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.

Speedway Motors Disc Brake kit, P/N 4624 and Speedway Motors Disc Brake Spindles, P/N 33377

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:

http://www.summitracing.com/parts/rs...model/chevelle

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:

http://www.summitracing.com/parts/cl...model/chevelle

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.

68Tom

Wow, thanks Joe. I was actually considering converting my front power drums to disc, as the brakes are completely shot on my car. However, after a little research, I learned that if you have 1968 SS I Rallye wheels, disc brakes will not fit, as the offset won't allow it. So, it's either new, non-matching wheels (would have to get the '70 SS I) or just replace the drums.

joe_padavano

You are correct that they won't fit, but the problem isn't the offset, it's the design of the wheels themselves. Prior to disk brakes becoming common, GM used wheels that had a smaller center disk and a deeper drop in the rim portion of the wheel. This made mounting tires easier and cleared the 9 1/2" drum brakes. Once disk brakes made their appearance in 1967, GM came out with a new wheel design that used a larger center disk and less of a drop in the rim. This cleared the calipers. Unfortunately, during the 1960s GM built both types of wheels and the early SSI wheels are the older style deep drop/small center design. Only the 1970-up SSIs will clear the factory 10.5" disks.

OKIEOLDS

If I do this conversion on my 70 cutty vert will the 15 inch rally wheels work on it and are the bolt pattern the same on the later wheels?

joe_padavano

All SSII and SSIII rims (14x6, 14x7, and 15x7) will clear the FACTORY disk brakes with the 10.75" rotors. All three versions of the SSII/III rims were factory available with these brakes and I have personally bolted them all to various A-bodies that I've owned. As noted previously, with aftermarket disk brake kits that do not use the original style brackets and calipers, there's no gaurantee

Maverick

Was there a 14 x 5" ? I had a set of SSI's from a '69 Cutlass Supreme that I tried to put on my '71 442 with discs. They wouldn't clear .

Just asking .

Brent

joe_padavano

Scroll up to post #3 in this thread:

jturkey69

Joe, I found a disc brake kit with 500 miles on a 69 Camaro a guy is selling on Craigslist for 275...2" drop spindles, assembled with calipers and rotors, backing plates and hoses. The links above are dead, so for my 71 with power drum brakes, I only need a disc brake m/c and a prop valve for disc, but from/for what?
will the 2" drop be ok with the control arm shimming that it may need?

Thanks for the help.

Turkey

joe_padavano

Be careful with the dropped spindles. The Camaro steering arms are different from those on the A-body cars. The stock steering arms bolt on, so you can swap them easily. If the aftermarket dropped spindles also use bolt-on arms, you're fine, just use your old ones. If the spindles have integral steering arms, they will not work.

jturkey69

The kit is from Classic Performance Products, otherwise I will also ask. Otherwise Im ok using my booster, and getting a new m/c and prop. valve? Should I buy new, or get one from a 67-70 disc brake car?

Thanks for the heads up, and the help!!

Turkey

jturkey69

Classic Performance Products web site says the camaro kit uses stock balljoints and steering arms...so does this mean it will work on my car?

joe_padavano

Yes, so long as the steering arms bolt on, you can use your stock ones. Any Cutlass disk brake M/C will work fine. Easiest plumbing for the proportioning valve is to use an external one like the 67-70 cars.

jturkey69

ok, gotcha...Thanks!!!

BIGJERR

Buy that camaro put it on Ebay and then take the profit and use the bolt on stuff!

jturkey69

I could do that, but I dont use paypal anymore...I may just buy the right stuff anyways...this way I can not have any mistakes. I just need to find the right one for a cheap price.

#1CutlassSupreme

Dang it! I wish I would have seen this post before Joe!

My 72' Supreme had factor disk in front and I just decided to spend the extra money and buy a complete upgrade to 4-wheel disk all the way around. The booster bolted right up, master cylinder fit well, and even the proportioning valve fit in the factory mount. There was a little work to get the rear drum backing off and since you've got to pull the axles, you may as well do new bearings while you got her opened up.

