Single to dual master cylinder...

I'm at the point in the rebuild/restoration/upgrade of my '66 912 where re-assembling the brake system is next on my list. Considering I plan to use the car for autocrossing and some track use, I'm really wondering if I should upgrade the single circuit master cylinder to the later style dual circuit-for safety reasons, if nothing else. I'm pretty sure the new cylinder will bolt up to the pedal box, but how different are the brake lines? Will I be able to re-use the existing fluid resevoir and tubing? I don't mind some fabricating, but if I have to buy numerous factory (i.e., ridiculously expensive)parts, I'll probably end up going the aftermarket (Willwood) route. I figured someone has already done this upgrade, and any input is welcome. Also-has anyone tried adapting the Willwood Dynalite II 4 piston aluminum calipers? For about $100 apiece and around 4.5 lbs with stainless pistons, they sound like a hell of a deal-provided they can be mounted without having to have custom mounting adapters made up-which will no doubt end up costing more than the calipers. Anyone know of a car that's had this done, or any race shops that performed this swap?

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Clay Mcguill www.geocities.com/the912guy

[This message has been edited by ClayMcguill (edited 11-12-2000).]

Anyone?

i've worked a bit with brakes and though i have not done the exact job you are talking about, i know it can be done.

i am a firm believer in rediculously powerful brakes. if you have a nice lightweight car then good brakes certainly don't hurt, especially when autocrossing.

if it were my car, i would upgrade to the dual curcuit in a heartbeat. i would use nice tough aftermarket lines also. as for the existing fluid reservoir, remember you will be upgrading the master cylinder, so go with an upgraded reservoir (whatever wilwood recommends).

i believe that if you shop right, the Wilwoods will not be as expensive as you think. i have seen very similar setups to what you are describing on track cars. i didn't pay too much exact attention, but i do know that it has been done and it did look nice.

the best people in this case to ask would probably be Wilwood themselves. they are very familiar with the exact work you are planning.

my suggestions:
dual circuit master cylinder
brake proportioning valve (in cockpit)
new lines (stainless steel)
slotted rotors
pagid pads
wilwood calipers
brake rotor ducting
Valvoline synthetic fluid
russel performance speed bleeders

a setup like that should be fine for at least 300+ horsepower in your car.
good luck!

obin

[This message has been edited by Obin Robinson (edited 11-13-2000).]

Not sure about the exact differences between the brake lines but I do know this. If you plan to do alot of brake line work (I mean the steel ones) you can save *alot* of money by buying the tube cutter, OEM tubing and ends, bender and the flare tool. Then you don't have to buy the original steel lines, you can make them yourself and have an exact factory look.

agreed, good advice orbmedia. worst case, if you don't use the tools again, someone else will buy them from you.

obin

Cool-actually, many of the upgrades you guys mentioned I've already done or have been on my "to do" list for some time. I ordered steel brake line tubing from JC Whitney and spent a few days cutting, bending, and flaring all new hard lines-Harbor Freight Tools is a great source for inexpensive tools. I installed an adjustable poportioning valve in the central tunnel, between the shifter and E-brake handle, plumbed into the line going to the rear brakes. I decided to stick with the stock calipers (rebuilt and powdercoated) and (new, solid) rotors for now for cost reasons and the fact that the car will be extremely light-less than 2000 lbs and only 150 hp or so(for now, anyway), so the stock parts should do a great job-I can always upgrade once ai get the car back on the road (and track) if they turn out to be not quite up to task. Stainless braided flex lines are already on my list, as are the Russel Performance Speed Bleeders (4 10mm front and 2 7mm rear.) Thanks for the advice so far, and again-if anyone knows details about the single-to-dual master cylinder swap, please reply.

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Clay Mcguill www.geocities.com/the912guy

http://www.wilwood.com/products/valves/valves.html

get one of those, you'll thank me later

and this master cylinder:
http://www.wilwood.com/products/master_cylinders/tandem/index.html


obin

Yeah, Obin, that's the porportioning valve I installed, and the Willwood dual master cylinder is one I considered using, but I don't think the fluid resevoir will fit up under the floorpan-that's why the stock cylinders have the resevoir remote mounted in the trunk. If the Willwood resevoir can be remote-mounted, I'll install it in a heartbeat. It shouldn't be too hard to fabricate a mounting plate to enable it to bolt up to the pedal assembly.

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Clay Mcguill www.geocities.com/the912guy

Clay,

I don't think the Wilwood bore size or the resevoir location is suitable for your 911. It is really a GM 'composite'master cylinder for 'F;-body' ... Camaro, Firebird applications!

The 911.355.012.02 non-boosted-dual circuit Ate master cylinder and a new 911.355.013.10 dual circuit reservoir is all that is required to convert your car to 1968 safety standards. The master cylinder is a direct bolt-in.

That's what I was afraid of, Warren-that the Willwood cylinder would not be compatible with my '66 912. Going through AJ-USA's excellent catalog, I see the cylinder you're talking about-911 355 012 02, and I can see how it'd be a direct bolt in-which is wonderful, and probably what I'll do. The only thing that worries me is that the Porsche dual-circuit master cylinders have 2 fliud lines from the resevoir to the cylinder, along with numerous odd seals, grommets, and clamps-will the new resevoir or cylinder come with those, or will I have track down all the small parts individually? (This is the reason I considered going aftermarket in the first place.) Thanks for the advice-now that I got you on the case, I know my problems are as good as over...:>

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Clay Mcguill www.geocities.com/the912guy

Clay,

No, it won't come with the reservoir lines, but you don't have to duplicate the factory's complex line ... one 8 mm OEM rubber line can be run up/down to the second reservoir connection!

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Warren Hall
1973 911S Targa