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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 168
Registered: 6-2009
Posted on Monday, 08 September, 2014 - 05:50 pm:   Edit PostDelete PostView Post/Check IP

I have just finished replacing the rear RH caliper (the old one had seized solid). All went well untill I bled the caliper.

From the bottom bleed nipple the brake fluid seemed very white. When looking at it there are plenty of small white fragments in it which look a bit like bits of thread sealer (which clearly has been used on the new caliper).
Could this be the case and is there a risk involved ?

On a subsequent test drive, the brakes worked fine once the new pads had bedden in.

Benoit

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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1255
Registered: 6-2006
Posted on Monday, 08 September, 2014 - 07:03 pm:   Edit PostDelete PostView Post/Check IP

Nasty, never come across that before.

I'd bleed it again and recheck.

I'd also get onto the repairer/supplier and let them know to. All sealing should be done with seals, not thread sealer so that's a bit odd.

Is it hard, supple, waxy?
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 170
Registered: 6-2009
Posted on Monday, 08 September, 2014 - 07:32 pm:   Edit PostDelete PostView Post/Check IP

Hi Paul,

the thread sealer has been used on the 2 little bolts that connect the small copper brake line to the caliper. I can clearly see it as there is some surplus sticking out of the thread and it has the same colour and appearance as the bits in the brake fluid.
Those bits are supple, a bit like rubber.

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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1256
Registered: 6-2006
Posted on Monday, 08 September, 2014 - 07:37 pm:   Edit PostDelete PostView Post/Check IP

Bleed again and make sure it's clear.

Make supplier aware of the problem.

It's the end of the system so nothing should go the other way.

Regards, Paul.
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Jan Forrest
Grand Master
Username: got_one

Post Number: 648
Registered: 1-2008
Posted on Monday, 08 September, 2014 - 09:16 pm:   Edit PostDelete PostView Post/Check IP

As the threads of the nut are only supposed to apply torque that translates into compression on the precisely machined face of the nipple and the seat inside the caliper, there should be no advantage to sealing them with PTFE (thread) tape, so I've no idea why anyone should use it.
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Omar M. Shams
Grand Master
Username: omar

Post Number: 429
Registered: 4-2009
Posted on Tuesday, 09 September, 2014 - 03:50 am:   Edit PostDelete PostView Post/Check IP

brings into question the build quality of the caliper really.................
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Bob Reynolds
Prolific User
Username: bobreynolds

Post Number: 153
Registered: 8-2012
Posted on Tuesday, 09 September, 2014 - 04:43 am:   Edit PostDelete PostView Post/Check IP

My replacement calipers didn't come with any pipes attached. So I would think that the fault lies with the person who fitted the calipers.
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Bob Reynolds
Prolific User
Username: bobreynolds

Post Number: 154
Registered: 8-2012
Posted on Tuesday, 09 September, 2014 - 05:32 am:   Edit PostDelete PostView Post/Check IP

I am trying to imagine how the tape got into the brake fluid. Whoever did it must have wrapped tape not only on the threads, but all over the end of the brake pipe as well.

If I were you I would take the pipe off, clean it up, and do the job properly.

It wasn't a plumber, was it?
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1029
Registered: 6-2009
Posted on Tuesday, 09 September, 2014 - 06:31 am:   Edit PostDelete PostView Post/Check IP

Several observations:

1. The tubing on the caliper should not be copper. It's probably CuNiFer (copper-nickel-ferrous), but if you know it to be copper it should be replaced.

2. It looks like there's a fair amount of white detritus in that fluid. I, like Mr. Reynolds, am trying to imagine how one would have had to have wrapped those line nuts to get that much in there.

3. Even though PTFE thread sealing tape is not required for thread sealing, I know some who use it as a type of anti-seize. It's chemically inert and if the threads on either side were to corrode it effectively prevents them from corroding to each other. Given what I've seen on one of my calipers the use of teflon thread tape for this purpose does not seem like at all a bad idea.

Brian
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David Gore
Moderator
Username: david_gore

Post Number: 1461
Registered: 4-2003
Posted on Tuesday, 09 September, 2014 - 08:05 am:   Edit PostDelete PostView Post/Check IP

"1. The tubing on the caliper should not be copper. It's probably CuNiFer (copper-nickel-ferrous), but if you know it to be copper it should be replaced."

