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Tech Editor's DeskProjects, papers, writings, thoughts, musings of our technical editor Joe Padavano. To begin with, he will be making threads and can approve posts to it if he wishes. This can be changed in the future if it does not work out well.
Joe, so if I use the 71 and up valve, will it mount on the frame and eliminate any plumbing work?
Does any adjusting need to be done once they are installed?
I assume you are referring to the one on your parts list?
thanks,
Steve
Joe, so if I use the 71 and up valve, will it mount on the frame and eliminate any plumbing work?
Does any adjusting need to be done once they are installed?
I assume you are referring to the one on your parts list?
thanks,
Steve
Steve,
Unfortunately the combo valve is shaped differently than the distribution block, so you'll unfortunately have to at least bend some lines. Also, GM used different threads on the flare nuts to preclude incorrect assembly, and you may need IFF adapter fittings on some of the ports. The lines down from the M/C to the combo valve will likely need to be replumbed. Also, if you have headers, you may want to relocate the combo valve. This is one reason why the M/C with the combo valve below it is attractive to some people. This gets it out of the way of any headers. It does require replumbing, or at least making up extension lines with couplers from the old distribution block location to the new combo valve location. And finally, if you choose to go with the 1969 setup that uses the metering valve, you only need to run new lines down from there to the distro block, but don't need to mess with the lines from the distro block to the wheels (well, other than changing the hoses at the front wheels). Of course, with my luck, I ALWAYS twist off at least one flare nut, so I always end up replumbing the whole car anyway...
If you are using the Speedway calipers how are you clocking the hose at the banjo bolt? It looks like the way the cut out is machined it should come in from the top. If you do that it significantly hits the upper control arm when fully turned. If you come in from the side it seems like it could get pinched in the spring.
My CPP kit came with the same style calipers which are not correct for the car and my brake lines hit the upper control arms , they may have worked okay if I didn’t have the drop spindles kit. I just bought calipers from Napa for my 71 and also new hoses that fit the Delta 88 so I can use my drum brake frame brackets They are about three inches longer than the disc hoses for the A body cars but I thought the correct hoses seemed a little short?
I know this is an old thread but what size brake booster was original. Doing a disc/power brake upgrade on a 1968 Cutlass S. the kits that I see being sold have an 8", 9", and 11" booster or an 8" dual booster. Which is correct and/or functionally better?
I know this is an old thread but what size brake booster was original. Doing a disc/power brake upgrade on a 1968 Cutlass S. the kits that I see being sold have an 8", 9", and 11" booster or an 8" dual booster. Which is correct and/or functionally better?
The amount of "boost" you get from a brake booster is directly proportional to diaphragm area, which is directly proportional to diameter squared.
8" = 50 sq in
9" = 63 sq in (this was stock in the 64-66 A-body)
11" = 95 sq in (this was stock in 67-77 A-body)
Dual 8" = 100 sq in.
Note that the change to the 11" booster in 1967 is why the 67 442s have one notched valve cover on the driver side. The different HVAC box design for the 68-72 cars is why those have two notched covers.
Just wondering if I went from power drum to disc should I have changed the booster?
Steve
69 Cutlass S
The factory lists different P/Ns for the booster for drum and disc applications, but frankly I've never changed the booster when converting to discs and I've had no issues. The disc M/C bolts to the drum booster and works fine. The only thing to watch out for is the pushrod length when converting a car that had a single circuit M/C. That's not an issue for your 69 Cutlass.
I ran a set of 98 disc brakes on my Vista cruiser, before I tore it down to re-do it. They worked amazing. Almost as good as the 14 / 13 inch wilwood brakes I have on now. I installed a chevy 10 bolt rear to do it though. I don't know that you can do this modification easily on a BOP rear because of the axle flange on a non c-clip rear. On the chevy 10 bolt they were a direct bolt on with about a 1/8" spacer between the axle flange and the backing plate as shown above. With the 98 camaro brakes, you will have 12" rotors on all four corners.
This is a great thread and Joe's spreadsheet is very helpful in getting the part list together. I just went through this and IMHO there are a few things that should be added to the spreadsheet:
Brake hose bolts (banjo bolts). They don't come with the hose in the spreadsheet.
