WHY?
Manual brakes bolt the master cylinder STRAIGHT onto the firewall - and have the arm attached that goes to the pedal..
On a booster setup - the ARM is on the BOOSTER, and the ,master cylinder just has a shallow recess where it in turn attaches to the booster.
* You cannot reuse your old master cylinder
Also - manual brakes use bolts on the body, and a booster comes with bolts fixed - so u end up with a bolt to bolt issue. I wouldn't try cutting re-drilling unless u are stuck.. If you decide to go this route, with a stretch u might be able to fit everything - but the risk of breaking an old line is there - if u cant find/make a bracket this might be an only option for u..
Since we are sandwiching in a +- 8" booster between the firewall and cylinders, you are indefinitely going to have line length issues (fret not!), but CHEAP (yes, happy smile/relief :)
** I have a mod I have done to a few cars which includes cutting/re-welding the brake arm - making it adjustable. Ive only seen one car come with this (A nissan), MOST cars dont. ONLY perform this if you are capable or have a professional welder do it for you. DONT take chances with this stuff!!!
in short you will need:
- new/donor master cylinder
- booster (make sure the holes match the bracket)
- booster to body bracket (see pic) - make sure it fits booster bolts AND body bolts
- 2 brake extensions (about 4/5 bucks from Napa, etc)
- clean fluid
- 1x 85mmx10mm bolt + 1x 2" long threaded nut with a non threaded jacket to fit (for mod)
- SPECIAL TOOLS/FRIEND: arc welder
Long nut (welded onto booster arm)
Bolt: This welds onto the eye u cut off from the booster to make up the extra length needed.
Bracket: this is a good idea of what your booster will look like with the bracket attached (left) and master cylinder right. Make sure it matches your booster AND firewall bolts. Cut the "eye" off @ least 1& 1/2" from tip to make sure welding doesnt interfere when u reconnect it to the pedal. this eye is bent - most are straight..
What you need to do:
- Remove brake lines from old cylinder
- unclip arm from brake pedal inside car and disengage it
- remove old master cylinder from car
- remove proportioning cylinder from bracket and all brake lines except the rear one
- Now use the cylinder to pull and get as much length fwd out of that line (still attached/WITHOUT KINKING) & make sure u keep it as far away from any steering / suspension part. I got about 6-8"
- The 2 lines that went up to the old cylinder will be replaced by longer ones. Reattach the other one
- Cut the arm off the brake booster (voids warranty) close to the eye - leave enough room so the welding bulge doesnt stop the eye from going flush against the pedal..(keep as much of the booster side shaft original as this travels in and out and you wouldnt want welding bulges possibly catching or doing damage..
- weld on the 2" threaded nut about 1/4-1/3 " inch over the arm for strength. Weld this VERY well / straight.. screw the bolt in as far as it can go, then back it out about 3 to 4 full turns (this leaves some play if your measurements were out a bit and the system too tight/long on minimum length)
- Now that the booster is on the car with the bolt head facing the brake pedal - u can gauge how much extra arm length you will need.
- Attach the eye to the brake pedal bush, line it up straight with the bolt and mark on the bolt where u need to cut/weld.
- Weld the eye to the back of the cut bolt. For extra strenght i actually gring the 2 ends almost like a pencil leaving a 2mm tip. Then i fill weld it from the centre outwards for max strength - plus some extra beads :)
- You should now have a brake system, when fully assembled leaves u will 2 turns play for increasing play on brakes, and about 2" of distances to 'fine-tune' the brakes. Do this LAST.
- Make sure when your booster is bolted on - your pedal should have a tiny bit of 'play' forwards/backwards indicating a 'loose' system - this is perfect. You never want to "apply" brakes when u tighten it all up because your measuring/welding was actually too long.
- Now your booster is bolted to the firewall and connected to the pedal
- Check your proportioning valve is as far forward possible and as far as it can be on all sides form any interference / rubbing on metal :)
- Attach and bend the 2 new brake lines you bought to run from the bottom and get them as close as u can to where the master cylinder will be.
- Now bolt on the master cylinder
- Gently play with the lines till they take on the threads without any stripping and tighten
- Attach the booster vacuum line to a source on the car (usually intake manifold)
- Your brake system is now complete and hooked up!
- Bleed the master cyl first by holding a rag around the nuts to catch fkuid, turning them in to lock and 1/4 turn out to "bleed".. then do your brakes (front first)
- Now that your system is bled - time for a setup
- I jack the wheels up and run the motor to create vaccuum.
- Spin the front wheels while a buddy slowly turns the long nut to INCREASE the arm length - when the wheel starts slowing - turn it back a full turn. Test this with both front wheels and use the one that brakes SOONEST as to when the brakes start to apply.
- Dont forget to apply the brakes HARD every now and then during the above procedure, sometimes brakes "relax" giving false braking results. Keeping the system pumped will be real world.
- After this - do the back brakes - however drums are manually set :) - for discs I would use the technique above
- Make sure NO brakes are applied on no brake pressure. A single turn out (or 2) will leave a safe margin, yet yield nice braking action with minimal travel/"squelching" before the brakes engage.
- Some systems use a thin lock bolt (screwed on before the booster arm) to "lock" the adjustment in place once you have that sweet spot- OR apply some plumbing thread tape to make it very hard to turn.. your choice.
Here are pics of mine after assembly: note the 2 new (badly bent) teflon lines - I hope i got them in the right place (!!) my back brakes are WAY better than front.. ill have to double check.
See my bracket - I only used 2 bolts.. They sat centreline across the hole - and since the pressure now is not there but between the boosted and the cylinder its not all that necessary. Manual brakes only came with 2 for decades and ALL the pressure was here - so Im not phased...
My bracket was angled - it came off a late 70's nova and the firewall must have been angled so I "spaced" it a bit using 2 large nuts to lower the whole system. Your master cylinder should be level (or as near as possible) to avoid air getting in there on steep inclines.. This was also crucial to maintain as straight as possible geometry between brake pedal travel and the booster..
My brakes are AWESOME now.. I haven't done the fine tuning procedure - but the difference is staggering.. theory has it boosters require about ten times less pedal force to achieve the same brake power using stored vacuum :) Your old ride with squelchy brakes just became SUPER kick a$$ :) (applies to newer cars too actually) ..
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