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Old 01-03-2021, 04:17 PM
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Default Rear brakes to compliment c5 13" fronts

Hi all, just picked up a new C5 13" disk setup for the front of my street TA over here in NZ. Parts are a bit gard to come by so I jumped on it.
What would be considered a good rear upgrade for the 10 bolt.
Would the "Right Suff" conversion be a good balance between from and rear (pretty sure theirs is a 12" single piston?).
Cheers
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Old 01-03-2021, 05:34 PM
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Maybe LS Camaro, I don’t know if you can get parts there, tho. It’s an easy swap but I’m unsure about how balanced it would be. Will you be using an adjustable prop valve?

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Old 01-03-2021, 08:53 PM
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Yes will be using adjustable, has stock disc / drum valve at moment

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Old 01-03-2021, 09:31 PM
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C5's have a pair of 2" pistons per caliper - giving an effective area of 6.28". Rule of thumb for a car like yours would be to run 70% of the area in the rear, giving a piston of 2.36" diameter. Stock 79-81 rear disc use 2-1/2" pistons, ours uses 2-1/4" versus the smaller S10 rear calipers and are drum-in-hat.

Find out what diameter piston a setup has first before buying - too small will be ineffective, too large cause excessive lock up.

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Old 01-03-2021, 11:05 PM
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Quote:
Originally Posted by Scarebird View Post
C5's have a pair of 2" pistons per caliper - giving an effective area of 6.28". Rule of thumb for a car like yours would be to run 70% of the area in the rear, giving a piston of 2.36" diameter. Stock 79-81 rear disc use 2-1/2" pistons, ours uses 2-1/4" versus the smaller S10 rear calipers and are drum-in-hat.

Find out what diameter piston a setup has first before buying - too small will be ineffective, too large cause excessive lock up.


The chart I looked at at listed the C5 front pistons at 1.75 inches. Scarebird knows his stuff, so if they are 2” then the LS rears are too small.

OP, sorry for the misinformation!

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Old 01-03-2021, 11:48 PM
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I may be wrong Murph - I took the info off Raybestos at rockauto - they are not always correct. If even smaller a different master would be wise.

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Old 01-04-2021, 06:33 AM
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Hmmmmm.

Not sure on the actual effective piston dia
At the pad facevit measures 1.575" dia past the rubber boot, but piston may be stepped down outside the bore to accommodate the boot?.
Does the 70 % rule apply irrespective of disc dia?. Ie with 13" fronts, and say 11" or 12" rears, obviously the leverage where the pad is acting is different.
Apologies for what may seem like simple questions, brakes are pretty new to me (boats don't have them lol)

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Old 01-04-2021, 06:49 AM
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Ok found this chart
Looks like 2x 40.5mm dia pistons for front and they had 1x 45mm dia for rear.
Guessing this would be a good srsrting point for a rear caliper?
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Old 01-04-2021, 07:20 AM
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IDK, I’m definitely no expert. If you used C5 front & rear you know it should be a great match. I don’t know how C5 rears mount, though.

According to the charts I’ve seen, the LS Camaro / Firebird uses the same piston size. I do know the LS setup is any easy swap on a 10/12 bolt GM rear. I used them on a C clip style 12 bolt but I wouldn’t think it would be too hard to accommodate the BOP retainer, if needed.

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Old 01-04-2021, 01:13 PM
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There are a lot of considerations to think about. I ended up with 13" C4HD fronts as the C5 set up did not fit my American racing wheels and 12" LS1 rears. I have a C3 master with a 15/16" bore and Wilwood adjustable combination valve. Full disclosure, I just bled the system and have zero miles on it but the pedal feels good on the jack stands .

I can tell you that the availability of new LS backing plates are sparse. I was able to get one side off of Amazon but the other side, I had to piece together out of a pile of parts I have collected. The install is easy enough and has been covered on the net but the primary reason I went with the LS brakes is that I "thought" I would be able to configure the set up to easily work with my factory E brake. I found out the hard way the S10/LT1 set up is not the same as the LS1 as the S10/LT1 backing plates have provisions cast into to them to fit your ebrake through. The LS1s do not and you will have to fabricate something to support the ebrake cable.

Another consideration is the LS1 rotor typically requires a 16" or larger rear wheel. So if bolting on a set of 15" wheels with drag slicks/radials is in your plan, the S10/LT1 rear disc set up might be a better all around choice as dealing with the ebrake is easier and both will accommodate most 15" wheels.

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Old 01-04-2021, 07:59 PM
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Thanks for the info

I will be going with 17"Snowflakes so clearance shouldnt be a problem

Diff #1 is pretty much the stock 3.32 posi factory diff, so looking for a reasonably simple disc bolt on if possible

Diff # 2 after engine upgrade will still retain a factory 10 bolt housing for looks, but with Powertrax centre, 30 spline axles and I will have the axle tubes modified for Ford ends with Axle retention and then use a Ford brake setup, lots of options there hopefully

Looks lime the C6 used a 305mm (12") rear rotor with a single 45mm piston, so might look for something similar
Although weight distribution will be a little different, hopefully adjustable proportioning valve will help dial it in

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Old 01-12-2021, 11:21 AM
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Make sure the rotor inner diameter or the axle hub are the correct size or the rotor will not fit. Most kits give you that info.

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Old 01-25-2021, 11:48 PM
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I have never been able to figure out how to fit the s10/ls1 backing plates with the axle bearing retainer.

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Old 01-26-2021, 12:20 AM
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Short answer is you cannot. That is why we made our setup that will.

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