60-62 clutch/brake combo master cylinder SWAP to ft discs and power??? clutch MC?

[Chuck78]

I'm looking for other options for the 60-62 GMC dual brake and clutch combo master cylinder when switching to disc brakes and possible power disc brakes. MPB or someone sells a $489 kit that has an 8" or 9" booster that's spaced off the firewall pretty far, with enough room to fit a small clutch master cylinder to the fender side, and behind the booster. That';s a lot of cash! They apparently eliminate the factory over-the-steering-column clutch linkage and take the new clutch linkage directly through the firewall (factory linkage took clutch linkage over top of steering column and more towards the engine from the brake MC).

I keep thinking maybe I can get a stock 60-66 power booster and space it out a bit further with some fabbed up brackets, and then for clutch master, use a stock 62 brake master (from an auto trans truck) as the clutch (have to disassemble and remove that check valve or residual valve or whatever). Not sure how all of this will fit up without spending the dough on the parts. Anyone ever done? $500 seems like an awful lot of cash for some basic parts with a custom fabbed clutch master cylinder mounting bracket.

Also, there are some places that sell just the booster wtih the long spacer bracket, so maybe that might be the ticket, although a pricey one. Then I don't have to fab anything for the booster at least, and the rod will be the correct length.

I'd like to hear from anyone who has done this or is even considering it.

Thanks guys,

Chuck in Ohio
62 GMC 1000 Panel
305D 3 on the tree (Tremec soon).

[Chuck78]

this particular one says auto only, no hydraulic clutch, but I still wonder if I could squeeze a clutch MC in there on one side or the other (probably have to move to the driver's fender side):
http://www.brotherstrucks.com/prodin...number=KORN62D


using a 62 single brake MC as the clutch M.C. (hard to find aftermarket 1-1/8" clutch MC's!):


and even with a factory 64-66 booster, I may be able to make something work, as they allow some extra space behind the booster:


and here's the $500 setup, know where I can get one of those clutch master cylinders?!??!?

[Chuck78]

looks like the aftermarket boosters and booster/MC combos start at $289 up to $350 for these trucks. Wish there was a common later model (say, 85 C10 or C20) booster and MC that would work great. I'll do some digging.

[Captainfab]

This was discussed just last night......
http://www.67-72chevytrucks.com/vboa...d.php?t=339335

[jonzcustomshop]

check out soba_03 build thread, here is a pic of his setup.

[Chuck78]

Wow, that's a trick looking I-6!!! I looked at both of the Wilwood MC's that I have now seen on here (the remote and this high capacity unit in soba's picture. I know mine is a 1-1/8" bore, but not sure on the stroke. I suppose I wouldn't have to necessarily match up the bore diameter, but rather the total displaced volume of bore x stroke.

So I now have three master cylinder options. The booster is still the thing I am up in the air on. I'd like to have a 7" or 8" dual diaphragm booster that is spaced off the firewall a good bit. The stock 63-66 power booster looks like it'd almost do the trick, and at $140 or so, it's still A LOT cheaper than some of the aftermarket units. Without seeing one in person (factory 63-66 booster), I'm thinking that would probably be able to cut/fab/weld up something to give myself enough clearance from the booster itself, and the mounting bracket, in order to squeeze the stock single brake master in there for use as a clutch master (removing internal residual valve piece). If the mounting flanges are too wide for that and will interfere, then Jeg's main store is just down the freeway from me, and that Wilwood aluminum unit like soba's is pretty darn narrow, more so than the factory brake unit that I pictured above. I was going more for the cheap and factory looking route, but if it works, that's the important thing! a plastic reservoir would make it look really modern, but then again, a machined aluminum MC would also...



ANYONE HAVE ANY OTHER 7" or 8" BOOSTER SOURCES??????? HELP!!!
I don't wanna spend $500!!!!!! Rather do some minor fab work and have my own craftsmanship in it rather than lots of money on fancy, shiny billet stuff!

