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Rear brake pad clearance

Posted: Tue Jul 05, 2011 3:34 pm
by bytecode
Hi again everybody.

I'm in the process of replacing the brakes on the 406 2.0 HDi 90 estate; new discs front and back, new pads and new shoes for the handbrake mechanism.
The fronts were a doddle, the rears however...

I've been working on them since Saturday (it's now Tuesday) and I'm supposed to be at work 27 miles away!
But...

There just doesn't seem to be enough clearance between the new disc and the pad - I've pushed the caliper piston fully back into the caliper - but the caliper wont come "outboard" enough to allow the outer pad sufficient clearance to fit in against the disc.

Is the lower rubber boot that the regular bolt goes through supposed to retract also somehow?
If so - any tips :-D
If not - is there something else that I'm "missing"?

Please see image via link below to see what I mean:
http://www.flickr.com/photos/50288784@N ... hotostream

Any info greatly appreciated, thank you.

B.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 4:34 pm
by steve_earwig
The pins should push in & out fairly easily but they're prone to rust.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 4:53 pm
by bytecode
steve_earwig wrote:The pins should push in & out fairly easily but they're prone to rust.
Hi Steve,
When you say "pins" are you referring to the two guide pins that are retained by "R" clips that pass through the holes in the pads ?
If so - they aren't what I'm referring to...

it's the Lower bolt boot that I'm talking about.
:)

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 5:12 pm
by steve_earwig
Where the caliper is bolted to the huband inside those boots are two pins.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 5:16 pm
by bytecode
steve_earwig wrote:Where the caliper is bolted to the huband inside those boots are two pins.
Ah! hidden inside the boots?
Ok, is there a guide as to how to get inside the boots?
Or do I have to hit it with a hammer?

Thank you for the reply :-)

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 5:41 pm
by omega
a quick fix would be to use one of the old pads.
if its a sliding caliper remove one pad then use a lever [big screwdriver] to move the caliper across.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 5:49 pm
by trem1
does this help

Image

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 6:05 pm
by bytecode
omega wrote:a quick fix would be to use one of the old pads.
if its a sliding caliper remove one pad then use a lever [big screwdriver] to move the caliper across.
Hi Omega - I'm not sure of the technique that you're suggesting - the problem with the old pads is that they are worn and scored.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 6:10 pm
by steve_earwig
You're just using them to push the caliper about so it doesn't really matter.
bytecode wrote:Ok, is there a guide as to how to get inside the boots?
Not that I can find, I did start doing a guide to changing the things but it was such a pig of a job with the fiddly little rubbers I stopped taking pictures :frown: All you need to do is get them moving though.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 6:11 pm
by bytecode
trem1 wrote:does this help

Image
Hi Trem1,
thank you for the diagram -
The one that I'm having trouble with is the one that bolt number 8 goes through.
I'm guessing that "box-out" number 6 (or maybe 10) is the portion that the bolt number 8 goes through - if so - I'm guessing that this is supposed to move freely (it's not moving freely).

Just to clarify - the bolt "unbolts" and comes out freely - but the "tube" that it goes through doesn't.

I tried getting my grips on the metal flange of that portion and twisting to see whether it merely needed rotating - but no luck (I don't want to give it too much force) - any ideas?

I also tried getting a clamp onto the caliper to try pushing the "tube" back through the caliper - similar to pushing the main piston back in - but it doesn't feel like it wants to do that either - and again, I don't want to force it if it's the wrong thing to do.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 6:49 pm
by steve_earwig

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 6:59 pm
by steve_earwig
Some pictures here (downsides it's a pdf and it's in French...) http://www.coupe406.com/documents/Tutor ... a_main.pdf

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 7:05 pm
by bytecode
thank you for that pic.

I have removed the "metal end cap rings" by twisting.
I've managed to push the rubber boot back and get some WD40 in - but the tube still wont budge.
The in-board side of the tube is pretty corroded inside the rubber boot - it felt like it was full of Rice Crispies!

The tube (what is it called anyway?) wont budge in-board or outboard, and with the caliper on the car, I can't think of a way to get my clamp on it in a reliable fashion.

I'm going to try again with some grips to induce some movement - but I don't have high-hopes of achieving anything.

Option B was to remove the caliper and get it into a vice to work on it - but I can't undo the (brass?) union nut for the brake fluid pipe.
I tried cutting a slot through the "ring" of a spare 11mm ring spanner with an angle grinder in the hope that it would offer more purchase without rounding out the nut - but no luck there either - it continued to round it out anyhow.

I'm running out of WD40 too.

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 7:07 pm
by bytecode
steve_earwig wrote:Some pictures here (downsides it's a pdf and it's in French...) http://www.coupe406.com/documents/Tutor ... a_main.pdf
Ah... the "tube" has a helical thread around it - so it must be wound? Thank you - back to the grips again :-)

Re: Rear brake pad clearance

Posted: Tue Jul 05, 2011 7:42 pm
by steve_earwig
There's no thread, that's just so the grease gets distributed. Shame Pug forgot to add any :roll: