r8 calipers
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Thread: r8 calipers

  1. #1
    Tadpole
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    Default r8 calipers

    hi could anyone help me ive recond my calipers and i would like to know were the screw driver slot faces on the back of the calipers i believe that if i dont get that right i will have probs bleeding. cheers barry

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  2. #2
    Fellow Frogger! R8philSA's Avatar
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    According to the R8/R10 Scientific Publication on Brake Reassembly Item (6) "Install the nut on the end of the piston pin and rotate the piston until the mark on the piston face is adjacent to and in line with the bleeder valve, then tighten the piston guide pin nut to 10ft/lb"

    Hope this helps

    Cheers

    R8philSA

  3. #3
    VIP Sponsor 59 Floride's Avatar
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    Possibly the reason you haven't been flooded with eager help is because it is a little hard to explain just with words.

    I found this page which should help...


    Basically the gap in the self centering ring needs to line up with the bleed nipple and so does the mark on the piston face.

    Attached Thumbnails Attached Thumbnails r8 calipers-capturennnnn.jpg  

  4. #4
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    Quote Originally Posted by R8philSA View Post
    According to the R8/R10 Scientific Publication on Brake Reassembly Item (6) "Install the nut on the end of the piston pin and rotate the piston until the mark on the piston face is adjacent to and in line with the bleeder valve, then tighten the piston guide pin nut to 10ft/lb"

    Hope this helps

    Cheers

    R8philSA

    RubberG


    The slot on the stud protruding thru the back of the caliper is ONLY there so you can stop it from rotating when you tighten and loosen the nut. This isn't the important part for keeping air out of the system.

    The absolutely dead set critical part is to ensure that the gap in the circlip (it functions as the self adjuster for the caliper) that sits inside the piston aligns with the bleed screw at the top of the caliper body. This is important because if the gap isnt in the right place air gets trapped behind the circlip. When they were assembled new that gap in the circlip aligned with a drilling on the front of the piston. As the cars are now 50 odd years old the calipers would most likely have been overhauled at least once in their life this can no longer be assumed. A couple of years ago, over a few months, I pulled down at least 20 calipers and found all but a few had been reassembled incorrectly, i.e. the circlip gap and the drilling weren't correctly aligned.

    I had a lengthy description of the process posted but was lost in The Crash.

    Phil, you're right but it assumes the caliper - or to be precise the self adjuster - was properly re-assembled in the past. As stated, its been my experience that this is rare. This aspect of the re-assembly is not covered on the page posted by the esteemed, and most respected, Mr 59Floride.

    Please take the opportunity to replace the brake hoses when you do the calipers. You are on a single circuit brake system. If one part fails you lose brakes completely.

    All the best

    P
    Daily Drivers: R10, R12, R17T(?) Decouvrable

    In the Shed(s):
    R8 (1.4 motor, 4 shock rear end), Dauphine, Pugeot 404

    In the Past:
    Dauphine X2, R10 X lots, R12 X2, R16TS, R17TS

  5. #5
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    On early R8 and Floride S vehicles the marks on the piston face were a very faint etched line not a drill or centre punch mark. My brakes were quite poor as all the air could never be bled out until I realized that there was a mark it was so faint. Obviously the last person to rebuild the brakes had not seen the marks either.

  6. #6
    Too many posts! JohnW's Avatar
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    Just a couple of comments from another who has done these callipers a few times now.
    1. I agree entirely regarding flexible hoses. Don't mess with them. If old, they can fail internally and jam the brakes on or off.

    2. The manuals say that it is forbidden to dismantle the self-adjusting mechanism, and I don't know why anyone does or ever did. But it is true that some have been dismantled and re-assembled. I recall my mother's R8 brakes in about 1972, and during an overhaul in which the self-adjusting mechanism was dismantled, it was clear from the internal markings that they'd been pulled apart twice before! Why? God knows.

    I've never had one misaligned internally, so must have been lucky!


    Quote Originally Posted by Exfrogger View Post
    RubberG


    The slot on the stud protruding thru the back of the caliper is ONLY there so you can stop it from rotating when you tighten and loosen the nut. This isn't the important part for keeping air out of the system.

    The absolutely dead set critical part is to ensure that the gap in the circlip (it functions as the self adjuster for the caliper) that sits inside the piston aligns with the bleed screw at the top of the caliper body. This is important because if the gap isnt in the right place air gets trapped behind the circlip. When they were assembled new that gap in the circlip aligned with a drilling on the front of the piston. As the cars are now 50 odd years old the calipers would most likely have been overhauled at least once in their life this can no longer be assumed. A couple of years ago, over a few months, I pulled down at least 20 calipers and found all but a few had been reassembled incorrectly, i.e. the circlip gap and the drilling weren't correctly aligned.

    I had a lengthy description of the process posted but was lost in The Crash.

    Phil, you're right but it assumes the caliper - or to be precise the self adjuster - was properly re-assembled in the past. As stated, its been my experience that this is rare. This aspect of the re-assembly is not covered on the page posted by the esteemed, and most respected, Mr 59Floride.

    Please take the opportunity to replace the brake hoses when you do the calipers. You are on a single circuit brake system. If one part fails you lose brakes completely.

