Technical Tightening brake hose when installing new calipers

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Technical Tightening brake hose when installing new calipers

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Aug 16, 2018
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Hi,
I decided to change the disk brake calipers on my Grande Punto. What I'm trying to figure out is how to tighten the brake hose properly. The issue started when I changed the calipers. Obviously the thread on the new calipers is different and therefore the hose will tighten differently than on my old calipers. With some internet searches, I read that this adjustment can be done at the brake line connection. However, when loosening the brake hose at the brake line (hard line) connection, I don't see how this is possible.

I have attached a picture to hopefully try and explain better my issue. At the brake line (the metal one), there is a nut but this does not turn because it is part of the brake line. The only nut that does turn or can be tightened is the flexible brake hose. However, how can I tighten the flexible hose so that it is not twisted with the new caliper?

I hope I'm just missing something stupid because this is my first time.

Thanks for your help,
Conrad
 
Model
Grande Punto
Year
2007

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Generally speaking you tighten the hose at the caliper correctly to stop leaks and then if the hose is twisted slightly out of line then undo the metal brake pipe union a little so the hose can untwist , then usually where you have taken the retaining clip out to allow the hose to move you should be able to position the hose in the clip holder with no twists, refit the retaining clip and retighten the metal brake pipe union where it fits into the hose, before\ bleeding as normal and checking for leaks etc.
The chassis mount for the hose will allow the hose to be located in it's best position before fitting the clip.
 
Thanks @bugsymike, that makes sense. The problem I have now is that I have tightened the hose and the hose is positioned correctly in the hose clip and I've put the retaining clip back into place. However, I can't retighten the metal brake pipe union becuase the brake pipe keeps moving with the nut.

Should the brake pipe union nut move freely? If so, how can I grab the brake pipe safely without damaging it and freeing it from the nut?

Conrad
 
Thanks @bugsymike, that makes sense. The problem I have now is that I have tightened the hose and the hose is positioned correctly in the hose clip and I've put the retaining clip back into place. However, I can't retighten the metal brake pipe union becuase the brake pipe keeps moving with the nut.

Should the brake pipe union nut move freely? If so, how can I grab the brake pipe safely without damaging it and freeing it from the nut?

Conrad
I see the problem, it's not uncommon. Do Not Grip The Pipe as It Will Be Damaged!!!
If very lucky a gentle forward and back on the pipe with a little WD40 may release the union to turn independent of the metal pipe, however worst case scenario is the pipe snaps and you have to fit a new metal pipe:(
Sometimes it is possible to juggle the flexible brake hose at both ends to overcome the fitting problem with the brake union tight, though only if very lucky and only a small adjustment required.
The problem is often caused by cheap copper brake pipe bonding to an over tightened union as the copper is too soft compared with the better quality Kunifer (copper and nickel) type that I use.
Note if the metal brake pipe starts to twist more than a tiny bit it will be seriously weakened so will have to be replaced.
Most good motor mechanics can soon make another metal brake pipe to your old pattern. Hopefully it only is a short length to a next connection such as a brake limiter valve etc.
 
Yeah, this is turning into a project. So on the one side, I will need to re-rivet the part that holds the brake hose/brake line to the chassis (broke off trying to untighten the nuts). I'll keep you posted about whether I will get the fitting off using only with WD40. Online people also seem to use gas torches to heat it up but I don't have that.
I'll have to follow the brake line and see where that goes. Hopefully, I won't damage them...
 
Just an update to the 'project' and a troubleshooting question. So after finally finding and receiving all the parts I needed, I replaced the calipers and brake pipe on one side. Not too bad. But.... for some reason my brakes feel soft after bleeding both sides (rear).

So my question to the members is what should I look for next to fix this issue?

I don't think the brake fluid was ever emptied out of the master cylinder during my work. Do I also need to bleed the front brakes? Any troubleshooting suggestions from the experts would be greatly appreciated. Thanks.
 
Just an update to the 'project' and a troubleshooting question. So after finally finding and receiving all the parts I needed, I replaced the calipers and brake pipe on one side. Not too bad. But.... for some reason my brakes feel soft after bleeding both sides (rear).

So my question to the members is what should I look for next to fix this issue?

I don't think the brake fluid was ever emptied out of the master cylinder during my work. Do I also need to bleed the front brakes? Any troubleshooting suggestions from the experts would be greatly appreciated. Thanks.
It may be just a case of the brakes needing bedding in if new pads etc.
However if it doesn't feel right then a good idea to check brake bleeding all round again to be sure and check in case of any leaks.
Does the handbrake feel good and effective, if not it can point to self adjusting not fully doing it's job. I always make sure the footbrake is 100% before adjusting any slack from the handbrake side, as it can "rob" the footbrake.
A quick check underneath should show with hand brake released the brake levers at the calipers should be right back against their stops.
 
