rear brake bleed nipple nut rounded

MGT · Dec 13, 2023

I'm changing rear brake hoses and of course the nuts are all seized. Before I try to take the old hoses off I am checking I can bleed the brakes afterwards. The nut on the bleed nipple is seized and rounded off in part already. Before I go at it I want to be as careful as possible and used the most efficient method . I may need to change brake cylinders, but I want to put that off to warmer months if I can.

First of all (asking because it is already rounded a bit) is the nut 11mm or 10mm?

Can I use heat in the form of blowtorch that close to brake fluid (and also a 50/50 ATF/acetone mix?

Is there a known best way of getting that nut off?
TIA

Anaconda · Dec 13, 2023

Pretty sure brake fluid is flammable.
A good quality brake pipe spanner would have been ideal for this job or even a socket if you could get one on it.

MGT · Dec 13, 2023

Anaconda said:
Pretty sure brake fluid is flammable.
A good quality brake pipe spanner would have been ideal for this job or even a socket if you could get one on it.

Thanks. I'm probably going to use the socket with a 1/4 drive. just have a hunch it is going to round it off instead of cracking it.

P38 Monkey · Dec 13, 2023

MGT said:
Thanks. I'm probably going to use the socket with a 1/4 drive. just have a hunch it is going to round it off instead of cracking it.

A better tool would be a socket designed to grip rounded nuts.
Bolt / nut extractors are cheap and generally work well.
Usual rules apply: get a set that is made by a known name, like Sealey or similar.
If the bleed nipple snaps then at least it is locked in there and won’t leak.

GrumpyGel · Dec 13, 2023

If you use a 6 sided socket, I wouldn't have thought it was possible to get a better tool for the job - if you can get it on.

If you replace the flexible hoses, there is a high chance you will need to replace the pipes from the cylinder to them also as they will be destroyed separating them.

If you are replacing the flexible hoses, you are going to need to do a complete brake bleed as well as the job of replacing hoses and probably pipes. The cylinders are cheap and having done all that work, I'd have thought it best to replace them... and the shoes and drums (which are also cheap). Do a 'proper job'.

If you start the job, you may choose not to purchase the pipes - as they are expensive, but start the job on the understanding that you may likely need to purchase them and ensure you know where you can get them from and in what time scales.

A '1 man brake bleeding kit' is cheap and will save a whole heap of agro bleeding the brakes. If you do a good complete bleed, do not be surprised if the brakes are still bad - you may need to do it twice. I have had to, but I'm not sure if that was when I did the rear brakes or the ABS unit. What ever, make sure you have plenty of brake fluid available.

andyfreelandy · Dec 13, 2023

Bleed screw usually seizes into the aluminium slave cylinder after time.
Have a spare slave to hand because if you apply force the cylinder can crack.

Kev12 · Dec 13, 2023

I know you want to avoid doing wheel cylinders til later, but replacing them now is only a couple more bolts and seeing as you have to bleed anyway

andyfreelandy · Dec 13, 2023

Yeah but those fixing bolts round off too !! Best bet is a smart smack with a chisel. I always replace the wheel cylinders with the end brake pipes. Always fractured and Inhave seen them weep fluid at the pipe to cylinder joint as the boss rots off.

Nodge68 · Dec 13, 2023

As Andy said, prepare to replace everything from the flexy hoses to the cylinders. Sometimes the solid lines don't come out the flexy hoses on the car side either, which means new back to front lines.

MGT · Dec 13, 2023

GrumpyGel said:
If you use a 6 sided socket, I wouldn't have thought it was possible to get a better tool for the job - if you can get it on.

If you replace the flexible hoses, there is a high chance you will need to replace the pipes from the cylinder to them also as they will be destroyed separating them.

If you are replacing the flexible hoses, you are going to need to do a complete brake bleed as well as the job of replacing hoses and probably pipes. The cylinders are cheap and having done all that work, I'd have thought it best to replace them... and the shoes and drums (which are also cheap). Do a 'proper job'.

If you start the job, you may choose not to purchase the pipes - as they are expensive, but start the job on the understanding that you may likely need to purchase them and ensure you know where you can get them from and in what time scales.

A '1 man brake bleeding kit' is cheap and will save a whole heap of agro bleeding the brakes. If you do a good complete bleed, do not be surprised if the brakes are still bad - you may need to do it twice. I have had to, but I'm not sure if that was when I did the rear brakes or the ABS unit. What ever, make sure you have plenty of brake fluid available.

