1995audi 80 brake pedal has gone hard brakes only working on o s f and n s r wheels

adjust the brake shoe not to much little bit drag the two rare brake

I would jack up a front wheel and see if pushing on the pedal with the engine running will stop the wheel from turning.
You need to know if the pressure is reaching the wheels, or if the pads and rotors are too slick to stop the car.
Usually if the pedal is hard, the booster is not working or the brakes are glazed.
Can you stop the car with the parking brake ? That only uses the rear brakes.
You may need a second opinion from a different shop.

In this case, you will need to leak the for wheels, never leak only one or two wheels when adjusting the breaks. If the leaking continues you need to check the conduit for potential damages. If pedal stay soft after checking everything else, check the break fluid unit. The unit has a piston if I'm not wrong. The piston has some parts that are of rubber material which can wear out or get damaged.

hard brake pedal and the engine is idling rough usually indicates the power brake booster has gone bad. the booster has vacuum going to it from the engine so if the diaphragm in the booster starts leaking then it affects engine performance.

You always change the set i.e both the wheels with new(u dont take risk with the wheels) BUT the other problem of pushing hard is that your brake booster is not working its a kind of drum in the engine compartment exactly opposite your steering wheel get it checked

Bleeding brakes can be very frustrating.There are two ways you can do them 1 gravity feed;this means that you undo the bleeder screw on the caliper or the wheel cylinder and let the brake fluid flow until all air is removed from the system or 2 suction bleed; this involves going to your auto supply store and buying a small hand held pump that creates a suction which in turn,once connected over the bleeder screw,allows you to pull brake fluid and the air out of the system.If you have a friend to help you have them depress the brake pedal until it reaches the floor while you loosen the bleeder screw and discharge the air/fluid.Tighten the screw before the brake pedal is released,release the pedal and repeat.Keep checking the master cylinder and do not let the fluid run low.Don't pump the pedal repeatedly,brake fluid is hydroscopic,which means it can absorb air directly into itself.Slowly and firmly does it until you have purged all the air.You will know when it is all gone because hard pedal will come back.Good Luck

How hard are you stepping on the brake pedal? What you are describing sounds like the ABS system activating. When you step on the pedal hard enough to engage the ABS the light will come on, in some cars it will blink. You will also feel the thumping/vibration in the pedal since the system works by repeatedly engaging and disengaging the brakes. If it is happening when you step lightly on the brakes then you may have a bad wheel speed sensor or possibly a bad or miss-adjusted brake switch.

The slides in your calipers are probably sticking. Remove the front wheels. Remove the caliper bolts. I have not worked on one of these but the principle is the same. There will be hard ware with a rubber boot and some kind of pin that the caliper is supposed to move on as you step on the brake pedal. Remove those pins and lightly coat them with brake silicone. reassemble and test drive, hopefully your problem will have gone away. If not I would suggest a more detailed brake examination.

They need to be bleed again all four wheels but your vacuum pump may be bad since diesels don't have vacuum then have to have a pump, check that the booster one way check valve is good if you can blow thew it both ways it's bad, to bleed start from the wheel farthest away from the master cylinder pump the brakes 5 times and hold down then open the bleed valve keep doing this until you get clear fluid out of each wheel once you have done that if it is still mushy and you know you have vacuum re bleed with engine running this will help push more out with power assist. most like the hard brake pedal had to do with no vacuum check out the pump. You may also have to reset the 2 way check valve if you need help with this let me know.

Well this is very serious I hope you deal with it right away. You mentioned that sometimes the pedal was hard,do you mean that its all the way up and it doesnt feel like you have power brakes?? If so have you noticed any sounds like air escaping (swoosh sound when brakes applied)? Failure of the power booster causes pedal to become very hard and could possibly be your problem for hard pedal if I understood you correctly. check to make sure that vacuum to the booster is conected properly and hose not kinked..Now for the solution for the pedal fading to the floor... You either have air in your brake system, A bypassing master cylinder , or a hydraulic leak...Were your brakes serviced recently?? if so try bleeding your brake system first...That would be the first step if still the problem persist I would isolate exactly where the problem was coming from.. To do this you would start at the passenger rear wheel and line clamp the brake hose to make that part of your brake sytem inoperable...when clamped try your brakes and note if brakes improved or had know affect on system (when testing obviously im not suggesting you drive to determine results of test procedure)repeat test for each wheel you have isolated the problem when brakes feel normal with one wheel clamped,which ever it may be.. This isnt as hard as it might soun and if you are confused at all dont hesitate to ask questions... Remember the only dumb question is the one you fail to ask I would hate for you to get into an accident ... Good luck!!!