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 Front brake binding
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 13 Jan 2019 :  14:59:22 Show Profile Reply with Quote
Put my foot on the brake yesterday and it binded; didn't just drag a bit when I took my foot off but actually locked solid. Can't happen with the font brakes, right? So I checked the back brakes. It isn't the back brakes; it's the front brakes. I can unlock it by reversing. Unfortunately can't get the wheel off today without a scaffold tube so I haven't managed to have a look yet. I can't imagine any scenario that would make the front brakes lock. Any ideas?

greg124
V4 Fan

United Kingdom
169 Posts

Posted - 13 Jan 2019 :  15:56:26 Show Profile Reply with Quote
Had a similar thing happen with one of my non-Saabs, and it was tracked down to a fault with the servo.
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ratty
V4 Fanatic

246 Posts

Posted - 13 Jan 2019 :  16:23:08 Show Profile Reply with Quote
Could be a collapsing flexi hose internally. Brakes will work but won't release. Unless they are new new try some new ones. Easy fix. I had the same problem a few years ago.
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 14 Jan 2019 :  14:45:02 Show Profile Reply with Quote
I had a look. The inner brake pad had moved upwards. I'm trying to figure out how this could happen. I fitted it all back the way it should be and oiled it up. I did notice I was low on brake fluid so topped it up. Seems to work now but I'm not happy not actually finding the problem; could happen again. Any idea anyone how the inner brake pad could move upwards? What's meant to keep it in place?
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deggsie
V4 Fanatic

United Kingdom
336 Posts

Posted - 14 Jan 2019 :  21:32:16 Show Profile Reply with Quote
quote:
Any idea anyone how the inner brake pad could move upwards? What's meant to keep it in place?

Unless the pads are really worn, the inner ones taper towards the top, so upward movement is quite strange. The pads are normally held in place by the spring clip and its split pins (as well as the caliper itself).

___________________________
Saab - beyond the conventional !
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melle
V4 Guru

United Kingdom
2831 Posts

Posted - 15 Jan 2019 :  10:45:01 Show Profile Visit melle's Homepage Reply with Quote
I'm afraid wear on the caliper is the culprit: http://www.saab-v4.co.uk/speedball/topic.asp?TOPIC_ID=34284 What did you 'oil up'? I wouldn't use oil on brake calipers.


Is the metal part of the pads still in good condition?



www.saabv4.com
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 15 Jan 2019 :  16:59:25 Show Profile Reply with Quote
Thanks Melle, That was exactly the problem. Both the metal part of the inner pad and the caliper were worn. I did a 'temporary' fix simply by replacing the inner pad (I know, I shouldn't but it's cold outside and not a lot of light). Seems to have solved it for the moment. I'll get the calipers welded in better weather and replace the pads. PS I just oiled the 'hinge' on the caliper and the other end where the two parts of the calipers rub; just to make sure it moved freely. Managed to find a spare caliper (which also needs welding), but of course it was the wrong side!

Edited by - OWEN on 15 Jan 2019 17:00:54
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melle
V4 Guru

United Kingdom
2831 Posts

Posted - 15 Jan 2019 :  17:19:17 Show Profile Visit melle's Homepage Reply with Quote
Common problem after 40-50 years of use. Your "fix" will hold up for a while. I did the same in 2014 and only replaced the calipers with refurbished ones last months (I refurb'd them in 2014 but never got around to fitting them...). I use copper slip on the hinges, sliding surfaces and the backside of the pads, but only very sparsely.

www.saabv4.com

Edited by - melle on 15 Jan 2019 17:20:45
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 28 Apr 2019 :  18:19:57 Show Profile Reply with Quote
Update: Got the calipers welded so that the pads fit snug and the surfaces that hold the pads in place are welded and filed square. Put it back together and discovered the root of the problem; the brake disc is worn to 7mm thick! It's meant to be 9mm min. Luckily I have a spare more than 9mm. Went to fit it and discovered the castellated nut in the front is different to the one at the rear drums. Rear drums is 28mm and I have a spanner for that but not for the front nut. Can someone tell me what size spanner/socket I need for the front castellated nut? Also some advice as to how to pull off the disc would be useful. I haven't got a puller. I'm doing all this at the side of the road!
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 28 Apr 2019 :  18:35:12 Show Profile Reply with Quote
Yes, of course I should have done a search before posting. The front castellated nuts are 1 and 5/16 in. I wonder what that is in mm.... 33.3375mm; not a good fit; I guess I could hammer a 33mm socket on....
Advice on how to pull the brake disc off without a puller anyone?
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72sonett3
V4 Fanatic

Spain
251 Posts

Posted - 30 Apr 2019 :  05:35:21 Show Profile Reply with Quote
I used an angle grinder to grind 0.3 mm off the flats to make it a 33 mm nut.

--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 30 Apr 2019 :  09:18:20 Show Profile Reply with Quote
Sorted............ for the moment anyway. With the new (used) brake disc, the shoulder on the caliper at the top of the inner brake pad fully overlaps the metal part of the pad. However, as the brakes wear this overlap will reduce and the pads might slip upwards and bind again so I really need to get new brake discs....... in due course.

Taking off the disc I was amazed to discover that the last clown I got to do some work had pushed (hammered?) the circular nut into place but luckily I had a spare.

Sorry, no pics of the work in progress; with my hands covered in muck I wasn't about to stop and use the camera.
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