C3 Race Car Build

[johng]

Have you seen this thread on the US forum where a guy has the same problem of the brake pedal coming back slowly?
https://www.corvetteforum.com/forum...is-slow-to-return-with-new-brake-booster.html

 

[Oneball]

Have you seen this thread on the US forum where a guy has the same problem of the brake pedal coming back slowly?
Brake Pedal is Slow to Return with New Brake Booster - CorvetteForum - Chevrolet Corvette Forum Discussion

Thanks. Seems like mine. We’ll find out next week

 

[Roscobbc]

The one that’s leaking is the only one of the 4 that isn’t a blind hole, it’s goes into the water jacket. If it doesn’t settle will try a Loctite rather than a PTFE paste.

Mine was a 'blind' tapped hole - leaks were from mating surface of pump to block - not thru' bolt hole itself........

 

[Oneball]

Rear lights cleaned and primed

 

[antijam]

Are you keeping the fibre optics?

 

[Oneball]

Are you keeping the fibre optics?

No that stuff is all in the bin.

 

[Oneball]

Rear lights cleaned.

Painted

And I’ve pressed in new non-Corvette holders as the originals were bent and the pig tails missing.

Also have confirmed nothing wrong with the servo but the return spring is missing on the pedal. So column and pedal box out.

 

[Oneball]

Second opinion/ thoughts please.

Brakes are fully bled but the pedal is slow to return. I’ve sent the servo off to be tested and it’s ok. The pedal doesn’t stick and neither does the master cylinder. With the servo off the car when you press it in it returns slowly.

Video of pedal in action: Corvette - oneball

 

[johng]

Sounds to me as if either there is some friction between the rod and the case, the air can't flow quickly enough out of the rear of the case, or the booster return spring is broken. Do you know what testing was done to establish that it is OK?

 

[Oneball]

Sounds to me as if either there is some friction between the rod and the case, the air can't flow quickly enough out of the rear of the case, or the booster return spring is broken. Do you know what testing was done to establish that it is OK?

Compared speed of return with another.

Have you got power brakes on yours? How quickly does it return without the engine running?

 

[johng]

I have got power brakes, but I'm in Gibraltar at the moment so can't press my brake pedal! Also my tablet won't play your video

 

[Oneball]

I have got power brakes, but I'm in Gibraltar at the moment so can't press my brake pedal! Also my tablet won't play your video

Peeing it down here. Hope you’re enjoying the sun!

 

[johng]

Just had a thought, if the servo is off the car or the engine isn't running then the check valve would stop airflow into the front of the servo. This might slow the movement. Have you tried removing the check valve?

 

[Oneball]

Just had a thought, if the servo is off the car or the engine isn't running then the check valve would stop airflow into the front of the servo. This might slow the movement. Have you tried removing the check valve?

Yep. No difference with or without the check valve.

 

[johng]

Not sure what else you can do then without dismantling the servo! By the way it's cloudy here tonight but still 22C

 

[johng]

Tim, I'm not pleased. I woke up in the middle of the night thinking about your servo!!! Do you still have the problem with the pedal spring replaced, the brakes fully bled and the engine running? I think all of these could affect how quickly the pedal returns.

 

[Oneball]

Tim, I'm not pleased. I woke up in the middle of the night thinking about your servo!!! Do you still have the problem with the pedal spring replaced, the brakes fully bled and the engine running? I think all of these could affect how quickly the pedal returns.

Me too.

Yep same problem with new pedal spring and fully bled. If anything it’s even slower to return with the engine running. Only reason I can think fir this is the valve in the servo isn’t balancing the pressure either side of the diaphragm when the pedal is released.
View my video at Corvette - oneball

 

[Forrest Gump]

I’ve just checked how my brake pedal behaves for your reference. It returns instantly. I would say there is as much force on its return as when depressed. I can hear a faint hiss of air in the servo as the pedal returns.

 

[johng]

Me too.

Yep same problem with new pedal spring and fully bled. If anything it’s even slower to return with the engine running. Only reason I can think fir this is the valve in the servo isn’t balancing the pressure either side of the diaphragm when the pedal is released.
View my video at Corvette - oneball

Yes it sounds like the valve is only letting the air pass very slowly from the rear to the front chamber. If that's the case then I guess you need a new servo.

 

[Oneball]

Dash pad recovered.

Rear lights in, beginning to look more like a Corvette now