Inner and outer wheel bearings and seal. The rotor does not come with them and you can possibly use the existing ones but you probably want to get these.
I'm trying to piece this front disk brake puzzle together and I have no old parts that can be re-used, nor would I want to given the ratty state of my existing components, so does anyone else have part numbers that I can use for other assorted parts such as those listed above? I am thinking about
Hardware to mounting the splash shield and caliper brackets to the spindle
Grease seals
Inner and outer bearings
Spindle nuts
Dust caps
On rock auto, for 1971 Oldsmobile Cutlass Supreme, there are a large amount of parts available in the above categories. None of them are expensive, but it would save some heartache if someone has already bought the required pieces and can post part numbers. Thanks
I ran a set of 98 disc brakes on my Vista cruiser, before I tore it down to re-do it. They worked amazing. Almost as good as the 14 / 13 inch wilwood brakes I have on now. I installed a chevy 10 bolt rear to do it though. I don't know that you can do this modification easily on a BOP rear because of the axle flange on a non c-clip rear. On the chevy 10 bolt they were a direct bolt on with about a 1/8" spacer between the axle flange and the backing plate as shown above. With the 98 camaro brakes, you will have 12" rotors on all four corners.
it it because the BOP rear axel tubes are not tapered at the ends liked the Chevy 10/12 bolt?
it it because the BOP rear axel tubes are not tapered at the ends liked the Chevy 10/12 bolt?
It is because the camaro disc brake backing plates are 1/2" to 3/4" thick and they bolt to the axle flange. In a BOP rear with no c-clips, the axle bearing is bolted into the end of the axle flange as well. If you put the backing plate on first, the axle will be sticking out 3/4" farther and the bearing will not be seated in the tube. I don't see a way to put the backing plate on after the axle because the backing plates have integrated drum brake emergency brakes. Another nice thing about running the Camaro rear brakes is that the emergency brake cables were a direct fit into my vista. I had to cut off the brackets from the camaro rear and weld them onto the vista (chevy 10 bolt) rear, but the other end of the cables went into the original holes in the frame, and even locked into the original clips for the intermediate cable.
I know this is an old thread, but it's new to me, and has a lot of great information. It would be nice to convert the front drums on my niece's '72 Cutlass Supreme. I asked a guy at work what route he went with his '70 Cutlass. He said he got a whole setup off a Cutlass at the junkyard, but when he got home it didn't fit, and that there were different spindles for disc brakes that year that were not a bolt-in replacement. Any thoughts on this would be appreciated.
I know this is an old thread, but it's new to me, and has a lot of great information. It would be nice to convert the front drums on my niece's '72 Cutlass Supreme. I asked a guy at work what route he went with his '70 Cutlass. He said he got a whole setup off a Cutlass at the junkyard, but when he got home it didn't fit, and that there were different spindles for disc brakes that year that were not a bolt-in replacement. Any thoughts on this would be appreciated.
The 1964-72 A-body, 1967-69 F-body, and 1968-74 X-body cars all use the same spindles. They all interchange. Disc brake spindles are different from drum brake spindles, but they swap on the ball joints. Early cars (1964-66) use smaller bolts to hold the steering arm to the spindle, but that shouldn't be an issue in your case. The F-body and X-body spindles use different steering arms, but again, you can unbolt those and bolt on the A-body arms from the drum brake setup. The only different spindles are the 1973-up cars, so either your "guy" is confusing those, or he's just completely incorrect. There is no "different" disc brake spindle for the 72-older A-body cars.
The easy way to tell if the spindles are 72-older or 73-newer is that the older ones use bolt-on caliper brackets and steering arms. The newer ones have integral caliper brackets and steering arms (in addition to completely different dimensions).
I know this is an old thread, but it's new to me, and has a lot of great information. It would be nice to convert the front drums on my niece's '72 Cutlass Supreme. I asked a guy at work what route he went with his '70 Cutlass. He said he got a whole setup off a Cutlass at the junkyard, but when he got home it didn't fit, and that there were different spindles for disc brakes that year that were not a bolt-in replacement. Any thoughts on this would be appreciated.
