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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 16 Apr 2019 :  21:35:33 Show Profile Reply with Quote
No handbrake, even fully adjusted, shoes not worn and drums not worn. I'm going to try putting some weld on the levers where they go through the backplates to compensate for wear on the linkage.

Looking at it, I'm having trouble understanding how it's meant to work. The cable pulls the lever forward, it bears against the backplate and the other end of the lever moves rearwards, thus operating the rear brake shoe. So far, so good, but what about the front shoe? I would have expected the mechanism to push that forward as well but it looks like it doesn't. Am I understanding it correctly? The handbrake only operates the lower part of the rear shoe?

OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 17 Apr 2019 :  14:48:36 Show Profile Reply with Quote
Another V4 mystery; looks like nobody knows!
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stevebod
V4 Fanatic

United Kingdom
336 Posts

Posted - 17 Apr 2019 :  17:01:38 Show Profile Visit stevebod's Homepage Reply with Quote
Hi Owen,
I know when things are worn the mechanism levers against the back plate but I don't think this is how it is supposed to work.

My mechanical mind tells me that pulling on the cable should apply similar force to both shoes. The reason is that as the cable pulls forward, the rear lever creates a spreading action between both shoes. The back plate shouldn't come in to it, because this way the shoes can "float" and still operate together. If you lever against the back plate only one shoe will work as you described.
I probably need to draw it to explain it better.
I know some people have improved braking by adding weld like you said to create a backplate pivot, but I think they may only be operating one shoe.

Can you tell us if the foot brake works OK on the back?

Edited by - stevebod on 17 Apr 2019 17:02:27
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 17 Apr 2019 :  19:30:18 Show Profile Reply with Quote
Thanks Steve,
The foot brake works fine on the back. The lever being pulled by the handbrake cable has to pivot against something. I think it pivots against the backplate and only operates the rear shoe. I would have expected the mechanism to work like the footbrake and operate both shoes; hence my post.

Your 'floating' theory wouldn't work because the lever's got to lever against something.
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stevebod
V4 Fanatic

United Kingdom
336 Posts

Posted - 18 Apr 2019 :  15:20:28 Show Profile Visit stevebod's Homepage Reply with Quote
Hi Owen,

You are right that the lever must pivot against something to "spread" the shoes, but if we assume it's not the back plate, then I think the braking sequence goes something like this.

you pull on the cable.
1. The front shoe moves forward OR the rear shoe moves backwards. Which shoe moves will depend on friction and spring strengths etc....
2. The moving shoe contacts the drum.
Now the other shoe has something to lever against.
3. As you keep pulling on the cable the second shoe now moves out to contact the drum.
4. At this point more pulling applies the brake harder and harder, and the shoes press against each other to share the braking force. They can float to compensate for any drum run-out and to share the braking force equally.

Here is a drawing.



Obviously when you pull the cable you don't know if the whole assembly will move forward activating the front shoe first, or if the lever will pivot and activate the rear shoe first, but ultimately once the first shoe touches the drum the second shoe can move out and both work together.

Another thing to check. I drew the lever at the 11 o'clock position here which is where it should start. If your lever is pointing forwards like the 1 or 2 o'clock position then you won't get the same mechanical advantage. This is when the lever starts to contact the back plate.
If you are going to add some weld then I would add it to the lever cut out's circled in red. This area can wear and by replacing it you will restore the mechanism to how it should be.

I hope this gives you some ideas.


Edited by - stevebod on 18 Apr 2019 15:22:41
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 19 Apr 2019 :  14:57:37 Show Profile Reply with Quote
Hmmm.... That makes a lot of sense Steve. Amazing how a diagram can help understand even simple moving parts.
I think I'll order new levers from Malbrad; there's a lot of play in the old ones.
I did find some faults on the brakes including wear on those little stainless steel wedges (tappets?) on the brake adjuster.
Someone mentioned longer wedges but I have no idea where to get them.
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deggsie
V4 Fanatic

United Kingdom
336 Posts

Posted - 19 Apr 2019 :  20:04:10 Show Profile Reply with Quote
quote:
Someone mentioned longer wedges but I have no idea where to get them.

Malbrad again (but not cheap) - see http://malbrad.co.uk/cart/products.php?318&cPath=26_35

___________________________
Saab - beyond the conventional !
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 20 Apr 2019 :  10:19:05 Show Profile Reply with Quote
Bloody 'ell! 15 per wedge! That's unbelievable. I'll get new linkages and see if I can get someone to make up longer wedges.
Surprised people with classic Minis/MG's haven't had these made up but can't see them anywhere.
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green96v4
V4 Fanatic

Canada
456 Posts

Posted - 20 Apr 2019 :  12:20:21 Show Profile Visit green96v4's Homepage Reply with Quote
are these the same? probably standard length but might be worth getting the full (standard) kit first and seeing if all new parts fixes it

http://minispares.com/product/Classic/Brakes/Shoes/Shoes/17H7618.aspx?040602&ReturnUrl=/product/Classic/Brakes/Shoes/Shoes/17H7620.aspx|Back%20to
http://minispares.com/product/classic/17H7620.aspx
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Woody
V4 Guru

United Kingdom
2442 Posts

Posted - 20 Apr 2019 :  12:23:43 Show Profile Reply with Quote
The levers wear, the slot in the shoe wears and the drum wears. If you need to put in longer wedges then it Is most likely that the drum is worn. You can also get stretch in the handbrake cable as well. I have seen the wedges wear on the chamfered face. Well worthwhile having the back plates blasted and the adjuster bolt removed and cleaned. Copper grease on it for re-assembly.
Good to see a photo of your components Owen.
Great diagram Stevebod.
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72sonett3
V4 Fanatic

Spain
251 Posts

Posted - 21 Apr 2019 :  05:44:10 Show Profile Reply with Quote
If you pull the cable, both red circled notches move outward, away from each other, pushing against both brake shoes. The lever pivots against whatever shoe it touches first.
Like stevebot explains.

