For quite some time now I've got front left brake drag - all wheels spin freely, only that one has got drag. Months ago I bleeded all brakes (and clutch), and of course exactly on that front left caliper I broke the bleeder valve -.-'

 

So today I got down on the car to fix the torn bleeder, but first I dissasembled the brakes so I can clean and lube everything and put back in place - immediately a problem arose. I took out the upper guide pin, it was completely dry, but functional. Then to take out the lower guide pin - STUCK! The lower guide pin rotates freely but wont come in or out even a milimeter!

 

My question is: Is it normal for the lower guide pin to not move in or out (thus preventing the caliper to move freely, and of course being unable to clean or lube the pin)??? If not, how is it possible it's stuck, how to get it out? I've tried carefully hammering it but it won't move. I've also noticed that it looks different than the upper pin (maybe not stock?). Again, it rotates freely without a problem.

 

Other than the stuck pin, I'm ashamed to admit but the complete caliper assembly is in horrible condition (that's what u get when using cheap mechanics...), the piston is corroded (also barely moves in or out), bleeder valve stuck and broken, lower guide pin stuck and everything is dry.

 

Sorry for the long post, I'm just curious. Thnx for the answers in advance.

 

P.S. of course, I'm getting a new caliper, this one is FUBAR.

Can't answer your question about lower caliper bolt but funnily enough 3 mins ago I ordered some red brake grease for the sliding caliper bolts on my rear calipers as just read copper grease is a big no no .

Just wondering what your going to use for lube ?

I think silicone paste all the way.

 

Subquestion - googling on removing calipers, what's the best way to remove them? Clamp the brake line or not? How long can an unclamped line drip?

It is not normal for the lower guide pin not to move out, the problem is just down to strange design.

The lower pin is different from the upper, it has what is like a small rubber sleeve 1/3 of the way from the end, with age this stretches allowing it to come out of its grove and move down the pin, where it then gets stuck between the larger end of the pin and the hole its in preventing removal but allowing it to rotate. I got mine out by taking it all off and using a bench vice while both pulling and twisting.

 

A new carrier won't actually help this problem as the pins are part of the carrier, you can however just remove the rubber sleeve completely from the pin, as a new one is only available as part of a brand new carrier.

 

But if the caliper is in poor condition as well you might as well get a whole new refurbed calliper and carrier, or even consider upgrading to 312's it won't be much more.

Edited 19 January, 201412 yr by tech838

It hurts when ever I find that someones put brakes back together using copper grease on the slide pins, its an anti seize compound not a lubricant, always use a high temperature silicone based grease.

 

As for clamping, I do, but someone will be along to argue not to, just do not let the reservoir run dry as you will need a VAGCOM cable to bleed the ABS pump when you're finished.

 

Good luck

Edited 19 January, 201412 yr by tech838

Update, I've given the calipers in for refurbishment, both front caliper refurb cost me just under 100€. The lower guide pins were stuck because previously the pins were obviously lubed with wheel grease, which, by the words of this brake specialist, make the rubber expand - thus seizing. I have one new piston, the other one was just polished. All seals were changed to new, torn bleeder screw machined out, got new copper shims and silicone grease. Calipers were pressure tested - everything is OK.

 

So I've assembled everything back in place, meticulously cleaning and (silicone) greasing every bit. What a great feeling!

 

Now a few questions for the experienced ones of you:

 

1) what is the best way from keeping brake lines (banjo bolt) dry, without brake fluid dripping, when removing calipers (crimping the brake line is not an option for me)? I used plastic bags, duct-tape and plastic ties, but still they were dripping just a bit (did not however dry out the fluid reservoir).

 

2) the brake fluid reservoir on the vRS does not have a min-max level. Whenever I topped up it just dropped to the middle, without any real effect when dripping or brake bleeding... Is this normal? Does the reservoir have and overflow feature or whatnot?

 

3) the car still has a bit of brake drag (eg. still stops quite quickly when rolling at just a few km/h's, and won't move on slight uphills/downhills) - although the front left wheel can now be rotated by hand, which was nearly impossible when the piston was seized. Please reassure me that once the new pads are bedded in the brake drag will go away 

 

4) My brake pedal is now a bit soft once the engine is running (while engine off, the pedal is firm as stone) - is it necessary to bleed all four wheels when changing calipers? I've gravity bled the fronts, and then by pressing on the brake pedal (alone), taking care no bubbles return to the calipers. I'm about to bleed all brakes, but wonder if anything might have gone wrong (air into the master cylinder)?

 

Thanks for the answers in advance and sorry for the long post - I just love DIY's!

Can't answer your question about lower caliper bolt but funnily enough 3 mins ago I ordered some red brake grease for the sliding caliper bolts on my rear calipers as just read copper grease is a big no no .

Just wondering what your going to use for lube ?

Wow you learn something new everyday.

 

I shamefully have to admit I used Copper slip to grease the sliding pins when I fitted my 312 brake upgrade. Looks like I'll have to invest in some red brake grease and re-grease the sliding pins.

 

I have some braided brake hoses to fit plus the rear calipers are binding, so it's not too bad.

 

Cheers for the info.

Wow you learn something new everyday.

 

I shamefully have to admit I used Copper slip to grease the sliding pins when I fitted my 312 brake upgrade. Looks like I'll have to invest in some red brake grease and re-grease the sliding pins.

 

I have some braided brake hoses to fit plus the rear calipers are binding, so it's not too bad.

 

Cheers for the info.

 

Red brake grease is normally red (rubber) brake grease, not for use with metal sliders, as said earlier, only use silicon grease.

 

Years and years ago, brake Girling used to market red brake (rubber) grease and blue (mechanical) brake grease, just a useless fact!

Edited 30 January, 201412 yr by rum4mo

Red brake grease is normally red (rubber) brake grease, not for use with metal sliders, as said earlier, only use silicon grease.

 

Years and years ago, brake Girling used to market red brake (rubber) grease and blue (mechanical) brake grease, just a useless fact!

All knowledge is good knowledge.

To answer myself partly (question 4), did all wheel brake bleed procedure yesterday and the firmness returned, all is as it should be. Odd enough, the rear left caliper had quite a lot air in it - how it got there, beats me. I've even bled all brakes and changed brake fluid less than half a year ago...