# 4 wheel Disc upgrade questions



## ylwgto (Oct 27, 2009)

I'm buying a mocked up, but unused, Wilwood 4 wheel disc kit from a buddy at a great price, so going to move forward with the swap. This kit bolts up to the stock front drum spindles, so I do not have to remove the knuckle. I do have a few questions I hope the forum pros can help me with before I get into it

'66 GTO
currently power drum car with single chamber master
stock 10 bolt 8.2 rear

I want to retain the current front wheel spacing, so I am going with this for the front:




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Wilwood Disc Brakes


1966 Pontiac GTO AllPart No: 140-10996, brakes, disc brakes, big brakes, bbk, brake conversion kit, bolt-on brake kits, front brakes, calipers, axle flange, housing, rotors, dynalite, dynapro, superlite, d52




www.wilwood.com




and this for the rear:




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Wilwood Disc Brakes


Part No: 140-13513, brakes, disc brakes, big brakes, bbk, brake conversion kit, bolt-on brake kits, rear brakes, calipers, axle flange, housing, rotors, dynalite, dynapro, superlite, d52, d154




www.wilwood.com





It comes with this tandem master:




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Wilwood Disc Brakes


MasterCylinder No: 260-8556-BK, master cylinders, aluminum tandem, combination remote, compact master cylinder, go-kart master cylinder, handle-bar master cylinder, rebuild kits, high volume, hvm master cylinder, tandem, bleeding kits




www.wilwood.com





For the proportioning valve, I'm wondering if there is any real world difference between the actual Wilwood valve:




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Wilwood Disc Brakes


MasterCylinder No: 260-13190, master cylinders, aluminum tandem, combination remote, compact master cylinder, go-kart master cylinder, handle-bar master cylinder, rebuild kits, high volume, hvm master cylinder, tandem, bleeding kits




www.wilwood.com




vs. 
a Wilwood "style" valve. I'm not one to skimp on brakes, but if they are for all purposes identical its a great way to save $80. Thoughts?








Wilwood Style Adjustable Knob Proportioning Valve Kit, 260-13190 | eBay


Kit includes mounting bracket for a Wilwood oval master cylinder to the proportioning valve and mounting hardware. Adjustable Proportioning Valve PV4 Universal GM CHEVY DISC/DISC BRAKE ACDELCO PROPORTIONING VALVE ALUMINUM.



www.ebay.com





Would a single diaphragm or a dual diaphragm booster be better for this set up? Any specific ones recommended?

Lastly, the biggest challenge will be re-routing all the hard lines. Currently there is just one line coming from the single pot master to the distribution block on the frame that feeds both front drums with a single line to the rear diff. Now I need hard lines from the prop valve all the way to both front discs calipers, and a new had line to the rear. Any pre-bent kits for my car out there? 

Any thing I'm missing?

Thanks!


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## deanhickey (Apr 6, 2015)

I would check with inline tubes or Ames and get factory tubes for your year. the other option is to bend your own get the right flatting tool for breaks and away you go.


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## PontiacJim (Dec 29, 2012)

I like to use Speedway Motors when I have certain questions on my build as they are Hot Rod orientated specialists which is nothing but fit/fabrication, and they offer just about everything except the kitchen sink for hot rods. They have been in business a real long time and have great tech info - can usually clear up my concerns and have me selecting the correct & matching parts. I also buy parts from them and have never been disappointed.

Here is a simple and quick explanation of single vs dual power brake diaphrams without searching for hours to figure out your needs and then do all that second guessing we often do to ourselves. LOL Looks like the dual unit is what you want.





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Single vs Dual Diaphragm Brake Booster


Should you use single or dual diaphragm brake boosters? Read our guide to learn which is best for your four wheel drum or four wheel disc brake system.




www.speedwaymotors.com





Have not done any conversions like yours. What I do know is that the master cyl bore diameter is important. So here is a great write-up on this and how to choose.





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Effects of Master Cylinder Bore Size on Your Brake System


Follow this guide to learn how the change of bore size on a master cylinder affects a four-wheel disc brake system. View the conversion chart to figure the total bore area for your brake setup.




www.speedwaymotors.com





This tech will answer your brake porpotioning valve question. I recently purchased their brake hold off valves for my brother's 1948 International box truck. I am hoping this will add to the trucks braking system as it is more like an automobile of that era with a single reservoir master cylinder for a car, rather than something I would think should have been a bit bigger. I'll know once I get them installed, but again, used by hot rodders.






Brake Valve Guide: Metering, Residual, Proportioning and Combination


Learn about the different types of brake valves. Our guide covers Metering, Residual, Proportioning, and Combination valves to understand your brake system.




www.speedwaymotors.com


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## ylwgto (Oct 27, 2009)

Super helpful, thanks PontiacJim. I ordered a dual 8" booster and luckily the master i am getting with the kit is 1.12 bore, which is ideal for 4 wheel disc. Thanks for the resources.


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