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brake upgrade 68" 520


itsallgood

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ok, so i am swapping all the brakes to rotors. i have all my parts except the new master cylinde, booster, and proportioning valve.

 

can i use any set up? as long as i get the brake linkage to hook up. i found a MC and booster off a 350z and i can get an adjustable PV.

 

dose it matter what MC/booster as long as it came off a car with front & rear disk brakes?

 

i have dual pistons up front and single in the rear.

 

also i have a port on my J15 intake manifold. is that where i hook up the booster vac line?

 

thanks for any info.

 

 

 

 

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The booster will only fit if it's not too large a diameter and hitting the clutch master to the left and the steering column just below it. I have no idea how large the 350Z booster is, I would imagine it's huge. The 620 and the B-210 use a small diameter booster but probably the 350Z master won't fit it and really you don't need one that large anyway. See how the fit is first before we go further.

 

 

 

First the 520 has a single master so you will have to split the front and rear brakes into two systems.

 

I guess the thing to know is what were the calipers from? If a later 720 or early D21 Hardbody then the master (with a booster) should be at least 7/8".  A 15/16' or 1" would work too.

 

Any master with drum rear brakes can easily be converted to rear disc by removing the residual valve for drum and replacing with any front disc brake residual valve.

 

Any intake fitting will do. The brake booster hose must have a one way check valve in line, to retain vacuum in the booster. This is so that if the engine quits while driving (no manifold vacuum) you will have at least one or two good pumps of the assisted braking.

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lets see if this will work.

 

MC 75-78 Nissan 280Z 

http://www.ebay.com/itm/111714375145?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

 

booster 1980 Nissan 720 

http://www.ebay.com/itm/111609935655?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

 

ADJUSTABLE BRAKE PROPORTIONING VALVE

 http://www.ebay.com/itm/321894894137?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

i think the 280z had drums in the rear. so can i just remove the residual valve and use the adjustable proportioning valve?

 

the 620 booster looks smaller

http://www.ebay.com/itm/121582996979?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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The booster will only fit if it's not too large a diameter and hitting the clutch master to the left and the steering column just below it. I have no idea how large the 350Z booster is, I would imagine it's huge. The 620 and the B-210 use a small diameter booster but probably the 350Z master won't fit it and really you don't need one that large anyway. See how the fit is first before we go further.

 

 

 

First the 520 has a single master so you will have to split the front and rear brakes into two systems.

 

I guess the thing to know is what were the calipers from? If a later 720 or early D21 Hardbody then the master (with a booster) should be at least 7/8".  A 15/16' or 1" would work too.

 

Any master with drum rear brakes can easily be converted to rear disc by removing the residual valve for drum and replacing with any front disc brake residual valve.

 

Any intake fitting will do. The brake booster hose must have a one way check valve in line, to retain vacuum in the booster. This is so that if the engine quits while driving (no manifold vacuum) you will have at least one or two good pumps of the assisted braking.

 

 

lets see if this will work.

 

MC 75-78 Nissan 280Z 

http://www.ebay.com/itm/111714375145?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

 

booster 1980 Nissan 720 

http://www.ebay.com/itm/111609935655?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

 

ADJUSTABLE BRAKE PROPORTIONING VALVE

 http://www.ebay.com/itm/321894894137?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

i think the 280z had drums in the rear. so can i just remove the residual valve and use the adjustable proportioning valve?

 

the 620 booster looks smaller

http://www.ebay.com/itm/121582996979?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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Had a Maxima and a zx booster... too big. Take note of the vertical mounting bolts... some boosters/masters are horizontal. I've seen a 720 booster but I think it's larger than the 620.

 

Your 521 probably has a 11/16" or 3/4" master and it works pretty well for the size of all the wheel cylinders. But when you go to a larger size wheel cylinder, or large caliper, it requires more fluid to move them. A 3/4" will have to travel farther to move more fluid and the pedal will go close to the floor and feel alarmingly soft and spongy. Using a larger diameter master will move more fluid BUT you can't get something for nothing. To move more fluid it will take more work and this is where a vacuum booster helps reduce the effort. I think if you check the D21 used a 1" master and to move one that big a large booster also.

 

Here's what I did on my 710 when I switched to Maxima calipers and a vented rotor. I kept my booster (naturally and because it fit) and put a '79-'81 280zx 15/16" master in front of it. (the '82-'82 master has vertical mount holes and would not have fit) This gives me enough fluid volume and the booster reduces the effort to a very comfortable level.

 

Because this is a 521 truck, the later 620 brake booster and the spacer behind it should fit and clear the 521 steering and clutch master. Now early 620 masters were 3/4" and the '78-'79 disc brake ones were 13/16". The disc brake master might work but 7/8" or even better a 15/16" should be used. (just an opinion)

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Many disc swapped trucks run without boosters.

 

If you really feel as though you need one...find one from a 620, B210, or a 210. 

The ones mentioned have an extension that will clear the clutch master that is barely an inch away from the brake master. 

With a booster you will need to get Klotz's custom pushrod or make your own. 

 

 

Do you have the conversion brackets?

 

If you are swapping to 4 wheel discs the need for a proportioning valve is minimal. Maybe 2lb. residual pressure valves for the rear, maybe. 

I will be doing a 4 wheel swap soon. I have no plans of a PV. I've ridden in a few trucks w/o the valve. No stress. 

 

Need more info. Your post is a bit vague. 

 

81 and lower Z/ZX had the vertical mounting tabs. Lots of people used the 7/8" master with no issues as the 15/16" is becoming harder to find quality reman'd units. 

My tip...buy a CENTRIC branded master cylinder. Top notch quality. 

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80-81 were the vertical 15/16" masters. 82 was horizontal. 

 

 

 

 

EDIT: 79-81 were 15/16". Prior to '78 were 7/8". Unsure of when they started disc/disc though. 

 

Yeah I wrote some stuff then erased/corrected it. Lost track

 

First year '79 280zx started rear disc but they look just like the early 620 style. They coincide with the vertical master mounting bolts and changed Aug '81 to the more familiar style. Seen both near me and got the better looking 'Sept '81 and up.

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ok. i am body dropping the 520 and loosing a bunch of room in my engine bay. i have decided to get revers mount pedals that will mount the MC and clutch cylinder in the cab. the brake pedal will have 2 MC's on the pedal and a bias bar where i can adjust how much the rear and front MC will be compressed. i have duel piston D21 calipers up front, Isuzu single piston in the rear. i plan on not using a brake booster since i will have 2 MC. my question is what size MC's should i use? i was thinking 7/8 for the front and 3/4 for the rear. the MC's will only be supplying fluid to 2 brakes. any info would be great. thanks. 

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i plan on not using a brake booster since i will have 2 MC.

 

 

Buy that reasoning we could have a master for each wheel and it would be 1/2 as much effort.... NOT. If you move more fluid you will need more effort to do so.

 

Nothing wrong with a booster, specially on a truck. It makes braking slightly easier, and in traffic reduces driver fatigue.  

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Why make it harder than it needs to be.

 

 

You are one of a few doing this to a 521. A pioneer, I guess.

 

 

 

Id rather use all the money you're spending on more things to improve your ride.

Especially since the tried and true has worked for many other 521 and 620s.

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