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Clementine the Cat
 
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Réparateur d'automobiles

Brake master cilinder

petak

Enthusiast
Messages
1,404
Location
Vodice, Croatia
#1
Short question!

I have noticed mastercilinder repair kit on Franzose.

But not sure if my brake mastercilinder is possible to repair....

I am noticing some oil on inner/piston side. Where rod from brake pedal is pushing piston.
Would like to repair it if it is possible.

Thank you in advance!

Here are pictures of my brake mastercilinder
P1020767.jpg
P1020768.jpg
 

laxeian

Enthusiast
Messages
241
Location
Galicia
#2
In photo looks like leak may be from front reservoir rubber?
 

petak

Enthusiast
Messages
1,404
Location
Vodice, Croatia
#3
Thank you Laxeian....i know where is leaking.


I just do not know if this master cilinder is possible to repair.



This pictures are old from time when i was restoring my R4....


Here are picture (again old picture) where i am noticing oil.....red circle.....
P1020341.jpg

P1020341-2.jpg
 

malcolm

& Clementine the Cat
Staff member
Messages
4,118
Location
Bedford UK
#5
It is likely the leak is caused by corrosion from brake fluid that hasn't been changed often enough and has sucked up water and in that case you would need a new master cylinder. You can get seal kits but a new cylinder would be lower risk. There were some knocking around on eBay a while ago.
 

petak

Enthusiast
Messages
1,404
Location
Vodice, Croatia
#6
I find new ATE brake master cilinder. That is not an issue. Will definitly put new one on the car.

But i was wondering if it is possible to repair it.
And where and which kit i need for repair.
Especialy as i do have 3 or 4 used one that could be renewed.

Malcolm.....how often do you think it is good to change brake fluid?
I did not some it since car is back on the road. 3,5 years now.
On last MOT check up(in Februara) brake fluid boiling point was somewhere aroud 180°C.
 

mr-reno-139

AKA Paul Cunningham
Messages
2,046
Location
lancing west sussex england
#7
If you get correct repair kit
If it is good quality rubber
It is possible to repair the master cylinder without taking it off car by pulling piston inside
You will need a honing tool of 19mm to clean inside bore and make sure it's not pitted or scored
Lots of diffetent master cylinders fitted dont forget
 

angel

Enthusiast
Messages
1,915
Location
Athens, Greece
#8
In case you wonder how to take out innards, since there is no circlip at the back holding the pistons, they are held by relatively loose fitting roll pins that can be accessed through the reservoir locating bores, after it is removed.
You have to get complete repair kit with pistons because rubber seals have odd sized inner diameter and cannot be found at brake parts shops, as is the case with other master cylinders.
 

petak

Enthusiast
Messages
1,404
Location
Vodice, Croatia
#9
Thank you guys...

I am aware that there are many different master cylinders for R4. I have found 3 mastercilinders that are looking same. Bought new one according to Renault numbers and according to ATE webshop catalog

Angel...i did not know that access to piston is thru reservoir hole. Do you know, maybe, who is manufacturing repair kit or where i can find one?
Franzose have some repair kits for mastercylinders but not sure witch is good for mine.
 

angel

Enthusiast
Messages
1,915
Location
Athens, Greece
#10
They used to be available from Stop as complete kits with pistons and springs. I can find them here from old stock, I don't know if this brand is still active though. If Autofren-Seinsa products are available in your country, look for kit D1304 (I assume you have 3/4" - 19mm master cylinder), always checking with your pistons that all is OK.
Franzose lists a kit for 3/4" diameter single circuit master cylinder (84235), noting that if you have a dual circuit master cylinder you have to buy two of them. With R4 dual circuit master cylinders it's not that simple. As I told you, on some of them I could fit standard 3/4" seals, while others had odd sized inner seal diameters, and I either had to get the piston/seal repair kit, or buy the complete master cylinder.
 

petak

Enthusiast
Messages
1,404
Location
Vodice, Croatia
#11
Thank you angel.

Will try to open one of 4 i have to see what is inside

I just do not like to throw away parts but like to restore them if it is possible.
But sometimes they are not repairable.
 
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