Frogman

So, yeah my brakes ARE leaking. where should I look? The drums are bone dry!

I did my front rotors by myself a year ago with no issues, I used a C clamp to hold the calipers in place, this is an old trick I learned that negates the need to bleed the system. I drove the car about 500 miles since then, the issue is the new since I JUST topped off the master cylinder and its back down at L

I have not replaced the rear drum breaks and don't even know where to buy the parts.

where should I look, my car is up on a ramp ATM

KansasCityREPU

iTrader: (9)

With that much fluid gone, there is a leak somewhere. The only way to find it is to either look for wet spots or remove each wheel and inspect the rear cylinders and front calipers. Also check the brake master. Can also be a bad brake line or hose.

Bleeding brake also serves the purpose of removing not only air but also old fluid that has water/condensation in it.

Frogman

Already checked the rear , not a drop :/ Also the oil on the floor is from my dad's Toyota truck .
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TomSmy

iTrader: (11)

You can get all the parts at RockAuto - I just did mine


Tom

Frogman

Found the leak immediately after taking the picture

the " Main vacuum" is leaking, not the master cylinder but the big black round thing attached to it with japanise text . Is it a gasket or the entire unit? On a bright note, my rear shocks are Koni Brand!

Edit it seems to be a brake booster.

TomSmy

iTrader: (11)

That's the brake booster, there is a gasket to the master cylinder and the firewall, but if its leaking its coming from inside and needs rebuilding. Personally I would just replace it.

You can get them at RockAuto for $80 or $95 including the master:


1983 MAZDA RX-7 1.1L R2 Power Brake Booster | RockAuto

Frogman

I have a SA not a FB =/ they are out of stock .

Qingdao

iTrader: (3)

The booster itself doesn't contain any brake fluid. However, the master cylinder can (and often does) leak fluid into the booster.


When you go to change out your master cylinder; make sure to bench bleed it prior to putting it on the car.

Frogman

So whats leaking then? The booster or my Master cylinder

The leak is in between where they bolt together

Ok so by the looks of it, I can simply Tighten the master cylinder harder to the Brake booster? and if it continues to drip, then I need to replace both? Mama mia.

Since im going to have to bleed the system anyway, do you guys recommend I upgrade to steel-braided brake lines? I want snappy brakes, the ones I have feel like mush !

t_g_farrell

iTrader: (1)

Ok, so it appears the master is leaking. If left alone it will be putting fluid into the booster which will eventually cause the booster to fail. You probably
need a new master. But wait, if you are doing a master that means a full system bleed. If doing a full system bleed I would seriously consider replacing
all the brake lines (stainless are nice) and the rear wheel cylinders, brake hardware and shoes. On an SA you will also need to manually adjust the rear
brakes every couple thousand miles as there is no auto adjuster. Since you just did the fronts, you can probably not touch those except to replace the hose
and bleed them.

You can get all the parts you need at rockauto and they are not expensive. I would hold off on the booster replacement and see how it goes.

Also make sure you adjust the master pushrod to spec before attaching to the booster. Once its assembled you may need to also adjust the pedal
freeplay from the inside of the car.

GSLSEforme

Tightening the master cylinder fasteners further will not stop the brake fluid leaking,it is not loose. This is a common failure on many old and not so old cars. Often the brake booster is not damaged as the fluid leaks down the front of it and doesn't go inside,sometimes it does and must be replaced,this to be determined by person servicing it.
Understand the braided stainless lines are an upgrade -to pedal feel,they do not make the car stop any faster. That mushy feel is due to air in your brake hydraulics. If fluid can leak out,air can seep in,along with it moisture. Brake fluid should be flushed every couple years for this reason,on all cars,motorcycles,atvs as moisture can seep into system with no apparent leaks. Moisture,heat break down brake fluid over time leading to discoloration,degradation,corrosion-all things you don't want in brake hydraulics. Brake fluid should be clear,if not,needs to be flushed.
Your car looks to be in good rustfree condition. It is 37 years old,mileage may be low,it is time that ages these components. The brake system is not like the oil,gas leaks you're dealing with,which are troublesome. Failure in brake system can total your car,injure you and possibly someone else on the road. Need to be proactive here,consider the whole brake system,take the rear drums off and inspect wheel cylinders for seepage/leakage,brake hoses for cracking,leaking. Often replacing master cylinder increases brake fluid pressure and the next weakest link in chain is revealed. Aware you have limited funds available to put into car at this time,brake system should be your priority,maybe park it til you can do needed repairs.