You will need 15" or larger rims for the factory 11" disk brakes to work up front. I believe the 14" rims were drum brakes only.
Also...you can run the C5 05/06 GTO 13"/4 piston PBR front brakes and 98-02 PBR 12"/dual piston Camaro rear brake out back for a factory GM big brake kit...THEY WORK....and work WELL (currently on my 68 442)! Need to figure out if you have the Oldsmobile rear end (no C clips holding the axles in) or Chevelle 12 bolt rear end (with C retaining clips.). I believe the Chevy 12 bolt rear ends were installed in 442s manufactured in Canada and Olds rear ends were installed in 442s in Michigan.
If you have the Chevy 12 bolt you need the BRP Hotrod rear brake adapter plate:
If you have the Olds 12 bolt you need to cut the drum backing plate to use as a 1-2 mm spacer/axle retainer to center the disks between the PBR floating calipers
These brakes will require 17" or larger rims and possibly wheels spacers for the front because the front PBRs are pretty bulky and wide (depending one wheel dish....I used the Year One Super Stocks which have a 3" dish up front and come really close to the caliper).
PBR' s are easily rebuilt (two rubber gaskets per piston) and can be painted or powder coated.....These are 1/3 the cost of wildwoods and probably stop as good at the wildwoods
Sorry I stand corrected....I thought I had read the 14" wheels were drums only. The 68 I'm working on had manual drums at four corners...
Once again, there are different 14" wheels for drum and disc cars. In this photo, disc on the left, drum-only on the right. Note the shaping of the rim to clear the caliper (yellow vs green arrows). Outboard is to the left for both wheels in the photo.
Thank you both. Once again, a lot of valuable info. Especially about the difference in the calipers from '72 and earlier and '73 and later. Happy 4th of July, and have a good weekend.
Thank you both. Once again, a lot of valuable info. Especially about the difference in the calipers from '72 and earlier and '73 and later. Happy 4th of July, and have a good weekend.
Just to clarify, the SPINDLES are different for 72-older and 73-newer. The calipers are actually the same for 1969-1977.
It's probably been mentioned earlier in this thread but there are a bunch of YouTube videos that show you how to modify drum brake spindles to accept disk brake brackets
Will any of these parts work on a 1974 Delta? I think my car is a B Body...any suggestions for going disk all around?
Thanks!!!
Jason
Originally Posted by joe_padavano
I originally posted this in the Brakes section, but it probably makes sense to put it here for more to see. I've also expanded the previous answer (which was specific to 1968 cars) to cover all 64-72 A-body cars.
There are a number of high dollar disk brake conversion kits for the 64-72 A-body cars. These kits are very complete, but also very expensive (well, at least by my cheap-@$$ standards). If you're willing to do a little work ordering from multiple sources, here's a low-cost way to convert any 64-72 A-body drum brake car to factory-size disks:
First is the basic brake kit and spindles. Here's the cheapest I've found.
Note that Speedway's current website won't let me link directly to those pages, so just copy and paste the part numbers into the search box on their website.
Brake kit: $240
Spindles: $130/pr
Total: $370
Note that you still need a disk brake master cylinder and proportioning valve.
If you don't care about complete correctness, a replacement M/C is $21 from RockAuto (Raybestos P/N MC36306).
Since I assume you're not looking at the megadollar four piston calipers that were factory on the 67-68s, this M/C will work fine. If you want the correct looking M/C, you can get P/N 36760 from Speedway for $59.
The 67-70 cars used an in-line metering valve shown here for $67 from Summit:
This mounted below the M/C and has the advantage of not requiring you to disturb the distribution block on the frame. If that's too pricey, you can substitute a 71-72 combo valve shown here for $46 from Summit, but you'll need to do more plumbing:
Then there's the issue of the brake lines. If you use the early-style proportioning valve, you only need to bend new lines from the rear outlet of the M/C to the prop valve to the distribution block. Take off the one old line and cut, bend and reflare the ends to plumb the prop valve, or bend up two new shorter ones to replace it. If you go with the combo valve you may need to replace or rebend all the lines. In any case the flare nuts going to the M/C may have different thread and you'll either need adapters (available at most auto parts stores) or get the right flare nuts and reflare the ends of the tubes when you replace them.
