Dennis Detweiler Posted August 1, 2018 Report Posted August 1, 2018 I'm in the middle of installing a scarebird front disc brake conversion kit. The instructions says, remove the RPV from the original master cylinder. The diagram of the master cylinder doesn't show a RPV? Is there a dual reservoir master cylinder conversion on the market? Quote
knuckleharley Posted August 1, 2018 Report Posted August 1, 2018 (edited) 5 hours ago, Dennis Detweiler said: I'm in the middle of installing a scarebird front disc brake conversion kit. The instructions says, remove the RPV from the original master cylinder. The diagram of the master cylinder doesn't show a RPV? Is there a dual reservoir master cylinder conversion on the market? If it were me,I would contact Scarebird and ask them what they recommend. Make sure you ask for OEM parts numbers as well as donor car year and model. I would definitely make an effort to use a dual-outlet master cylinder,and I would ask them about one that didn't need a power booster. Edited August 1, 2018 by knuckleharley Quote
Plymouthy Adams Posted August 1, 2018 Report Posted August 1, 2018 6 hours ago, Dennis Detweiler said: I'm in the middle of installing a scarebird front disc brake conversion kit. The instructions says, remove the RPV from the original master cylinder. The diagram of the master cylinder doesn't show a RPV? Is there a dual reservoir master cylinder conversion on the market? the repair manual parts breakdown drawing does indeed show the valve...in big black letters it says VALVE ASSEMBLY Quote
Dennis Detweiler Posted August 1, 2018 Author Report Posted August 1, 2018 Strange? My diagram of the internals only shows (in sequence) push rod, piston stop plate, push rod, piston, cup, piston return spring, intake port and by-pass port? Where is it located in relation to these parts? Quote
Plymouthy Adams Posted August 1, 2018 Report Posted August 1, 2018 looking in the manual, all 1936-1940 the parts breakdown list it as item number 14..I have not scanned pic to send...what book/diagram are you using? Quote
Dennis Detweiler Posted August 1, 2018 Author Report Posted August 1, 2018 I've been looking at an on-line diagram which I just compared to my 39 shop manual. The manual does show a "valve assembly" as #17. It's the last part before the brake line connection. Since the rear brake shoes require residual pressure, I'm just wondering if the rear brakes would be less effective without the valve? However, would the valve cause the disc brakes to drag under residual pressure? Seems like it's less than ideal either way? A dual reservoir master cylinder conversion would be the answer? Quote
Plymouthy Adams Posted August 1, 2018 Report Posted August 1, 2018 10 lbs is usually the residual valve rating and yes that is a bit much for the disc...solution as recommended by most folks selling kits with use of stock cylinder, remove the valve, install inline 10lb to rear, inline 2lb to front caliper... Quote
Plymouthy Adams Posted August 1, 2018 Report Posted August 1, 2018 (edited) the 10lbs was needed as the shoes used some very strong springs to push fluid back to the master....disc on the other hand only have the rolling of the square cut o-ring to return the piston..often aided by a very slight run out... Edited August 1, 2018 by Plymouthy Adams Quote
plymouthcranbrook Posted August 1, 2018 Report Posted August 1, 2018 http://www.ecihotrodbrakes.com/chrysler_master_assemblies.html Quote
Adam H P15 D30 Posted August 1, 2018 Report Posted August 1, 2018 I pulled mine out of the stock master cylinder because of front disc brake drag. Didn't affect the 8" Ford rear drum brakes at all. Always a good firm pedal. Did it on the car, took about 20 minutes including bleeding the air out. Adam Quote
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