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Aluminum master cylinder ?????

Posted By: mopars rule

Aluminum master cylinder ????? - 04/08/10 11:23 AM

I would like to get an aluminum master cylinder for my 67 Dart. I would like to go to my local parts store to get it so if it should ever go bad I can take it back and swap it without having to order a special one from some out of state parts dealers. Plus the aftermarket ones are expensive. I went to get one for a 85 dodge diplomat because they had aluminum ones but the one they had was cast iron. Does anyone know of a factory replacement one that has the 1 1/32" bore.
Posted By: BDW

Re: Aluminum master cylinder ????? - 04/08/10 01:26 PM

I copied this from Dr Diff

OEM 2-bolt aluminum master cylinders with plastic reservoir:

'95 Lebaron 7/8" bore**

'89 Dakota 15/16" bore**

'85 Diplomat (F-body) 1 1/32" bore*

'85 D-150 1 1/8" bore*

**Back of piston must be bored to accept manual brake push rod and retainer.

* Back of piston will accept manual brake push rod and retainer.

Rule of thumb:

1. Master cylinder piston size is relative to caliper piston size. Large caliper pistons require large MC piston.

2. All things equal, smaller bore master = higher line pressure and longer, softer pedal stroke.
Posted By: RapidRobert

Re: Aluminum master cylinder ????? - 04/08/10 01:31 PM

I think the oe alum started in 79 as a D100 truck app for that yr disc/drum is alum but iirc it is a 1&1/8 bore. I'm surprised that an 85 dippy came up as iron as my 83 cordoba was alum. I'd find one of your parts houses that can look up the bore dia of a 79 up app and most of them are rebuilt & rebuilt M/C's have a very poor reliability (alot of comebacks) whereas one from Doctor Diff here on Moparts or Rick Ehrenberg would be a new unit and there wouldn't be any prob getting the right bore size. From the bore size you have in mind I am assuming manual,fyi just be sure to request (& check if a parts house one)that inside the piston that it has the wide recess for the neoprene retainer to lock into as opposed to a smooth surface like the inside of a "thimble".
Posted By: krw71ragtop

Re: Aluminum master cylinder ????? - 04/08/10 02:25 PM

I just purchased one from Autozone part #M1822 for $16 plus core and asked for an 85' Diplamat MC, and it is aluminum.
Posted By: AndyF

Re: Aluminum master cylinder ????? - 04/08/10 02:34 PM

The factory ones were aluminum but a lot of times the rebuilt ones will be cast iron. Ask for a new one at the auto parts store but check the price first. You might be better off just ordering the correct one from Doctor Diff.
Posted By: Locomotion

Re: Aluminum master cylinder ????? - 04/08/10 04:08 PM

I've had good luck ordering late '70's Aspen/Volare with manual disc brakes master cylinders by Cardone. I believe they are 1 1/32". Don't have the part # handy here at work.
Posted By: DoctorDiff

Re: Aluminum master cylinder ????? - 04/08/10 04:47 PM

Unfortunately, the rebuilt aluminum master cylinders don't usually come with the reservoir.
Posted By: DusTed74

Re: Aluminum master cylinder ????? - 04/09/10 01:36 AM

I have a 15/16" bore master. Does anyone know the specs for boreing it for the push rod?

Thanks...........Ted
Posted By: mopars rule

Re: Aluminum master cylinder ????? - 04/09/10 03:03 AM

Quote:

I just purchased one from Autozone part #M1822 for $16 plus core and asked for an 85' Diplamat MC, and it is aluminum.




Looks like I will be taking the one I got from Advance Auto Parts back tomorrow and getting the one from Autozone. Thanks.
Posted By: RapidRobert

Re: Aluminum master cylinder ????? - 04/09/10 04:10 AM

Quote:

I have a 15/16" bore master. Does anyone know the specs for boreing it for the push rod?


A M/C for a power brake app it's piston in the rear and the inside recess walls of the piston will be smooth like the inside of a sewing thimble whereas a manual brake app, inside the "thimble" there will be a circular groove for the pushrod retainer to lock into. You wouldn't want to bore anything just eyeball your particular M/C you have in mind to see if it has that groove if you have a manual brake app. And you want the correct bore diameter. fyi I think a PB app can use a M/C with or without the groove but MB's require it.
Posted By: BigBlockMopar

Re: Aluminum master cylinder ????? - 04/29/10 10:56 AM

Do these alum. MC's actually have a residual pressure valves built in?
Posted By: RapidRobert

Re: Aluminum master cylinder ????? - 04/29/10 12:45 PM

no as the disc half next to the firewall cannot have one and the drum half the metal quarter sized reinforecments behind the wheel cyl cups take care of the RPV function but always stick a drill bit deep into the brass cones to check as it is a piece of neoprene on top of a spring and you'll feel the springiness if it has one and if the drum half does have one it's not a prob.
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