New power booster but still hard to stop

dogbone · 06-14-2008, 05:34 PM

Hello:
I put a new power booster in my ford 350 truck, a new master cylinder and bled the brakes. I adjusted the booster rod and I don't see any leaks in the vacume tube from the pump. When I press the brakes and start the car the break pedal goes down. I still have to put alot of pressure on the brake pedal though to get the truck to stop. I can't figure this out. Any ideas?
Thanks
John

Chevy_Finatic79 · 06-14-2008, 05:50 PM

either you didnt bleed the abs if the truck is equipped I dont know what year yours is. or it souinds like a bad proportioning valve

mudseeker · 06-14-2008, 07:45 PM

how are the rear brakes, i assume they are drum type brakes. could just need to convert them to a disc setup to get the results you are looking for.

z07 · 06-14-2008, 08:00 PM

Did you bench bleed the MC?

dogbone · 06-15-2008, 12:24 PM

Thanks for the replies. It is a ford f-350 one ton diesel truck, 1984. They are drum brakes that have had good stopping power up to now. I did bleed the mc. I could have done a better job bleeding the brakes though. I am going to purge all the old brake fluid from the system this time. I don't know what the proportioning valve is so I will look that up. Thanks again.
John

z07 · 06-15-2008, 07:39 PM

Quote:

Originally Posted by dogbone

Thanks for the replies. It is a ford f-350 one ton diesel truck, ...

How are your vacuum pump, storage tank, and related hoses? Any leaks, crimps, or bad haircut and sandals?

dogbone · 06-15-2008, 09:04 PM

z07, I will check those things tomorrow. I couldn't see anything wrong with the vacuum hoses the other day though. No bad hair cut and sandals. A hint of an attitude though. It could be partially blocked up or something. I also figured the vacuum pump was alright since I was getting a vacuum when the brake pedal went down after starting the truck up. But maybe the pump is messed up. I am going to pull the mc off and measure the push rod distance also. It looks like it is supposed to be just a hair away from the mc seat when installed.
Thanks z07
Why is vacuum spelled with two uu's. It just doesn't look right.
John

leolkfrm · 06-16-2008, 05:22 AM

Did you try flushing the brake system........Bleed it till fresh fluid is thru the system. when you were bleeding did the pedal push easy or hard when the bleeder is open?

dogbone · 06-16-2008, 09:01 AM

Leo, the pedal was hard to push with the bleeder open. I bled the brakes really good although I couldn't tell if the fluid was clear or not. I bled each brake about four times with good flow using up half of the fluid in the mc. What am I looking for?
John

dogbone · 06-16-2008, 03:57 PM

Doh!.... it looks like I had the power booster rod out to far. > : / With it adjusted in properly, I am getting help from the power booster now when I apply the brakes.
Thanks for all the suggestions.
John

06-14-2008, 05:34 PM	#1
dogbone Full Member Join Date: Mar 2008 Posts: 19	New power booster but still hard to stop Hello: I put a new power booster in my ford 350 truck, a new master cylinder and bled the brakes. I adjusted the booster rod and I don't see any leaks in the vacume tube from the pump. When I press the brakes and start the car the break pedal goes down. I still have to put alot of pressure on the brake pedal though to get the truck to stop. I can't figure this out. Any ideas? Thanks John

06-14-2008, 05:50 PM	#2
Chevy_Finatic79 Senior Member Join Date: Mar 2008 Location: Lincoln NE Posts: 439	either you didnt bleed the abs if the truck is equipped I dont know what year yours is. or it souinds like a bad proportioning valve __________________ "She's gonna Freak when she see's my wheels" 85' Chevy C-10 Longbox (Rat) TBI 5.7 Liter/THM350 90' Chevy Suburban 4x4 TBI 350 Cu.In./700R4 http://www.truckforum.org/forums/truck-pictures-176.htm

06-14-2008, 07:45 PM	#3
mudseeker mod-o-tator Join Date: Feb 2006 Location: michigan Posts: 4,052	how are the rear brakes, i assume they are drum type brakes. could just need to convert them to a disc setup to get the results you are looking for. __________________ member map add yourself

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06-14-2008, 08:00 PM	#4
z07 Senior Member Join Date: Feb 2008 Posts: 176	Did you bench bleed the MC?

06-15-2008, 12:24 PM	#5
dogbone Full Member Join Date: Mar 2008 Posts: 19	Thanks for the replies. It is a ford f-350 one ton diesel truck, 1984. They are drum brakes that have had good stopping power up to now. I did bleed the mc. I could have done a better job bleeding the brakes though. I am going to purge all the old brake fluid from the system this time. I don't know what the proportioning valve is so I will look that up. Thanks again. John

06-15-2008, 09:04 PM	#7
dogbone Full Member Join Date: Mar 2008 Posts: 19	z07, I will check those things tomorrow. I couldn't see anything wrong with the vacuum hoses the other day though. No bad hair cut and sandals. A hint of an attitude though. It could be partially blocked up or something. I also figured the vacuum pump was alright since I was getting a vacuum when the brake pedal went down after starting the truck up. But maybe the pump is messed up. I am going to pull the mc off and measure the push rod distance also. It looks like it is supposed to be just a hair away from the mc seat when installed. Thanks z07 Why is vacuum spelled with two uu's. It just doesn't look right. John

06-16-2008, 05:22 AM	#8
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 1,067	Did you try flushing the brake system........Bleed it till fresh fluid is thru the system. when you were bleeding did the pedal push easy or hard when the bleeder is open?

06-16-2008, 09:01 AM	#9
dogbone Full Member Join Date: Mar 2008 Posts: 19	Leo, the pedal was hard to push with the bleeder open. I bled the brakes really good although I couldn't tell if the fluid was clear or not. I bled each brake about four times with good flow using up half of the fluid in the mc. What am I looking for? John

06-16-2008, 03:57 PM	#10
dogbone Full Member Join Date: Mar 2008 Posts: 19	Doh!.... it looks like I had the power booster rod out to far. > : / With it adjusted in properly, I am getting help from the power booster now when I apply the brakes. Thanks for all the suggestions. John