master cylinder?

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7dart0

7dart0

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i have a drum/drum 70 dart. my master cylinder has a larger reservoir in the rear and a smaller reservoir in the front. does this mean when i do the disc swap up front i can keep the master?

thanks tom
 
Should work. It would be nice to know the bore diameter. Smaller would make the pedal easier if manual brakes. Anyway, a preference thing, so see how it feels after the swap. You will need a prop valve in the rear circuit, either after-market or a factory "combo valve".
 
i all ready plumbed in an aftermarket prop valve because the rear lines were all rusted. i just have it all the way open for now until i do the swap.
 
7dart0 said:
i have a drum/drum 70 dart. my master cylinder has a larger reservoir in the rear and a smaller reservoir in the front. does this mean when i do the disc swap up front i can keep the master?

thanks tom
Click to expand...

Should be. Look at some pix on a site like NAPAOnline to idenify. The drum/drum MCs used the same sized reservoirs front and rear, AND the disc/drum MC will be taller than the drum/drum MC.

BTW, the rear reservior goes to the front brakes and vice versa.
 
i know about the rear reservoir to the front brakes and vise versa. but my master doesnt seem as tall as a disc one. but it does have different size reservoirs. kinda wierd.
 
That is wierd and getting beyond my ken. The 1970 MC's listed on NAPA are different from the later disc brakes MC's. I do see 1 listing for the 1970 with a larger rear reservior that is listed for power brakes. But it is the tall version of the MC body. (And online listings aren't 100% reliable.) And who knows if someone put an oddball MC other before you just to get it going.

I would be inclined to replace it then; the tall reservoirs for dics drum provide extra fluid capacity for the front reservior for the caliper pistons as they move out with the pad wear. And the extra height helps keep the rear reservoir fluid capacity the same as in earlier, shorter drum/drum MC's, despite the rear reservoir's length being reduced.
 
Since already plumbed, I would just run it and see how it feels. The extra fluid capacity is for original owners who would neglect maintenance. If you check the level every 1-2 years, you should be fine. I wonder if the factory set the fluid capacity to match wearing the pads down to the steel.

If really worried, install a modern MC like I did (see avatar) to get a "fluid low" warning switch. I haven't figured how or if I will wire it to the dash. I regularly check fluids in all my cars anyway.
 
haha check level 1-2 years. i check fluids just about every month. even on my daily driver ram. im just nuts like that
 
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