Drum To Disc Brake Conversion

sleeton · November 3rd, 2009, 11:27 AM

A friend of mine has a 72 cutlass that has power drum brakes and he is thinking of changing the front brakes to disc brakes. Can he use the same spindles and put the disc on or does he have to change the spindles. Once he changes over to disc brakes does he need to install a proportioning valve?

Olds64 · November 3rd, 2009, 12:33 PM

The easiest way to convert to front disc, rear drum would be to find an early 70s Cutlass in a salvage yard with the parts on it. I know they were available. Then your friend can get all of the parts off of the salvage car and install them on his 72. Ultimately, I'm not sure if the early 70s A bodies had different spindles for front drum and disc brakes.

70 cutlass s · November 3rd, 2009, 01:15 PM

Yes you have to change the spindles, proportion valve, power brake booster, master cylinder, front rubber brake lines. If you can find an A body in the bone yard that would be the cheapest way, but you can buy a kit that has everything. Also when changing over to disc. Its a good time to change front coil springs if they need it since it will be all apart.

Eightupman · November 3rd, 2009, 05:57 PM

No, you do not have to change the spindles. HOWEVER they will need one additional bolt hole drilled and tapped to accept the caliper bracket (available aftermarket as well). I have heard that if you already HAVE a power booster, it does NOT need to be changed either. proportioning valve is available in the aftermarket catalogs.

now, with the costs involved, its better to get parts from a donor, or a kit.

John

joe_padavano · November 4th, 2009, 01:24 PM

[quote=Eightupman;120920]

Quote:

No, you do not have to change the spindles. HOWEVER they will need one additional bolt hole drilled and tapped to accept the caliper bracket (available aftermarket as well).

Not quite. The caliper bracket bolts to the existing holes. The problem is that you need to machine the boss around the upper bolt hole on the spindle. Here is some additional info (note that first gen Camaros use the same spindles as 64-72 A-body cars):

http://www.pozziracing.com/brakes.ht..._brake_spindle

Quote:

I have heard that if you already HAVE a power booster, it does NOT need to be changed either. proportioning valve is available in the aftermarket catalogs.

Correct. I have done this swap several times keeping the existing power booster.

mugzilla · November 5th, 2009, 12:24 AM

The disc brake spindle is taller which is beneficial for handling ...

This guy did a good job on his front end and I will update my spindle/ball joint set-up when I tear muh beastie down ...

http://classicoldsmobile.com/forums/...tml#post117971

sleeton · November 5th, 2009, 07:05 AM

thanks to all that have replied it has been very helpful and will help guide my buddy in the right direction.

joe_padavano · November 5th, 2009, 08:28 AM

Quote:

Originally Posted by mugzilla

The disc brake spindle is taller which is beneficial for handling ...

No, it is not. The A-body 67-72 disc brake spindles are IDENTICAL to the 64-72 drum brake spindles except for the height of the boss around the upper bolt hole. Go back and look at that link I posted above. The 77-90 B-body spindles ARE taller, but they are NOT a bolt-on swap.

mugzilla · November 5th, 2009, 02:58 PM

Quote:

Originally Posted by joe_padavano

No, it is not. The A-body 67-72 disc brake spindles are IDENTICAL to the 64-72 drum brake spindles except for the height of the boss around the upper bolt hole. Go back and look at that link I posted above. The 77-90 B-body spindles ARE taller, but they are NOT a bolt-on swap.

(*0*) ...

I'm leaning toward tubular upper a-arm with a tall ball joint ...

November 3rd, 2009, 11:27 AM	#1 (permalink)
sleeton Registered User Join Date: Aug 2009 Location: corpus christi,tx Posts: 14	Drum To Disc Brake Conversion A friend of mine has a 72 cutlass that has power drum brakes and he is thinking of changing the front brakes to disc brakes. Can he use the same spindles and put the disc on or does he have to change the spindles. Once he changes over to disc brakes does he need to install a proportioning valve?

November 3rd, 2009, 12:33 PM	#2 (permalink)
Olds64 Landyacht Club President Join Date: Jul 2007 Location: Lawton, OK Posts: 4,286	The easiest way to convert to front disc, rear drum would be to find an early 70s Cutlass in a salvage yard with the parts on it. I know they were available. Then your friend can get all of the parts off of the salvage car and install them on his 72. Ultimately, I'm not sure if the early 70s A bodies had different spindles for front drum and disc brakes. __________________ Ferris, my father loves this car more than life itself... Apparently, you don't understand! Ferris, he never drives it! He just rubs it with a diaper! Cameron Frye Ferris Bueller's Day Off 1986

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November 3rd, 2009, 01:15 PM	#3 (permalink)
70 cutlass s Registered User Join Date: Sep 2009 Location: Elizabethtown,KY Posts: 242	Yes you have to change the spindles, proportion valve, power brake booster, master cylinder, front rubber brake lines. If you can find an A body in the bone yard that would be the cheapest way, but you can buy a kit that has everything. Also when changing over to disc. Its a good time to change front coil springs if they need it since it will be all apart.

November 3rd, 2009, 05:57 PM	#4 (permalink)
Eightupman Registered User Join Date: Nov 2006 Location: Ladson, SC Posts: 499	No, you do not have to change the spindles. HOWEVER they will need one additional bolt hole drilled and tapped to accept the caliper bracket (available aftermarket as well). I have heard that if you already HAVE a power booster, it does NOT need to be changed either. proportioning valve is available in the aftermarket catalogs. now, with the costs involved, its better to get parts from a donor, or a kit. John

November 5th, 2009, 12:24 AM	#6 (permalink)
mugzilla is Fast Enough ... Join Date: Jul 2008 Location: dogtown Posts: 849	The disc brake spindle is taller which is beneficial for handling ... This guy did a good job on his front end and I will update my spindle/ball joint set-up when I tear muh beastie down ... http://classicoldsmobile.com/forums/...tml#post117971

November 5th, 2009, 07:05 AM	#7 (permalink)
sleeton Registered User Join Date: Aug 2009 Location: corpus christi,tx Posts: 14	thanks to all that have replied it has been very helpful and will help guide my buddy in the right direction.