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mgf
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Discussion Starter #21
Anyone who has squirted WD40, or freeing oil into the brake actuator mechanism to free it, ( and YES thats ME INCLUDED should read this

http://www.youngsgarage.uk.com/Brake%20Lubricants.htm


For lubricating hydraulic components such as the piston seals inside calipers and wheel cylinders, you can use a silicone-based brake lubricant or ordinary brake fluid. This type of lubricant will help assure smooth movement of the seals in their bores, and will help prevent these parts from sticking or corroding.

RED RUBBER Grease, i guess probably found in a motorbike service agent.. - not listed at Halfords or Wilco.... or a dedicated silicone grease..

NOT WD40... ETC ETC anything petroleum based will naff the seals...

so i am glad i bought a new seal kit.. and havent put any of them in yet...

i need the right grease first.

And i will now never be tempted to put anything else in that actuator bore...

:)
 

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Discussion Starter #22 (Edited)
OK..

I got some red rubber grease and some silicon spray..

but.. for those who dont know... red rubber grease is not compatible with mineral oil based brake fluid..

You need DOT5 silicone fluid in your system to use red rubber grease anywhere the fluid and the grease come in contact.. and where will that happen..?

in the actuator shaft, because you want to put, red rubber grease in there to lubricate the outer rubbber seal of the actuator, the bore with its needle rollers in, and the pin that pushes the piston drive shaft..

and there... because the O ring has fluid on one side and red grease on the other, is where the two will come in contact..

Castrol make red rubber grease, for example. and say specifically, that it should not be used in brake systems where it come in contact with mineral oil... but that silicone DOT5 fluid is fine..

http://www.bp.com/assets/bp_internet/castrol/castrol_south_africa/STAGING/local_assets/downloads/t/Red_Rubber_Grease_TDS.pdf

Silicone brake fluid and silicone grease and red rubber grease are compatible... mineral oil brake fluid and silicone grease and red rubber grease are not.

Mineral oil brake fluid should not be mixed with silicone brake fluid.. (this is because mineral oil brake fluid absorbs water uniformly ) DOT5 silicone rejects water.. it doesnt mix..

so.. if you want to make your braking bullet proof.. like me :) and know that you have done as much possible to eliminate stuck handbrake problems and naff braking...

Then, like me you can totally drain your brake system.. when you have 4 good serviceable calipers ready.., dry it.. or force dry it.. and refill with DOT5...

DOT5 does not need replacement like mineral oil brake fluid.. it wont degrade over time ( even though the pipes might ) and doesnt mix with water at all..

then you can use silicone based grease and spray.. for assembly of external seals... and just brake fluid for internal ones.. like the piston seal and its drive shaft O ring...

:)

PHEW... this becomes more involved all the time... but i now have a much better understanding of why the handbrake and piston assemblies are easily made scrap.. by using petroleum based lubricants, that destroy the seals, and boll ocks up the brake fluid in the piston, and that though you can put silicone based fluid in a system with mineral oil or glycol in it anywhere, the result will be you have weakened it....

which leaves me with the problem of using red rubber grease, and say DOT 5.1 fluid....

i just dont think i can get all the glycol fluid out of the system, to replace it with silicone...

and though i know, there is incompatibility with red rubber grease, and glycol DOT 5.1 i am just going to live with that knowledge and see how the reconditioned brakes work.. and then know i have to keep changing the fluid... after all said and done, the cars i have - have met the MOT standard for over 9 years of their life now... they are going 12 years old.
 

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mgf
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Discussion Starter #23 (Edited)
ive added some pics further back showing the outer caliper disassembly, and today i am going to reassemble the caliper so will post pics of that..


does anyone know what the torque pull of the handbrake is? ie how much effort the handbrake cable is pulling when used? i want to make a bit of kit to
check the calipers for leaks and effort, before i say they are good enough..

so having such knowledge would help.. else i`m guessing..
 

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This is a great thread! Thanks for taking the time to assembly it with all these great pictures. I now feel confident that I could rebuild the rear calipers.

One comment though, not all read grease is the same. Many a Lockheed and Girling m/c rebuild kits for cars like the MGB would come with a packet of red grease to be used during reassembly on systems where DOT3/4 was being used, not DOT5.
 

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Discussion Starter #25 (Edited)
Yeah i understand, and thats why....... given the expensive option of using DOT5 - silicone base, is one ive decided to NOT follow... even though, i know that red grease should only be used in places where it and glycol fluid ( like DOT 5.1 etc ) does not come in contact with it..

