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 Brake Fluid leak- front calliper seals?
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EdinburghJoe
V4 Fan

United Kingdom
162 Posts

Posted - 09 Apr 2018 :  21:21:49 Show Profile Reply with Quote
Hi ,
I’ve been losing quite a lot of brake fluid from my ‘73 96. No visible sign of leaking around the master cylinder , but a drop of fluid was hanging off one of the front callipers. I’ve searched around on this forum and it seems replacing the slave cylinder seals is the thing to do.

I’ve ordered two sets from John-Saab, and read the relevant sections in Haynes,but had three questions:
1) do I need imperial wrenches, or are the bolts all metric? Would flared wrenches be best for this job?
2) Haynes says I should replace the lock plate, but I can’t see these parts available easily. Is this really necessary?
3) I have a brake bleed kit (hand pump suction type) but is there anything else ‘specialist ‘ I might need?

Plus any useful tips (I’ve read about using a piece of wood to ease the seal in)

Thanks for any help,
Joe.

Derek
V4 Guru

United Kingdom
2187 Posts

Posted - 10 Apr 2018 :  14:08:19 Show Profile Reply with Quote
Slave cylinder is for the clutch. If you have fluid dripping from the caliper I would be looking at that very closely. It may not be coming from the piston seal itself. Clean down with brake cleaner and go for a drive. That should allow you to pinpoint the leak.
Rear cylinders can leak a surprising amount before it shows at the bottom of the back plate.
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Mos6502
V4 Fan

USA
133 Posts

Posted - 10 Apr 2018 :  14:52:36 Show Profile Reply with Quote
I've done the caliper rebuild several times. You may want to pick up new pistons while you're in there, before you pull yours apart - do they look crusty?

The hardest part for me was figuring out which seal was the inner seal and which seal was the outer seal, one is flat, and one is grooved. I've already forgotten which is which. Second to that is pressing in the metal retaining ring which is a royal pain in the neck. It's very easy to bend and I've go no ideas for how to make it easier to push in.
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EdinburghJoe
V4 Fan

United Kingdom
162 Posts

Posted - 10 Apr 2018 :  20:54:55 Show Profile Reply with Quote
Thanks guys, I also spoke to John Wyatt this morning- he confirmed that the bolts are imperial (not metric), and that the lock plate can usually be re-used.

Am I right to think the front brake cylinders are more likely to leak than the rear? Just looking at posts on this forum it does seem that people seem to discuss the front more than the rear...

Mos - the trick I read on this site was to use a piece of wood, I think to push in the retainer. I’ve not tried it yet, but I think the idea is to use it to apply even pressure around the retainer while pushing it in.
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pchristy
V4 Guru

United Kingdom
1790 Posts

Posted - 11 Apr 2018 :  08:52:19 Show Profile Reply with Quote
When I rebuilt mine, I used the piece of wood trick. BUT, its important to make sure the rim of the cylinder is as clean as you can get it beforehand. Any trace of rust dust will prevent it going in! I thoroughly cleaned mine, washing them out with brake cleaner, then applied a small amount of brake rubber grease around the lip. I used the wood trick in a large vice, but make sure everything is perfectly positioned before applying pressure.

When it goes in, it does so surprisingly easily! If its not going in easily, its not square, so STOP!

As Mos6502 says, its worth getting new pistons before you start. You will almost certainly find yours corroded. I got a set of stainless steel ones from a guy on Ebay, who was advertising ones for a BMC 1100, which used the same calipers. The BMC ones are fractionally longer, but otherwise identical. There is still plenty of space for fitting new pads.

--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"

Edited by - pchristy on 11 Apr 2018 08:53:52
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72sonett3
V4 Fanatic

Spain
269 Posts

Posted - 11 Apr 2018 :  16:58:19 Show Profile Reply with Quote
The solid (square) seal (12) goes in first, then the grooved one (8), then the steel ring. The anti squeek sheet thingy (14) is usually missing...



--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T

Edited by - 72sonett3 on 11 Apr 2018 16:59:14
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EdinburghJoe
V4 Fan

United Kingdom
162 Posts

Posted - 13 Apr 2018 :  18:05:51 Show Profile Reply with Quote
Thanks everyone- I’ve got two new seal kits, two new pistons (from Brakeparts), plus imperial sockets and flared spanners. I’ll see how I get on...
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 31 Aug 2023 :  13:27:34 Show Profile Reply with Quote
quote:
Originally posted by pchristy
When I rebuilt mine, I used the piece of wood trick. BUT, its important to make sure the rim of the cylinder is as clean as you can get it beforehand. Any trace of rust dust will prevent it going in! I thoroughly cleaned mine, washing them out with brake cleaner, then applied a small amount of brake rubber grease around the lip. I used the wood trick in a large vice, but make sure everything is perfectly positioned before applying pressure.

