Just finished my front drum to disc conversion on my 69 cutlass. I share my experience for others. I was pleased to find that all my wheel bearings and grease seal from the drum brakes fit into the new rotors (this was a conversion using stock A body parts for the 68-72 cars). I milled my drum brake spindles down .6 to make them work for disc. Worked nice, except the top hole in the spindle was 1\2 inch and the stock caliper brakets have a 5\8 hole. So get your machine shop to drill and tap the hole to 5\8 fine thread, or use a bushing to make the braket hole smaller to fit a new 1\2 inch bolt. I think the 1\2 inch top hole in the spindle is unique to 68 and 69 cars, as I think from 70-72 the top hole is 5\8 diameter on the drum brake and disc brake cars.

I found the stock A body disc brake hose was too short for my calipers. It measured 12.5 inches. I looked in the Wagner book and found 14.5 inch hoses for a 74 Monte Carlo. They worked perfectly, and they even fit nicely into the stock drum brake hose braket!!

For those scrouging their own A body stock parts, get Chrysler banjo bolts off a minivan, 7\16 by 20 threads x 1 and 1\16 inch long. They fit the hose above described. Also, while at the boneyard, get those anti-rattle clips that hold the inside brake pad to the caliper piston. New ones cost almost 9 bucks a pair. Banjo bolts aren't cheap new either.

The toughest part of the conversion was mounting the combination valve on the frame. If you have a column shifter, make sure you shift thru all the gears before mounting your valve. I forgot to, and had to grind some to enable the shifter to hit drive and low gear.

Great write up! Always nice to see how others did it. I'm sure this will help someone out!

The toughest part of the conversion was mounting the combination valve on the frame. If you have a column shifter, make sure you shift thru all the gears before mounting your valve. I forgot to, and had to grind some to enable the shifter to hit drive and low gear.

Bhawk,
I know you wrote this a long time ago, but I was wondering if you remembered how you went about mounting your combo valve to the frame?
I am putting '72 disc brakes on my '69 chevelle, so there aren't any bolt holes where the valve should go, since combo valves weren't used in 69. (I'm assuming you had the same issue?) I am using a factory 71-72 cast iron combo valve, by the way...
I bought a combo valve bracket from inline tube, because they said it was necessary for your lines to line up right, otherwise they'd be off if I bolted the valve directly to the frame. What did you do? Do you have pictures?
Thanks!
-gambi69
:confused:

Great info on the hoses. That kind of data is super helpful.
Thanks!!

Chevelles that used the one piece proportioning valve (71-72) had it bolted directly to the frame, no bracket. If you are using a factory piece that is how it is mounted, just install it with the lines attatched and wherever it lines up to the frame bolt it on. Chevy just drilled a couple holes and used self tapping bolts to hold it in place. Other GM lines like buick did use a bracket to mount the valve but chevy had it bolted right to the frame. Also when doing a disc conversion if you get the correct disc brake hose frame brackets the factory chevelle disc hoses work fine.

Thanks Dave!
I called Inline Tube, and the guy insisted that ALL A-bodies used the bracket, but I had heard the same as you....Chevy did not. I think they guy just doesn't want me to return my bracket! I think I will just bolt it to the frame. It sounds like an easier job that way.
Thanks again,
-gambi69

Good info, bhawk! Tips like that is the reason why I'm addicted to this site. :thumbsup:

Would you happen to remember the Wagner part number for the hoses ?

Also Disc brake hoses from a 69 Camaro will work with the drum brake frame brackets. This info comes from Pete Lohr FO_FTYFO. Pete

What type and size of wheels are you using on your Cutlass? I have a '68 that I want to convert to front disc, and I'm using 14" Superstock II wheels. I'm concerned that they might not clear the calipers/brackets when I convert. Has anyone run into this problem with the stock 14" GM
wheels?

-Karl

Whether the 14" wheel will clear depends on how the wheel was made. They should be fine unless they were made before disc brakes were common, I normally only have an issue with some factory steel wheels that are mostl likely 1970 and older. The drum brake only rims will rub on the caliper.