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Master cylinder... 1 1/32" vs 1 1/8"

Started by Nacho-RT74, June 26, 2015, 11:21:47 AM

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Nacho-RT74

I can' recall which one my car has actually, but If it has the 1 1/32"... Will the 1 1/8" a noticeable upgrade on braking power ?
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

Kern Dog

My understanding is that a larger bore requires MORE pressure from your foot to stop the car, but the pedal travels less. A smaller bore travels further to the floor but is easier to get the car to stop.

Nacho-RT74

Ok... More ppl agreed in this ?

Now another question: just for curiosity I have being searching stock 4 holes master cylinder with the large bore on rockauto, but it seems the large bore are really 2 holes to booster? i can see large bore on jegs to stock 4 holes thought. Is this Jegs piece a regular stock replacement or some HiPo aftermarket piece made for upgrades ?
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

Charger-Bodie

68 Charger R/t white with black v/t and red tailstripe. 440 4 speed ,black interior
68 383 auto with a/c and power windows. Now 440 4 speed jj1 gold black interior .
My Charger is a hybrid car, it burns gas and rubber............

Nacho-RT74

Yes I saw that one, but I have serious doubts about replacement kits locally for  1 1/16" bore ( seals or pistons )

Beside that, would like to find it on a stock replacement price rate, LOL.
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

John_Kunkel


Disc Brake MC's
Pardon me but my karma just ran over your dogma.

Nacho-RT74

Ok, I'm seeing those earlier units with 1 1/8" bore... They are HUGE reservoirs!!! LOL.

Are they same outputs sizes and threads than laters ?
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

John_Kunkel


AFAIK, all have the same thread size on the line fittings.

Keep in mind that a lot of the 1 1/8" MC's are mated to dual-diaphragm boosters and that reduces the leg effort that is normally associated with big bore MC's.
Pardon me but my karma just ran over your dogma.

b5blue

I just installed 1 1/32 master with the 11 3/4 slider disk swap. Brake is fine, even with manual brakes. (Bought new not rebuild from Rockauto.)

Nacho-RT74

ok so is true about the bigger bore makes more leg effort... ok, will despite that idea then.
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

John_Kunkel


An example, with 100 lbs. of leg pressure, a 6-1 pedal ratio and no boost:

A 15/16" MC will make 1058 PSI line pressure

A 1 1/32" MC will make 717 PSI line pressure.

A 1 1/8" MC will make 604 PSI line pressure.

Pardon me but my karma just ran over your dogma.

Nacho-RT74

Nice comparision... thanks!!!

However, I think volume would make its effect of course, because allong with the pressure, still needs an ammount of fluid volume to fill calipers moving the pistib, and the rear cilinders action.
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

b5blue

From researching manual brakes master cylinders and some testing, the volume is accounted for with travel. I tried a true manual disk brake master from 3rd gen B body. Smaller bore, longer travel and did not like the longer travel at all. (Just to save a bit of foot pressure.) I've a 1 1/32nd from 75 year up working fine now with manual so I'd think with power disk 1 1/8 may give less foot travel and better "feel". (Power boost being almost too strong on most Chrysler.)

John_Kunkel


Yes, increased pressure comes at the cost of extended pedal travel but, keep in mind the pedal ratio. Manual brakes typically have a pedal ratio of 6-1 while the power brake pedal ratio is 4-1. Lower pedal ratio means less pedal travel.
Pardon me but my karma just ran over your dogma.

Nacho-RT74

one question abour Rick's master cilinder auction ( the one with 1 1/16" )

it was really a stock piece ? never have found that info or kits available for that bore.

There is one supossely Mopar original remanufactured MC being sold around with this bore per seller answer to my question:

"looks like 1 1/16" ( that was the answer to the question I sent )
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

1974dodgecharger

I use a 85 diplomat master cylinder  its 1 1/32 bore size....works great got it because it accepted the shaft linkage.