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 Front brakes stucked. how to repair?
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x96
V4 Fanatic

Spain
314 Posts

Posted - 07 Oct 2021 :  21:02:55 Show Profile Reply with Quote
The front brakes are stucked, it is impossible to move the car pushing by hand.
I could unlock them by pressing the piston inside but then when I press the brake pedal, they came again stucked.

I suppose it is the piston that doesn't return correctly.

One metal and rubber ring went out easily. How do they work? It seems that when I brake the ring can comes out easily following the piston. Is there a lip inside the caliper for fitting the rubber?

I don't know if it is a simple reparation that I can handle. Any advise?
I imagine that to fit new pistons with rubber rings can be very difficult.



Héctor

Edited by - x96 on 07 Oct 2021 21:03:42

x96
V4 Fanatic

Spain
314 Posts

Posted - 07 Oct 2021 :  21:05:08 Show Profile Reply with Quote
the other side still has its rings fitted.

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Héctor
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x96
V4 Fanatic

Spain
314 Posts

Posted - 07 Oct 2021 :  21:10:35 Show Profile Reply with Quote
Happy to discover how the system works, I found also a big difference between old and new pads.

The TRW ones have bigger friction pads.

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Héctor
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Dirtbiker
V4 Mad

United Kingdom
884 Posts

Posted - 08 Oct 2021 :  07:04:28 Show Profile Reply with Quote
Hi,
Change the rubber hoses too.
Sometimes they collapse and cause the brakes to stick.
Also you can get stainless steel pistons on eBay. These are not too expensive and do not corrode like the original ones.
Good luck!

Edited by - Dirtbiker on 08 Oct 2021 07:05:25
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christophe
V4 Fan

France
127 Posts

Posted - 08 Oct 2021 :  09:17:32 Show Profile Reply with Quote
Like Dirtbiker, my bet is on the brake hoses. Change them if they are more than 10 years old. I just had to refurbish my calipers and this was pretty straightforward. The seals kit is readily available. Remove the two bolts securing the calipers to the front hub after flattening the tab locks. With the calipers away from the hub, use the hydraulic pressure to get the pistons out. There are two grooves in the caliper for the seals, but the upper one is opened and the seal is held by the metal ring there. If you find small rust areas on the pistons after the section covered by the inner seal, these are not critical if they smooth out well. Always lube the hydraulic parts with Castrol red rubber grease and use copper grease on the friction points between the calipers and the brake pads. Take also care of the caliper hinges if these don't move easily.
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x96
V4 Fanatic

Spain
314 Posts

Posted - 09 Oct 2021 :  12:42:20 Show Profile Reply with Quote
Thanks for your replays.
I had changed the brake hose time ago, it was in bad shape.



I also notice that the spring looks upside down.



If it is not too much difficult I will try the complete refurbish by myself.

Christophe, when you tell me to use the Castrol red rubber grease for hidraulic parts do you mean it is for the inner seals? Maybe for helping to insert them?

The caliper hinges at the bottom where with reasonable movement, a bit worse at the top with the spring and surroundings rusted.



thanks

Héctor

Edited by - x96 on 09 Oct 2021 12:48:20
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andydeans3
V4 Guru

United Kingdom
1579 Posts

Posted - 09 Oct 2021 :  13:53:11 Show Profile Reply with Quote
Make sure that the calipers move back and forward quite easily, with no pads in place.
As you say the you can get quite a lot of corrosion around the spring assembly at the top. This can stop the caliper moving smoothly.
I removed the whole spring assembly at the top, and replaced the spring and other parts,(available from Skandix) but fitted the new ones with stainless steel bolts and nuts. Two nuts locked together, one of those nuts with a nylon locking system in the nuts, and a circlip on the end for good measure.
This allows you to adjust the tightness of the sliding assembly.