[Captainfab]

I don't remember the diameter, but the S10's had a smaller booster.

For your clutch master, have you considered moving the clutch master to the other side of the brake master. I haven't looked to see what it would take to move the arm the pedal swings, but it might be doable. My 1990 1/2 ton DD has an arrangement like that. In fact that might also be a possibility for a clutch master for you.

[Chuck78]

the S10's aren't a dual diaphragm booster, which is what we will need if we want the full benefit of power brakes. They are a couple bucks cheaper than a stock 63 booster, and more plentiful at any random parts store, but I think I'll stick with the 63-66 dd unit unless I find an 8" dual diaphragm that looks like it';ll accommodate the clutch.

really the bigger reason I am looking into power brakes is mainly due to my 60-62 combined clutch/brake combo mc, as it'd be easier to just do some fab work for the booster mount to fit a clutch cylinder in, rather than redesign the whole clutch linkage and go with an aftermarket remote reservoir clutch MC. I'd like to keep it looking somewhat factory, and have my own craftsmanship in there. Also trying to use all factory parts for the most part.

As pointed out elsewhere on this board, the CPP unit with the real small booster really just uses a Wilwood brake master cylinder for the clutch anyway, and the only thing special about the setup really is just the booster bracket. All the other parts can be matched with something that is a factory part.


My slave and master have both seen better days, so I;m trying to do work in phases now. upgrade to a power booster and relocated clutch master to do away with the clutch/brake combo master, as I will eventually go to front disc, but don't have the time at the moment. So I will probably do this work with the booster and clutch, and bolt a drum master to it for now. But then when disc swap time comes, it'll just go that much faster with one less obstacle to figure out.

[Chuck78]

http://www.piratejack.net/

found here an 8" dual diaphragm booster with universal MC for about the same price as the factory 63-66 stuff! $145! Probably will go with that, but still not sure if I should try to use the factory stuff for more reliable replacement parts sourcing in the future. That site was a goldmine for good deals.

[Chuck78]

I FOUND THE AFFORDABLE ANSWER!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!

http://www.piratejack.net/



found here a 1955-1970 GM 8" dual diaphragm booster with universal MC for about the same price as the factory 63-66 stuff! $145! Looks to be the exact thing that soba_03 has with the $60 wilwood brake master for the clutch master in the stock location!!! Probably will go with that, but still not sure if I should try to use the factory stuff for more reliable replacement parts sourcing in the future. That site was a goldmine for good deals.
Part # BCK1005-8531
GM 1955-70 Booster Conversion 8" Dual


Heck, for $200, their 1967-72 truck 8" dual diaphragm booster setup looks like it not only raises it for more clearance above my big block GMC V6's tall valve covers, but also gives me more room to squeeze in a 62 brake-only master cylinder as a clutch cylinder in the stock firewall penetration next to the brake!!!!

Part # PBUCT6772
Chevy Truck 1967-72 Bracket & Pedal Assembly 8" Dual

For the $200 plus about $32 for the 62 brake MC for use as clutch, I think I have found the answer!

[Chuck78]

Got my rockauto.com order today, which has a 62 single piston brake master cylinder on it. It measures about 4-1/2" front firewall to the end of the extension that the line comes out of. The WIlwood is almost the exact size, but the line comes out the front. The factory unit, the line comes out the bottom.
The only advantage to using the Wilwood, other than weight, would be that the line would come out of the front, right against the side of the 7" or 8" booster (9"+ would interfere -see soba_03's picture), where as the factory master would be a pain to get to the line fitting once the brake booster and master are installed. The factory brake cylinder used as a clutch cylinder WOULD permit reusing the factory clutch line, however... And it costs half as much.
So the $150 booster and master would do the trick if you maybe made some 1" aluminum spacer blocks to push it off the firewall further than the clutch MC, otherwise the $200 setup would be the almost direct bolt in solution.
I say "almost bolt in" because you will have to of course drill holes, and might have to modify (trim/grind) the pass. side of the booster mount (at the firewall) as to permit bolting up of the new clutch master.
I scaled off their photo, knowing that the booster bolt pattern is 3.5" apart, and the top of the bracket is closest, with almost exactly 3.5".
I'll probably go that route and make some spacers or else cut the booster bracket and weld/extend it.

