Whoa Nellie! Brake pedal to floor! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

grayw0lf · 04-28-2007, 03:25 PM

I just had a weird problem. My truck has been apart for a few months, only going around the block on occasion.

I started her up just a moment ago, let it sit for about 1 minute & went down the driveway. The pedal just kept sinking. Very soft.

It acted almost like I had air in the lines. I was driving around town w/ a nice hard pedal in November.

I didnt' see any obvious leaks. The only weird thing was the front chamber of the Master Cylinder was full to the top & the read chamber was just over 1/2 full. Stock 1970 drum/drum.

What do you think is going on? Leaky cylinder letting air in? Bad MC?

sodak69c10 · 04-28-2007, 03:34 PM

same thing was on my truck mine the back seal of master cylinder was out

65-72 chevytoys · 04-28-2007, 03:38 PM

This is common on MC piston seals. I just replaced mine the front was full and the rear was empty. Pull your carpet back and see if there is fluind on the drivers floor boards. If there is you MC is leaking and will need to be rebuilt or replaced.

grayw0lf · 04-28-2007, 11:41 PM

Well... that sucks. I've been working furiously to get her painted & was planning to take it out next weekend.

& I'm not about to buy a new Drum/Drum MC. On the flipside, maybe I'll have to go ahead & order my Disc/Drum conversion kit tonight.

**70C10Toejam** · 04-28-2007, 11:44 PM

same thing happened to me last fall. truck sat all winter waiting for warm weather to change it to disks. almost done with it now.

grayw0lf · 04-29-2007, 01:07 AM

Toejam,

How long has it taken you to change to discs?? What are the odds of doing it in a day? (wishful thinking, I know).

**70C10Toejam** · 05-01-2007, 11:05 PM

grayw0lf

sorry about the delay...been busy with the brakes.

don't really think it could be done in one day...but my job was not the one to say it would be impossible. it took me the better part of a week, but i did not spend all day everyday on it. lost about 3 days to rain, except for the MC and booster ( there is a thread about that, not gonna try to link it right now) you can see the rain drops if you look closely. i made the '85 hard lines fit my truck. that took the better part of a day. changed the steering linkage, and all new tie rods. two trips and three sets of flex brake hoses to get the right ones. took prob. 30 mins just to get the original 9/16 shoulder on the pushrod-to-brake pedal ground down to the 1/2 inch hole in the '85 pushrod. there was a lot of time spent looking at the situation and trying to figure out the best way for me to get things to work for my situation.

BUT...NOW IT IS DONE!!!!!!!!!!

Jackiesh · 05-24-2007, 12:48 AM

How much exactly did you spent for that? I’m planning to have same thing done. And, is there something that would be affected when I put in Chevrolet Pickup Pedal Covers?

04-28-2007, 03:25 PM	#1
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Whoa Nellie! Brake pedal to floor! I just had a weird problem. My truck has been apart for a few months, only going around the block on occasion. I started her up just a moment ago, let it sit for about 1 minute & went down the driveway. The pedal just kept sinking. Very soft. It acted almost like I had air in the lines. I was driving around town w/ a nice hard pedal in November. I didnt' see any obvious leaks. The only weird thing was the front chamber of the Master Cylinder was full to the top & the read chamber was just over 1/2 full. Stock 1970 drum/drum. What do you think is going on? Leaky cylinder letting air in? Bad MC? __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

04-28-2007, 03:34 PM	#2
sodak69c10 Registered User Join Date: Mar 2007 Location: Rapid City, South Dakota Posts: 285	Re: Whoa Nellie! Brake pedal to floor! same thing was on my truck mine the back seal of master cylinder was out __________________ ,Clint LOUD PIPES SAVE LIVES 69 C-10 short stepside 406 sbc, 02 YAMAHA WR250F, 07 SUZUKI SV650S, 81 Grand Prix 355 sbc, 81 XT 500 YAMAHA

04-28-2007, 03:38 PM	#3
65-72 chevytoys Registered User Join Date: Dec 2006 Location: Wesley Chapel, Florida Posts: 1,113	Re: Whoa Nellie! Brake pedal to floor! This is common on MC piston seals. I just replaced mine the front was full and the rear was empty. Pull your carpet back and see if there is fluind on the drivers floor boards. If there is you MC is leaking and will need to be rebuilt or replaced. __________________ 2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer

04-28-2007, 11:41 PM	#4
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Re: Whoa Nellie! Brake pedal to floor! Well... that sucks. I've been working furiously to get her painted & was planning to take it out next weekend. & I'm not about to buy a new Drum/Drum MC. On the flipside, maybe I'll have to go ahead & order my Disc/Drum conversion kit tonight. __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

04-28-2007, 11:44 PM	#5
70C10Toejam Hellasick Join Date: Jul 2006 Location: Death Moans, IA Posts: 876	Re: Whoa Nellie! Brake pedal to floor! same thing happened to me last fall. truck sat all winter waiting for warm weather to change it to disks. almost done with it now. __________________ I keep two MAGNUMS in my desk. One's a gun, and I keep it loaded. The other's a bottle and it keeps ME loaded. I'm Tracer Bullet. (Calvin and Hobbes) This life was a test. It was only a test. If this had been an actual life, you would have received instructions on where to go and what to do. RED meat is not bad for you...FUZZY BLUE/GREEN MEAT is bad for you!!!!!!!!!!!!! BUILT FORD TOUGH WITH CHEVY STUFF--sticker at Goodguys

04-29-2007, 01:07 AM	#6
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Re: Whoa Nellie! Brake pedal to floor! Toejam, How long has it taken you to change to discs?? What are the odds of doing it in a day? (wishful thinking, I know). __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

05-01-2007, 11:05 PM	#7
70C10Toejam Hellasick Join Date: Jul 2006 Location: Death Moans, IA Posts: 876	Re: Whoa Nellie! Brake pedal to floor! grayw0lf sorry about the delay...been busy with the brakes. don't really think it could be done in one day...but my job was not the one to say it would be impossible. it took me the better part of a week, but i did not spend all day everyday on it. lost about 3 days to rain, except for the MC and booster ( there is a thread about that, not gonna try to link it right now) you can see the rain drops if you look closely. i made the '85 hard lines fit my truck. that took the better part of a day. changed the steering linkage, and all new tie rods. two trips and three sets of flex brake hoses to get the right ones. took prob. 30 mins just to get the original 9/16 shoulder on the pushrod-to-brake pedal ground down to the 1/2 inch hole in the '85 pushrod. there was a lot of time spent looking at the situation and trying to figure out the best way for me to get things to work for my situation. BUT...NOW IT IS DONE!!!!!!!!!! __________________ I keep two MAGNUMS in my desk. One's a gun, and I keep it loaded. The other's a bottle and it keeps ME loaded. I'm Tracer Bullet. (Calvin and Hobbes) This life was a test. It was only a test. If this had been an actual life, you would have received instructions on where to go and what to do. RED meat is not bad for you...FUZZY BLUE/GREEN MEAT is bad for you!!!!!!!!!!!!! BUILT FORD TOUGH WITH CHEVY STUFF--sticker at Goodguys

05-24-2007, 12:48 AM	#8
Jackiesh Registered User Join Date: Mar 2007 Location: Detroit, MI Posts: 2	Re: Whoa Nellie! Brake pedal to floor! How much exactly did you spent for that? I’m planning to have same thing done. And, is there something that would be affected when I put in Chevrolet Pickup Pedal Covers?



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