    All the best

    P
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  7. #7
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    Hi John

    I recall the old overhaul kits you got for the caliper had an adjuster circlip in them. I suspect this meant people thought they had to be replaced. These cars were common, calipers looked easy to overhaul so I guess every man and his dog had a crack

    I routinely take them apart during overhaul to get the crud out that seems to find a home there. It gives me a chancre to spin some steel wool inside the piston imagining it will make self adjusting a little easier.


    P
    Daily Drivers: R10, R12, R17T(?) Decouvrable

    In the Shed(s):
    R8 (1.4 motor, 4 shock rear end), Dauphine, Pugeot 404

    In the Past:
    Dauphine X2, R10 X lots, R12 X2, R16TS, R17TS

  8. #8
    VIP Sponsor 59 Floride's Avatar
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    I retrieved a set of calipers out of a wreck that hadn't been driven in 10 years and there was a fair bit of accumulated crud and rust inside the piston, so pressing the self adjusters out for maintenance was necessary.

    I was acutely aware of the need for correct re-assembly and must have got it right because bleeding has never been a problem with said calipers.

  9. #9
    1000+ Posts Frans's Avatar
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    Quote Originally Posted by 59 Floride View Post
    I retrieved a set of calipers out of a wreck that hadn't been driven in 10 years and there was a fair bit of accumulated crud and rust inside the piston, so pressing the self adjusters out for maintenance was necessary.
    Same here

    Frans
    Old enough to know better
    Young enough to do it anyway.

  10. #10
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Exfrogger View Post
    Hi John

    I recall the old overhaul kits you got for the caliper had an adjuster circlip in them. I suspect this meant people thought they had to be replaced. These cars were common, calipers looked easy to overhaul so I guess every man and his dog had a crack

    I routinely take them apart during overhaul to get the crud out that seems to find a home there. It gives me a chancre to spin some steel wool inside the piston imagining it will make self adjusting a little easier.


    P
    Well I never knew that about the early kits! It explains quite a few things from about 40 years ago!

    I've never had a piston so dirty that I thought of dismantling the thing - must have been lucky all these years.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  11. #11
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    I suspect dear old RubberG has torn his hair out by now, bought a moped and lit out on a world tour vowing never to start a thread on AF again...

    Anyway I thought I'd try to make clear what I was rabbiting on about so I ventured into my shed, rolled up my sleeves and reached deep into one of the bins marked "Manky Old Renault Parts - brakes" and plucked out a brake piston no doubt hidden for a rainy day.

    Would you believe, its assembled all wrong!

    The first picture shows the front of the piston with the drilling (in the box) and a solid line to the back of the piston. The dotted line indicates the gap in the self-adjuster circlip lies.

    The rear view indicates the position of marking on the front of the piston. Note where the gap in the circlip (dotted lines) lies in relation to the drilling.

    This piston, were it to be overhauled requires the circlip gap to straddle the solid line indicateing the position of the marking at the front of the piston.

    If the calipers are working okay but you suspect air trapped in the system a workaround is described here:

    http://www.aussiefrogs.com/forum/showthread.php?85805-Heads-up-for-all-R8-10-owners-brakes=&highlight=caliper

    I find the non-assisted all-wheel disk brake system on these cars to be firm, progressive and an absolute delight to use when set up properly.
    Attached Thumbnails Attached Thumbnails r8 calipers-front.jpg   r8 calipers-side.jpg   r8 calipers-rear.jpg  
    Last edited by Exfrogger; 11th October 2012 at 08:53 PM.
    Daily Drivers: R10, R12, R17T(?) Decouvrable

    In the Shed(s):
    R8 (1.4 motor, 4 shock rear end), Dauphine, Pugeot 404

    In the Past:
    Dauphine X2, R10 X lots, R12 X2, R16TS, R17TS

  12. #12
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Exfrogger View Post
    I suspect dear old RubberG has torn his hair out by now, bought a moped and lit out on a world tour vowing never to start a thread on AF again...

    Anyway I thought I'd try to make clear what I was rabbiting on about so I ventured into my shed, rolled up my sleeves and reached deep into one of the bins marked "Manky Old Renault Parts - brakes" and plucked out a brake piston no doubt hidden for a rainy day.

    Would you believe, its assembled all wrong!

    The first picture shows the front of the piston with the drilling (in the box) and a solid line to the back of the piston. The dotted line indicates the gap in the self-adjuster circlip lies.

    The rear view indicates the position of marking on the front of the piston. Note where the gap in the circlip (dotted lines) lies in relation to the drilling.

    This piston, were it to be overhauled requires the circlip gap to straddle the solid line indicateing the position of the marking at the front of the piston.

    If the calipers are working okay but you suspect air trapped in the system a workaround is described here:

    http://www.aussiefrogs.com/forum/showthread.php?85805-Heads-up-for-all-R8-10-owners-brakes=&highlight=caliper

    I find the non-assisted all-wheel disk brake system on these cars to be firm, progressive and an absolute delight to use when set up properly.
    Thanks for that link, which I'd forgotten. Mine are lovely but and progressive but just a tad soft so a calliper rotation play might just be the go!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

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