When it goes in, it does so surprisingly easily! If its not going in easily, its not square, so STOP!

As Mos6502 says, its worth getting new pistons before you start. You will almost certainly find yours corroded. I got a set of stainless steel ones from a guy on Ebay, who was advertising ones for a BMC 1100, which used the same calipers. The BMC ones are fractionally longer, but otherwise identical. There is still plenty of space for fitting new pads.

--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"


I'll be darned if I can get the outer steel ring in, into the caliper cylinder.
I've now knackered two of them, trying to get them in. Fortunately apart from the set I just bought, I found another set that I bought years ago.
I'm now in last chance saloon, and I havn't gotten one in yet!

Anyway, I've tried the vice trick, (Just can't keep it square),I've tried heating the housing a little with a heat gun, but not too much.
I've tried putting the ring in the freezer to try and shrink it.
Trying that again.
Any other tips?

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 31 Aug 2023 13:28:30
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EdinburghJoe
V4 Fan

United Kingdom
162 Posts

Posted - 31 Aug 2023 :  17:38:42 Show Profile Reply with Quote
Hi Andy, I remember it being a real swine to get in - maybe a go with your beloved dremel to take just a little bit off the internal rim of the caliper might give you the fractional extra clearance that you need.

Plus it's possible that trying to push in one of the rings has distorted it slightly, flaring the edges which could make it even harder to get in. Maybe better to get another set than persevere with a set that's potentially distorted?

Good luck with it,

Joe
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EdinburghJoe
V4 Fan

United Kingdom
162 Posts

Posted - 31 Aug 2023 :  17:41:08 Show Profile Reply with Quote
I think if there's any possibility your new ring might have flared slightly then I'd get another one - if you did grind the caliper to try to fit a distorted ring then you might end up ruining the caliper...
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christophe
V4 Fanatic

France
224 Posts

Posted - 31 Aug 2023 :  19:07:49 Show Profile Reply with Quote
Hi Andy.
I might have understand this wrongly (one of my specialties!), but you're only supposed (works better with Michael Caine's voice) to expand the cylinder and shrink the ring. So, you must use heat on the caliper and cold on the ring, not the opposite.
When I overhauled my calipers, I did not notice the rings at once. The outer seal came off and in again without touching the rings and fairly easily.
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melle
V4 Guru

United Kingdom
3830 Posts

Posted - 31 Aug 2023 :  19:18:31 Show Profile Reply with Quote
It's much easier to put the retaining ring on the bench and fit the cylinder over it, than trying to wrestle the retainer into the cylinder, if that makes sense. If you put the assembly near the edge of the bench you can use a clamp as a press, ask an assistant to do up the clamp while you square up the cylinder if you feel you need a third hand. Alternatively, tap the cylinder with a soft/ hide hammer, or use a pillar drill or bench press if you have access to one.

www.saabv4.com
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 31 Aug 2023 :  23:07:03 Show Profile Reply with Quote
In the end I used my Dremel power tool, with a very, very small grinder on it to increase slightly the bevel on the cylinder. I then greased it up with red rubber grease, I then managed, with my fingers/hand to get the ring started into the cylinder. Once I'd got it started, I used a very small piece of wood to gently tap it all round. Once it was roughly half way in, I put the seal in, and then put the whole thing in the vice, and pushed it home. Job done, but what a gudddle.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 31 Aug 2023 23:16:24
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 31 Aug 2023 :  23:13:46 Show Profile Reply with Quote
quote:
Originally posted by christophe
Hi Andy.
I might have understand this wrongly (one of my specialties!), but you're only supposed (works better with Michael Caine's voice) to expand the cylinder and shrink the ring. So, you must use heat on the caliper and cold on the ring, not the opposite.
When I overhauled my calipers, I did not notice the rings at once. The outer seal came off and in again without touching the rings and fairly easily.


Yeah Christophe, I tried putting the seal ring in the freezer, to shrink it, and also at one point tried heating the cylinder assembly to expand it.
Seems logical to me, but did not really work. I was worried about heating the cylinder assembly too much, so probably not enough expansion.Freezing the ring that needed to be inserted, just did not shrink it enough. Perhaps I need to freeze it overnight, to get anoiugh shrinkage?
Certainly was the right way round, heat the part that your trying to fit into, and freeze the part you're trying to fit in,


1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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Woody
V4 Guru

United Kingdom
2758 Posts

Posted - 31 Aug 2023 :  23:41:30 Show Profile Reply with Quote
never had to freeze or heat anything on the calliper piston assemblies.
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melle
V4 Guru

United Kingdom
3830 Posts

Posted - 01 Sep 2023 :  18:36:23 Show Profile Reply with Quote
Me neither.

www.saabv4.com
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