Total loss of brakes Sometimes!!!!

[greg5436]

Wondering if anyone has had this problem.wilwood master cylinder,no booster.
First time going down a long hill decided to hit brakes hard,jammed on pedal first hit lost half of pedal second hit no pedal at all.thought I had broke a line or hose.I was five miles away from my house, started driving home when I pulled in my driveway hit the brakes had half pedal first hit and full pedal second hit.check over everything did not find nothing wrong.wrote it off maybe air pocket in master.

Went to car show in tennessee this last weekend.20 miles into a cruise something happened again.pulled over let everyone go by.took off again 5 miles later brakes worked fine again.

Next morning got in car to go to show drove 1 block,stopped to get ice,got back into car no pedal again,drove to show 2 miles still no pedal.I removed master cyl. Lid told someone push on the pedal slow to see what was happening.he said the pedal was fine.so right then when I removed lid the brakes worked immediately. Kyle from DSE was there told him story and he said never heard of that.

That evening drove 15 miles to race track to watch DSE autocross event.drove all the way there just fine.when I was parking the car pedal felt funny.pushed it again, no pedal once again. Pushed 20 times still no pedal.popped the hood loosened up the master lid bolts 2 turns,went back in car and the first hit had perfect pedal again. So I thought is there a vacuum building up inside the master?I removed the lid and poked a few small holes with the small Allen wrench in the rubber boot. Drove it back later and no problem yet.

Called wilwood said they had never heard of this. Just wondering any suggestions or if someone has had a similar problem like this. It is a twin turbo car but it is not heat related like some of my other problems. Thanks for any advice. Greg

[GregWeld]

Originally Posted by greg5436

Wondering if anyone has had this problem.wilwood master cylinder,no booster.
First time going down a long hill decided to hit brakes hard,jammed on pedal first hit lost half of pedal second hit no pedal at all.thought I had broke a line or hose.I was five miles away from my house, started driving home when I pulled in my driveway hit the brakes had half pedal first hit and full pedal second hit.check over everything did not find nothing wrong.wrote it off maybe air pocket in master.

Went to car show in tennessee this last weekend.20 miles into a cruise something happened again.pulled over let everyone go by.took off again 5 miles later brakes worked fine again.

Next morning got in car to go to show drove 1 block,stopped to get ice,got back into car no pedal again,drove to show 2 miles still no pedal.I removed master cyl. Lid told someone push on the pedal slow to see what was happening.he said the pedal was fine.so right then when I removed lid the brakes worked immediately. Kyle from DSE was there told him story and he said never heard of that.

That evening drove 15 miles to race track to watch DSE autocross event.drove all the way there just fine.when I was parking the car pedal felt funny.pushed it again, no pedal once again. Pushed 20 times still no pedal.popped the hood loosened up the master lid bolts 2 turns,went back in car and the first hit had perfect pedal again. So I thought is there a vacuum building up inside the master?I removed the lid and poked a few small holes with the small Allen wrench in the rubber boot. Drove it back later and no problem yet.

Called wilwood said they had never heard of this. Just wondering any suggestions or if someone has had a similar problem like this. It is a twin turbo car but it is not heat related like some of my other problems. Thanks for any advice. Greg

Did you BENCH BLEED the master cylinder before installing it in the car?

[greg5436]

Originally Posted by GregWeld

Did you BENCH BLEED the master cylinder before installing it in the car?

Yes we did. Ileft out a few things.the brakes have been functioning for the last year and I just started driving it in the last month.I had put about 70 miles on it working out all the bugs from heat related problems.it never did this until I hit the brakes really hard one time.I also checked to make sure the master cyl. Piston was releasing all the way.the only thing so far is that as soon as you break the seal on the lid you instantly have a full hard pedal without pumping them at all. Greg

[Vegas69]

Sounds like a master cylinder bore issue.

[greg5436]

Originally Posted by Vegas69

Sounds like a master cylinder bore issue.

I was going to change the master no matter what,but was just more curious to see if anyone else had this problem ever. Thanks Greg

[clill]

I would pull the master apart and see what you can see.

[Jon69RagTop]

Although i didn't have the guts to keep driving it as much as you did.

Sent it to Wilwood and they tested it, reported no problems. I bought a second unit not trusting the first one, 4,000 miles later ans zero problems.
I too found no leaks and bench bled the unit before installatio.

[Apogee]

Originally Posted by Jon69RagTop

Although i didn't have the guts to keep driving it as much as you did.

Sent it to Wilwood and they tested it, reported no problems. I bought a second unit not trusting the first one, 4,000 miles later ans zero problems.
I too found no leaks and bench bled the unit before installatio.

Jon,

Your instance is the only other case I can think of with similar symptoms...it makes me wonder if there wasn't a bad batch of seals or something, because it sounds like the MC is rapidly bypassing fluid around the seals. It would be interesting to see if both of your MC's were built/purchased around the same time.

Tobin
KORE3