The Pirate Jack masters come in a 1" or 1-1/8" bore, so we are set there! If still retaining 4 wheel drums, they say you need a metering block or something. Otherwise they will work for disc/drum or 4 wheel disc.

[Eagletucky]

That all good info......Make sure you take ALOT of pics when you perform this install. I plan to do the same thing in a few months and would love to have step by step instructions.

Thanks,

[Chuck78]

A member here emailed me a good tip to look up a 69-70 1 ton Chevy/GMC truck for a slightly cheaper remanufactured dual diaphragm booster from local parts stores. I'd guess it's an 8", but not for sure.

Looking at soba_03's photo from the front, and then looking under my dash at the proximity of the brake and clutch bores, I am wondering if this "stock" location would in fact require elongating the hole for the clutch bore register? If you look at the clutch linkage under the dash, you can see that the pushrod bolts to the left side of the linkage, and you could easily gain 3/4" more space moving towards the engine by unbolting it and bolting it back to the other side with some spacers and/or a little work. I am thinking that might be necessary fro clearance to the booster bracket, unless you modified it quite a bit. The firewall is reinforced there with a second layer of thicker sheetmetal, so this didn't make me terribly happy, but it is still quite feasible. I didn't look too closely, but maybe it'd be possible to drill out the spot welds and move the entire piece of sheetmetal backing? All of these high dollar aftermarket units come with a large reinforcing plate to bolt to the firewall, so maybe on soba's, this is there to give it stiffness after moving the hole???? Soba, any comments?

Here's the parts store unit with and wtihout MC. Basically the same thing you'd get from the pirate jack's unit, same style MC and all. can be used for drum and disc with appropriate prop/metering valve due to both reservoirs being fairly large.
A-1 CARDONE Part # 547101 {w/o Master Cylinder; Reman.}
w/7,200 lb. Rear Axle w/Vacuum Booster $113.79

A-1 CARDONE Part # 501011 More Info {w/Master Cylinder; Reman.}
w/7,200 lb. Rear Axle w/Vacuum Booster $148.89



no bracket included though, but for the $150 pirate jack unit, you'd have to re-make the bracket or at least make some aluminum spacer blocks behind it. The email tip guy said his buddy used some pieces of C-channel to make his brackets out of to gain enough space, and used a random junkyard clutch master that he found. The Wilwood high volume unit like Soba's was one of the VERY FEW that I have seen in the proper bore size, and I would be hesitant to go with something smaller, but maybe smaller might work if you found a smaller bore with a longer stroke than the stocker (1-7/16" seems to be the max) and extended/lowered pushrod attachment point on the linkage to give it the longer needed stroke , but most of the clutch mc's I have seen aren't that long of a stroke. Not sure how that would work with the pressure, decreasing the bore and increasing the stroke.

[Chuck78]

Did some quick measuring last night. The stock 60-62 clutch/brake combo master has the bores about 2-1/2" apart. I have a spare 89 Suburban booster and an 85 C20 brake master disc/drum that I got at a boneyard. Holding the single piston 62 brake master (proposed new clutch master) next to the booster bracket of the 89 booster, I could easily just make a 1-1/4" spacer for where it bolts to the firewall, and grind/cut/trim out about 9/16" of one area of the booster mount, and the two would mate up flawlessly in the stock locations.
The only clearance issue is that the booster is a 10", and leaves about 1" clearance to my big GMC V6 valve covers. Not sure if I'll still plan to use this booster, or spend the cash on a dual diaphragm for more clearance and easier access to the line on the new clutch master.

