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S12+8 vented caliper


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#1 skipz

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Posted 20 August 2010 - 09:39 PM

I've read numerous posts about the S12W (43mm bore) caliper upgrade, but hear very little mention of the S12+8 (43/34mm bore) vented caliper as an alternate. 

See post #5 here <http://forums.hybrid...ed-real-facts/>

Has anyone here used the S12+8 vented caliper, particularly in comparison to the S12W?  Any noticeable performance difference?  (I'm mainly coming from a street application viewpoint, but open to all) 

Any noticeable size/width difference (for wheel clearance) or fitment difference? Post #3 here <http://www.zcar.com/.../685227/brakes> implies no width difference but to me, the S12+8 looks a smidge thinner (by eye only, off pictures - so a very crude comparison).


Thanks
Skip

#2 Scoota G

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Posted 20 August 2010 - 10:12 PM

Welcome,
                now for me this has been a topic of much discussion as i did a S12+8 Conversion on another members car and i used the S12w on my car. I compared and measured the both and although some members tell me different, i think they are almost identical. It was suggested That the "W" stands for wide as in the distance where the rotor slides in is a different width but i had the two calipers together and they measured the same.

They bolted up the same.
They had about the same performance from what i could tell.

I was told that if the brake pads wore down too far that the piston would pop out and i would have no brakes. I can tell you that this is not the case as i actually scrubbed out one side of the pads (which dusted up and wore down really quick) The pistons were fine. I'm going to shim them anyway but point being is the +8 was no different and if the pistons would pop out of the +8 then they should be shimmed too.

I'll get off my Bum and get photos of the pair, then ill post them here.

#3 Ben

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Posted 02 September 2010 - 01:05 AM

My recollection of the S12W vs. the S12+8 is that the +8's don't have external ribbing and are therefore a little narrower, providing some extra wheel clearance.

There is also the piston size difference (the +8's have the same 2-sizes of pistons as the S12's, while the S12W has 4 equal sized pistons).

I had S12's on my car and the pedal was too soft once I did a disc upgrade to the rear. It was then a bit firm once I fitted a 1" M/C. I'm hoping that the extra displacement of the S12W's will make the pedal feel 'just right' (there are vented discs and braided lines in the equation now, so who knows...)

#4 DatPilot

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Posted 25 October 2010 - 01:08 PM

I just had a conversation with another Z nut, he says the GC8 WRX brake pad will fit the Hilux caliper (with the 4 equal pistons) (wiht just a small tab to be grinded off)

opening up a whole lot of possiblilties with Bendix/QFM and all the manufacturers

#5 nat0_240_chevZ

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Posted 25 October 2010 - 04:36 PM

there are 2 variants of both calipers & one of the smaller+8 (su suit solid rotor)
one to suit a much narrower rotor ie only approx 20mm thick & one to suit a 24-26mm rotor fom memory.
all are available but some are less common, hyridz has the full score but i still think 1 variant is missing from their data,
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#6 Ben

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Posted 25 October 2010 - 05:02 PM

I just had a conversation with another Z nut, he says the GC8 WRX brake pad will fit the Hilux caliper (with the 4 equal pistons) (wiht just a small tab to be grinded off)

opening up a whole lot of possiblilties with Bendix/QFM and all the manufacturers


Correct. The same pad suits Nissan 4-spots too (R32/33/34, Z32 etc.)

#7 nat0_240_chevZ

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Posted 25 October 2010 - 05:13 PM

WELL  i didnt know that one, bloody marvellous, opens up heaps of options, wohoo......
nat0

#8 skipz

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Posted 19 February 2011 - 07:38 AM

Adding/collating some info I've found on this topic from other sites.

http://forums.hybrid...eed-real-facts/
http://forums.hybrid...showtopic=29024 - about half way down post #14

And this from a 4x4 site ih8mud.com (which ironically references a z site as the original source)
"There are two different Toyota 4x4 calipers with the casting mark "S12+8". One for a solid rotor and one for a vented (wider) rotor. The 1979-85 4x4 calipers are for use with a solid rotor but the 1986-88 4x4 calipers are also marked "S12+8" but they are designed to fit the wider, vented rotor.
If you examine and compare the two different S12+8 calipers you will see that they are the same casting, (actually they are a pair of castings, one for each side of the caliper) except one is machined more that the other to be used on the solid (thinner) rotor.

There are advantages of using the S12+8 caliper (for the vented rotor) over the S12W caliper: It is lighter in weight; The S12+8 caliper body is not as wide as the S12W caliper, so clearance to the wheel is increased; The S12+8 caliper has two 43.0mm diameter pistons and two 33.8mm diameter pistons whereas the S12W has four 43.0mm diameter pistons. This increase in piston area requires a larger (1") diameter master cylinder when using the S12W calipers."

On thing I haven't been able to find so far is how using the S12+8 vented caliper, with rear disc & 15/16"MC goes.  Anyone using this setup?

#9 Gareth. J.

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Posted 19 February 2011 - 08:08 AM

I have disc rears and have run s12+8 non vented and due to brake fade now run 12+8 vented. The pedal is fine with non vented setup but fitting the vented calipers it has become longer but is still fine IMHO.




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