problem with my brakes.

[Robin260z]

hi guys,

i have a problem with my brakes.

They are shocking when i brake. I feels like your rotor is bended. not straight.

So i put some new rotors on with new brakepads. I've also mounted new brake lines to the hoses at the front.

After this the problem is stil there. then i opened up my calipers and found out that the cilinders inside were rusted. So i bought some second hand calipers with perfect cilinders inside. Also bought a sealkit for the calipers but i havent had time to repair the calipers.

could this be the solution? Otherwise where do i have to look then? I also bought a new brake master cilinder from a 280zx. I am going to clean up that one and install it.

I have also read about a vacuum booster? Where do i find this and what does is.

Could this also be the problem?

A lot off questions but i hope someone could give me some advice.

thank you

[5thhorsemann]

What year and model is it?

[Robin260z]

i forgot to tell that

It is a 1975 260z 2+2

[IdahoKidd]

If the calipers aren't working smoothly, it definately could affect the way the vehicle brakes. Stick with the correct parts for the car until you get the initial problem fixed. By changing out or upgrading, you may be creating secondary issues. (don't use the zx master for example-use the correct one) It will be money very well spent.

[5thhorsemann]

The vaccume booster is the black doughnut that the master cylinder mounts on, don't think that is your problem.

Jack up front wheels and spin the tires by hand to make sure they are spinning true, could be a hub issue.

Did you get new rotors, or used?

If you don"t see A problem with the wheels on, pull the tires, replace the lugnuts and spin the rotors and check them for wobble. If you have rear disk brakes do the same on the rear.

Are you getting feedback through the peddal, or steering wheel, or both?

[Zed Head]

Can you give a better description of what your brakes are doing? This is hard to understand - "They are shocking when i brake. I feels like your rotor is bended. not straight."

[Robin260z]

The rotors are new.

I only feel it when i am braking not during normal ride.

I meant to say that i feels like my rotors are bent when i brake. But that is not the problem because i installed new rotors.

when driving normally i dont feel anything wrong more that normal. so i only feel it when i am braking.

when i brake the steering wheel vibrates en i also feel a small vibration in the brake pedal.

I could use the original brake master cilinder to solve the problem but i also want to upgrade the brake master so why not changing them immediatly.

so a good advice is to jack up the car and turn the hub around without a wheel on it. I that has''nt affect i have to renew the lugnuts or let my tires installed again?

p.s Sorry my technical english is not that good for now.

[d240zx2]

Your English is OK, don't sweat it. If we don't understand something, we'll ask you to explain it in a different way...

Based on what you said, new rotors, and you bought used calipers but haven't rebuilt them yet, I'd suspect a definite possibility of caliper failure. Rebuild the used set you bought, bleed properly, and test. I suspect your problem will have gone away.

[Zed Head]

What I'm reading is that Robin260z feels vibration through the steering wheel and brake pedal when he applies the brakes. He is focusing on the front brake system, but also suspects that there might be something wrong with the wheel balance or the wheel lugs and lug nuts.

If you think that the wheel balance is incorrect, you should also check your wheel bearings, and your steering assembly. I had a bad front wheel bearing and the steering wheel would vibrate occasionally, although it did not get worse when I applied the brakes.

While you have the front end jacked up, grab the wheel at top and bottom and try to move the top and bottom back and forth. You will feel play in the wheel, and hear it, if the bearings are loose.

[JLPurcell]

Robin, I sounds like you are getting some good advice at this point. I did notice that you had asked about the purpose of the brake vacuum booster. It is the early answer to power brakes, it simply uses vacuum to assist you when braking so you do not have to use as much foot pressure.

As for the vibration, it does not sound like a caliper problem. I would jack the car up and check for play in the steering rack, wheel bearings, ball joints and shock mounts. A set of rebuilt calipers can't hurt. JLP

[Robin260z]

well thanks for the great advices.

What i think i am gonna do:

-Replace the wheel bearings at both front wheels ( already got new ones whith seals

-The ball joints are replaced already

-Replace the tie rod ends (already got them )

-Repair my sway bar mount ( it got rusted away so i have to weld it )

-Rebuilt a second set of calipers with good cilinders inside and new seals )

-Check the steering installation

-check my hubs and/or wheels for something strange.

[Zedyone_kenobi]

That is a great long weekend of work Robin. Please let us know how this goes, and I think together we can all fix this. Glad to help somebody overseas. Your English is fantastic!!! Good for you knowing more than one language!