Master Cylinder Difference.

[nqkjw]

Below is a pic which explains it all.
My car was originally a 1970 318 non boosted disc front drum rear.
It's now a 440 non boosted disc front drum rear.
The master installed is the one that came on the car when I got it.
The master on the left is a new one that I have.
A bit of research tells me I need a 1 1/8" bore MC which seems pretty std  across disc models except hemi cars.
Can someone tell me what's with the mirror reversed reservoir shapes?
Is it just different manufacturers?
I haven't bothered asking on any Australian sites since I doubt there'd be anyone over here who'd really know.

[Chryco Psycho]

Both have the large reservoir for the Front disc brakes & the same cover fits both , not sure why they would reverse the curved end but it should work just as well either way .

[nqkjw]

Actually the covers and the cover seals are different to suit their respective cast bodies.
Just checked my barracuda and Dart.Their MCs are the same as the challenger.
Could be an aftermarket thing?
Something to do with patent designs maybe?
No one else ever come across this?

[nqkjw]

Just pulled the MC out of my challenger and it's 1 1/16" bore.
The new one I have is 1 1/8" bore.
Someone on FABO said with non boosted brakes I should be using 1" bore.

Can someone tell me what I SHOULD have in there?
I'm happy to purchase the correct part so it's not about trying to save a dollar.

[nqkjw]

No one seems to have a definitive answer and trying to check what was original seems to come up with several different answers.
I seem to have found they came in bores of 1 1/8",1 1/32",1" and 15/16".
Can't find any reference to 1 1/16" which is what was in there.Measured it again and it's definitely 1 1/16" so maybe it's been sleeved or something?
Anyway,the brakes seemed OK but firm with the 1 1/16" so I'm thinking if I try a 1 1/32" it will require a little less leg effort.
If I'm not happy with the result it's no big deal to try a smaller bore later.

[Chryco Psycho]

I was trying to figure out what you are trying to solve with different bores , smaller bore will increase pedal travel & decrease pedal effort , larger is the opposite .
I have no clue why the reservior is reversed I would have thought the cover will swap but the gasket would be different but I can see why the cover would not work either .

[JH27N0B]

By non boosted I assume you mean your car was originally manual brakes? Disc brakes in '70 were only power.  Manual disc brakes weren't an option on E bodies until '72.  There were 4 different brake setups available on E bodies in '70.  Manual and power drum brakes which used the same 1" bore master cylinder (the style with the bolt on cap).  Non hemi power disc brakes used a different 1" bore master cylinder (commonly referred to as the "171").  And power disc brake hemi cars used a 1-1/8" master cylinder (often referred to as the "191").  In '71, they used different master cylinders than '70 except on the hemi disc brake cars.  Both the drum and the disc brake master cylinders for that year were 1-1/32".
My T/A challenger had a later 1-1/32" style master cylinder on it when I bought it and the brakes seemed to work OK.  On my '70 disc brake convertible I put a aftermarket 1-1/8" master cylinder on it and the brakes seemed "grabby".  Later I found and rebuilt a rare one year only original "171" disc brake master cylinder and installed it and the brakes work pretty good.  My '71 Challenger is a power disc brake car and it has a stock 1-1/32" master cylinder on it and the brakes work pretty good on it also.

[nqkjw]

Thanks for the reply JH27NOB.That clears a lot up.
I went and checked my option plate which shows B11.
Now if I'm reading it right that means my car had manual 4 wheel heavy duty drum brakes from new.
This means someone has fitted the front discs at some stage.
I received two new master cylinders from RockAuto today so I now have new 15/16,1 5/32 and 1 1/8 masters to try.

Out of interest ,the 2 new masters I got from RockAuto are Centric brand and have the reversed reservoirs as shown in my original post.

Still can't figure out what the 1 1/16 bore master I pulled out is about.Can't find any reference to any 1 1/16 bore master on any Chrysler.

The blokes on FABO reckon with manual disc/drum the 15/16 master gives the best feeling brakes so I'll start with that and see how it goes.

Will keep you informed of the results for those interested.

[nqkjw]

I was trying to figure out what you are trying to solve with different bores ,

chryco,originally I was just trying to replace what was in there but then when I measured 1 1/16 existing and couldn't find any reference to that sizing I was trying to figure out what SHOULD be in there.

[nqkjw]

15/16" master cylinder is good!!!