defiant1

What conversion kits are you all using to upgrade your power front drum brakes with disc brakes? I saw Joe Pad's sticky but am a little confused on what I need when it comes to the distribution block/proportioning valve and whether or not I can use the booster and master cylinder I already have on my '70 Cutlass.

Looking for practical applications and advice. I am trying to get the setup purchased as soon as possible so I can get it installed by the end of the month.

I have seen kits from Inline Tube and Right Stuff, but don't have any info to validate their fit, quality or reliability.

d1

RonFX

Hey:
I bought my conversion kit thru OPG, the kit met their free shipping as well. Everything I needed came in 2 or 3 boxes and fit and functioned great, the only mods I had to make were enlarging 4 holes to 1/2" , the prop valve was mounted to the M/C instead of the frame, it came w/ prebent lines as well. The conversion uses basic 69 and up parts, nothing odd or special and was made by a major brake house in CA. You may be able to get yours going for a few bucks cheaper by finding used items, but by the time you clean / blast / paint them it almost a trade off. It was really nice to work w/ all new parts.
Thanks, Ron

defiant1

Thanks for the input. What part number did you purchase?

d1

442craig

I upgraded my 68 with The Right Stuff kit. It was easy to install. Their tech support was great and made for a real nice install. It was one of the best upgrades I did. The car stops on a dime now. My SSI 14" wheels didn't fit with it but I was putting 17" aftermarket rims on so it didn't matter.

Craig

joe_padavano

The factory did the prop valve two ways - they are functionally equivalent and either way works. Since disk brakes were an afterthought at first, the factory used the external metering valve along with the same distribution block as the drum brakes on the 67-70 cars. Starting with the 71 models, the metering (prop) valve was combined into the same housing as the distribution block, and called (appropriately) a combination valve. This is functionally identical to the earlier two-part system; GM only did it to reduce assembly costs and eliminate potential leaks. If stock appearance isn't important, get an aftermarket brass combo valve, as it won't rust internally.

The drum and disk boosters carry different part numbers, but I've converted a bunch of cars and simply bolted the new disk master cylinder to the existing drum booster, with no issues whatsoever. Be sure your older booster is in good shape, however.

As for the 14" wheel problem, despite what some aftermarket kits say, ALL factory 10.75" A-body disk brakes came with 14" wheels. The problem is that through the late 1960s, GM made two styles of wheels, the older style with a backside contour that only cleared the 9.5" drums, and the newer style with a different backside contour that cleared the factory disks. Early SSI wheels were drum-only. Later SSI wheels and ALL SSII/III wheels will clear the factory disk brakes. I cannot speak for clearance on aftermarket kits that do not duplicate the factory designs.

There is at least one vendor selling a disk brake kit that claims to clear the drum-only 14" wheels. Avoid these like the plague. They use Honda-sized 10" rotors that can't stop appreciably better than the drums.

defiant1

Thanks for the input Joe. Based on my situation and having the "70 model, which prop/metering valve do I need? Or all they all the same? Or can I just use the combination valve found on '71 on up? Sorry, I am having a hard time wrapping my head around this...


I replaced my 11" power booster last year, so it should be good to go with a new master cylinder.


Thanks again.
d1

joe_padavano

Yes, yes, and yes.

The 67-70 and 71-up designs work EXACTLY the same. You can use either way. It's your call. If you want your car to look correct for a 1970, use the external metering valve and keep your drum brake distribution block. If you want to simplify plumbing and reduce potential leak points, use the later combo valve. Either way will work exactly the same. If you do choose the combo valve, get the aftermarket brass one, as it won't rust like the stock cast iron unit.

This isn't complicated. Stop losing sleep over it.

defiant1

Copy that. I will purchase the aftermarket brass combination valve. Thanks again

Sampson

I used this kit from The Parts Place. The calipers were not machined correctly for the copper washers and leaked. Ended up buying new calipers to fix the problem.



Product Name Price Quantity
BR10785T (1964 - 1972 Cutlass/442) POWER DISC BRAKE CONVERSION KIT WITH CADMIUM PLATED POWER BRAKE BOOSTER WITHOUT STAMP

defiant1

Purchased a kit from inline tube, should have it by next weekend. d1

dalilama

I have 14" SS1's that came with the 1972 drum-based Cutlass Supreme that I bought last year. I'm thinking about converting my front drums to disk and I want to know if the wheels I have would support the 10.75" A-body disk brakes. What wheel measurement can I do that would confirm this?

