GCF Posted August 19, 2021 Report Share Posted August 19, 2021 I am in the process of changing the master cylinder on my 521 to a dual reservoir master but keeping the drums all around. I have this new master from what I believe an early 70s 510. I know I need to change the residual valves to keep 10 lbs in the front and rear. Am I able to buy internal parts for these? Or could I remove both residual valves and run external valves in each line? Notice the rubber valve for the front has two extra slits in it (red lines in the photo). 1 Quote Link to comment
banzai510(hainz) Posted August 19, 2021 Report Share Posted August 19, 2021 (edited) just remeber the 521 uses SAE threaded brake lines(also the Roadster) so your going to adapt at a certain point as the 510- uses metric threads Edited August 19, 2021 by banzai510(hainz) 2 Quote Link to comment
Crashtd420 Posted August 19, 2021 Report Share Posted August 19, 2021 Is it possible to use the residual valve out of the original single master cylinder? Wouldnt that be a 10lb valve too? 1 Quote Link to comment
Charlie69 Posted August 19, 2021 Report Share Posted August 19, 2021 I am installing the same master on a 71 521 that I am also installing a Mike Klotz disc brake kit. IK had to open up the hole in the firewall to except the new 3/4" dual reservoir master cylinder. Like mentioned above the new master is metric 10mm-1 and the line nut for the old master is 3/8"-24. What I did is made a new line to go from the new master cylinder to the tee. The tee line nut is 3/8"-24 and the master line nut is 10mm-1. This way I did not have to buy or use any adaptors. Since I am doing front disc I pulled the rear line from the Tee (4 way) and tweaked it to screw into the Wilwood proportioning valve. Both inlet and outlet on the proportioning valve are 38"-24 so I made a second new line from the rear port on the master to the inlet on the proportioning valve again 3/8"-24 line nut on one end and 10mm-1 line nut on the other end. Where the 521 hard line connected to the hydraulic hose for the caliper I used a tubing cutter with the grooved wheel for close cutting and cut the double inverted flare off removed the 38"-24 line nut and slid a 10mm-1 line nut on and did a new doulbe flare. The hard line on both front sides now screw into the metric calipers with no adapters. I will take pictures of the new lines tomorrow when I am finishing up the disc brake brake install. 1 Quote Link to comment
Crashtd420 Posted August 19, 2021 Report Share Posted August 19, 2021 I'll throw this here .... Best brake line flare tool in my opinion... perfect every time even I tight places..... https://www.amazon.com/dp/B06XPRVCPV/ref=cm_sw_r_cp_apa_glt_fabc_FJX003MBCRA33SJ9YE7E?_encoding=UTF8&psc=1 2 Quote Link to comment
GCF Posted August 19, 2021 Author Report Share Posted August 19, 2021 2 hours ago, Crashtd420 said: Is it possible to use the residual valve out of the original single master cylinder? Wouldnt that be a 10lb valve too? Good thought. Ill take it apart and see if its the same. 53 minutes ago, Charlie69 said: I am installing the same master on a 71 521 that I am also installing a Mike Klotz disc brake kit. IK had to open up the hole in the firewall to except the new 3/4" dual reservoir master cylinder. Like mentioned above the new master is metric 10mm-1 and the line nut for the old master is 3/8"-24. What I did is made a new line to go from the new master cylinder to the tee. The tee line nut is 3/8"-24 and the master line nut is 10mm-1. This way I did not have to buy or use any adaptors. Since I am doing front disc I pulled the rear line from the Tee (4 way) and tweaked it to screw into the Wilwood proportioning valve. Both inlet and outlet on the proportioning valve are 38"-24 so I made a second new line from the rear port on the master to the inlet on the proportioning valve again 3/8"-24 line nut on one end and 10mm-1 line nut on the other end. Where the 521 hard line connected to the hydraulic hose for the caliper I used a tubing cutter with the grooved wheel for close cutting and cut the double inverted flare off removed the 38"-24 line nut and slid a 10mm-1 line nut on and did a new doulbe flare. The hard line on both front sides now screw into the metric calipers with no adapters. I will take pictures of the new lines tomorrow when I am finishing up the disc brake brake install. I am running all new lines so shouldnt have any issue adapting to metric. I noticed the threads were different but didnt know what size it was so thanks for telling me. Where can i find info on the Mike Klotz disc brake kit? Think i might have seen a thread on it. Maybe while im at it....... 2 Quote Link to comment
Charlie69 Posted August 20, 2021 Report Share Posted August 20, 2021 bluehandsinc.com 1 Quote Link to comment
Charlie69 Posted August 21, 2021 Report Share Posted August 21, 2021 (edited) On 8/19/2021 at 2:52 PM, Crashtd420 said: I'll throw this here .... Best brake line flare tool in my opinion... perfect every time even I tight places..... https://www.amazon.com/dp/B06XPRVCPV/ref=cm_sw_r_cp_apa_glt_fabc_FJX003MBCRA33SJ9YE7E?_encoding=UTF8&psc=1 I bought the 3/16" and the 1/4" models of these off of Amazon and the day after I ordered the 3/16 tool they went up to $52 from$37. Edited August 21, 2021 by Charlie69 1 Quote Link to comment
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