It is a problem i cant aford to resolve, since bleeding and drying the whole braking system of DOT 5.1 fluid so i can use Silicone.. is just too much of an unknown consequence for me to consider.. in effect the only way i could do it, would be to scrap the whole braking system bar the recon calipers.., and replace all the pipes etc with new..

i cant afford to do that... right now..its why i decided to recon the brakes myself and save money..

so.. im going to live with the consequence of red grease on one side of the piston drive shaft O ring and DOT 5.1 on the other, at least its better i think than WD40 and freeing oil on one side... :) since though red grease can enter the piston bore past that O ring.. it wont degrade the O ring.. since its compatible with it.. it just shouldnt be in the piston bore, but the amount that does go through, will be tiny.. certainly no worse than natural ingress of moisture affects brake fluid...

CERTAINLY... anyone who has used a freeing oil to free up that handbrake actuator mechanism, must now know, reading this topic, that what they have done.. almost certainly means that O ring has degraded ( the one i took off, did not look anywhere as good as the new one i put on ) and that they probably have put freeing oil into the piston bore.. past that degraded O ring.. and that brake fluid can now escape into the actuator housing.... and that brake fluid atracts moisturs and rust... and why probably, the actuator siezed up in the first place... brake fluid in it..
 

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Discussion Starter #26 (Edited)
STEP7.

With all the bits ready to go back together with new seals...

Im going to be using Red Grease for the outside of fluid seals, and DOT 5.1 Fluid in the internal brake seals.


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 011a.jpg


1. the first thing to do was put back in the actuator assembly, i used some red grease and a paint brush to coat the needle rollers and inside of that bore


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 001a.jpg

2. then i filled the actuator hole, where the pin will go with red grease..


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 002a.jpg

3. The hole in the actuator when inserted in, must be facing the piston..., it will slide in without force, and turn easily... since there is no pin in it yet... be sure that when you have put it in.. you are sure its the right way round, ;) and that the needle rollers are not blocking the shaft hole for the pin.. its easiest if the dust seal is put in first then you can slide in the actuator.


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 003a.jpg

4. the actuator fitted the right way round with its seal.. job done.. then one can insert the backing plate into the piston base, it is obvious how it goes in, its got a central locator bush on it that fits the piston housing.. - then assemble the drive shaft with its new O ring, and a little red grease to secure the pin in its end ( REMEMBER - NO GREASE ON THE O RING you can lube it with DOT 5.1 though..) and screw on the piston screw thread housing since it gives you something to hold and push on.. ( look at the prevous pics to see those in bits )

its an easy hand push... all one needs to do is make sure that the pin goes into the shaft.. and it will meet the actuator hole... then remove the outer piston screw thread.. and check that the base plate and the shaft are sitting right...


www.incony.org/webpics/MGFRearBrakeStep7Sept2012 004a.jpg


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 006a.jpg

5. with the shaft home in the bore, one needs to fit the circlip that holds in that base backing plate
These long reach ( 50mm) right angle circlip pliers are vital to do that..

http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 006a.jpg

its a fiddly job... one can use a flat blade screw driver to get the circlip to stay level and not tilt... and again.. like in the above picture check that the circlip is in.. and free to rotate in its housing..

6. one can try the spring housing in the bore, without its spring fitted, to see that it will go in clean.. and lay with all its feet flat... before one assembles the spring compressor... and then inserts the washer, spring, and spring housing, and pushes it in hand tight..


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 008a.jpg


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 009a.jpg

7. The circlip that holds that lot in can now be put in.. and again its fiddly.. a flat blade screwdriver can help keep the circlip flat on the spring cover feet..


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 009a.jpg

8. If youve done it right.. you will now have a fully functional actuator :) and one can check its operation now using a 12mm spanner one will be able to feel the force of that spring as one turns the spanner.. and feel the piston drive shaft rise as the pin is pushed.. by the actuator.


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 010a.jpg

9. Reassemble all the parts of the Piston internals, with its new seal... the circlip for that only needs hand pressure, and a little jiggling - no big spring to compress .. :)

One can now fit the new piston seal in the bore, and test fit the outer seal.. and lube the piston with DOT5.1


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 012a.jpg

its best if the outer seal is first put on the piston half way.. and not fitted to the bore, ie the seal is on the piston.. since that means the the bore part of that seal can be introduced and fed in, without the bottom of the piston in the way.


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 013a.jpg

10. once the outer seal is in , its top edge which will never see, DOT5.1 fluid.. can be lubed with red rubber grease.. and as the piston is turn in, the two will mate up..


