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Traction Brake Lines

gerrypro

1000+ Posts
I took all of mine apart. I wasn't too worried since I planned on making new lines anyway. The steel lines are all 1/4 inch SAE 45 degree flare, which are easy to source here in the states. I invested in a decent turret double flaring tool from Eastwood, and I purchased a few bags of steel flare nuts, which made fabricating the new lines easy.View attachment 127279View attachment 127280
Your left rear has the same system as used on the Slough built cars with a transverse line running across the beam axle.
 

DoubleChevron

Real cars have hydraulics
I am a little worried that your length of flexible line will be a little short now to properly flex when the trailing arm moves. I wonder whether it may have been better to get both the rears made to match the longer one you had on the other side. Then you could have included a 'bounce' loop in the line to lessen the strain. Refer to John's picture on Sunday at 4.04 PM.
The workmanship appears to be very good!

I'm not concerned, I'll be replacing everything in the future :) .... THis allows the car to be moved and driven in the meantime.
 

DoubleChevron

Real cars have hydraulics
I was wondering how they would be able to re-use the fittings. Clever indeed.

I had no idea it would come back so well done. If I'd had any foresight I would have measured the brake line on the other side and request that length of line (the other side has the updated longer line)!
 
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DoubleChevron

Real cars have hydraulics
Well I just fitted the rear brake line and did two laps of the street. Certainly it feels like its still dragging the brakes. The wheel is now cold to the touch. The whisp of smoke coming off the front passenger side tells me the brakes aren't releasing over there now. So its a full set of new lines before I can do anything else.

Ever get the feeling the car is screaming at me "just replace all the damn lines you tight arse :mallet: "
 

citroenthusiast

Active member
You may need check the master cylinder also. Drum brake systems as on the Traction Avant have a residual pressure valve (RPV) in the master cylinder. The idea is that the brake lines are always under a little pressure, but not enough to overcome the brake return springs. The purpose of the RPV is if you have a leak it will force fluid out of the leak rather than allow air in. I recently helped someone else with an 11BL who had sourced a generic master cylinder rebuild kit and was having trouble with one of the front brakes not releasing, unless the pressure was bled from the wheel cylinder. It turned out the RPV in the kit he sourced was incorrect so it was holding too much pressure. Installing the correct RPV cured the problem.
 

DoubleChevron

Real cars have hydraulics
You may need check the master cylinder also. Drum brake systems as on the Traction Avant have a residual pressure valve (RPV) in the master cylinder. The idea is that the brake lines are always under a little pressure, but not enough to overcome the brake return springs. The purpose of the RPV is if you have a leak it will force fluid out of the leak rather than allow air in. I recently helped someone else with an 11BL who had sourced a generic master cylinder rebuild kit and was having trouble with one of the front brakes not releasing, unless the pressure was bled from the wheel cylinder. It turned out the RPV in the kit he sourced was incorrect so it was holding too much pressure. Installing the correct RPV cured the problem.

Oh, I wonder if me bleeding the brakes has introduced air into this. I only bleed the one rear wheel. I better bleed the system end to end.

I just measured the soft lines. Those looped rear brake lines, they are just fronts right? People are buying two sets of front lines and looping them for use on the rear!

Its only the front right dragging, I imagine the RPV will effect both sides at the same time ?
 
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citroenthusiast

Active member
In the case I referred to only the RF was dragging. If he released the pressure from the RF then it was fine until he applied the brakes again. I suppose if one brake return spring is weaker than the rest it would manifest as only one wheel dragging. I am not saying this is necessarily your issue, just that most people who grew up with disk brakes don't know about the RPV, so I wanted to alert you to its presence.
 

DoubleChevron

Real cars have hydraulics
In the case I referred to only the RF was dragging. If he released the pressure from the RF then it was fine until he applied the brakes again. I suppose if one brake return spring is weaker than the rest it would manifest as only one wheel dragging. I am not saying this is necessarily your issue, just that most people who grew up with disk brakes don't know about the RPV, so I wanted to alert you to its presence.
Yes, I'd certainly never heard of it!
 

Artificer

Active member
Grew up up with all braking systems & the residual pressure check valve will not cause a problem as described [one wheel].
Dragging brakes plural ~ 1st IA after doing all this type work is to check & adjust the brake pedal free play.
Must be @ least 0.5mm" or hacksaw blade thickness.

Having no free travel or worse negative can cause the master cylinder piston to not return fully home, not uncovering enough [brakes dragging] or not @ all [brakes eventually locking up after a couple of applications] the master cylinder compensation port.
If releasing & re-tightening quickly any bleed screw solves the problem temporarily, free travel is the issue.

One wheel dragging & with no heat exhibited to feel on the other 3 hubs is:
1. sticky/seized wheel cylinder
2. bad adjustment
3. pressure retained in that section of the brake line ~ bad flex line or crushed steel line.
4. anything in 3 can be eliminated by opening & closing that wheels bleed screw quickly.
If dragging is gone it is the flex line [most likely with old components] or less likely a badly restricted bundy line.
 
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