Master cylinders?? whichone?

[dodgepaul]

I went to replace the master cylinder and found the one the parts store gave me is a lil smaller than the one on my truck. My Bronco is a 74 302 3 spd manual originally I am pretty sure. Now it has the late 70's f150 disc brake conversion on it. I put it on so long, 15 years, ago I don't remember having or not having to change the master cylinder along with it. I'll try to post a couple pics of the new smaller capacity M Cyl and the larger M Cyl that was on my truck the past many many years. Can anyone identify the larger one and if this smaller one will work or not. and if not what do I order to replace the one I have had? is it a M Cyl for a 78-ish full size maybe? It looks like a part #30009 is on the bottom but its so rusty it's hard to read. The measurements seem the same for the brake rods, but the bigger one seems like it'll hold twice the amount of fluid as the new one?? the front brake capacity holds probably 3 times the fluid as the rear

 

[dodgepaul]

I can't seem to post any pics :-(

 

[74strokerbronco]

I believe in less your a contributor you have to use a hosting site like photo bucket etc. and link to them. I may be wrong tho, wouldn't be the first time lol

 

[dodgepaul]

I believe in less your a contributor you have to use a hosting site like photo bucket etc. and link to them. I may be wrong tho, wouldn't be the first time lol

Maybe that's my problem, I'll look for photobucket and see what I can come up with. Thanks!

 

[Past_Miner]

A common master cylinder upgrade when front disks are added and drums remain in the back was from a 1978 F250 camper special. It is physically much larger than the stock M/C and has a larger bore, 1 1/16 inch I think. That's probably what you have, or some other similar cylinder from a '70's era 3/4 ton PU.

 

[Past_Miner]

Does it look something like this?

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Master-Cylinder-New/_/R-NMAM2227_0358751675

 

[dodgepaul]

yep, thats it! You found it, Thanks. I did some digging on Oriellys site and found a similar one listed for a 1 ton 78 manual brake truck. I seemed to of forgotten about changing the master cylinder when I did the brake conversion so many years ago. problem seems to be solved, Thanks for the help!!