Disks down to 20 mm

526 Views 6 Replies 5 Participants Last post by Baldrick, Mar 5, 2010

ronniescot

Discussion Starter · Mar 3, 2010

Just did a rear caliper on my Mk 3 Mondeo. Now looking at the front disks which are down to 20 mm. I have a couple of questions about fitting the replacements.

First off, am I correct in thinking I don't have to undo the giant nut at the middle of the hub? I think I should just remove the caliper and then knock the disk off, Right?

Second, the instructions that came with the new disks tell me to use a dial gauge to ensure the run out on the spinning disk is less then 0.15 mm. I have read some of the other threads on the subject of replacing the disks and none of them mention the gauge. Do I really need it, and what to do if they are more than 0.15 mm out?

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motorman116

· #2 · Mar 3, 2010

Ok you dont touch the centre hub nut.
Undo the 2 13mm nuts to remove the caliper
Undo the 2 15mm bolts on the carriers (they have been known to be 13mm also)
Then remove the disc

Clean the hub mating face with a wire brush, make sure its nice and clean
Clean the new disc, with brake and clutch cleaner, and then fit
Clean the brake pad carrier and refit
Lubricate the top and bottom of the brake pad, with copper grease, where it goes onto carrier
Undo the Brake res cap, then push back the piston into the caliper, then refit caliper,

Then do the same for the other side
once all done pump the brake pedal, till pedal comes up to the top and goes solid, then do up res cap on the brake fluid res.

As for the run out guage, you dont normally use these, unless you have problem with warped discs

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Morbidos

· #3 · Mar 3, 2010

motorman116 said:
Ok you dont touch the centre
Clean the brake pad carrier and refit
Lubricate the top and bottom of the brake pad, with copper grease, where it goes onto carrier

Not offence

Put copper grease on the carriers instead, this keeps them from jaming up, if you put the copper grease on the pads it will only lube utill the pads move over 4mm then the grease have worn of and is no longer effective!

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ronniescot

Discussion Starter · #4 · Mar 4, 2010

Thanks for all the advice. The job went without a hitch and I spent a very pleasant day in the sun messing with the car. Knocked the old discs off with a 3 lb hammer (it would have been impossible with a standard 12 oz household hammer). Got 140K on the clock, so this pair of disks will probably take the car through to the end of its life, certainly in my ownership.

I should say that the hardest part of the job was the rubber grommet where the handbrake cable is attached to the rear caliper. Just could not force it through the hole. Then my dad reminded me how to do it. You tie a loop of string round the grommet, pass the end through the hole and pull the grommet through. Its much easier to pull rubber than to push it.

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ronniescot

Discussion Starter · #5 · Mar 4, 2010

PS I've been changing brake pads on cars for 30 years and have never used copper grease and never had a squeak. I think the mistake you guys are making is to clean the caliper.
:content:

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The Guv.

· #6 · Mar 4, 2010

It's common practice in the trade to use copper grease. Unless everyone else has it wrong, it's right.

I didn't have any copper grease when I needed to get my transit through the MOT, put new pads straight in, squeeks at slow speeds when braking. Applied copper grease when I had the chance, all's good.

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Baldrick

· #7 · Mar 5, 2010

ronniescot said:
PS I've been changing brake pads on cars for 30 years and have never used copper grease and never had a squeak. I think the mistake you guys are making is to clean the caliper.
:content:

Am sure some do both on here, I myself do, I would never build one back up with out putting copper grease on, no matter how clean I get them. I know the trade do that care for there customers and do I proper job.

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