The rotors were a bit bigger than stock at 11" and even going up to SSIII JJ 15x7 Rally wheels, I still had issues with the calipers rubbing on the wheels in the back.

I fixed that issue by putting on some 1/2" spacers which gave me about 1/4" - 3/8" clearance between the wheel and the ear on the rear calipers.

Sorry to Hijack, but just some FYI for the guys looking to upgrade.

jturkey69

Its all good #1, I will take all the info I can get!

elie ayoub

hi guys my name is Elie,i am new to the forum.i have a 72 cutlass four door 70000 miles,with power drum brakes and 14"wheels..i want to convert the front to disk brakes with 11"rotors and original gm parts caliper etc...i have a question for mr.Padavano JOE .. currently on this car i have SSI 14" wheels all chrome with black paint on the mounting pad circle. it has a nbr. stamped on it 14x6 JJ31C and another 1240831.. measurements i took reads as follows.. back space is 4" 1/8 .. inboard side diameter is 14" at the begining ,stays inset unchanged for 2" 1/2 straight towards the center line before it drops down. my question to u JOE does this rim clear the caliper .. i appreciate yr help and many thks .E.A my email is eaca44@optonline.net

big_wheel1971

Joe,

I have a 71 Cutlass S coupe that is at the front end of a resto. I want toi convert the drums to discs and I read your posts. I am in Canada and the complete kit will be almost $1300 Cdn. Most of the sites you hyperlinked in your post have expired. Could you re-send with some of the p/n's from the websites? Sorry for the work, but you seem to know what you're talking about.

Later,

Darrell

joe_padavano

Yes, I had planned on updating those links, but unfortunately it's not going to happen until after Nationals this week.

66ninetyeightls

italian ice

Question for Joe Padavano please. Can you look at this kit and comment on if it matches up to your low cost suggestion? It will be for my 68 F85 which currently has all stock power drum brakes. As far as I could tell it seemed to be at least equal.

Thank you


http://cgi.ebay.com/ebaymotors/64-72...item3efc66fd2e

jturkey69

That is the same place, and same kit I got for my 71 S except I got the 4wdb conversion with hardlines.

joe_padavano

That kit is fine if you need the booster. Your existing booster will work fine with a disk brake master cylinder if you want to save a few bucks. The Speedway Motors kit is still $240 but does not include the M/C, combo valve, or booster. You should be able to score a rebuilt M/C and a combo valve for less than the difference in price with the ebay kit. Your money, your call.

italian ice

Both of your comments are appreciated. Thank you.

BTW If I add the spindles & hoses, seems like a push on overall cost.

Turkey, were you satisfied with the kit?

Again thanks!

Bob D'

jturkey69

Yes I am, I have not givin them a full bore stomp test, or torture test, but having the look, and feel of modern brakes makes me comfortable knowing that I am not going to have a failure, or rearend some pocket rocket who can stop on a dime because of indecisiveness..lol
there is a detailed thread on a 4wdb conversion I was following that has alot of pics, and also reading some on pro-touring.org to help with my decision. The kit is very well put together...I went with normal rotors instead of slotted or zinc washed as I wanted the cheapest 4wdb first then tackle other needs like bodywork and bushings which is next.
hope whichever way you go, it all works out for what you want it to do.


Turkey

italian ice

Thanks very much for the feedback. Maybe I should check into the 4 wheel option.

Bob D'

jturkey69

I really wanted them because we went with 18" Boss staggered 338's, and would rather show off discs then drums..plus we wanted the pro touring vibe without the pro touring pocketbook..lol there is nothing wrong with converting the fronts only, and it is cheaper then all 4. best of luck to ya!

Turkey

mike b

what do you think of this for $545
http://www.buyautoparts.com/addtocar.../71-20002.html
would this fit a 69 Super Stock II wheel 14" x 6" ?
thanks

jmbond111

No spindles either.

