Spongy brake issue

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hedonist
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Spongy brake issue

Post by hedonist » Sun Apr 14, 2013 6:24 pm

Hi guys,

Been a while since we've logged on and also been quite a while since we had the chance to get the sj dirty. Finally now we're trying to get a bunch of issues sorted, would love some inputs regarding what you all think...

Brakes - ever since we went playing in some mud last year, the brakes got quite spongy and deteriorated over time. First time you press the pedal, nothing much happens and pedal hits the floor, second time pressure builds up and the brakes start working.

We tried bleeding them which only improved the issue a little. Then we had someone look at them who has now changed the wheel cylinders and the brake shoes because they were very worn. He also says he bled the brakes a few times but even though there is some improvement, the sponginess remains.

After reading about maybe having to bleed from the proportioning valve as well, we checked and it doesn't look like it can be bled.

After reading up on the issue some more and it would seem like the backplates of the rear drums are up-side-down? The cylinder is at the bottom with the bleed nipple being the lowest point, am I right in thinking that it should be at the top? I remember reading this on a forum thread somewhere but I can't find the link now!

Anyway, we brought this up with the mechanic who just refused the whole idea. Instead he thinks we've got an issue with the master cylinder perhaps. Obviously we won't know if that's the case until we get a rebuild kit or a new one, which is yet further money spent. After checking the lines, it doesn't look like there's a leak anywhere. Any thoughts?

Also, we seem to have an intermittent fault with the alternator, I guess I'll put another topic in the correct forum for that :)

Any help would be awesome :)
Cheers, Laura

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Re: Spongy brake issue

Post by Darrell » Sun Apr 14, 2013 7:07 pm

drum.jpg
drum.jpg (196.89 KiB) Viewed 9369 times
The cylinders should definitely be at the top. :shock:

If the self adjusting mech is not working it can cause this problem. (number 4)

This digram may not be correct for yours as there are a few variations, but all have the cylinders at the top.
Not sure how the handbrake cables must be routed :er: .
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Re: Spongy brake issue

Post by Pugsley » Mon Apr 15, 2013 12:11 am

Absolutely as Darrell says - the wheel cylinder should be at the top of the brake back plate. I can only talk from a sj410 point of view because I don't know if this applies to the 413 but it is imperative that the wheel cylinders are correct for the vehicle based on its country of build. My 410 was of Japanese build and I bought new wheel cylinders which turned to be for a Spanish built version - they fitted perfectly but the piston travel was incorrect leading to all sorts of problems.

I'm also surprised that you can't bleed the proportioning valve - mine had an 8 mm bleed nipple which is very easy to break, so much so that I had to remove the valve and place it in a vice to ensure that I wasn't going to strain the nipple and snap it. Whilst removed I stripped the valve to find it was siezed solid - amazing how a price of £400 from Suzuki for a new one motivates you to fix the one fitted!

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Re: Spongy brake issue

Post by hedonist » Sat Apr 20, 2013 8:20 pm

Thanks for the advice! We had a look at it and couldn't quite figure out if flipping it around would work because it didn't seem as though the handbrake cable would reach if it was flipped. In the end went to Rhino Ray who poked around in it as well and it turned out that there are two layouts of wheel cylinder. Bleed nipple between the fixing holes or brake hose entering between the fixing holes... and the ones originally on the vehicle as well as the new ones put by the other mechanic are both the wrong way round.

So I guess, the backplate being the way it is isn't necessarily a problem, perhaps it's a spanish/japanese thing? But if the cylinder is at the bottom, then the bleed nipple has to be between the fixing holes...

long story short, the brakes work brilliantly now. Does anyone need a pair of barely used wheel cylinders which should be appropriate if your brakes have the cylinder at the top? They're not much use to us as it stands.. ;)

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Re: Spongy brake issue

Post by Darrell » Sat Apr 27, 2013 4:09 pm

Right then after looking at all the variants and searching for pictures I have found that some Spanish built Samurai's do have the backplate around the other way. (Sorry for saying defiantly at the top, as of then I had never heard of the cylinder being at the bottom)
I have found one picture
Lucus Girling Spanish brakes.jpg
Lucus Girling Spanish brakes.jpg (26.77 KiB) Viewed 9320 times
The reason I re-searched this is because I found a cylinder listed for the samurai with the bleed nipple on the other side to normal which lead me to believe it's designed to be fitted at the bottom.

This one ??
SJ 413 samurai rear cylinder types Spanish.jpg
SJ 413 samurai rear cylinder types Spanish.jpg (29.95 KiB) Viewed 9320 times
Just imagine this backplate inverted and fitted on the opposite side.
Attachments
Spanish Backplate.jpg
Spanish Backplate.jpg (300.92 KiB) Viewed 9320 times
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Re: Spongy brake issue

Post by hedonist » Mon Apr 29, 2013 9:35 am

Hi Darrell,

Indeed that picture is spot on, exactly how ours looks. So the problem would've occurred when at some point before we owned it, the wheel cylinders were mistakenly replaced with Japanese style ones..Then the first mechanic we went to just matched the part number and got the same Japanese style ones again, when all along it just needed the other configuration specific to Spanish built sj's... It's as if they made things confusing on purpose!

Well now at least we know ;)

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Re: Spongy brake issue

Post by SJ40 » Mon May 06, 2013 2:43 am

Do you still have 4 wheel drum brakes or have you got disc front end. I have replaced rear shoes and wheel cylinders but still have spongy brakes. Wheel cylinders seem to be the correct ones. There doesnt seem to be a proportioning valve any where, just a brake line splitter straight below the master cylinder bolted to the chassis rail. Brakes are very spongy and poor.

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Re: Spongy brake issue

Post by SJ40 » Tue May 14, 2013 3:15 am

Have you swapped out the master cylinder. I want to replace the master cylinder on my SJ40, do you know if you can use a master cylinder which is made for disc brakes on the front and use it on an SJ40 with drums on the front.??

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Re: Spongy brake issue

Post by hedonist » Tue May 14, 2013 2:45 pm

Hi,
No, didn't need to change the master cylinder at all in the end because it was just that the system wasn't being bled properly with the wrong wheel cylinders in there. No idea about master cylinder compatibility, maybe someone else can answer that... :S

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Re: Spongy brake issue

Post by ScottieJ » Tue May 14, 2013 2:48 pm

There should be no reason why you can't use the master cylinder off a 410 with front discs for one with front drums.

(I still think you should upgrade the front to discs :thumbup:)
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