I had said before that you will need 4-1/2" of clearance between the booster and firewall for the new clutch master in the stock clutch location, but after holding my 62 brake (now clutch) master next to the booster, the extra 1/2" bumpout on the front of the new clutch master (at the bottom of the front where the line comes out) actually fits in well around the profile on the back of the 10" booster where it starts curving forwards, so only about 4" is needed from the back of the booster to the firewall. Not sure on how this would work on other boosters. It depends on how bell shaped the backs are, as opposed to being flat all across the back.

This mock up trial is nothing but good news for me and the rest of us looking to do this on the cheap with a little extra elbow grease! Now I think I may start to make up the new extra line that I will need when converting to a dual brake master, the new line that I will need to run down alongside the single line that goes to the junction block where the front and rear brakes tee together. There was another thread on here about this quick conversion. I'll try and have the new extra line all bent up an ready, and maybe even mounted and taped off, so that when the time comes to at least switch to power 4 wheel drums with a separate clutch master, I will have less work to do.

[Chuck78]

The pirate Jack's master cylinders are universal like I said, and they have no residual valves for the drums, and now I realize they recommend using a metering block and three separate residual valves for a drum/drum setup. that's a lot of stuff to buy! a metering valve to split the two fronts, and a 10 lb residual valve in each line, plus a residual valve to the rear! I think (especially since I plan to do discs up front eventually) that I will buy their booster and bracket, and just use a 67-70 truck master, or maybe a 70 impala master like:
http://67-72chevytrucks.com/vboard/s...d.php?t=338777

Buying a $30-40 stock master for drum/drum is a much easier solution, and then I can put on my 85 truck disc/drum master and 89 prop valve when I swap over to discs up front.

also, with mine being a 62, not so sure on what drum/drum dual res. masters will have a 1-1/8" bore, but I would think the bigger trucks would be more likely. I think most of the later 60's used 1" bores. I'll do more research and post what I find.

EDIT: 67 C-3500 GMC master:
DORMAN Part # M66787 More Info {First Stop #18008616, 3912128, 3941939, 5458531, 5458905}
w/Power Brakes; Bore = 1-1/8"; RWD; Bendix; Exc. 11000 Lb Rear Axle
$50
not sure if it's the deep cup version that requires the longer pushrod, but pirate jack's I think sells pushrod extensions for booster to master

[Chuck78]

For a disc/drum master, If you look at mid 1980's trucks, there are several options for master cylinders. They typically have a stepped bore in some of the ones I am seeing (looking at the rebuild kits to see exact bore size). They'll have the rear of the master for the front brakes, because the discs will I would imagine need a lot more fluid, so they will have the rear (first) piston be 1-37/64" bore, and then the second bore many of them are available in 1-1/8". As long as you keep your stock pushrod location and the strokes are similar, this will be exactly what we need for a disc/drum setup.

I am thinking I will take my 89 calipers back in and use them as a core charge for a much older set of calipers, as I am betting that starting in 1979-ish, almost everything went metric. I am not sure, but I'll have to look it up and see if I can find out what years had SAE fittings, as if I can keep the hoses coming from the same fitting as the drum hoses are at, it'd be nice not to have to track down any oddball metric to SAE adapters, and also have one less joint to leak in the system! Maybe the ones I have use an SAE hose, but then again, I know the 89 steering box is for sure using metric hose connections.

[Captainfab]

I would think you could just switch the hoses on the calipers. I could be wrong though......

[Chuck78]

but the hoses are threaded on both ends, and where it ties into the hard line are SAE threads, and I'm afraid the calipers are metric threads. I'd prefer not to have a special hose made with one side metric and one side SAE.

Checked, they are M10x1.5.
From memory, 79 Camaros and up had metric stuff for a lot of the parts, and looking at 1/2 ton suburbans, it appears that the parts listings with M10x1.5 go back as far as 79. 1978 shows no mention of metric threads on parts listings.

I still may need an threaded adapter bushing to go from the old drum lines to the new disc hoses, but I might just end up bending new lines for the front if that's the case. The more I replace, the more faith I can have in the truck for long road trips.