Agree 100% and the pipe looks like Copper refrigeration capillary tubing. It appears the use of Copper refrigeration tube by "el cheapo" individuals [I cannot describe them as mechanics] is common practice in the UK as it is easier to form than proper Bundy tube when making replacement hydraulic lines. DRH14434 was similarly afflicted with Copper capillary brake lines all around the rear sub-frame when it arrived from the UK in common with other UK imports that I have seen over the years. Now Cunifer [90/10 Copper Nickel] tube is available at a reasonable price, this is the material of choice for brake line replacement especially where corrosion from road de-icing salt is prevalent.

IMHO pure Copper tube is not suitable for brake lines as it work hardens when bent and is prone to fatigue when subjected to repetitive stresses such as those encountered in a brake system.

No way I would consider using PTFE plumbers tape in a brake system; Murphy's [Sod's] Laws apply...
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Randy Roberson
Grand Master
Username: wascator

Post Number: 304
Registered: 5-2009
Posted on Tuesday, 09 September, 2014 - 08:36 am:   Edit PostDelete PostView Post/Check IP

Hard to imagine a situation in which the use of thread tape would result in that much debris in the fluid so it was thread sealing paste, no?
The user must have really slathered it on, plus he did not understand how brake piping seals: at the flare face, not in the threads of course.
Ditto on not using copper for brake or hydraulic tubing; I use CnNiFer from FedHill or a BrakeQuip dealer. It is DOT approved and plenty easy to bend, plus corrosion resistant to boot.
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 171
Registered: 6-2009
Posted on Tuesday, 09 September, 2014 - 05:04 pm:   Edit PostDelete PostView Post/Check IP

I might have to explain myself better.

The pipe is very probably not copper but Cunifer. And by the look of it a sealing paste was used, not thread tape.

The brake caliper came with the pipe already fitted and I installed the caliper myself and I certainly didn't use any thread sealer.
I'm somewhat surprised as the supplier has a good reputation and I have never had problems with them before.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1259
Registered: 6-2006
Posted on Tuesday, 09 September, 2014 - 06:19 pm:   Edit PostDelete PostView Post/Check IP

just lost my long reply. :-(

Basically, I bet it was weeping when tested.

Probably due to pipe nut being drilled out.

BloBed with sealant and retested.


Not something I would do.Perhaps they have a special sealant.


Doubt suppliers reconditioned themselves.
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Bob uk
Unregistered guest
Posted From: 94.197.122.72
Posted on Tuesday, 09 September, 2014 - 10:43 am:   Edit PostDelete PostView Post/Check IP

Dave is absolutely right about copper tubing. It's ok in low pressure applications such as fuel line in short lengths such as connecting twin carbs. But even using it all the way to the tank van cause it to work harden if it is allowed to vibrate as in tally cars.

Kunifer or cunifer or cupro nickel is much better and only about 10% more.

Cunifer is kind to flaring tools. I use castrol red rubber grease to lubricate the tool.

Working pressure is 2250 psi and burst is 12000psi

There are places where cunifer should not be used. Which is where there is low to high pressure pulses such as pump to sphere. Only steel here I afraid. I wasted having two cunifer pump pipes made they both failed within 1000 miles.

Most copper brake 3/16 pipe advertised in the UK is actually cunifer. But always check. It also stays brighter whereas copper goes browny green.}

(Message approved by david_gore)
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 172
Registered: 6-2009
Posted on Wednesday, 10 September, 2014 - 12:30 am:   Edit PostDelete PostView Post/Check IP

I contacted the supplier who promptly reacted.
Apparently, a paste is used on assembly of the caliper and the white bits in the brake fluid are residue.
Bleeding untill the fluid is clear (which I did) should be enough.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 899
Registered: 9-2004
Posted on Wednesday, 10 September, 2014 - 09:13 pm:   Edit PostDelete PostView Post/Check IP

"Should be enough" is not good enough for RR Bentley!
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1263
Registered: 6-2006
Posted on Thursday, 11 September, 2014 - 06:34 am:   Edit PostDelete PostView Post/Check IP

Hi, just wondering if it helped with your vibration issue?
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 173
Registered: 6-2009
Posted on Thursday, 11 September, 2014 - 04:54 pm:   Edit PostDelete PostView Post/Check IP

Hi Paul,

it didn't really make a difference.

Next on the agenda will be to replace the front suspension rear lower bearing pins as they are in very poor condition. (I have already tried to loosen (not remove) the bolts that hold them in place but no amount of force can make them move).
As replacing the front compliance mounts very much improved the whole vibration issue, I hope this might be a next step to eliminating it completely.

Benoit

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