Caliper seizing... the what, the where and the why.

[I-S]

Kieran and I spent a very productive day messing about with my GLS. On the agenda was some thorough engine servicing, and as a "nice to get done" were looking over the brakes. Again.

First point about the brakes was that the calipers were seizing up again, although I'd discovered a sort of temporary work around. The Ceratec grease was totally useless for the brake pins, but worked fine on the back of the pads.

We dismantled the brakes as usual, and determined that the cause of the seizing is the seal boots that the pins slide through. Two of them were extremely tight and no matter how well greased, the pin just would not slide easily.

So we went a step further than normal and removed the seals... the reason for the problem became pretty obvious. The seals have a lip on them that sits in a groove in the pad cradle. In the two cases where the pins were stuck, the groove was almost non-existant, filled with corrosion, muck and general "stuff". This meant that the seals were sitting in a smaller hole than otherwise they should, and so they exerted too much pressure inwards on the pins, preventing them sliding easily.

So, scraping the stuff out of the grooves, and replacing the seals and all of a sudden....


Oh yes. Oh very definitely yes.

Which prompted a rather strange look from Kieran.... a few minutes later when he looked at how it was working now he understood... His words


That's like new!

Now we just have to hope that the grease will hold up over time...

[Paul Beazer]

This sounds very similar to my mates mx3 problem. If i remember the boots go all the way through the caliper body and the pin slides through them. As you say rust and crap basically swell the pin and it siezes on the boots, jamming it solid. Very annoying. Hopefully you've got your brakes sorted this time!

[g6acb]

Good work Isacc / Kieran.... but......

14235

As a fellow GLS 'brake eater' it would be good to get this licked once and for all!!!

[I-S]

Afraid there are no pics (mucky hands, camera was inside, it was getting dark, cold, rainy, etc).

Can draw you a diagram perhaps... If you take the seals out of the cradle it will be obvious.

[g6acb]

14237


are these the thingymibobs you removed?

[I-S]

Yes.

This image shows a cross section of the seal (black) and the caliper pin (green) in the cradle (grey).

You can see how the seal sits in the groove in the cradle. When that groove fills up with crap then the seal is pressed inwards, putting too much pressure on the pin (ie gripping it too tightly).

[Kieran]

Only other thing to add is that we're on Grease #3 in the quest to find a suitable alternative to the Mitsubishi 'Special Grease' that coats their caliper pins. It looks like CV grease to me. This time we tried this:

http://www.clubvr4.com/forum/showpost.php?p=170841&postcount=37

And for anyone else reading this thread - read this one too!:book:

http://www.clubvr4.com/forum/showthread.php?t=14433&highlight=copaslip

[g6acb]

ok, so does clearing all the crap out put less imporance of what grease you coat the pins in or is the hunt still on for the mysterious mitsu red stuff??


// hehe beaten to it by K

[g6acb]

Kieran, did you cast your eye on the rocol stuff i mentioned on the other thread - is that in the right direction??

[Kieran]

Kieran, did you cast your eye on the rocol stuff i mentioned on the other thread - is that in the right direction??

I didn't Ade - I'll have a look.

[I-S]

I don't think it puts less importance on the grease... beyond the seal, the Ceratec grease had dried up and in fact become very sticky... It was perhaps making things even worse, and I only put it in in june (and the car stood for 3 weeks in that time too), so that didn't last long at all.

So far we know that copper slip and Ceratec do NOT work as caliper pin grease.

[psbarham]

i put fairly normal HMP lithium grease on the vr4 calipers that i fitted way back in may , and i noticed that when i put the new pads in this weekend it was still perfect , now i know its not ideal for the seals but it works for every thing else

[Kieran]

i put fairly normal HMP lithium grease on the vr4 calipers that i fitted way back in may , and i noticed that when i put the new pads in this weekend it was still perfect , now i know its not ideal for the seals but it works for every thing else

That's encouraging - The grease Isaac and I are now using is a synthetic, high temp/friction lithium grease. It's soap based so it shouldn't cause the seals to swell either.

[HowieP]

I now use Morris Lubricants Race Grease which is available from motorcycle shops. It says "Red, high performance, high temperature lithium complex grease designed to meet the high stresses found in racing applications". "An NLGI No.2 consistency grease". Another reasonable product is the clear gel looking grease that comes with Blue Print refurb calipers but I can't find out where they source it.

I am always trying to find ways of preventing the pins drying out as the same thing happens on my wife's Shogun that has the same brakes, slanted pad syndrome is very common.

[g6acb]

Good god it is windy outside - its woke me up and I can't get back to sleep - and I've been hitting the internet re the grease thing again......


This is lifted from the Pajero owners forum, written by a guy who works for mitsu



Posted: Wed May 03, 2006 19:03 Post subject: http://www.pocuk.com/forums/templates/subSilver/images/lang_english/icon_quote.gif (http://www.pocuk.com/forums/posting.php?mode=quote&p=365513) NOt standing on anyones toes , but the best lube for calliper slides is Rubber lube , it comes in tins or small satchet's always but always rember if yuo are going to rmove the callipers to clean and remove the small rubber bellows that ascs as a guide for the calliper slide , if yuo insert a drill a litte smaller than the calliper slide and rotate it a bit with fingers only yuo can remove or loosen a lot of the copper slip the mindless idiots have used in the past , then a quick blast with some WD 40 or the like will wash it out , now get a thin electrical screw driver witn a litte bit of thin cloth wound around it and remove the last of the dirt , now apply a bit of rubber lube to the screw driver and force it into the guide hole , a small quantity applited to the inner working diameter of the bellows and refit , now when reasebeling a small amount on the slide pin as yuo refit it and yuo will be well and truly protected from the road dirt and grime thrown at it , and at the same time putting it back to howe it should be , oh and remember Copper slip is for metal working faces , ie backs of pads and contact points only .