The calipers in 78 don't designate JB5, 6, or 7, but the master cylinders still do. Have to do a little research to make sure you get the right bore for the calipers you are using. 1-1/8 would be for the front bore for rear brakes, and the larger rear bore for the fronts needs to be matched to the calipers.

I would imagine that the calipers will interchange on the spindles with no problem. On Camaros, you can put a 1970's-early 90's non-ABS 12" rotor station wagon spindle on the Camaro and still use the Camaro calipers from the 11" Camaro discs. Probably pretty standard. Also, for less fade and longer wear, use Caprice Police issue "D61" brake pads vs the stock D52 size.


our masters use a 7/16x24tpi outlet. The 78 uses 9/16x18tpi primary and a 1/2x20tpi secondary outlet. I have a feeling the line size is a step up for the discs, so I might be doing some line changes twice since I don't have the time to do the whole disc swap at once, and just going to power drums with separate clutch master for now.

[Chuck78]

more info - For the 1978 and earlier SAE stuff, I don't see any of the step bores notated, but I do see 1-1/8" bore masters vs 1".
The later 80's stuff has 25.4mm (1"), 1-1/8", 1-1/4", 1-1/8" & 1-37/64" step bore, but only list the two or three different caliper bores, from 2.94", 2-15/16" (=2.9375"), and 3-5/32".

I would venture to guess (research on your own!) that the 1-1/8" bore master cylinders (straight bore both pistons) are intended to be ran with the calipers of 2-15/16"/2.94" bore. The listing I have does not notate any caliper bores for the 5 or 6 calipers available. I do not see the 3-5/32" bore calipers listed in the 78 and earlier models, nor do I see the masters with the larger first bore for discs. I know on Trans Am's, 80 models started using the plastic quick take-up reservoirs on aluminum masters on their 4 whl disc models. Looks like 79 on trucks.

So this brings another issue up - maybe by running metric parts, you can get more powerful front brakes? Anyone care to chime in and tell me what advantage a larger master bore and caliper bore would have? 1-1/8" master and 2-15/16" caliper vs 1-37/64" master and 3-5/32" calipers? Aside from any hydraulic pressure reasons that there may be, maybe the larger calipers will do nothing more than keep the fluid cooler due to having more capacity????

Also, I am thinking the JB5, JB6 (not as common), and JB7 designation just assigns the rotor size possibly? JB7 was available on an 89 'burban, and also on a 78 'burban, but 78 did not have the 1-37/64 master available.
the "B" in JB7 means power booster, where as a JD7 would mean it has hydroboost. The higher the number, the more heavy duty the brakes where (higher GVWR ratings). I think there was the standard brake (probably the smaller 1-1/8" thick rotor), and then eavy duty (probably all 1-1/4" thick rotors) JB5,6, and 7. JB5 was 11.86"x1.28" rotor, and JB7 was 12.5x1.28": thick rotor. the JB7 was rated for a much higher GVWR.

Ran out to the garage, my 89 burb front clip and my beater 89 burb winter driver both have the JB5 11.86"x1.28" rotors. Both have the plastic master reservoir. Measured the donor parts, definitely the step bore 1-37/64 master, but the caliper piston measures about 2-7/8" for the protruding part, but to the outside of the seals, measures close to 3.5". I know the pistons have a slight step in them, so do I have the 2-15/16" calipers? The larger are 3-5/16". the step only looks to be 1/16", so I doubt I have the 3-5/16" pistons on these.


From doing some reading, I learned that if you have too large of a bore master, your brake pedal will move so much fluid that your pedal travel will slam the brakes on RIGHT NOW, really firm and sudden, and a smaller bore than what you need will actually give you more brake power, but a much longer and spongy feeling pedal stroke, to where you risk bottoming out the cup/piston in the master and scoring the bores of the master cylinder. So this does seem to be a pretty important selection process.