Kid Thunder

Has anyone used OPG front disc conversion for 14" wheels? If so did it work on 14" hubcap wheels? I have a 67 Cutlass.

joe_padavano

Again, it depends on WHICH 14" wheels you have. If they are the drum-only wheels, they will not clear. If they are disc brake compatible wheels, which GM started making in the 1967 model year (but did NOT install on all cars) they they will clear. As noted in all the other threads about this, the disc brake wheels have a different backside contour that clears the factory discs. You need to figure out exactly which wheels you have, or try them on a friend's disc brake car.

Kid Thunder

Thanks from this newB. I have no way to try it on another car & just by looking at the contour of the rear of the wheel will not help if I have nothing to compare it to. I thought they might be a # on the wheel to help determine which one it is. As I said my car is a 67 & as you say that's when they started & may be either

defiant1

Can someone send me a picture of the the combination valve installed underneath the master cylinder? The instructions call for the combination valve to be installed on drivers side of master cylinder. However, the brake lines supplied do not support that configuration.

I did a search and cannot find a picture of how the brake lines are routed to the combination valve with it installed directly under the master cylinder.

Any help would be appreciated.

d1

joe_padavano

First, just so we're clear, you are talking about a 1971-up combination valve, not the 1967-70 metering valve, correct? The metering valve was mounted under the M/C, with the distribution block on the frame in the same location as it was for drum brakes.

Second, if you really are talking about the combo valve that replaces the metering valve and distribution block, the factory only mounted it on the frame rail. If you purchased a factory-style metal line kit, it is bent to fit the factory configuration only. The mounting of the combo valve under the M/C is an aftermarket invention that was never factory installed that way. How it mounts and what the lines look like are dependent on how that particular vendor chose to mount the valve. There is no "standard" or "factory-designed" configuration for that mounting. Vendors who do offer the M/C-mounted combo valve also offer the pre-bent lines for their particular configuration, but you need to specify that when you buy them. Also, there is no guarantee that one vendor's pre-bent lines for this mounting will fit that of another vendor.

defiant1

Yes, the 1971-up combination valve was sent with the front disc conversion kit. And yes, I understand that the under M/C mount is not factory. I was looking for someone else's install (aftermarket) so I can see any limiting factors/issues before I go to install mine. As I alluded, the vendor's install instructions were lame and did not provide pictures or install advice.

d1

joe_padavano

Unfortunately, it depends on the vendor for the kit. Some mount vertically, like this.



Some mount horizontally, like this.



Orientation doesn't really matter once you bleed the system. In all cases, the bracket that holds the valve mounts to one of the M/C bolts.

defiant1

Mine will have to mount similar to above, but the combination valve will have to be turned 180 degrees in order for the brake lines to match up.

Thanks for the pictures.

d1

joe_padavano

Yeah, I've seen versions that use the aftermarket M/C that has ports on both sides. They orient the combo valve to use the passenger side ports. Just be sure that when you turn it around, the front port still goes to the front of the M/C. You will likely need to turn it and flip it to get that to work.

defiant1

Well, that may be a problem, if you are talking about the port covered by the black cap. The section of brake line that runs from the combo valve to the beginning of where the long run of brake line goes to the rear drums is pre-bent in a fashion where the port it connects to has to be positioned to the front.


Conversely, the supplied pre-bent front brake lines aren't long enough to connect to the front positions either if I turn the combo valve to have the port with the black cap facing the front.


Can you explain the importance of the proper position of the combination valve?


d1

joe_padavano

The combo valve has specific ports that can only be connected one way. The two inlet ports need to be correctly connected to the front and rear ports on the M/C. There's only one outlet port for the rear. The two outlet ports to the front are the only ones that don't matter which is RH and which is LH. If you're trying to make a prebent line kit work that isn't designed for your combo valve or mounting orientation, then you've got some fabrication to do.

