The first thing I had to do was to pull out the old Master
Master Cylinder Upgrade
Once that was pulled, I also had to get rid of the the line to the rear brakes from the splitter block on the passenger side firewall...it is the line that comes straight out of this block, turns back before going down the firewall and then the frame towards the back end...I ended up pulling out the splitter block completely...
I need to note that the new master I selected was originally an 11/16" one from a ebay auction...when I installed it and went to bleed it, it was discovered that NOS meant that the seals had rotted after being on the shelf for 30 years or so...totally trash...
I then decided that I will be going 4 wheel discs in the future and selected a master from a 1981 280ZX as it has discs all around...it is a 15/16" bore master and after installing and bleeding everything,it was discovered that the pedal "feel" was extremely stiff as this master had a vaccume booster ...I could have used a master from a 1979 620 as they were 3/4" bore (which matched the 521's) and were front disc and rear drums, but this unit requires a booster also...it can be used without but will be stiffer pedal, but not as hard of feel as the 81 master I used...the best solution would have been to get a 1974 620 master that was drum all around as it would have kept a better pedal feel...not to mention correct bore ratios...
the next thing to note is that the master is metric threads when the 521 came stock with SAE threaded brake lines... for the front, the new splitter block I found on a mitsubishi truck had the exact thread combo I need for this...one metric thread and 2 SAE threads...for the rear I remedied this by running all new line back to the flex hose at the rear end and had a custom hose made cheaper than a stock hose would have cost..12 bucks vs 17 for the stock one and would have had to wait a week for the parts store to get it in...this custom hose is this combo:
Female 10x1mm STD connector (HFMF01)with 17" of 1/8"brake line (BQ101) and a Male 3/8" NF SHORT (HFIM01) connector on the other end...made here in Tacoma by WOFSCO (Williams Oil Filter Supply Co.) 253-627-8163...GRAND TOTAL OF $12.47
old hose on top vs the new one on bottom:
I then decided that I will be going 4 wheel discs in the future and selected a master from a 1981 280ZX as it has discs all around...it is a 15/16" bore master and after installing and bleeding everything,it was discovered that the pedal "feel" was extremely stiff as this master had a vaccume booster ...I could have used a master from a 1979 620 as they were 3/4" bore (which matched the 521's) and were front disc and rear drums, but this unit requires a booster also...it can be used without but will be stiffer pedal, but not as hard of feel as the 81 master I used...the best solution would have been to get a 1974 620 master that was drum all around as it would have kept a better pedal feel...not to mention correct bore ratios...
the next thing to note is that the master is metric threads when the 521 came stock with SAE threaded brake lines... for the front, the new splitter block I found on a mitsubishi truck had the exact thread combo I need for this...one metric thread and 2 SAE threads...for the rear I remedied this by running all new line back to the flex hose at the rear end and had a custom hose made cheaper than a stock hose would have cost..12 bucks vs 17 for the stock one and would have had to wait a week for the parts store to get it in...this custom hose is this combo:
Female 10x1mm STD connector (HFMF01)with 17" of 1/8"brake line (BQ101) and a Male 3/8" NF SHORT (HFIM01) connector on the other end...made here in Tacoma by WOFSCO (Williams Oil Filter Supply Co.) 253-627-8163...GRAND TOTAL OF $12.47
old hose on top vs the new one on bottom:
Another point to note is that the master will not bolt directly in place of the old one without mods...these mods are simple with a Dremel or similar tool...I used a round file and worked on enlarging the firewall hole by 1/8" for about and hour before I was able to borrow a Dremel from a friend..(thank goodness!) took less then 5 minutes with the Dremel!
all total this upgrade has cost me not really that much at all...
35 for the master...20 for the connectors and lines to run to the rearend...2-30", 1-40" and 2 inline connectors...12.50 for the new custom made hose...1.50 for the splitter at Pull-a-Part
here is a picture of the master now that it's plumbed and functional...notice how the line loops over the bleeder? I had a little too much and had to loop it to take up the extra...
35 for the master...20 for the connectors and lines to run to the rearend...2-30", 1-40" and 2 inline connectors...12.50 for the new custom made hose...1.50 for the splitter at Pull-a-Part
here is a picture of the master now that it's plumbed and functional...notice how the line loops over the bleeder? I had a little too much and had to loop it to take up the extra...
The last thing I can think of to note is that I had to use the actuator rod and bracket from a spare clutch master that I had laying around....I have seen these on ebay from time to time as this type has a threaded rod that screws into the bracket that mounts to the pedal bracket...the longer one is the one I used and had to put on to the master and the shorter one came with the master:
great info there I appreciate this, im about to do the brakes in anticipation of a few more cubic inches under the hood. I was wondering if you remember the year of the mitsubishi you pulled the block off of.
Thanks I will post pictures of my brake enhancement, I will probably go with the 74 620 drum master for now.
Thanks I will post pictures of my brake enhancement, I will probably go with the 74 620 drum master for now.
-
firebirdparts
- Posts: 5
- Joined: Wed Dec 31, 1969 5:00 pm
I am probably going to do this myself, before I lose brakes and crash. I might have to custom flare a couple of lines, but I would prefer just using a metric/english adapter.
That's not the kind of thing you can buy at Autozone. The type of auto parts stores that would have small oddball brass items have closed here. The adapters are still manufactured, but I can't buy them locally. That couldn't be good for the manufacturer, could it?
That's not the kind of thing you can buy at Autozone. The type of auto parts stores that would have small oddball brass items have closed here. The adapters are still manufactured, but I can't buy them locally. That couldn't be good for the manufacturer, could it?