| Author |  Topic  | |
EdinburghJoe
V4 Fan
United Kingdom
162 Posts |  Posted - 05 Aug 2019 : 14:46:08  
| Hi all,
I’ve stripped the rear hubs on my 1973 96 to fix a brake imbalance (it failed the MOT). I found one of the pistons was seized in the offending wheel, so I’m wanting to replace the cylinder and pads on both wheels.
I’ve got the cylinders off, and realised that they are 3/4 inch, and the eBay replacement (Borg and beck bbw1551) are 5/8 inch.
I’ve read here (and in Haynes) that 5/8 is the right size for the car, but I can’t fit them because the end of the brake line will not screw into the new cylinder. It’s the right width, but I suspect the thread pitch is wrong. They certainly look similar by eye.
Does anyone know what the difference might be between the thread dimensions of the old and new cylinder? I’m going to get a new pipe length made up and it would be handy to know what to ask for!
Thanks,
Joe.
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 05 Aug 2019 : 17:19:59
| The standard thread is 3/8 UNF; it would surprise me if the new ones are different. Are you sure the threads on the brake hose aren't damaged? Bill at Saabits sells nice stainless HEL brake line kits, if you're a UKSaabs member he'll give you a 10% discount.
Unless there is a lot of pitting in the cylinders, cleaning and reassembly with brake grease normally is enough to give them a new lease of life.
www.saabv4.com |  |
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StefanM
Starting Member
Sweden
34 Posts | Posted - 06 Aug 2019 : 13:46:23
| These lockheed cylinders is pretty common back then and most likely they have used whatever they could find and they had 10mm thread perhaps. Late mini or Ford Transit perhaps or whatever.
The correct V4 cylinders is 5/8" bore with 3/8" UNF thread as mentioned. | |
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melle
V4 Guru
United Kingdom
3833 Posts | |
EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 07 Aug 2019 : 21:46:53
| Thanks for the replies. I took the pipes and new cylinders to our local garage and he made up a new set of pipes for me, and they definitely fit the new 5/8” cylinders. I’ll ask hiim what size he used when I see him for the retest, but I’m guessing it would have been 3/8” unf as suggested here, and my old cylinders must have had something different, maybe metric?
Now all I’ve got to do is get it all back together (with new shoes) and hope it passes... | |
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andydeans3
V4 Guru
United Kingdom
2012 Posts | Posted - 22 Aug 2019 : 04:55:40
| Joe
How did you get on with the MOT?
1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 27 Aug 2019 : 16:19:37
| Passed - thanks for asking!
The brake test printout showed that the rear brakes are now even, though less powerful than before (compared to the previously 'working' side). I guess that will be down to having the smaller bore size, or maybe new shoes not yet bedded in. Anyway, the MOT guy said it was much better so I'm hoping this is now all taken care of.
Joe | |
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Derek
V4 Guru
United Kingdom
2190 Posts | Posted - 28 Aug 2019 : 12:23:45
| | The hand brake is mechanical so the cylinders don't come into play. Yes, should improve a bit as the shoes bed in. Were the rears down a bit when the brake pedal was used? Poor hand brakes often caused by wear in the levers. Very common and can be fixed by welding and redrilling. I think Malbrad has replacement levers, maybe on exchange. Not particularly cheap but time-saving for a quick changeover. | |
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| | Topic | |
Rear brake cylinder bore
