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drum to disc swap

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Old Oct 22, 2008 | 11:10 PM
  #1  
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drum to disc swap

got a 88 firebird and swapping in a 86z28 rearend with disc brakes? what else should i grab from the z28?
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Old Oct 22, 2008 | 11:24 PM
  #2  
Stephen's Avatar
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From: Bertram (outside Austin), TX
Car: 87 GTA
Engine: L98
Transmission: 700R4
Axle/Gears: Dana M78 3.27 posi
Re: drum to disc swap

You COULD grab the prop valve, but most people just swap the rear ends & the brakes are PERFECTLY fine without doing that.
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Old Oct 22, 2008 | 11:43 PM
  #3  
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Re: drum to disc swap

well i a complete z28 to part out, so ill grab that
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Old Oct 23, 2008 | 06:52 AM
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From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: drum to disc swap

If they parking brake cables are in good condition, grab them and the S-hook guides as well (should you be missing them).

JamesC
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Old Oct 23, 2008 | 07:43 AM
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From: Woodstock, GA
Car: 1989 IROC
Engine: 305 TPI
Transmission: T-5
Axle/Gears: 3.23
Re: drum to disc swap


JamesC helped me and was great with all the info I needed.

If you are going from drum to disk get the prop valve you will need it. Disk wont work properly with drum valve. I tried it and they have no power it wont push enough fluid.
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Old Oct 23, 2008 | 11:17 AM
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From: Vancouver, WA
Car: 87 IROC-Z28
Engine: 305 TPI-New 355 on the engine stand
Transmission: T56
Axle/Gears: 3.73 Eaton posi-Soon a 9" Ford!
Re: drum to disc swap

My experience was the same as yours FUNIROC. They didn't work perfectly, nor did they hardly work at all with the drum prop valve. With the car on stands the rear brakes wouldn't even lug the motor down with has hard as I could push on the brake pedal. Changed to the disk/disk valve and problem solved immediately.
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Old Oct 28, 2008 | 11:22 PM
  #7  
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Re: drum to disc swap

ROB?
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Old Nov 4, 2008 | 02:31 AM
  #8  
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From: springfield OR
Car: 85 Z28 scca C Prepared
Engine: 5.7 348 RWHP
Transmission: t5
Axle/Gears: dana 44 3.41
Re: drum to disc swap

my dad questioned re using essential brake parts when i swapped my dana44 disc rearend out of a turbo ta so i just ordered the ssbc brake proportioning valve from summit SSB-A0707E. this also allows me to set it exactly how i want it. all it took was a little cutting the tubes and re flaring them with new fittings
Attached Thumbnails drum to disc swap-brake-prop2.jpg  
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Old Nov 4, 2008 | 02:33 AM
  #9  
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From: springfield OR
Car: 85 Z28 scca C Prepared
Engine: 5.7 348 RWHP
Transmission: t5
Axle/Gears: dana 44 3.41
Re: drum to disc swap

Oh and almost forgot the master cyliders are different too although with the right proportioning valve i don't know if it would make a difference
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Old Nov 4, 2008 | 06:21 AM
  #10  
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From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: drum to disc swap

Originally Posted by cprepared125
Oh and almost forgot the master cyliders are different too although with the right proportioning valve i don't know if it would make a difference
The master is apparently inconsequential:

https://www.thirdgen.org/forums/susp...fferences.html

JamesC
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Old Dec 10, 2008 | 03:56 PM
  #11  
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From: League City, TX
Car: 90 Formula -- tot resto in progress
Engine: 350
Transmission: 700R4 w/ 2500 stall, by Owen @ ARD
Axle/Gears: 3.23 posi disc
Re: drum to disc swap

Question for cprepared125:
It may sound trivial, but how do you adust the valve to get the best braking?
These valves can only reduce the line pressure: so is the effect of having
to much, that rear wheels lock-up w/ insufficient braking by the front? to
little that there is now insufficient rear brake effect?
Maybe the question is better phrased by asking what should the car feel like
when the optimum proportion is reached?

thanks,
kk
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Old Dec 10, 2008 | 10:27 PM
  #12  
cprepared125's Avatar
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From: springfield OR
Car: 85 Z28 scca C Prepared
Engine: 5.7 348 RWHP
Transmission: t5
Axle/Gears: dana 44 3.41
Re: drum to disc swap

with my system the front brakes run full pressure and we adjust the rear and from what i've been told it is optimal to reduce rear brake pressure to where the fronts lock up just before the rears. this allows you to find your braking limits without upsetting the car and putting it sideways when they lock up. well thats my theory anyway
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Old Dec 11, 2008 | 11:14 AM
  #13  
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From: League City, TX
Car: 90 Formula -- tot resto in progress
Engine: 350
Transmission: 700R4 w/ 2500 stall, by Owen @ ARD
Axle/Gears: 3.23 posi disc
Re: drum to disc swap

Thanks for the input.
Is that the way you set-up for SCCA activity?
I would have assumed setting rear wheel lock-up just before
front, would allow for steering control. Or is this an idea
better in theory than practice?

thanks again,
kk
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Old Dec 11, 2008 | 06:16 PM
  #14  
cprepared125's Avatar
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From: springfield OR
Car: 85 Z28 scca C Prepared
Engine: 5.7 348 RWHP
Transmission: t5
Axle/Gears: dana 44 3.41
Re: drum to disc swap

yes it is a dedicated scca car. I'n not pro by any means but just from my few years of driving experience for me anyway it is easier and quicker to recover when the fronts lock up (just let off the brake) than when the rears lock up.(let off, counter stear and continue the corner sideways)
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