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 014a.jpg

11. one can now refit the the Handbrake lever arm to the actuator... and its securing bolt and the external spring.. the lever arm needs a jiggle with a pair of long nose pliers, since now its working well its putting some force against lining up to the lever arm.. and the two are a snug fit..


http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 015a.jpg

12. Now one has a working assembly one can refit...
I pumped some DOT 5.1 into the piston with the bleed nipple open, to A, put fluid in the bore, and B, flush out anything i might have introduced getting it back together.. i just used a new unused finger oil pump can.. and filled it with DOT 5.1.. and injected it in through its old cut of brake line.. it worked well i got a few psi pressure in it from that little hand pump... and the fluid squirted out..:) not enough to move the piston but enough to flush it well.



http://www.incony.org/webpics/MGFRearBrakeStep7Sept2012 016a.jpg

all ive got to do now is fit it... and try it..

Costings -FOR ME TO DO TWO CALIPER PER1 (TOTAL)
The two wheel assemblies complete with brake calipers £25 (£50)
The Right Angle Circlip Pliers £8 (£16)
Red Rubber Brake Grease - 1 Sachet £0.50 (£1.00)
DOT 5.1 Brake Fluid For Flushing / Lube - 1/4 Litre £3 (£6)
BIGG RED seal Kit - for two calipers £16 (£32)
Brake cleaner Solvent 1 Can. £3 (£6 )
Sundries .. Things i already had £5 (£10)

Totals £60.50 £121

so for about £120 i will have two properly reconditioned calipers complete with serviceable brake pads, serviceable brake discs and hubs.. (2012 prices)



END OF STORY - RIGHT NOW :)
 

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Mineral oil brake fluid should not be mixed with silicone brake fluid.. (this is because mineral oil brake fluid absorbs water uniformly ) DOT5 silicone rejects water.. it doesnt mix..
just found this, very good write up.

but there may be some confusion.
mineral oil braking fluid is very rarely used, in some Rolls-Royce and Citroen for example. it has nothing to do with the regular DOT3/4/5.1 glycol base braking fluid. it does not absorb water, beeing an oil it does not mix easily with water, just like silicone braking fluid.
even if this sounds like an advantage, it can be a big disadvantage. the glycol fluid absorbs water, you may say it dissolves it to stop the water making rust inside the calipers (up to a level, but you change it on a regular basis anyway, don't you?). the water, beeing the normal humidity in the air, condensing inside the open to the air reservoir will collect at the lowest point beeing heavier than mineral oil and silicone fluid. sadly this is mostly the calipers/wheel cylinders. and it doesn't take much and the parts start to rust. just the thing you wanted to avoid. and the water droplets may start to become vapor under heavy breaking, giving no brakes as worst case.
most say that the silicone fluid won't need regular replacement. that may be true with trailer-queen or other seldom driven cars. if you use such a car as an every day drive you should replace it at the same regular interval as glycol fluid because the fluid itself wears (getting hot and under pressure) and you should remove the particles from the seals as they wear. some may have seen this as black steaks from bleeding very old fluid out of a neclected system.
and as a side note: someone at a Harley-Davidson dealer told me that H-D uses silicone fluid from the factory and they advice to replace it regulary with service. and the US Army manual, for converting the vehicles, states to use only fresh fluid, if it has changed the color don't use it.

i'm not against silicone braking fluid, if you like it, use it. even if it's just for the color. but it may not be as service free as it may seem.
 

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Aaargh!
Incony you keep giving me work!!!

I just completed replacing my timing and VVC belts by following your excellent "How To". Then while the car was up on ramps I realised the handbrake was sticking on one side. Now I find this "How to" for brake rebuild and I am going to have to do it too.

HAVE YOU NO HEART???


Just kidding, Really glad to see this as I can't afford new callipers and am reluctant to buy used ones which are probably as bad as my own. I just ordered a repair kit off Big Red on Ebay so will have a fun job ahead. Just have to make sure I don't use the handbrake for a few days or keep a mallet and screwdriver handy to knock the leaver back to the off position.


Handy tip to use a bolt with PTFE tape too.
 

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mgf
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Discussion Starter #29
well.. at least you might be saved making the same mistakes as i did..

laughs... remember incony changed his cambelt three times before he was sure it was right.. and took his brake calipers apart twice, because he didnt understand how they came apart..and nearly missed changing the most important bit inside them..

maybe i should call them "how not to`s "
 

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LOL, Even with your How To I still managed to cock up the VVC belt. I refitted it at least 5 times before I got it right. Also just as I was congratulating myself (and being a little smug too) on being able to get the tensioning spring on I then remembered I forgot to take it off again. Doh! No way am I stripping down again to remove it though. The old spring was still there when from the last belt change so I figure it will probably be ok.
 

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I had a sticking nearside caliper.