Finally, there's the issue of the frame brackets for the rubber hoses to the front wheels. If you want to do this on the cheap, you can file the holes in the current brackets, but the easy way is to just buy P/N 45896 from Speedway for $10:
OK, so what's the total?
$370 from Speedway, $21 for the M/C, $46 for the combo valve, and $10 for the brackets gets you disk brakes for $447. If you want the correct M/C and prop valve, its a few dollars more. Either way, this is substantially less expensive than the complete kits, at the cost of some extra ordering time for you. If you like to scrounge, you can find parts even cheaper on ebay or at swap meets.
If you have power drums now, the disk brake M/Cs shown above will bolt to any 67-72 power booster (drum and disk brake boosters are interchangeable). The 64-66 cars with single brake systems use a different pushrod length in the booster and the dual circuit M/C will not work with it. You'll need to either get a 67 power booster or swap out the pushrod ($4 from Inline Tube). If you have manual drum brakes and want to keep manual disks, (my 70 W30 stops fine with manual disks) then just get the correct manual disk M/C and transfer the pushrod from your drum M/C. If you have manual and want power, you'll need a brake booster in addition to everything above.
Resurrecting this old thread rather than starting a new one for a somewhat related question, and hoping Joe is still subscribed as the OP to his thread.
On a ‘70 Cutlass with factory power front disc brakes, can I upgrade the stopping power of the front brakes using slightly larger front discs and calipers when using 15” wheels (larger than stock 14” wheels)? If so, are there any other modifications required?
Resurrecting this old thread rather than starting a new one for a somewhat related question, and hoping Joe is still subscribed as the OP to his thread.
On a ‘70 Cutlass with factory power front disc brakes, can I upgrade the stopping power of the front brakes using slightly larger front discs and calipers when using 15” wheels (larger than stock 14” wheels)? If so, are there any other modifications required?
Larger diameter rotors will require you to change the caliper mounting bracket. See this link about fitting 12" Corvette rotors to the stock spindles Note that increasing the front brake force changes the front/rear brake balance (as does changing tire sizes and rubber compounds from OEM). Any such modification can be enhanced by using an adjustable aftermarket proportioning valve and adjusting it properly for the equipment on your car.
Doesn’t look to be a straight-forward (easy) swap in parts solution. Upgrading the rear drum to disc brakes would (probably) be easier, but the rear only do about 1/3 of the braking so the braking improvement may not be worth the effort.
Doesn’t look to be a straight-forward (easy) swap in parts solution. Upgrading the rear drum to disc brakes would (probably) be easier, but the rear only do about 1/3 of the braking so the braking improvement may not be worth the effort.
Not only is it not worth the effort, but converting the rears to disc without also upgrading the fronts means you need to use the prop valve to restrict pressure to the rears until they are only providing the same braking force as the drums were. Any more and you lock up the rears in a panic stop, which is a good way to swap ends.
Doesn’t look to be a straight-forward (easy) swap in parts solution. Upgrading the rear drum to disc brakes would (probably) be easier, but the rear only do about 1/3 of the braking so the braking improvement may not be worth the effort.
Even if it were an easy swap, the usefulness of the swap would be nearly zero, nada, negligible: UNLESS you were planning to increase the vehicle's weight by an additional 3,000 lbs - you might find some benefit. Your money and time would be far better spent elsewhere.
I originally posted this in the Brakes section, but it probably makes sense to put it here for more to see. I've also expanded the previous answer (which was specific to 1968 cars) to cover all 64-72 A-body cars.
There are a number of high dollar disk brake conversion kits for the 64-72 A-body cars. These kits are very complete, but also very expensive (well, at least by my cheap-@$$ standards). If you're willing to do a little work ordering from multiple sources, here's a low-cost way to convert any 64-72 A-body drum brake car to factory-size disks:
First is the basic brake kit and spindles. Here's the cheapest I've found.
Note that Speedway's current website won't let me link directly to those pages, so just copy and paste the part numbers into the search box on their website.
