Caravelle Brakes

R

rob pignolet

New member
Fellow Frogger
Joined
Aug 25, 2003
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8
Location
melbourne
I have a 1963 Caravelle that i can't get full pressure on the pedal.
Have replaced calliper kits, lines, changed master cylinder.no air in lines at all.
It seems the calipers are releasing and going too far back in the cylinder.
Same discs as renault 10.
Any brake gurus out there, it's been 8 months of torture.
New master cylinder also required maybe
Any thoughts
 
rob pignolet:
I have a 1963 Caravelle that i can't get full pressure on the pedal.

Any thoughts
Click to expand...
Rob,

These can be hard to get a good "pedal" on. Careful bleeding is one key to this. Check whether yours has the antilocking pressure valve where the rear rigid pipes go to each side.

The calliper kits are fine and worth doing but if there is/was corrosion INSIDE the grooves in the alloy calliper, they won't seal properly and may suck air back in when you pump the pedal to bleed.
There are different kits too. I use the square ones regardless but don't know for sure.

Finally, the very early R8s (maybe then the early Caravelles) had ever so slightly different piston size or groove size, can't remember which. So you may have an "O" ring that isn't quite large enough in diameter. I seem to remember this from the 70s, when I changed our R8 (very early R1130) to later type callipers. I polish the inside of the grooves with very fine wet and dry and then with metal polish before replacing the seals and this seems to work well.

The adjuster can't pull the piston back too far, as it is the "O" ring that flexes and pulls the piston back. The adjuster merely allows the piston to gradually move further out as the pads wear.

If this isn't enough, give me a ring or email for my phone number. But do it this week!!

Cheers

JohnW

(There may be a response from Simon in Adelaide too!)
 
When putting the pistons back in the calipers the small dot on the outside edge must line up with the bleed nipple, or all of the air cannot escape the tight spring like mechanism that holds the bolt in the back of the piston. This arrangement is to allow only minimal pad knock off.
 
Stuey:
John, Simon seems to have disappeared. Hope he's OK...

Stuey
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I hope it's a holiday. Haven't seen his wise words for a while, now I come to think about it.

Good point about the lining up! It must be time I did mine again as I'd forgotten. About every 5-6 years I do the callipers. I'm planning to go to silicone fluid next time.

There are also two diameters of master cylinder piston, 19 and 22 mm, if I remember. Now the early ones had 22 mm cylinders and the kits I've bought have the wrong size non-return valve (or retarder, as it isn't truly a non-return valve.

I'd guess one of the things we've covered should sort Rob's problem. I've had great difficulty getting good pedal feel sometimes with these brakes.

The other thing is disc wear, but this isn't the problem. Mine are 1 mm under thickness and fine. They've done over 300,000 km too!

Cheers

John
 
John, thanks. Maybe i need to replace all the o rings with the square ones. I do have the valve at the rear and it seems ok. Funny thing is i replaced the master cylinder. The old one would hold the pads on too tight and then go to the floor after 3-4 days, great pedal though!. Now with the replacement cylinder i can't get good pressure in the pedal but they release like never before, i actually roll down hills now. I clamped each line and could get good pedal with clamping, release clamp and pedal gone. Discs are in great condition too.
 
On R8 &10 there were 3 sizes of master cylinder 19, 20.5 and 22. I like the 22 for the short pedal travel, but you need to push a bit harder. I have always used O-rings in my calipers whether they had square or round type. I had some nasty Spanish brake pads in at one stage that did nothing, and have since bought EBC Blacks that are good. Any old stock Valeo or metalkings are OK also.
 
alan moore:
On R8 &10 there were 3 sizes of master cylinder 19, 20.5 and 22. I like the 22 for the short pedal travel, but you need to push a bit harder. I have always used O-rings in my calipers whether they had square or round type. I had some nasty Spanish brake pads in at one stage that did nothing, and have since bought EBC Blacks that are good. Any old stock Valeo or metalkings are OK also.
Click to expand...
Alan,

Ah. A 4CV with discs???? Such things are possible. I presume if I looked that I'd find your name in the 4CV Register?

I'm seriously planning to overhaul my R8 (R1130)system ere long. I was thinking of going the other way for lighter pedal, but I reckon I'd prefer less travel on balance.

Have you measured disc thickness?

Cheers

John
 
Maybe your new master cylinder was a smaller diameter bore than the old one?
I have just changed my master cylinder from 22mm to 20.5mm on the Dauphine. There is definitely more pedal travel and a softer feel but it should give me more powerful brakes.

