantage of getting rid of the oldest and should be replaced brake fluid. Your gonna need to bleed em anyway when your done, and your supposed to change the brake fluid every few years so flush it through

Lots of copper grease on all contact surfaces of disk to hub is the big secret

[stef123]

No wind back tool required for front calipers. A pair of grips or clamp of sorts is enough. 

[mjt]

I find a suitable-sized G-clamp is very good for pushing the pistons back. Whatever you use it's importand to push them back squarely. I agree with Madmole, the fluid in the caliper will have been exposed to a lot of heat and moisture so it's best to clamp off the brake hose and crack open the nipple while pushing the piston back otherwise you run the risk of returning contaminated fluid back into the reservoir.

[stef123]

Thousands of cars probably have new pads fitted daily, how many do you ever hear of problems because 'contaminated' fluid has been pushed back into the resevoir.

if ever it was a problem it's down to the owner not changing the fluid at the specified intervals. 

If anyone changing pads wants to do a proper job then perhaps they should just do the fluid while they are there and have the wheel off.

I have fitted countless sets of pads and never once opened a bleed nipple and quite frankly never will, I don't see any need.

just my 2p worth. 

[madmole]

and how many owners or garages do you think actually change the bike fluid at the correct interval?

Bleeding some out doesn't hurt, avoids the chance of the reservoir overflowing  (and you having to get up from the wheel to check or remove some) and ensures that the brake fluid actually does get changed. 

Agreed on many cars it doesn't matter but on my old track mondeo the fluid was always darker than fresh fluid and I'd let it drain till clear (Brakes would get very hot on that car)

Only reason I wouldn't do it is if I was in a rush and didn't want to bleed the brakes, but doing it that way has worked well for over 35 years for me, also do the same for disk brakes on bikes and I service them as a business (although a lot now don't have bleed nipples!!)

[stef123]

But if you ain't paying them to do it then they ain't doing it, the garage can only recommend it to be replaced - which many probably won't because in this day and age would cause a witch hunt because someone is looking for business.