Frogman

For the rear drums , what do I need ? I can only find shoes for sale . No pads etc.
So I need a
Master cylinder
Brake lines ( optional but kinda needed )
drum brake components


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GSLSEforme

This is one time we can assume... might need everything,replace it all and be done with it.
Raybestos 429RP brake shoe set 9.39-in stock
Raybestos H17116 brake hardware kit(both sides) 9.42-in stock
Kelsey Hayes W53101 left rear wheel cyl. 3.97-in stock
Kelsey Hayes W53100 right rear wheel cyl. 3.97-in stock
Raybestos BH38231 front brake hose need two 16.97 ea.-in stock
Raybestos BH38143 rear brake hose 12.48-in stock
Raybestos MC39160 master cyl. 35.09-in stock (fits 1979 model year)
Beck Arnley 0728104 master cyl. 38.04-in stock (fits 1980 model year)
These are all name brand parts(new),some on closeout,all in stock at RockAuto,a little over 100.00+ shipping which is probably another 10.00 A quart of DOT3 brake fluid, some penetrating oil for all brake line fittings, some flare nut wrenches for brake line fittings(10mm-11mm) approx 30.00 to send rear drums out to be machined. When all done your brake system will be 100%.
Not a huge investment,worth every penny. P.S. rear brakes have brake shoes,no pads.

Frogman

What if my drums are too worn to be machined? Im probably going to dunk them in vinegar before taking them to remove all surface and deep rust.

Frogman

The second part is Out of stock FUUU , im going to buy that from summit racing, Same price! Front brake hoses, only one in stock , I need two =/ Do Rock auto and amazon share inventory, because i foudn said part on amazon, but its only one available

GSLSEforme

Here's my thoughts on this... from my experience,miles on car,the fact that it's a light car, probably has only had a couple sets of brakes replaced on back-if that. So lets say drums were machined once,twice in life of the car-should most certainly be plenty of meat there to allow them to be turned at this point. Once removed,measuring them will tell.

Frogman

it has 120k miles and by my estimates, was poorly maintained by the second owner. The first owner kept up with maintenance until he sold the car in 2005, miles on the odometer, 75k. I bought the car with 121k. The drums are probably in bad shape, but you're right, I won't know until I remove them. Do I need the hardware kit?It's Out of stock and the only one on Amazon has pictures of the wrong parts. The springs might or may not be in good condition. Also thank you very much for all the help, I greatly appreciate it . At 21, I have very few guy friends interested in cars. Most of the mechanical knowledge I have is from my much older neighbors and the old manuals. And prior to buying this car all I had ever done was restore Hotwheels ( not real cars but I learned a good deal about painting/machining/polishing/working with rotary tools ) and watch repair videos since im a huge gearhead. Not much real world experience. That said I changed my front brakes by myself and basically took apart my sentras entire manifold system, and put it back together to swap in spark plugs ( dunno what idiot designed it that way ). So seriously appreciate all the help I can get! I owe you one x 20 haha!

KansasCityREPU

iTrader: (9)

I just looked on RockAuto and they have most of the parts. They have the rear shoes, brake cylinders, and rear hose. They are out of stock on drums and hardware kits. They probably won't get any from my experience.

For the front, they have everything.

I remember posting in another of your threads that all the sub-systems need to be gone through on these cars, especially if they have sat. Based on all the different threads you have going, I'd consider going through the brake and fuel systems. The time to fix an issue is not after it happens, especially with brakes and fuel. These cars are old and need lots of preventative maintenance. Kind of like our healthcare system. Keep things healthy before there is an issue.

GSLSEforme

Have worked on these cars a lot of years,most unusable drums were from owner's that let brakes go to where the metal frame on the shoes carved up the drum and had to be replaced. The other failure is from seized brakes from rust,seized wheel cylinders making drum so hot it warped,also a throwaway. You would have noticed thumping coming from whichever wheel had the problem and possibly pulsation in brake pedal like that of a warped rotor. Not making mention of these conditions,i'd be optimistic of condition of the drums. You'll know once taken off & inspected/measured. I would pursue locating the brake hardware kit,likely all of it is original,might be in ok shape,won't know til it's apart. Would be best to replace all the brake hardware.

GSLSEforme

Summit Racing has a listing for that Raybestos spring kit,they don't show it as out of stock.

Frogman

I just bought the last Performance front brake hose. The others ones look pretty meh quality . I got the other at Amazon

GSLSEforme

The Raybestos hoses i gave you the #s for are the best quality you can get=to oem hoses. Only way to put any better hoses on would be to go to stainless braided hose. I thought you were on a budget...

Frogman

That's the hose i bought . They only had one left. I bought the last one and bought the other on Amazon . The steel ones are 150$ ;0; I paid 16.95+ 7.99 shipping on rock auto and 16.09 + 8 shipping on Amazon

Frogman

Would you guys recommend I replace the rear wheel bearings? how much extra work would it be? My front bearings were in pretty great shape and i just re-lubed them. But i hear a humming noise in the rear coming from the right side, Might be the brake or might be thebearing !

t_g_farrell

iTrader: (1)

Its easy to get the axle out but you will likely have to take the new bearings and
collars to a shop to press them on. The old bearings come off easily after you cut
off the collar behind them. The jobs is pretty simple really.