AS I say not standing on feet I worked for Lockheed for 5 years I have seen so many DIY mistakes all with the best of intentions , that it worries me so see how simple mistakes cost money and could cost a life .
I have a saying , if yuo run out of Engine oil yuo stop , If yuo run out of Brakes yuo dont . well yuo do, yuo can end up in a 6 feet pine box .

please please be carefull when working with brakes




bit dramatic at the end there but recomends 'rubber grease'

as sold on fleabay

http://cgi.ebay.co.uk/Castrol-Red-Rubber-Grease-4-Brake-Caliper-Rebuilds-100g_W0QQitemZ150076785598QQihZ005QQcategoryZ30917 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[White Lightning]

Good find Ade. :thumbsup:

Might have to give some of that a go myself ...

[I-S]

Think you might be about right there Ade... that looks remarkably similar to the Mobil stuff we used in mine last time out.

[psbarham]

the only problem i know of with rubber grease is the melting point , it is fairly low . but apart from that it makes sense

[g6acb]

http://129.35.64.91/bpglis/lubtds.nsf/technicaldata/DA9E707906915D4C80256C4E005B813F?OpenDocument (http://129.35.64.91/bpglis/lubtds.nsf/technicaldata/DA9E707906915D4C80256C4E005B813F?OpenDocument)

110 C
NLGI wotsit no 3 apparently


maybe the low temp is why it fails.... to much attention to keeping the rubber in good nick, not enough on longevity.... maybe the higher melting point of Kierans Mobil stuff would be better if it is as good for the rubber thingymybobs :book:

http://www.exxonmobil.com/UK-English/Aviation/PDS/GLXXENAVIEMMobilgrease_28.asp

[Kieran]

The only extra comment I can make is regarding it's NLGI classification... #3 is quite thick I believe, whereas the Mobil stuff is either 1 or 1.5. The reason I think this may be an issue is that it is possible to trap air in the pin cavities and cause them to keep pulling in. I think a thick grease might exacerbate this - also, the thickness might mean the pins are slow and 'draggy' in operation, perhaps? In real life I don't know how much of an issue this would be?:inquisiti

[psbarham]

i'll be the guinea pig , i'll grab some tommorrow and try it on the brakes ready for the mot , if it just needs a quick top up every oilchange and keeps everything sweet then that'll do me

[g6acb]

i'll be the guinea pig , i'll grab some tommorrow and try it on the brakes ready for the mot , if it just needs a quick top up every oilchange and keeps everything sweet then that'll do me


The pig's allready been guinea'd - its going in mine on saturday


Was thinking along the same lines - check at oil change, its can't be more than 30 mins work after all

[I-S]

Just to add to this...

My brakes still feel rather better than they did before doing this. When the pins weren't sliding easily it was hard to stop smoothly because as you let up on the pedal as the car came to a stop, the pads didn't move away from the disc... you let up some more and then they'd sort of "pop" away from the disc. You could not smoothly modulate the brakes, which is now possible.

I think my back brakes might want the same treatment...

[I-S]

So, how did it go Ade?

[g6acb]

All a bit pants really

Sourcing of grease was fine - under my nose all the time at the Autospares Place.....

But the brake people sent the wrong brakes - different brand to what I ordered and for a E88 Galant ?/Grrr ?


That problem has taken a back seat now though since after Mitsu replaced the Cam belt, tensioner, PAS Belt and Alternator belt on friday I have developed the most amazing tap tap tapetity noise at idle from nowhere - at 3000 rpm the is a vibration audiable in the cabin and over 5000 rpm it sounds and feels as if the enigne is going to lunch itself/help


Back again in the morning............

[I-S]

Ah. Bulwarks.

Hope you get it sorted painlessly!

[Paul Beazer]

All a bit pants really

Sourcing of grease was fine - under my nose all the time at the Autospares Place.....

But the brake people sent the wrong brakes - different brand to what I ordered and for a E88 Galant ?/Grrr ?


That problem has taken a back seat now though since after Mitsu replaced the Cam belt, tensioner, PAS Belt and Alternator belt on friday I have developed the most amazing tap tap tapetity noise at idle from nowhere - at 3000 rpm the is a vibration audiable in the cabin and over 5000 rpm it sounds and feels as if the enigne is going to lunch itself/help


Back again in the morning............
Aaah poo! Sounds like the timing "may" be out a notch. Drive it gently......

[Kieran]

That problem has taken a back seat now though since after Mitsu replaced the Cam belt, tensioner, PAS Belt and Alternator belt on friday I have developed the most amazing tap tap tapetity noise at idle from nowhere - at 3000 rpm the is a vibration audiable in the cabin and over 5000 rpm it sounds and feels as if the enigne is going to lunch itself/help

Hmmmm..... I wonder if they've left your balancer shaft belt a tooth out?

[psbarham]

Hmmmm..... I wonder if they've left your balancer shaft belt a tooth out?
thats what i would suspect , if the cam timing was out it would be a bit more than a rattle

[Paul Beazer]

Ok, but i was close!

[miller]

Ive just sourced a Carlube LM2 Multi Purpose Grease that is Lithium based and high melting point, i am about to replace my rear brake pads and use this for the caliper bolts. I think this is the right stuff, can anyone shout if they think its different? Ill check back in an hour when cars up, rear wheels are off and pads out.
If its not then its going back together without!!


Cheers

Mike

[Ryan]

When I suspected having a sticky caliper I used the same sort of compound (ie: lithium based).

So far so good!