First you adjust the top side wedges until they lock the brake, then back out 1/4 turn or until the wheel just rotates free.

Then you pull the hand brake lever all the way up and grab a cable between the front seats with pliers.
Then you release the hand brake lever (but still hold the cable tight with the pliers), and pull it up again three clicks.
Then you take out the slack in the cables by turning the nuts in until the wheel locks (still holding the cable).
Then if you release the hand brake lever it should rotate freely again. Repeat for the other cable.

If you run out of thread to take away the slack, the cables are stretched too far and should be replaced.

--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T
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andydeans3
V4 Guru

United Kingdom
1194 Posts

Posted - 27 Apr 2019 :  09:56:09 Show Profile Reply with Quote
This is a great thread because my 96 just failed its' MOT for the handbrake.
I took the brake assemblies apart both sides, and replaced the levers with new ones that I bought at the SAAB festival in 2105. Also replaced the brake shoes. The cable on one side was pretty hard to move, so thinking that I had nothing else to do but replace them with new cables that I have, I set about it.
However it proved utterly impossible to release the handbrake cables from the point where they passes through the stops on the back axle, just above the drums. So, I got the old cables moving, greased them oiled them, until they slipping back and forward nicely.
Put it all back together, (as per the drawing in the manual -
as per the photo below of the left nearside, prior to strip down) adjusted everything. The rear drums were locking up at the 3rd click on the handle. I even put 2 bolts in the hubs, and tried to turn the hubs with a cheater bar. Solid.
BUT, took it for a test drive, and quite frankly the handbrake is still pretty poor...
From 15 or 20 mph I can lock the back wheels with the handbrake on my MGB, with the Saab there's a vague feeling of slowing down a bit, that's about it.
I'm not sure it will pass its re-test with the handbrake like this.
I always drive on free wheel, so the handbrake may one day be the only way to stop the car!!!

Does anyone have any ideas?

Are the shoes orientated the correct way? ie the operating lever on the side(back) where the brake lining goes right to the top of the shoe.

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

Edited by - andydeans3 on 27 Apr 2019 18:17:50
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 27 Apr 2019 :  10:31:39 Show Profile Reply with Quote
You've got further than I've got Andy.
The shoes look correct. Have you measured the internal diameter of the drums? Haynes says it should be 205mm max.
You don't say that you've gone through the adjustment procedure in the previous post, but I assume you have.
All I'd try is adjusting the cable more so that it bites on the second or first click and see if that does it.
If that don't do it, then maybe replace the drums (or obtain the thicker brake linings someone suggested).
Good luck!
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OWEN
V4 Fanatic

United Kingdom
285 Posts

Posted - 27 Apr 2019 :  10:43:20 Show Profile Reply with Quote
Looking at your photo again; looks like you've still got a lot of adjustment on the top adjusters.
If the drums are worn and the brakes were adjusted, I'd expect to see less or no wedge showing.
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chris steeden
V4 Beginner

United Kingdom
92 Posts

Posted - 27 Apr 2019 :  15:24:08 Show Profile Reply with Quote
Andy, Your set up with springs etc seems fine but looking at the bottom brake shoe where the shoe touches the piston, I can see a round cut-out in the shoe similar to the earlier type 1 and type 2 shoes where the cut out fits snug into an adjuster cam (Two stroke). I would suggest that although very similar you might have the wrong brake shoes fitted as I believe that the shoe for the V4 has a flat end against the piston. Not sure if this makes any difference but it could be that I have not appraised your picture correctly (this wont be the first time)

Edited by - chris steeden on 27 Apr 2019 15:30:16
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andydeans3
V4 Guru

United Kingdom
1194 Posts

Posted - 27 Apr 2019 :  18:16:18 Show Profile Reply with Quote
Update.
Guys.
Well I had another look today, and can say that as per Steve Bod's drawing the handbrake actuating levers are more at 1 O Clock, than 11 O'Clock, with the handbrake off.
If I'm not mistaken that usually is a sign of wear in the actuating lever system, but mine are new, never been used, bought at the autojumble at the SAAB festival in Trollhatten, in 2015.
Brake shoes are also new.
Chris - I'm not sure exactly what you mean when referring to a round cut out in the shoe. I can only say that the new shoes came from Malbrad.

Owen - Remember the photo shows the arrangement when I first removed the hubs. ie I had backed the adjuster right off, in order to be able to remove the drums.
I did not measure the ID of the drums. Something I will do if I have to take it all apart again, ie if it fails the re-test.

I have had the wheels off again today, and tightened the adjusters to bring the shoes closer to the drum. ie just "skiffing" when you spin the drums.
The handbrake is marginally better, but nowhere near as good as the one on the MGB!!!
Hopefully re-test on Monday. have to have everything ship shape for Swedish day!!!


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

Edited by - andydeans3 on 27 Apr 2019 18:20:32
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