I'm picking up a flaring tool, brake pipe and unions tomorrow plus shoes, springs and cylinders. I figure once I start everything is going to start unravelling so I may as well be prepared. If I can get away with it, and the nuts crack without shattering everything they are attached to, then I will leave the proper job until spring or summer. Never done brake pipes before but it's something that's useful to master and avoids having to source preformed lengths. Thanks for the reply.

MGT · Dec 13, 2023

andyfreelandy said:
Bleed screw usually seizes into the aluminium slave cylinder after time.
Have a spare slave to hand because if you apply force the cylinder can crack.

Yes, it seems pretty well welded in there. I haven't applied much torque yet but I will have the bits ready for when I do. I have slathered everything in an acetone/atf mix after wire brushing, so maybe I will get lucky.

MGT · Dec 13, 2023

Kev12 said:
I know you want to avoid doing wheel cylinders til later, but replacing them now is only a couple more bolts and seeing as you have to bleed anyway

it's a thought. I will have the cylinders to hand. I will see how I feel. if the force is with me I may crack on.

MGT · Dec 13, 2023

andyfreelandy said:
Yeah but those fixing bolts round off too !! Best bet is a smart smack with a chisel. I always replace the wheel cylinders with the end brake pipes. Always fractured and Inhave seen them weep fluid at the pipe to cylinder joint as the boss rots off.

Thanks for the tip re chisel. One bolt looks ok but the other one is corroded as hell. Odd since they are so close together.

MGT · Dec 13, 2023

Nodge68 said:
As Andy said, prepare to replace everything from the flexy hoses to the cylinders. Sometimes the solid lines don't come out the flexy hoses on the car side either, which means new back to front lines.

Yes. That I really would like to postpone if I can. I was wondering whether there was enough flex in those back to front line to nip the end off and flare for re-attachment. My guess is that would be a no though. How tricky is it to do the length from front to back?

Nodge68 · Dec 13, 2023

MGT said:
Yes. That I really would like to postpone if I can. I was wondering whether there was enough flex in those back to front line to nip the end off and flare for re-attachment. My guess is that would be a no though. How tricky is it to do the length from front to back?

There's not enough free play to put another flair on the end of the original steel lines. I've replaced the whole lot on a couple of FL1s, it's not that difficult. I used copper/nickel lines for one, and pure copper for the other. You need a couple of 20ft rolls to do the whole car. There's often debate on which type of solid lines work best, but I've never had a issue with either material. Steel is cheaper, which is why the OEM uses it, but most DIY tools can't form an accurate flair on steel, so copper or copper/nickel is the DIY option.
Andy did a whole thread on brake lines in great detail, so well worth a read.

Alibro · Dec 13, 2023

An electric power file is a Godsend when replacing wheel cylinders, I've never tried breaking the bolts off with a chisel but it only takes a couple of minutes to grind the heads off with a power file.
Something like this would do the trick

Evolution EVOFILE Power File Sander 240v Belt Sander Finger Belt With Dust Bag | eBay

Features adjustable sanding arm allowing the operator to keep their hand/wrist in a comfortable position and instead alter the angle of the sanding arm to suit the job. Soft -Grip Handle: Rubber Coated Grip.

ebay.us

MGT · Dec 13, 2023

Nodge68 said:
There's not enough free play to put another flair on the end of the original steel lines. I've replaced the whole lot on a couple of FL1s, it's not that difficult. I used copper/nickel lines for one, and pure copper for the other. You need a couple of 20ft rolls to do the whole car. There's often debate on which type of solid lines work best, but I've never had a issue with either material. Steel is cheaper, which is why the OEM uses it, but most DIY tools can't form an accurate flair on steel, so copper or copper/nickel is the DIY option.
Andy did a whole thread on brake lines in great detail, so well worth a read.

Thank you Nodge, I will look Andy's thread up.

KISSMYAURA · Dec 13, 2023

Heat NO!
Bolt extractor YES google irwin ones then find cheap copy on amazon for a one off job

MGT · Dec 13, 2023

Alibro said:
An electric power file is a Godsend when replacing wheel cylinders, I've never tried breaking the bolts off with a chisel but it only takes a couple of minutes to grind the heads off with a power file.
Something like this would do the trick

Evolution EVOFILE Power File Sander 240v Belt Sander Finger Belt With Dust Bag | eBay

Features adjustable sanding arm allowing the operator to keep their hand/wrist in a comfortable position and instead alter the angle of the sanding arm to suit the job. Soft -Grip Handle: Rubber Coated Grip.

ebay.us

Thanks for that. That's useful to have as a back up plan if they won't shift.

MGT · Dec 13, 2023

KISSMYAURA said:
Heat NO!
Bolt extractor YES google irwin ones then find cheap copy on amazon for a one off job

Picked some up today.

rear brake bleed nipple nut rounded

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