Exactly what kits are you trying to make work? The brake line companies that I've seen all sell line kits that work with their specific combo valve mounting configuration. If you are mixing and matching, you're making a WHOLE lot of work for yourself and wasting money.

brown7373

I converted mine using all factory parts from a parts car. I was lucky to find a guy who had a whole set up with everything I needed except the brake lines. One advantage of using factory is you can just order the brake lines (or any other part for that matter)and they fit with no questions asked. I did need to replace the 1972 valve with one from InLine and had no problems.

defiant1

Inline tube kit. I am connecting the brake lines to the correct ports on the combination valve. However, you indicated I had to turn the combo valve a certain way. That "way" will not allow me to connect the brake lines to their respective ports.


I guess it's possible they sent me the wrong combo valve. As I indicated earlier, I can attach everything to the combo valve. But I have not seen anyone's set up like that, so it was throwing me for a loop.


I will mock up everything tonight and post pictures.


d1

joe_padavano

All the aftermarket brass combo valves are the same, so I doubt you got the wrong valve. More likely is the wrong tubes. Is your kit designed for the M/C with ports on both sides?

defiant1

Here is what I am working with...

joe_padavano

Wow, that's a rat's nest. Unfortunately, I don't see any other way to route the lines. Most of the kits I've seen have the combo valve flipped so the front port on the combo valve is directly under the front port on the M/C, but it doesn't look like your lines would work in that case.

70cutty

I just finish installing that exact same kit from inline tube. Everything lined up perfect. Actually it was a first time that I didn't have to modify, cut or alter anything on a aftermarket part for the Cutlass. I am very happy with their product.

What are you having a problem with?

Townie

Wow is that a clean looking firewall, where did all the wires go? Very nice set up. My valve mounts to the frame.

joe_padavano

Not my car, that's just an example photo I stole off the web. Note the non-Olds valve cover.

defiant1

Basically, I haven't seen an installation like this before and everything seemed backwards to me. I figured it out and installed it and as Joe Pad indicated, it is a rat nest of brake lines underneath the combination valve. I still have to hook up the line going to the rear axle and install all the mounting clips before bleeding the system.


d1

joe_padavano

Functionally the orientation won't matter, but that plumbing is way more complex than it needs to be.

jeffsims

Joe - I am wanting to upgrade my 67 442 from front drum to disk. I called Right Stuff and was recommended the following:

http://www.getdiscbrakes.com/afxwk01c

I worked with BJ. He told me my drum booster and m/c will work just fine, but stated that it is a must to get a proportioning valve. Well, I started working with him on that direction and it quickly turned into all new brake lines front to rear. The list kept growing and growing. That's not the simple upgrade that I was intending.

I am very interested in your comments to defiant1's thread. I really want the original look under the hood. Do you have any pictures or other information to help me set up this external metering valve?

Thanks,
Jeff

joe_padavano

Booster - yes

Drum brake M/C - yes - BUT...

The "but" is that there are two things to be aware of. First, since the drum M/C has a smaller reservoir to feed the front brakes as compared to a correct disk M/C, you must get in the habit of checking brake fluid level more frequently. Disk brakes adjust for pad wear by projecting the pistons further out of the caliper (this is why you have to push them back in when you replace the pads). Fluid from the M/C reservoir "backfills" the added volume in the caliper bore behind the (now extended) piston. Let this go too far and you'll suck air into the system.

The second thing is that you must remove the residual pressure valve that is pressed into the port on the M/C that feeds the front brakes. The residual pressure valve is under the flare fitting in the outlet port.



Use a sheet metal screw to extract the pressed-in flare fitting, remove the valve, and press the flare fitting back in to place.

jeffsims

Thanks Joe. I found this picture from one of your comments to a previous thread. The external valve appears to be inline with the front brake port of the m/c. Is this correct?

Also, the external metering valve has 7/16-24 threads on the inlet and outlet assuming I buy PV68 from Right Stuff. This means I need a new line from the front 1/2-20 port to the inlet 7/16-24 port on the valve.

I also need a new line from the 7/16-20 valve outlet to the front inlet of the original distribution block. Would you happen to know what the inlet size is on the distribution block? I want to get all the material order before I start tearing it down.

I have found plenty of detail on the proportioning valves, but nothing on the distribution blocks.