who has done a front disc brake conversion, help

I have a 1969 Skylark which I'm converting to front disc. I have almost everything covered except the line coming off the proportion valve for the rear brakes. When you did your conversion what did you use to connect the rear brakes line to the proportion valve.
Thanks in advance
Jaye

 

Try inline tube jaye

 

There shouldn’t be any adapter needed. You should be able to undo all of the lines from the drum brake proportioning valve,swap the valves,and reconnect the lines.

 

I thought the rear line for a disc brake prop valve was large thread. I looked at one at the NSRA show in Louisville this weekend and they were different. The 4 drum is just a distribution block, not a prop valve, correct?

 

Same size thread. Been there done that. I never had to change lines when converting from drum to disc.

 

I used the MBM kit and ended up getting a mobile brake line guy to come over & modify the existing steel lines. Ended up bolting the proportioning valve to the frame, in the same location as the OEM junction block/pressure differential switch

 

So, the 4 wheel drum distribution block has all the same size fittings as the front disc/rear drum proportioning valve? I would have sworn it had a different rear line nut.

 

Correct. When I have done the OEM conversions,I have been able to reuse all of the existing lines. With all of the newer kits out on the market,there might be some that have a proportioning valve with different sized fittings.Some also have metric,which would call for some adapters.
I usually do everything like a 71-72,with the proportioning valve down on the frame. If I do a 68-70,and it has to be concours,then I leave the existing block on the frame,and add the correct combination valve next to the master cylinder.

 

I converted my 70 stage one Two disc brakes very easy on a 68 through 70 skylark or GS you don't have to replace the proportioning valve you install a hold valve on the Master cylinder for the disc brakes. 71 and up you have to change the proportioning valve that's mounted to the frame. In-line tube should have all the parts you need, stainless steel or metal brake lines rubber hoses.clips correct master cylinder and hold valve.

 

I had planned on installing the proportion valve under the M/C however, if it will bolt up I will put it on the frame where the distribution valve is currently located. Hopefully next week I'll get them installed shouldn't take no more than a day.
Another topic but still brakes; I'm working on a customer's 68 conv skylark w/disc I looked and didn't find a hold-off valve just the distribution block on the frame.

 

I replaced my rear line with new lines from Inline tube on my 65 Skylark when I swapped to disc brakes

 

Disc front/drum rear brakes without a hold-off at the master or a proportioning valve will generally lock the rears very easily, not even a panic stop is required.

 

I completed (almost) the conversion today, of the 5 lines only 3 will bolt to the new proportion valve. I replaced the driver side brake line, use an adaptor for the inlet from the master cylinder and also for the rear lines. Hopefully Thursday I can get it completed and bleed the brakes.

 

I ordered one based on the information above from Brian Trick. We'll see what it does when it gets here. If this doesn't work I'm going to go ahead and make it 4 wheel discs.

 

Brian is referring to OEM conversion using the same parts that would have been on the vehicle if it came from the factory with disc. The new proportion valves have some inlets that are different sizes.

 

That's what I have, a 1971 GS with 4 drums that was converted to 2 disc up front with power booster. I ordered a combination valve for a 1971 Buick GS with front disc brakes to replace the factory distribution block. If that isn't correct, what am I missing? If not, then the statements above are in error or at the least incomplete.

 

I have also used the newer brass proportioning valves,and I still did not have to modify or replace my existing lines. I just did one like that in the last year. A 71 that was 4-Wheel drum,and was converted to front disc. I didn’t like that particular disc kit because it reused the drum spindles,and had some Mickey Mouse adapters for the caliper brackets,but that is what the customer bought. I bought the proportioning valve from Inline Tube.

 

Did yours have same post type for the brake failure sensor wire? Looks like most are the newer style. Are the sensors interchangeable?

 

OK, my disc/drum combination valve arrived with my tie rod ends and adjusters. Here's a pics of the one I got. The driver front brake line is going to have to be bent a little angled up since it normally goes straight in the front. The rear one looks like it will have to be pushed back a little, maybe an inch or shift several of the lines around, as the rear of the new valve is longer than the distribution block. Also, the sensor plug is different. We'll see how that goes.

 

My car had already been converted to discs up front but when going through it the last month or so, I noticed I couldn't get the hose clamps and hoses to fit into the frame clips(this is the hose that goes from the tubing to the caliper). I had to order new brackets, which I got from inline tube.