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Remover front caliper

N

nickharman

Enthusiast
Messages
94
Hi

My R4 1987 has just emerged from the barn after 11 months and the front right side brake piston immediately didn't retract, stayed on and is cooking the wheel

I can recall the procedure for getting the calliper off,it's been a while and my other antique car uses brake drum and shoes so I am out of practice,

I cant initially see how to free the anti rattle springs.

Could anyone tell me procedure please?

Thanks
 
Hi Nick

Once you have taken the caliper off. Remove the pads, you should then be able to prise off the anti rattle springs. As the car has been standing for a long time, it looks like the piston has at least partially seized as it has been in the same position for so long. Get some WD40, fit the straw to the can which comes with it, gently lift the rubber dust seal on the caliper and target that area with the lubricant. Then push the piston back using your brake caliper piston push back tool of choice, if you don't have one, you can use a large flat ended screwdriver to push the piston back by wedging it between the caliper and disc and trying to push it back. The piston should gently press inwards, if it does not move at all then the piston might be completely seized. If so a complete strip down of the caliper, thorough clean and rebuild would be required or alternatively replace with a new caliper.
 
Yes I thought one had to remove the anti rattle first

I don't immediately see how to remove the calipers, usually on other cars I see a dust cover over an allen key bolt? Can you advise?

These damned pistons, they were both sides taken apart and refurbished last year by the local garage as most of my tools are back in the Uk.

The car has since been barn bound for 11 months as I was trapped in UK by Covid. Apart from the mice destroying my two gilets jaunes in the back it was ok, started first time!

It would seem that when I pressed the brake down the brake on that side came on and then didnt retract owing probably to a rust ridge?

I can see the rubber dust seal has curled back and exposed part of the piston and I see rust

I cant get anything between caliper and disc pad as the pad is tight against the disc

So basically I need to get the caliper off I think

Thanks!

N
 
Maybe you can post a picture of the caliper.
Renault put on bendix and girling calipers. Removing the the blocks is completely different from one and other. If you can pry the pads out it’s easier to remove the whole caliper
 
Hi Nick

As you had the calipers refurbished in the not too distant past, as you mentioned it is probably a rust ridge due to the piston being stuck in the same position for 11 months. My instructions above assumed you had already taken the caliper off. Once the caliper is off, remove the outer brake pad (this will give you enough purchase to attempt to push the piston back). Offer up the loose, unbolted caliper back up to the disc as if you were in the process of putting it back minus the outer brake pad, wedge the flat end of the screwdriver between the caliper and the disc where the outer pad would usually be located and lever the screwdriver towards you, if the piston is free it should gently move inwards. If you are unable to figure out how to get off the caliper in the first place, as Harbourseal has mentioned there are two types 'Bendix' and 'Girling'. Post a picture of the type you have and one of us will be able to inform you how to remove.
 
Hi Nick

OK, with this type, you need to remove the little circular retaining clips which are clearly visible in your images, grab hold of them with a pair of pliers and pull them out. The clips are attached to wedges. Tap these wedges out with a flat ended screwdriver and hammer. They only come out in one direction as there is a lip at one end, check for the lip first and then tap the wedges in the opposite direction to the lip, once both top and bottom wedges are out, the caliper should slide off.
 
It's more likely the wedges have seized than the piston. Push the piston back a bit while it is off, and clean up the wedges and the surfaces on the calliper with a wire bush or a file and then smear copper grease on them before reassembly.
 
Just to be sure. You need to pull out the thin wire clips. And then knock out the wedge.
the thick wire ends are the anti rattle springs.
 
harbourseal said:
Just to be sure. You need to pull out the thin wire clips. And then knock out the wedge.
the thick wire ends are the anti rattle springs.
Click to expand...

Right yes, I see. The tiny wire clips are retainers for the wedges?

See pic, yellow dot is clip?

N
 
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nickharman said:
Right yes, I see. The tiny wire clips are retainers for the wedges?

See pic, yellow dot is clip?

N
Click to expand...

update, the caliper is off!

Exposed end of piston is mucky (see pic)

I have tried pushing the piston back with a C clamp but its not keen, I presume I would need to loosen the bleed valve to allow it push back? I am bit loathe to do that for fear of letting air in

I am going to clean up the piston end as much as I can and also the wedges and apply copper grease and reassemble and see if perhaps pumping the brakes a bit might ease everything?

Th
 
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Hi

There is no need to unlock the bleed nipple, if the piston is not seized it should press inwards with gentle persuasion.
 
Its not responding to massive persuasion with a C clamp :-(

I will have to get it out, presumably by using the brake pedal to push it out. It may be beyond my limited tool set though. The rubber seal at the end is a mess, presumably what helped allow the corrosion in, I blame the garage for that.

Also I did try and reassemble but when one wedge is in, the other wont go in and vice versa. Is there a trick for that?

And can I buy any copper grease here in France? No, I get blank looks from most places, even though I am using the correct words and I do, though I say it myself, speak fluent French! Ou est Halfords when you need them?

If I can get the wedges in I shall have to limp it to local garage where he will be delighted to be paid to do the same job again he did last year!
Although I will have to source the kit for him again.

Sigh

N
 
Have you asked someone to gently push down on the brake paddle for you, while you look for any movement in the piston.
You can put the c clamp on as a limiter at for example 1cm. Once it moves you can replace the rubber easily.
When you put the caliper back put in the lower wedge first, then push in the the caliper inwards against the anti rattle spring and put in the upper wedge.
 
 
I will try that, Perhaps pushing it out will crack the rust,

The rubber boot I think is too distorted to reuse, but maybe

Yes I get bits from melun usually

those second hand calipers look as bad as mine! But i could get them sent to uk and spend the lockdown months cleaning them up!

Thanks!!

n
 
No problem getting copper grease here in France, I got mine from Brico LeClerc, thats the hardware section, but LeClerc Auto have it as well.
 
I didn't try brico le clerc as it's a lot farther, away but 3M didnt have it and nor did it the local parts bloke.who had everything else!

I may be able to get to le clerc before I leave for UK on Wednesday. It would be good to at least coat the wedges before leaving the car back in the barn for at least five months :-(

The car has no MOT at the moment, I now have the vehicule de collection classification and it would be good to get it CT'd (E78!!!) and then enjoy six years no MOT needed when I come back. I think one of CV boots is going to fail me, Its cracking just enough to ooze grease, so I may bring one of those with me and change it

I
 
Thanks everyone. I've freed the piston, it appears to be working okay now. But the rubber dust seal is no good anymore, too mashed up They must have fitted it cockeyed at the garage last year

So I have reassembled the brakes with some ordinary oil lightly smeared on the wedges for now to hold off the rust until I come back armed with copper grease, a new seal kit and a haynes manual ( I had one but it mysteriously disappeared). As long as its not too cold to work in the barn, it

I might as well bring a CV boot as well and change it (if it's not too difficult. I could I suppose superglue the crack in the present one?) . Hopefully I can then get the MOT with no problems

N
 
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