Hi all!

 

About 6 months ago I replaced my front brake discs and pads, cleaned up the slide pins and the insides of the caliper where they live, and re-greased with silicone grease and reassembled. I noticed here that the one pin on both calipers seemed stiffer to get out (the one with the rubber sleeve), and just thought it was due to that. 

 

I had to replace my other brake disc backing plate on the O/S so had the brakes apart again, and thought i'd check the pins and possibly clean/re-grease them again. What became immediately apparant was that when I came to reassemble the caliper, the pin with the sleeve would absolutely not go into the caliper - when inserted the sleeve would ride up the pin meaning it couldn't advance. I checked for damage to the pin / caliper, cleaned everything again, took the sleeve off the pin (to clean out grease that may have got under it), put it back on, greased the hole and the metal part of the pin, and re-inserted it. I eventually got it back in, and it slides similar to how I remember they did the last time.

 

I wonder if the wrong grease has been used in the past (the old grease was totally black), age has caused it to swell, or just that my silicone grease may have affected them? Does anyone have a confirmation that 7N0698647B is the right part number (aftermarket, that comes with the rubber bit or boots/pins/rubber bit) for my car? and i'll remember to order some next time i'm disassembling the brakes - hopefully - not for some time.

 

Cheers

Edited 9 July, 20223 yr by micro

People use all sorts of grease on slider pins; usually what they have to hand at that moment. Quite a lot are unsuitable for long term use and will migrate from the bearing surface, damage the bearing surface, rot the rubber and generally cause headaches.

 

Silicone grease is not normally recommended for metal/metal surfaces and what you have may not have the high temperature / pressure specifications of a dedicated guide pin grease like Molykote G-3407 https://www.dupont.com/products/molykote-g-3407-caliper-pin-grease.html. Hard to find in small quantities but occasionally pops up on your favourite auction site.

 

Wurth make a brake paste but only rate it to 160C and not the 200C of the G-3407. But at least you can buy it easily in sachets. Or Proslip pin grease. Ceratec from Mintex is OK. New pins are cheap enough and will remove any doubts about galling caused by incorrect lubrication.

Yeah. I've used ceratec and didn't have problems.

 

To check part numbers you will need to confirm brake size / type or better the pr code for the brakes fitted. 

Aah, I was informed by my mechanic friend that Ceratec wasn't rubber friendly, and may cause the rubber part of the pin to swell (which I did wonder if that had happened causing the pin/rubber to not want to slide back into the caliper), from previous servicing though there was a pitiful amount of grease left on the pins when I went to disassemble the brakes the first time around. He recommended high temp silicone instead.

 

I'll definitely get them apart at the next available opportunity though and replace with Ceratec or other appropriate lube if that isn't the case though!

Edited 10 July, 20223 yr by micro

5 hours ago, micro said:

there was a pitiful amount of grease left on the pins when I went to disassemble the brakes

 

I have never seen any grease on factory fitment brake assemblies and have never ever used grease when refitting, if the pins are sticking I dismantle, clean and reassemble dry, the only sticking ones I have encountered had been greased which became contaminated by pad dust and road dirt.

Ceratec & other greases are absorbed by the plastic/rubber "bush".....been there done that..

 

Only use the caliper manufactures (TRW) grease on the slide pins which is PFG110

 

trw pfg110 grease - Google Search

1 hour ago, J.R. said:

 

I have never seen any grease on factory fitment brake assemblies and have never ever used grease when refitting, if the pins are sticking I dismantle, clean and reassemble dry, the only sticking ones I have encountered had been greased which became contaminated by pad dust and road dirt.

Given that the service manual specs grease (but not what kind), I'm not sure dry slide pins would be such a good idea...

 

Thanks @fabdavrav I'll grab some of that and replace the grease when I'm next able to!

I spend my time doing with dirty hands, not reading service manuals.

15 hours ago, fabdavrav said:

Ceratec & other greases are absorbed by the plastic/rubber "bush".....been there done that..

 

Only use the caliper manufactures (TRW) grease on the slide pins which is PFG110

 

trw pfg110 grease - Google Search

I have heard ceretec potentially causes issues with rubber, as it is still minetal based, but I have used it rebuilding brakes on a mk5 golf and mk2 vrs and got 5 years or more out of rebuilt brakes. If the pin had a tight interference fit with a rubber bush, rather than just a bellows or protective cover, I think I'd worry a bit more and consider other options. I'll note that trw grease for a next purchase! I use ceratec  sparyingly on metal pins and slides but not on  rubber parts directly. 

3 hours ago, TheClient said:

I have heard ceretec potentially causes issues with rubber, as it is still minetal based, but I have used it rebuilding brakes on a mk5 golf and mk2 vrs and got 5 years or more out of rebuilt brakes. If the pin had a tight interference fit with a rubber bush, rather than just a bellows or protective cover, I think I'd worry a bit more and consider other options. I'll note that trw grease for a next purchase! I use ceratec  sparyingly on metal pins and slides but not on  rubber parts directly. 

 

Most of the MQB platform..including your cars brakes have two pins on each caliper..& under the rubber bellows..one pin has a plastic/rubber bush on it..this makes the fit very tight..the other pin without the bush allows for "tolerance" due to various factors.....& thus the bush absorbs  the grease if the wrong grease is used..& thus the pin sticks & then the caliper sticks!!....Wrote off a new set of pads/discs that way!!!...So yeah feck Ceretec type greases!!

 

Also I don't use copper grease or Ceretec on the pad backs/pad ears......they all calcify & fail or wash out too easily.....I only use Loctite LB8009 heavy duty....high temp, graphite grease, won't wash out, won't calcify, safe on stainless steel etc...

 

Loctite LB 8009 - Google Shopping

 

 

Edited 11 July, 20223 yr by fabdavrav

Big redd ship new pins with silicone grease. Silicone seems to be the preferred option if not going for the expensive trw stuff. 
 

have also seen a tip that you can trim a bit of the rubber bush off if they swell, ie shorten it to allow more room for it 

I didn't know about the TRW PFG110 grease so I used the Permatex Silicon Ceramic Extreme which again says that it's for slider pins. TRW PFG110 is significantly cheaper..

16 hours ago, T07 said:

Big redd ship new pins with silicone grease. Silicone seems to be the preferred option if not going for the expensive trw stuff. 
 

have also seen a tip that you can trim a bit of the rubber bush off if they swell, ie shorten it to allow more room for it 

 

TRW stuff is cheap I bought two of the 25g tubes at under £6/tube...still on the first tube & I've done 4 calipers..!!...you don't need much...well there isn't room for much anyway!

 

The silicon stuff which will cause problems is just as expensive...then the double expense of new pads/discs as it eventually causes the caliper to stick due to it not being 100% compatible with the rubber/plastic bush...