Thanks @bugsymike - I'll pick up a larger bottle of brake fluid and do a full flush. I haven't seen any leaks in the work that I have done, so it could just be remaining air somewhere in the system. When you say 'all round' you mean all four brakes? Even though I only changed the rear ones?

I didn't put the handbrake cable back on the calipers yet because I wanted to first make sure the breaks were fine. This will be the last job so they should not be afffecting my brakes.

Keep you posted.
 
Another question that I forgot to ask. The brake hoses I didn't change in the end because they sent the wrong parts. However, they don't look worn or damaged. I read that sometimes they are damaged inside. Could this produce such an issue?
 
Another question that I forgot to ask. The brake hoses I didn't change in the end because they sent the wrong parts. However, they don't look worn or damaged. I read that sometimes they are damaged inside. Could this produce such an issue?
Yes, bleed brakes all round to be sure no air in them.
Another point is under certain circumstances vigorous pumping of the brakes such as when bleeding can result in more air getting in system from an old or lazy master cylinder. Not common but I have seen it. The air getting in from the back seal.
Some time ago another OP had an issue with poor brake, I think it was on a Seicento? At the beginning I suggested a new master cylinder from the symptoms he gave, he said they had tried three ( though I don't think all were new) in the end a good quality master cylinder cured his problem several months down the line from when it was suggested. ;)
If your wheels are still off and handbrake cables not reconnected, try moving the handbrake levers at the calipers, if fully adjusted automatically then a short move from the stop should activate the brake and stop you turning the disc just with your finger, once released it should spring back to the stop and the disc turn freely or very slide drag easy to turn with your hand. If one moves further or more than a small amount this will give a poor brake pedal.
I don't recall in your case, but if old discs and new brake pads for example it can give a poor pedal until the new pads have worn in over any wear ridge on brake discs.
I recall a customer who didn't want his brake discs replacing so just had pads front and rear, on initial road test it was all I could do to stop the vehicle, however after a few miles of firm use the pedal improved to a normal level.
Re brake hoses, occasionally people report a sticking brake or strange braking and on removing the brake hose have found a restriction, I would say from my experiences not common though.
Much in the same way a older brake hose may expand slightly on heavy pedal pressure if you hold your hand over it . This is why they sell things like Aeroquip Racing brake hoses which give a much firmer pedal, however not required under normal circumstances.
If you are familiar with using them, a set of brake hose clamps can be used to locate a problem at one wheel for example. Though I do recall as an apprentice in the 1970s my boss loaned a set to a regular customer who came back to report they had damaged his brake pipes, it turned out he had fitted them to the metal pipes rather than the rubber ones!!!:ROFLMAO:
 
I'll start with a full bleed then @bugsymike , just picked up a litre of DOT4 and will go around all four brakes. Funny you should mention the 'vigorous pumping'. I did do that a few times during bleeding just for testing. I guess I shouldn't have...
 
I'll start with a full bleed then @bugsymike , just picked up a litre of DOT4 and will go around all four brakes. Funny you should mention the 'vigorous pumping'. I did do that a few times during bleeding just for testing. I guess I shouldn't have...
Apart from anything else it aerates the brake fluid, so any air still in the system becomes tiny bubbles harder to bleed.
If left overnight it should settle. :)
It is also why it is a bad idea to reuse brake fluid apart from any contamination.
You may even be able to bleed the last of any air by simply filling the reservoir and undoing a bleeder completely to let fluid and bubbles flow out, then when just clean fluid refit and tighten bleeder before the reservoir runs out and repeat on all the rest.
I have done that many times, though don't let it run out;)
A good pressure bleeder is best, though many are happy with vacuum types.
 
Would like to ask a question since I found this in the Hayne's manual which goes against everything else I've read/seen on the internet:

Screenshot 2024-06-13 at 18.44.51.png

I thought that I'm supposed to bleed the system from the furthest brake to the closest to the master cylinder. This says to do the reverse... thoughts?
 
Would like to ask a question since I found this in the Hayne's manual which goes against everything else I've read/seen on the internet:

View attachment 446359
I thought that I'm supposed to bleed the system from the furthest brake to the closest to the master cylinder. This says to do the reverse... thoughts?
The possible reason would be working from nearest to master cylinder first.
If I had a completely dry system I would first bleed the master cylinder at it's unions and then work in that suggested way. However as yours has fluid in already and is semi working, then I would just bleed as you like and just check as doing it to see if fluid free of air bubbles is coming out.
 
Bleeding sequence is a complete bulls**t. It's a test (if you really understand what's going on) - most people will fail (and argue).
It doesn't matter what the order is if you already have most of the system filled.
Maybe some sequences are "inefficient" (you'll use/waste a bit more fluid, like extra 100-200 ml, that's it).

Completely dry, empty system is a rare scenario for normal/average user, so don't bother (what's the "proper sequence").
 
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