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nzarano

wilwood 1" mc pedal way too hard?

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Just upgraded to wilwood dynalite calipers, have an 8.5" booster, and put the wilwood 1" mc in and now my pedal is hard as a rock barely any travel...have to hit the pedal super hard to get brakes to work. Thought it was getting softer and better then realized one of the resevoirs had emptied ( which i beleive ive now remedied..) is it supposed to be this hard? for people whove done caliper upgrades is it worth switching down to a 15/16 to get a better pedal or what? Thanks 

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Sounds like a booster problem.

 

Check your booster and vacuum hoses to the booster. Also, make sure that the check valve is installed correctly.

 

Check that the push rod between the MC and the booster is adjusted correctly.

 

Booster check:

 

With the engine off, place your foot on the brake pedal and apply pressure like you are trying to stop the car. Hold that pressure.

While  still applying pressure on the brake pedal, start the car.  You should feel the brake pedal sink a bit and become softer to push.  It means that the booster is working. If the pedal remains hard to push during the test then there is a booster issue.  Most likely the booster is leaking or it is not getting vacuum from the engine.

 

The other cause of a stiff pedal would be if the MC push rod is adjusted too far out such that it is pushing the piston inward in the MC. What happens is the piston gets pushed past the the point where the the fluid return port is covered so fluid gets pumped out to the brakes but can not return to the tanks when the pedal is released. So the brakes become locked.   If this happens you can relieve the pressure by opening the bleeders on the MC.

Edited by Miles

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Thanks for the response! The pedal has been making a bit of a hissing noise since the upgrade.... the booster was working fine before the install of the new master cyl (or at least i didnt have these problems....), check valve hasnt been touched. going to bleed brakes then do this test today then check mc push rod, are there common areas where the booster can leak from? is it possible that something broke in the booster when i installed the new master? Thanks again!

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The hissing sound suggests a failed booster. After you test the booster per my previous post, and it fails the test, replace the booster.

 

Typical booster installation errors include push rod adjustment and/or the reaction disk falling out. See the brake FAQ and brake forums for details.

 

Suggest that you read up on push rod adjustment and the raction disk.

 

 

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8 minutes ago, Miles said:

The hissing sound suggests a failed booster. After you test the booster per my previous post, and it fails the test, replace the booster.

 

Typical booster installation errors include push rod adjustment and/or the reaction disk falling out. See the brake FAQ and brake forums for details.

 

Suggest that you read up on push rod adjustment and the raction disk.

 

 

 

I pulled the rod and reaction disc out and glued the disc in place as per the faq.... would the rod adjustment being wrong create a hiss or is that just from the booster failing? 

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Also losing fluid from one of the reservoirs is usually a symptom of a bad primary cup seal in the master. If it's in the front it will usually push fluid into the rear reservoir. If it's in the rear it will dump fluid into the booster. 

I've had a brand new Tilton master leak. I'm sure it's not unheard of with Wilwood as well.

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1 hour ago, JMortensen said:

Also losing fluid from one of the reservoirs is usually a symptom of a bad primary cup seal in the master. If it's in the front it will usually push fluid into the rear reservoir. If it's in the rear it will dump fluid into the booster. 

I've had a brand new Tilton master leak. I'm sure it's not unheard of with Wilwood as well.

 

I had three Wilwood MCs fail right out the box. Two of them leaked internally and the third MC had smashed MC bleeders.  I ended up purchasing a 79 280ZX 15/16 MC from Dave at Arizona Z Cars for about $125.

 

4 hours ago, nzarano said:

 

I pulled the rod and reaction disc out and glued the disc in place as per the faq.... would the rod adjustment being wrong create a hiss or is that just from the booster failing? 

 

Good deal.  The last time a reaction disk fell out I made a new one from a rubber stopper and used JB Weld to glue it to the push rod.

 

Please post how you get things worked out.

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topped up the resevoir with fluid without doing a full bleed (think it might need to be done but i was lazy) warmed car up then turned it off, put foot on brake and started it and felt no change.... how could have booster gone bad just from a master cylinder upgrade is my question? Is it possible that taking the cylinder out of the booster to glue the reaction disc had an effect? 

 

pedal feels a bit better but i have a sneaking suspicion that its because a bleed needs to be done 

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Changing the MC will not damage the booster.

 

Your booster has failed internally or you are not getting vacuum from the engine.

 

Suggest that you inspect the vacuum hose and fittings between the intake manifold and the booster. Verify that you have vacuum at the booster connection.

 

 

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so today went to work on car, found slight leak from bottom of master that was easily fixed by a quarter turn of the fitting, then go to bleed the master again, then take wheel off to bleed rears, hit brake pedal and boom goes the wheel cylinder.... mystery on pause awaiting new wheel cylidners

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On 8/25/2019 at 3:40 PM, nzarano said:

so today went to work on car, found slight leak from bottom of master that was easily fixed by a quarter turn of the fitting, then go to bleed the master again, then take wheel off to bleed rears, hit brake pedal and boom goes the wheel cylinder.... mystery on pause awaiting new wheel cylidners

 

Tales of a Datsun...

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1. Replace the booster. Before installing the booster,  glue the reaction disk in place. Hold the booster so the push rod is pointing  up to minimize dropping the reaction disk inside.

2. Install the booster.

2. Adjust booster to MC push rod to the correct length. The reaction disk is glued in place so no worry about loosing it. You can fine tune the length after the MC is installed.

3. Bench bleed the MC. See various threads on bench bleeding.  Take your time and remove all of the fine bubbles.

4. Re-install the MC.

5. Bleed the brakes.

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@Miles I´ve bought that exact same MC from Arizona Z, too. Don´t know exactly if it is from a 79 280zx, but its a 15/16, PIC blow.

 

spacer.png

 

Seems you´re able to help me out - the fitting on the right goes to the front brakes and the one on the left to the rears, just like on a stock 240,260 or 280z, right?

I downloadet the service manual of a 280zx, but couldn´t find any infos.

 

Thanks in advance.

 

Thats how I routed it now. If the carbs clear the factory heatshield will bolt right up on that lower bolt of the prop valve. The spacer originally fitted will be gone then:spacer.png

Edited by PrincePaul

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