Brake kit: $240
Spindles: $130/pr
Total: $370
Note that you still need a disk brake master cylinder and proportioning valve.
If you don't care about complete correctness, a replacement M/C is $21 from RockAuto (Raybestos P/N MC36306).
Since I assume you're not looking at the megadollar four piston calipers that were factory on the 67-68s, this M/C will work fine. If you want the correct looking M/C, you can get P/N 36760 from Speedway for $59.
The 67-70 cars used an in-line metering valve shown here for $67 from Summit:
This mounted below the M/C and has the advantage of not requiring you to disturb the distribution block on the frame. If that's too pricey, you can substitute a 71-72 combo valve shown here for $46 from Summit, but you'll need to do more plumbing:
Then there's the issue of the brake lines. If you use the early-style proportioning valve, you only need to bend new lines from the rear outlet of the M/C to the prop valve to the distribution block. Take off the one old line and cut, bend and reflare the ends to plumb the prop valve, or bend up two new shorter ones to replace it. If you go with the combo valve you may need to replace or rebend all the lines. In any case the flare nuts going to the M/C may have different thread and you'll either need adapters (available at most auto parts stores) or get the right flare nuts and reflare the ends of the tubes when you replace them.
Finally, there's the issue of the frame brackets for the rubber hoses to the front wheels. If you want to do this on the cheap, you can file the holes in the current brackets, but the easy way is to just buy P/N 45896 from Speedway for $10:
OK, so what's the total?
$370 from Speedway, $21 for the M/C, $46 for the combo valve, and $10 for the brackets gets you disk brakes for $447. If you want the correct M/C and prop valve, its a few dollars more. Either way, this is substantially less expensive than the complete kits, at the cost of some extra ordering time for you. If you like to scrounge, you can find parts even cheaper on ebay or at swap meets.
If you have power drums now, the disk brake M/Cs shown above will bolt to any 67-72 power booster (drum and disk brake boosters are interchangeable). The 64-66 cars with single brake systems use a different pushrod length in the booster and the dual circuit M/C will not work with it. You'll need to either get a 67 power booster or swap out the pushrod ($4 from Inline Tube). If you have manual drum brakes and want to keep manual disks, (my 70 W30 stops fine with manual disks) then just get the correct manual disk M/C and transfer the pushrod from your drum M/C. If you have manual and want power, you'll need a brake booster in addition to everything above.
Joe my 69 A body had power drums. I had to remove booster because of my camshaft. I just bolted M/C to firewall. I know I’d need to get a disc brake M/C. If I understand correctly I would also need a combo valve from a 71and up car right? And would I need to change my stock rear wheel cylinders? I want manual disc brakes like your W-30.
Joe my 69 A body had power drums. I had to remove booster because of my camshaft. I just bolted M/C to firewall. I know I’d need to get a disc brake M/C. If I understand correctly I would also need a combo valve from a 71and up car right? And would I need to change my stock rear wheel cylinders? I want manual disc brakes like your W-30.
Yes, you will need a combo valve. Be sure your disc brake M/C has a 1" bore, not the more common 1.125"
Can I use my stock rear wheel cylinders or do I have to change to smaller ones? I ask because you said in one thread that disc brake cars had small rear wheel cylinders.
You either need the separate proportioning valve, or a combi valve that does both distribution and proportioning, or smaller cylinders. If it's all the same to you, perhaps you should set it up the way that year was, which is the smaller cylinders for 69, says Joe.
You either need the separate proportioning valve, or a combi valve that does both distribution and proportioning, or smaller cylinders. If it's all the same to you, perhaps you should set it up the way that year was, which is the smaller cylinders for 69, says Joe.
Either the use of smaller rear wheel cylinders or an appropriately-adjusted prop valve will accomplish the same thing, which is to reduce rear wheel brake force and thus avoid premature rear wheel lockup. I'm actually an advocate of an adjustable prop valve because the factory settings are only appropriate for factory weight distribution and factory tires. If you have tires with more grip, you can likely use more rear brake force before lockup, so a stock prop valve would potentially reduce the available braking capability.
January 12th, 2020, 07:26 AM