I am using custom made Mintex pads. They seem to perform very well. :)

Ross
renault_
 
Yes my 4CV has R10 discs allround, a modified R10 box and a fairly modified 16TS motor, plus lots of other stuff. Yes, I am on the register, and went to the last muster at Corowa on the NSW VIC border. Rego. NOT 750
 
alan moore:
Yes my 4CV has R10 discs allround, a modified R10 box and a fairly modified 16TS motor, plus lots of other stuff. Yes, I am on the register, and went to the last muster at Corowa on the NSW VIC border. Rego. NOT 750
Click to expand...
Interesting car - I imagine it goes quite well! Faster than my original 1951 car.....

The musters are just a bit too far for us in Perth, as you'd imagine. But our little 4CV group is keen anyway. Three on the road, one partly back together ("gonna be finished") and a few lurking in sheds.

Cheers

JohnW
 
I won't give away any of alans secrets except to say that NOT-750 goes very well. head_ban Even with 2 aussiefrogs aboard. (or is that toads) roll_lau

Chris
 
Originally posted by rob pignolet:
[QB]I have a 1963 Caravelle that i can't get full pressure on the pedal.
Have replaced calliper kits,
If you dont know whether to use square or round seals, have a close look at the caliper on the side that goes outside. There is a small symbol in the casting (2mm) with a square or cicle on it. That tells you which seal to use. The caliper piston moves out and uses the seal's flex to return it a fraction. That releases the pads from the disc. This will happen a few times until the pads have worn a bit and then the piston will slide a fraction on the spring tension to make up the additional distance. Then the rubber seal will flex again with the forward motion and return the piston.If you use an O ring instead of a square it might return the piston to far back and then you need a lot of travel again
Hope this makes sense
Frans
Click to expand...
 
Frans:
Originally posted by rob pignolet:
[QB]I have a 1963 Caravelle that i can't get full pressure on the pedal.
Have replaced calliper kits,
If you dont know whether to use square or round seals, have a close look at the caliper on the side that goes outside. There is a small symbol in the casting (2mm) with a square or cicle on it. That tells you which seal to use. The caliper piston moves out and uses the seal's flex to return it a fraction. That releases the pads from the disc. This will happen a few times until the pads have worn a bit and then the piston will slide a fraction on the spring tension to make up the additional distance. Then the rubber seal will flex again with the forward motion and return the piston.If you use an O ring instead of a square it might return the piston to far back and then you need a lot of travel again
Hope this makes sense
Frans
Click to expand...
Rob,

Frans could have a point here. If you are using the wrong seals for the calliper this might happen I guess. I don't know from experience although I'm not sure that mine (which are fine) should have round or square, but I've used the square section (later type) ones for many years.

Please let us know how you get on.

JohnW
Click to expand...
 
orange17:
I won't give away any of alans secrets except to say that NOT-750 goes very well. head_ban Even with 2 aussiefrogs aboard. (or is that toads) roll_lau

Chris
Click to expand...
Very well indeed I imagine!!!

JohnW

(My car has been called "toad" since I bought it in 1966, because that's how we got it home. Terrible pun. But what do you expect for $60?)
 
Check any flexible hoses, as these can delaminate and bulge with pressure, damn hard to find though. Clamp the front of the hose and check pedal, clamp the rear and check pedal, if it is different get someone to look for bulging when pedal applied.
 
G'day JohnW and Alan Moore

Yes, Alan's NOT750 is a neat package: have a few pics of it and will try to fit one in the next "Fourword".

Not sure I can add much more on the brake problem, though from memory the pressure valve (on R10s, anyway) can cause problems.

On silicone brake fluid, JohnW, I have it in the 4CVs. Good stuff in terms of no hygroscopic tendencies, but *very* penetrating. Finds its way into brake light switches and insulates between the contacts so they operate (if at all) like dimmer switches! Then need to fit mechanical switch. Cost is on the wrong side of $100 per litre also... but I still like the stuff.

Cheers
 
If the pressure valve is shot, just put in a t peice (just bear it in mind when braking heavily on wet corners - did a very nice 360 degree turn that way in my R10S.... :D I kinda strained my arm patting myself on the back, as I got it straght and kept going without even stopping wink Had to clean my dacks out though...)

I have seen Carevelles with R12 front disc brakes for extra oomph.

When overhauling R8/10 calipers, get the calipers plastic bead blasted - only way to get 'em spotless and avoid all piston jamming problems that these things seem prone to.
 
Gee, thanks everyone for your thoughts. I,m not sure i understand the "plastic beads" thing. I have managed to source some calliper kits, so i'll try that. I have also discoverd a small thin brass washer at the base of the piston between the rubber washer, this is covering all the small holes at the base of the piston. This washer is not shown in any of the manuals. Does anybody out there have a new master cylinder for sale?. On another subject can i put a renault 12 head straight onto a 1108 motor. I've been told they go much better.
Thanks again
rob
 
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