I am thinking that with the quick takeup style masters with the huge front brake (rear on master) bore, that there is something special about the way they work, and they cannot be compared bore size vs bore size with a standard master. I'm not using the Wilwood stuff and not using the quick takeup stuff because this is a 1962 truck, and I want it to look fairly period... My F#$! Taurus electric fan will contradict that, but it's worth it to free up a little power on the beastly and thirsty GMC 305D V6!

[Chuck78]

Quick take up masters explained:

---------------------------------------------
QUICK TAKE-UP MASTER CYLINDER
Some late model vehicles have a special kind of master cylinder with a "quick take-up" valve. This design reduces brake drag for improved fuel economy. The master cylinder has a stepped bore which delivers a larger volume of fluid when the brake pedal is initially depressed. This allows the caliper piston seals to retract the pistons when the brakes are released so the pads don't drag against the rotors.

-from http://www.babcox.com/editorial/cm/cm20119.htm

---------------------------------------------

So it appears that maybe this plastic reservoir master may have benefits over using the older style... Hmmm... Have to weigh these thoughts.

[Chuck78]

Got most of my parts do do the swap to drum/drum dual reservoir with separate clutch master. The Pirate Jack's master came in, 8" dual diaphragm. Those things are tiny! Glad I didn't go with a 7"! Factory DD's must be a 9"?
Problem that I did not foresee was that GM factory masters have a bolt pattern of about 3-7/16" I believe, and I think the pirate jack's units use aftermarket 3-3/16" spacing! I went through my drill index last night on the drill press, and just tried to enlarge the holes in the master up to 1/2", rather than trying to elongate them slightly, but I think I need a 35/64" drill bit to do so in order to have the holes not be sloppy (studs resting on the very insides of the holes). I didn't have a problem with this, as the master's registering flange fits snugly in the booster hole, and the studs would be fairly self-centering as long as I don't oversize the holes anymore than I need to to get the correct inside to inside measurement.

The 67 power brake drum/drum dual master I got has a pretty typical 9/16"x18tpi rear (front brake) outlet, and 1/2"x20tpi front (rear brake) outlet, so I got some off the shelf brass adapter bushings that go from those sizes down to the standard 1/4" tubing thread (not sure on thread diam. or pitch, but it is the SAE standard for typical 1/4" tubing. the 1/2" thread is typical for 5/16" tubing. Then I got a 1/4" tube size threaded plug to block off the tee at the right front where the line to the rear splits off from the supply line coming across the crossmember. Other portion of the tee feeds a 10" or so hard line to the right front hose. Then you just need to run two new lines from the master, one to the tee at the left front (stock will be slightly shorter if your master exited out the bottom and not the new master's side location) - use probably a 30" or 40" tubing section, and then a new line from the master to the rear line that is on the pass. side frame rail at the crossmember. This will require using an inverted flare coupling for 1/4" tube thread, also referred to as a union. Mine has a 3/16" line to the rears, but I think it still has an adapter inv. flare fitting that has the standard 1/4" thread. CheifRocka's thread (where I got this info) shows his having 1/4" all the way to the rear. I have a GMC with a Dana 44 rear.

So as far as the master, it costs $99 for the standard 8" dual diaphragm, but I got the $129 version that is the same but has an adjustable master pushrod so you don't have to worry about having to custom space the master off the booster to have the proper minimal freeplay. Most are fairly standard, but you never know, and I'd rather spend $30 than have to grind down my booster pushrod or space the master off the booster, or else have to make an extension for the pushrod.
Using this master, I basically just had to enlarge or elongate the holes in a standard GM master to get it to fit. It's made for the old style masters that still have the deep bore like manual brakes (60's and early 70's masters). It has a threaded 3/8x24tpi booster pushrod on the firewall side. This is a standard thread, so pedal pushrod fabrication will be much easier.