Ctott70

Anyone know anything about this conversion set I've seen on Ebay? Seems a little too cheap to be a decent conversion.

http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

Thanks,
Chad

joe_padavano

The kit is cheap because it is ONLY for the brackets. Personally I'm skeptical of those flat plate brackets as opposed to the factory style brackets with the ears that keep the caliper from cocking. More to the point, you can get repros of the factory style brackets for about $35 a pair and with some simple machining the drum spindles become disk spindles.

OLDSMORAT

This disc brake kit uses chevy celibitry calpers and is not worth the price. Try performance online.com there kit has spindles, brackets and dustsheilds for $159. And you use gm replacement calipers and rotor for a bodys. I used it and had good results

Ctott70

Thanks OLDSMORAT this is very good info! BTW I agree about the Ebay set, I was very skeptical about them when I saw them, the Performance Online set looks much more durable and like stock, I like it.

Thanks again,
Chad

blacksunshine

oldsmorat / joe padavano / anyone who knows
the bearing and seal numbers listed in the performanceonline.com spindle kit, are those gm part numbers? will the guy at o'reilly or whereever be able to look them up?
and i'd still need rotors, calipers, pads, hoses, porp valve, etc. right?
I'm looking into putting discs on my 68 cutlass s with power drums, but I'm still trying to figure out how much I'm going to have to swap out, and need to do it as cheap as possible. Thinking about the back too, since I'm not getting any fluid to the rear brakes anyway and will have to replace lines until I find the culprit (I guess).
any input would be appreciated. is the complete kit worth the money (I'm not too sure of the quality/accuracy/fit of the china-made "parts" from the o'reilly/autozones)?

RonFX

Say it ain't so Joe:
All that time to save less than $65.00 over the price of the kit I bought from a mail order shop. The price even included shipping, lines prebent, everything assembled and ready to go. I am as cheap as the next guy, but they make it all look great and your time has to account for something.
Thanks Ron

arodenhiser

This upgrade is always on my mind. Can you tell us where you got the kit? Thanks.

Adam

The_Jeremiah

I just recently found out, ss396, i think its groundup.com. they have the spindles, caliper brackets, and backing plates as a kit for around 150, then you can just get calipers and rotors, pads, etc from your local parts house, just a thought. Also I recently found out if you have the equipment to machine the spindles, you can modifly the drum spindles for mounting discs, the only difference is the upper mounting hole. anyways, just trying to add more options!

RonFX

Jeremiah:
You are right about the bracket kit, everything else is from either a GM A Body or Camaro platform. I asked the company that actually made the kits about replacement parts and that is what they told me. If you go to one of the large chain parts stores to buy the remainder of the stuff, sometimes they almost walk away when they see you coming in, not because they don't want to help you, guys like us scare the hell out of them when we want something but cannot really give exact info just a sample or casting. I worked for 15 years in a parts store. This was WAY before computers, each guy had his own catalog rack and you had to know it. If you find a GOOD Parts guy, treat him good, they are getting harder to find.
Thanks Ron

Bitburger

[QUOTE=joe_padavano;33950]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.

http://www.speedwaymotors.com/Speedway-Deluxe-1964-74-GM-Car-Front-Disc-Brake-Kit,4624.html
http://www.speedwaymotors.com/1964-74-GM-Car-OEM-Style-Disc-Brake-Spindles,33377.html

Brake kit: $240
Spindles: $125/pr

Total: $365

************************************************** ********

An older post with a newer twist.

Speedway now lists the following.

Deluxe 1964-74 GM car front disc brake kit
new part number 91031958 still $240
Now listing the rotor as 11" instead of the old 10.75"

So, will this 11" kit clear 14" SSII and SSIII rims ? or does the 1/4 diameter change prohibit this.

Speedway also lists 1964-74 GM car OEM style disc brake spindles as part number 91034900 and still $123

Sorry I'm not computer savvy enough to provide the links