jja Posted June 2, 2015 Share Posted June 2, 2015 I have a 1970 MC that has factory front disc brakes and factory rear drums. I purchased a number of brake system parts from Inline tube to replace factory parts, I successfully removed and replaced the booster and master cylinder. I also replaced a valve (PR-115) referred to as a hold off valve that attaches to one of the bolts on the booster and a distribution block that attaches to the driver's side of the frame. They also sold me another hold off valve (PR 104D) that I cannot seem to figure out where it attaches. Anyone have an idea or picture where it goes? Quote Link to comment Share on other sites More sharing options...
overdrive Posted June 2, 2015 Share Posted June 2, 2015 GM Valve Notes: This item is an exact reproduction disc brake hold off valve. This valve was used to hold off pressure to the rear brakes so the front brakes would go on a split second before. This was also considered a correction valve for the 1970 model year. During extreme braking conditions, this valve prevented the car from getting sideways and evened out braking loads. This valve is located at the rear of the car, mounted to the back cross member close to where the rubber brake hose attaches through the frame. In 1970, these cars had three valves that made up the disc brake system. The valves include: above hold off valve, distribution block, and round golf ball valve. In 1971, these three pieces were combined into one valve which simplified the system. This item is an exact reproduction featuring a brass body, the correct bracket, phosphate plating and working insides. You will also find with current manufacturing procedures, the reproduction has no tool stamping marks and the edges of the part are much cleaner than the original. Quote Link to comment Share on other sites More sharing options...
jja Posted June 4, 2015 Author Share Posted June 4, 2015 Thank you. Any pictures or diagrams from a 1970 service manual? I only noticed a T-like part that attaches to the top of the differential cover. Quote Link to comment Share on other sites More sharing options...
monte70car Posted June 4, 2015 Share Posted June 4, 2015 Here is a picture of the valve I believe that's in question might have to zoom in. The frame belongs to a 70 El Camino. I don't believe my 70 Monte has that valve could be wrong. I know 72 doesn't as its a single line from the valve on the frame at the firewall to the rubber line at the rear end. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted June 5, 2015 Share Posted June 5, 2015 Will this Help? http://www.buickperformanceclub.com/discbrak.htm Quote Link to comment Share on other sites More sharing options...
jja Posted June 5, 2015 Author Share Posted June 5, 2015 Yes. Thank you very much. I was looking in the wrong area of the car. Quote Link to comment Share on other sites More sharing options...
jja Posted June 8, 2015 Author Share Posted June 8, 2015 Rod, I still am unable to find that valve. I traced the brake line all the way back to the rear after it leaves the proportioning valve (top left device in the 3 device pix above) and do not find it. I specifically focused on the drivers side near the cross member (around where the driver's door is). Could my 70 not have had that part? Quote Link to comment Share on other sites More sharing options...
monte70car Posted June 8, 2015 Share Posted June 8, 2015 It made not have that valve, does it feel like the hard line goes right into a rubber line? You are in the right area where the valve should be on the rear cross member that the upper control arms for the rear end mount to. I know my 70 Monte doesn't have that valve as I taken the line lose at that spot to suck the brake fluid to that point in the brake system. Quote Link to comment Share on other sites More sharing options...
jrod Posted February 26, 2016 Share Posted February 26, 2016 I have a question. I ordered Model: J10035171 from Right Stuff Detailing. I have found that I have the set up listed above with the golfball valve, etc. My question is, will the replacement valve that came with the Booster/Master Cylinder kit replace all three of the valves listed above? Quote Link to comment Share on other sites More sharing options...
jrod Posted March 2, 2016 Share Posted March 2, 2016 Spoke to Inline Tube.. They stated that the proportioning valve that came with the Booster/Master Cylinder kit I purchased would not work unless I re-plumbed the brake system. So I ended up purchasing the following items. PR115 - PR107 - PR104D - SMFG70611A - 1970 A,F,X-body Hold Off Valve- Pr115 | Inline Tube - The brake plumbing experts Factory Hold Off Valve 1970 Olds Cutlass / 442 Factory Hold Off Valve1970 Buick Skylark 70-72 A-body Distribution Block w/ Bracket PR107 | Inline Tube - The brake plumbing experts frame rail of all drum and disc cars.Front to rear brake line fitting, orange 9/16 " -18 thread 1970 GM A-body Hold Off Valve- PR104D | Inline Tube - The brake plumbing experts PR104D Inline Tube Exclusive! Applications: Chevelle/ El Camino/ Monte Carlo SMFG70611A - 69 GRAND PRIX & 70 GRAND PRIX/ MONTE CARLO POWER DISC M/C LINE Now we shall see how everything comes together.. Will update once all is installed. Quote Link to comment Share on other sites More sharing options...
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