When I looked at it I noticed that the actuator was sticking on release, just enough to bind the pads onto the disc and it was possible with very little encouragement to release it fully. So I removed the spring off the handbrake actuator lever which I found to be quite easy, i.e. not much spring compression which got me thinking.

On removal I bent the ends of the spring a little in such a way that when refitting, more effort is needed to fit it, therefore the spring has more 'springback' certainly enough to push the actuator back to it's fully open state. Note, when the spring and actuator arm where removed I did work the actuator to free it a little.

Since then it hasn't stuck despite not being driven every day! I am sure I have simply postponed the inevitable, but it worked for me and got it through it's MOT in August.
 

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Discussion Starter #32
I had a sticking nearside caliper.

When I looked at it I noticed that the actuator was sticking on release, just enough to bind the pads onto the disc and it was possible with very little encouragement to release it fully. So I removed the spring off the handbrake actuator lever which I found to be quite easy, i.e. not much spring compression which got me thinking.

On removal I bent the ends of the spring a little in such a way that when refitting, more effort is needed to fit it, therefore the spring has more 'springback' certainly enough to push the actuator back to it's fully open state. Note, when the spring and actuator arm where removed I did work the actuator to free it a little.

Since then it hasn't stuck despite not being driven every day! I am sure I have simply postponed the inevitable, but it worked for me and got it through it's MOT in August.
yes.. a fix that worked is all it needs to be..

what it tells you, and you know that, i sense from your post i quote...

is that the cause isnt the spring.. since only you have changed its spec,

and likely - the cause is something else.. like a contaminated actuator roller bearing mechanism, or a contaminated actuator pin shaft, or pin shaft seal, sticking in the shaft.. or something else, even a piston sticking.. and holding the shaft.. and actuator just at one point..

:)

but.. quids in.. a fix is a fix...

folks have used wd40 to get a handbrake working again..

a fix is a fix..

not a solution..
 

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I had a sticking nearside caliper.

When I looked at it I noticed that the actuator was sticking on release, just enough to bind the pads onto the disc and it was possible with very little encouragement to release it fully. So I removed the spring off the handbrake actuator lever which I found to be quite easy, i.e. not much spring compression which got me thinking.

On removal I bent the ends of the spring a little in such a way that when refitting, more effort is needed to fit it, therefore the spring has more 'springback' certainly enough to push the actuator back to it's fully open state. Note, when the spring and actuator arm where removed I did work the actuator to free it a little.

Since then it hasn't stuck despite not being driven every day! I am sure I have simply postponed the inevitable, but it worked for me and got it through it's MOT in August.
I thought of doing that but dismissed it as being a silly idea. Maybe not so silly after all, in fact I might give it a try myself before going to all the trouble of rebuilding the caliper. Even if I only get another few months out of it.
 

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I thought of doing that but dismissed it as being a silly idea. Maybe not so silly after all, in fact I might give it a try myself before going to all the trouble of rebuilding the caliper. Even if I only get another few months out of it.
You don't need to bend each end by very much, probably 2-3 degrees. You will be able to tell when you come to refit it, and it should pop the actuator arm back open position without any encouragement.

As Icony has said it is only a 'fix', how long it lasts we will have to wait and see. A refurb of the caliper or a 'new' refurbed caliper is the best solution, I think we all agree?
 

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Yipee! it worked. I bent the spring buy putting it in the vice and twisting it with a pair of pliers. Now the handbrake is back to normal. Only thing is I know it is only a temporary fix so I am now on the hunt for a pair of old rear cailpers. Condition not too important as I intend to recon them. Anybody out there have a couple of old duffers I can have for the price of the postage plus a couple of beers?
 

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Discussion Starter #37
Yipee! it worked. I bent the spring buy putting it in the vice and twisting it with a pair of pliers. Now the handbrake is back to normal. Only thing is I know it is only a temporary fix so I am now on the hunt for a pair of old rear cailpers. Condition not too important as I intend to recon them. Anybody out there have a couple of old duffers I can have for the price of the postage plus a couple of beers?
:) that made me laugh, Alibro, thank you. now you know where i started from.. mine were £25 each off ebay..

you will be making a " how not to" next...
 

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I sourced a pair locally for £30 from a disheartened F'er who is breaking his car, pick them up Monday. Look out for the How NOT to coming your way soon.
 

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Aaaargh!
Got the calipers a couple of weeks ago and, as you do dumped them in the corner. Had a go at stripping them last night and found they are in a bad way. One of the bolts was so corroded I had to cut it off. Then I checked the pistons and found one was seized. So after quite a bit of thumping, banging and not a little swearing I finally got it out but it remains to be seen what damage, if any has been done.

Also ordered these, http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=290839999235 Will report back if they do the job.
 
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