The other option was the factory dual diaphragm booster 68-70 or so (most one ton trucks and some 1/2 and 3/4's had these), or an 85-87 or 87-89 Chevy Astrovan/GMC Safari dual diaphragm booster. the 60's truck units have the longer pushrod for the old power brake masters, but have a pretty short pedal pushrod with just the through bolt eye hook type connection to bolt to the pedal arm. I think these bolted straight to the firewall, and the pushrod is real short. The Astro/Safaris all had the dual diaphragm boosters in the yards (and a few S10 trucks had them). They have the shorter pushrod to use a newer shallow pushrod bore disc/drum master from the mid-70's and up, and also have a much longer pedal pushrod. These still have the non-threaded pedal pushrod with the through bolt flange on the end. I'm sure you could use a piece of round bar stock to couple onto this after cutting the end off, as on our trucks, the pushrod will need to be around 14" or more pedal pivot to booster total, which is a long ways. This is to accommodate the 4.5" long clutch masters and 9.5" from pedal pivot to firewall. The earlier astro units are under $100 at rockauto.com, but the later units every few model years make a big jump in price.

So with 4 wheel drums, you're best drilling out or elongating the holes in a 4 whl drum master to fit the pirate jack's master or else use the late 60's 8" dual diaphragm truck booster and fab up the pedal pushrod. For disc/drum or disc/disc, you're either best using the pirate jack's booster with their specific masters for those boosters, or else use the astrovan units.

I recalled that the pirate jack's 3/8x24 TPI pedal to booster pushrod happened to be the same thread size as a bicycle axle for a bike with rear coaster brakes, and those come in hardened steel, so those would make a nice pushrod extension in combination with a pair of 3/8x24tpi rod couplers that Pirate Jack's sells, and maybe one of their pedal pivot attachments or their truck extension pushrod with a heim joint on the pedal side. This makes it an easy bolt on if you just want to buy the parts and do minimal fab work.

I think both my GMC clutch and brake pushrod adjustment sections are a 7/16x24tpi, which isn't so common. Thought about trying to tap threads onto the end of the manual brake pushrod, but I think I may need to turn down the diameter, which would be a no-go if so. If that was the correct diameter and not 7/16", I would just need a couple inches of extension to make it work.

Might get around to taking the $5 pirate jack's booster brackets and chopping them up and extending them sometime this next week. Got a spare 89 suburban booster from the hard that was going to sit too close to my GMC's plaid V6 tall valve covers, so I might just chop those brackets off (riveted on) and use them to add onto the Pirate Jack's brackets to make them fit the new master. Basically you just need to have about 4-5/8" spacing off the firewall, and if using the $30 62-63/4? single res. brake master for clutch, you need to clearance the engine side bracket for the booster mounting flange. If you use the $60 aluminum Wilwood high capacity single reservoir master for the clutch, the mounting flange has top and bottom bolts, so minimal if any clearancing/notching would need to be done to the firewall portion of the brackets. This notching would be to the 90 degree flange that mounts to the firewall. The 62 single brake master as clutch would basically need to sit directly against the booster bracket to maintain the 2.5" center to center spacing of the brake pushrod to clutch pushrod. The new clutch master's bore register will fit perfectly into the clutch hole in the firewall, and you will need to use the original master's rubber boot somehow to seal the hole where the brake pushrod will go through.
If necessary, you could fudge the brake booster a little closer to the fender since you will have a 3/8" rod or 5/8" OD coupler now going through a 1-5/8" hole in the firewall. 1/4" might be a safe bet to allow some up and down movement of the pushrod.

Hope you all can digest this much info at once! Trying to put it all out there to save others from having to spend all the time I spent researching this stuff, looking up parts interchanges, and browsing the boneyards to see what late model factory parts I can use!

Let me know what you guys think of all this. Hope this info can get passed along quite a bit in helping other 60-62 owners save money and not have to spend $500 to have a big firewall blockoff plate to mount their stuff to! I like the idea of re-using the clutch hole that's already in the firewall. Keep it nice and clean, keep stock linkage location, etc.

[hAetWagon]

Lotsa words. ugh...

