Curs-ed Rear Drum Brake Cylinder Backing Shims

Suspension, including wheel, tire and brake.
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defdes
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Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 25 Feb 2014 10:51

I KNOW this isn't a 2 hour job, but I have been struggling to get all 3 spring clips slipped in between the backing plate and the brake cylinder. I have tried putting the first one in, then the 2nd, then the 3rd. The 3rd will constantly splay outward as if there is not enough room for them. I tried stacking the 2nd and 3rd and couldn't get them started in the little space that there is for them.
Sorry, no pics my camera is NLA, but anyone familiar enough with this to give me any guidance sans visual information?

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zKars
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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby zKars » 25 Feb 2014 10:58

Not sure if this will help, but at least you will confirm the correct order and sequence of the clips.

510_drumBrake.jpg
510_drumBrake.jpg (149.05 KiB) Viewed 1684 times


The drawing shows 4, but only 32, 31 and 30 are required I think. 21 looks like an extra 20,32

I have to do this too soon, let us know what tricks you discover.

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defdes
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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 25 Feb 2014 11:04

Thanks, for that. Never hurts to check something other that what's on the other side of the car. I have the order and placement correct, it's just the space for all of them I don't!

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby zKars » 25 Feb 2014 11:58

If space truly is the issue, then its either this new slave has a slightly different dimension where the shims sit/fit (less!), or the backing plate is rusty/dirty/dented causing the slave to not sit flat on the backing plate . Can you compare the old one to the new one? Maybe a little judicious filing on the slave body might provide a little more room?

Do you have the hydraulic line attached? The slave has to be able to float it will not auto-center, being too tight is not a good thing! Wait, do these things have the hard line attached directly to the slave? then no motion is possible. hmmm...

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defdes
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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 25 Feb 2014 12:39

All is cleaned, I did a little filing on the cylinder as I thought the casting was a bit out of square (the "T" groove where the shims slip into). I also filed the leading edges of the 3rd shim to allow it to slip under at all. It will get about half way there, then it gets so tight that it pushes the legs of it outward leaving me with a shim that I have to go straighten.
Hard line is attached directly to cylinder (not attached during this install), but as you are supposed to grease the backs of the cylinder, it is designed to move some.
I have not compared to the old one, but will do so.

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defdes
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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 25 Feb 2014 13:53

Thanks for the insight or I probably wouldn't have mic'd them both. The newer unit had .020 less clearance for the shims, the last shim was .035 hence the tightness. Filed it out and all is well...only wasted half a day!

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby Byron510 » 25 Feb 2014 19:25

John, I share your frustration. When I assembled the Bronze I had the same issue with my new cylinders - same issue. When I finally checked the shim pack, the new ones were thicker. I too filed out the cylinder slot and all went well. And I spent more than a half a day on it..... :evil:

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defdes
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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 26 Feb 2014 03:49

Working on cars one can get very used to frustrations, but this one pushed me to the limit. It does make me feel better that I am not alone, however. Chalk this one up to the Live and Learn Archives.

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby zKars » 26 Feb 2014 06:57

Well, thanks to the both of you for saving me (and hopefully many others) a half day of pain.

Shims too thick? Who would'a thunk it. Glad that's solved without major incident.

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 26 Feb 2014 08:48

Shims weren't to thick more that the newer castings are not to spec.

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby zKars » 26 Feb 2014 09:32

Alright, here's another thought. The FSM and parts fiche shows FOUR shims! The new slave you got, and the ones I got, and those referenced by Byron's experience only came with three (I'm guessing).

Notice from the drawing I posted, that parts 21 and 20,32 appear identical, while 19,31 and 18,30 are unique from the others.

This leads me to believe, that there has been a variety of shims and slaves with varying dimensional specs, and it is up to us to pick if you need one or two, and maybe even file down the slave slot to make room, all just to make it fit "just right". The FSM is no help there, just the useless "assembly is the reverse of dis-assembly" stuff... Has to be snug, but still allow full travel of the slave in its backing plate slot.

How much you want to bet that 21 and 20 were originally spece'd with different thicknesses... There Description is "Plate-Lock A B, C and D". Why would they have different part numbers?

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby defdes » 26 Feb 2014 09:44

I believe I read in some Z-Car, OldDatsun forums that some of the earlier cylinders actually did use all four shims, that does not mean what you are saying might not be true though for our application. Shim #20 actually has a right angle tang bent into it in the middle which would make getting #21 over it difficult unless it had a different profile cut into it. #18 and #19 click together.

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby zKars » 10 Mar 2014 08:34

Ok, I went through the slave cylinder shim madness over the weekend. Good thing I had this thread to keep me sane. I had the control arms w/backing plates on the workbench and I still struggled.

Here's the complete story. Sorry no pictures for the moment.

I purchased the slaves through Rock Auto. The castings appear to be new, rather than rebuilds. Sounds good, right? Wrong. The castings are flawed, especially around the necked down area where the shims sit. . Knowing that the shim area likely had to be filed to open it up to allow the shims to fit, I measured the gap on the old ones, and compared that to the new ones, to see how much casting I'de have to remove. Well dang it, when I measured the two with a caliper, yes some had to be removed, but it wasn't the same on both sides! One needed a good 1/16" removed, but the other was only about 1/2 of that! Studying the casting, it was obvious that the thing looked like a blind, one-handed three fingered sculptor had created the mold for this thing. Even the sticky-up-part /rectangle boss thing, (sorry for the technical terms) that rides inside the backing plate slot to locate and guide the master as it slides, is about 1/16" too narrow, and only sticks up about half as high as the stocker. That's real confidence inspiring.

So after filing and fitting, the thing went in with little further trouble. I used a combination of old and new shims to get the "right" degree of tightness and slidy-ness (there I go again) that I liked. All three of the new shims were different thicknesses from the originals, and were roughly the same interlocking shapes. Apparently made from whatever sheet stock they had laying around and bent up with needle nose pliers. or teeth...

Let's hope the piston bores are something round-ish... The brake line fittings went together ok, the Inverted flare cone looks ok, we'll see how it seals.

I can just imagine how long these will last. The old ones looked pretty darn near new anyway, I'll keep them around for spares. I have no confidence in the life expectancy of these.

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby datzenmike » 10 Mar 2014 14:49

Got a set of rear cylinders from NAPA in Spokane for my 710 and collected them at Canby two years ago. Same thing. I gave up trying right away and ended up using one original spacer clip to get them on. Feels good to see it wasn't me and can admit what I did. :lol:
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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Re: Curs-ed Rear Drum Brake Cylinder Backing Shims

Postby sss1600 » 21 Mar 2014 20:07

Had the same experiences over here aswell and just learnt to fit them securely the best way i could at the time.
I remember doing it a few times in particular that were all in different ways with different aftermarket rear wheel cyls.
Once i filed the slots a bit on the wheel cyl body, another time i left one of the new shims out altogether and another time i used the original shims that came off the car.
They all worked fine. Go figure...


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