Photos below







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

Edited by - andydeans3 on 09 Oct 2021 14:09:44
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christophe
V4 Fan

France
127 Posts

Posted - 10 Oct 2021 :  01:09:36 Show Profile Reply with Quote
Hi again, Hector.
I use Castrol red rubber grease when I rebuild disc calipers or wheel cylinders to act as a barrier against moisture at the end of the piston. Usually, you apply it liberally under the outer rubber boot but I also like to coat pistons and cylinders with it. It is a thick compound that also acts as an extra seal. I also use it when installing the seals in their grooves, as it will protect them from any further corrosion. Of course, I am not affiliated with Castrol and you can use any other equivalent product. Bendix makes a similar product but much more pricey.
Yes, the spring clip is upside down in your picture.
About the hinge components of the caliper, all you have to do is to use some sandpaper to make all friction surfaces smooth and protect them with a coat of copper grease. Don't forget to use it too but lightly at the friction points between the spring clip and the brake pads.
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x96
V4 Fanatic

Spain
314 Posts

Posted - 11 Oct 2021 :  17:20:51 Show Profile Reply with Quote
thanks for your advices, I feel more confident now, I will give a try.

Héctor
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melle
V4 Guru

United Kingdom
3418 Posts

Posted - 11 Oct 2021 :  22:16:56 Show Profile Reply with Quote
Some good information in Andy's thread: http://www.saab-v4.co.uk/speedball/topic.asp?topic_id=49039 and here as well: http://www.saab-v4.co.uk/speedball/topic.asp?TOPIC_ID=34284&whichpage=1 I'm sure there are a few more useful threads, use the search function.

www.saabv4.com
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Woody
V4 Guru

United Kingdom
2549 Posts

Posted - 12 Oct 2021 :  00:07:09 Show Profile Reply with Quote
X96, the smaller brake pad is off a Morris 1100/1300. I have some in the Troll. Can't get into photobucket at the moment to add a pic and cannot find my previous posting on the subject.

http://www.saab-v4.co.uk/speedball/topic.asp?TOPIC_ID=845&SearchTerms=Morris,1100

Edited by - Woody on 12 Oct 2021 20:13:48
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x96
V4 Fanatic

Spain
314 Posts

Posted - 13 Oct 2021 :  18:40:36 Show Profile Reply with Quote
Thanks, very useful information. I've already red those topics but I will refresh it again.


Héctor
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72sonett3
V4 Fanatic

Spain
264 Posts

Posted - 16 Oct 2021 :  22:31:42 Show Profile Reply with Quote
Héctor,
I have new brake pad mounting kits (spring plate and split pins) here in Spain. I can send one kit to you.

The spring plates (#6) on your car are upside down (and L ---> R)...


I think I would fit new discs as well.


--
'72 97
'77 96L conv.
'95 900SE conv.
'99 9-3T
? 006

Edited by - 72sonett3 on 23 Oct 2021 12:42:27
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x96
V4 Fanatic

Spain
314 Posts

Posted - 18 Oct 2021 :  19:41:12 Show Profile Reply with Quote
quote:
Originally posted by 72sonett3
Héctor,
I have new brake pad mounting kits (spring plate and split pins) here in Spain. I can send one kit to you.





--
'72 97
'77 96L conv.
'95 900SE conv.
'99 9-3T
? 006




Great, I'm going to need them for sure.
Thanks.
I will collect all the bits and then jump on to the restoration.

Héctor

Edited by - x96 on 18 Oct 2021 19:44:29
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Derek
V4 Guru

United Kingdom
2050 Posts

Posted - 19 Oct 2021 :  14:47:16 Show Profile Reply with Quote
Just me, but I'd be freshening up those calliper parts as much as possible and giving them a lick of paint. I hope they are getting new pistons.
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x96
V4 Fanatic

Spain
314 Posts

Posted - 20 Oct 2021 :  21:35:45 Show Profile Reply with Quote
quote:
Originally posted by Derek
Just me, but I'd be freshening up those calliper parts as much as possible and giving them a lick of paint. I hope they are getting new pistons.



Of course, Derek, removing rust and painting is the funny part. And easier. takes time but no need of special ability.
I will put new pistons, yes, old ones are scratched.

Héctor
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