[tonythezeek]

wow this is awesome! I am about to re-start my project 62 (had to stop due to the economy) and the brakes was where I stopped (no pun intended). I would love to see some pics when you do the install as well as a definitive parts sheet.

one-thousand thank yous would not be enough for your diligence and hard work!

[Chuck78]

5 months later, I finally got this project bolted on!
With this stock brake master (auto trans truck or 63 model manual or auto) being used as a clutch master, I discovered that there were SURPISINGLY even already dimples in the firewall in over the clutch hole where that master will bolt to! How weird???? Never a factory option. Hmmm...??? Brake and clutch have the same bore x stroke ratio on the masters, so the brake was exactly what I needed but with the residual check valve stuck into the end of the spring (disassemble and remove this).
For a master, in keeping with the same bore and stroke, I used a 67 Chevy C30 1 ton truck master, dual reservoir, and required two brass fitting adapters to get down to the correct thread for the 1/4" line size. I used a Pirate Jack's dual diaphragm 8" booster with adjustable pushrod, but the spacing for the master was unique to their stuff, so I drilled holes on master out to 1/2" diameter and it bolted to the pirate jack's $130 booster. Booster had 3/8x24tpi pushrod, and I bought their pedal pushrod extension and heim joint pivot, a 3/8x24 rod coupler from them, and a 3/8x24tpi coaster brake bicycle axle for the extra extension length. This worked out perfect. I'd recommend for the money, looking into an AstroVan (or a few S10 truck models) booster and newer compatible master (shallow bore for pushrod), but the pedal pushrod extending you'd have to come up with on your own. those parts I got added up in cost. Could use stock factory pushrod, cut off end here taper gets smaller than 3/8", thread to 3/8x16 with a die, use standard rod coupler from Lowe's and threaded rod, and then weld a rod coupler (or drill and pin) to the rear pushrod on the booster. Then you'd want to get a newer master (after 70/71-ish) with the shallow bore pushrod. My 67 master uses the manual brake style deep bore master and long pushrod. After 70-ish, they switched power brake masters to the shallow style. Confirm with clay/play-dough that you have the correct length on booster to master pushrod!!!! Pirate Jack's unit can come with an adjustable booster to master pushrod for the long/deep style for $30 extra. They also sell masters, but those DO NOT have residual valves, must purchase them seperate and plumb into lines externally.

The brackets I made up myself. I used half of an 89 suburban booster bracket cut down, and half of a Pirate Jack's booster bracket, cut at the necessary agles, welded together. I think making one out of plate steel or channel/angle iron would have been easier and faster than what I did! Too many angles to calculate and cut just right, lots more thinking than working from a clean slate.

I kept the same bore master and same pushrod location from stock manual application, even though swapping to power. Seems to work fine for me. No proportioning valve, was told it's not necessary from most people. Worked fine in the 1 mile that I drove it. that bore master (after removing the front residual valve) will also be correct for later model disc brake calipers on a 1/2 ton truck for when I swap x-members to disc, so that was a big part of the reason I went with that master and didn't go bigger bore. bigger bore means more pedal effort, but with power assist boosters, you don't notice, and you move more fluid. smaller bore means less stroke on the other end, but you have more power with your foot.
I had to notch out the side of the booster bracket to clear around the flange on the new clutch master, and had to make the bracket about 4-5/8" long or so. Also, I offset the centerline on the brake pushrod and master over to the fender just a slight bit to fit the clutch master centered in the stock linkage location.
Performance is AWESOME now!
Very glad I did this. Wish I had the front discs and front sway bar now, and maybe power steering, but afraid to add any engine accessories for fear of even worse gas mileage!

photos before plumbing hydraulics and vacuum hose. more upon request.

[creep]

Wow, nice job! I may have to make a trip down to Columbus one day to check out your setup. How much clearance do you have between your booster and valve covers?

I was thinking of getting the set-up from LMC but it's so expensive and I don't know if it requires custom fabbing or not. Another route I was considering was to use an under dash set-up like some of the hot rodders use.