I agree with checking the E brake. I had the same problem and after I thought I adjusted the rear brakes I had a soft pedal and the E barake wouldn't hold the truck while in drive. Made the adjustment and all is good.
Need advice on brakes!?!?!?!?
- Thread starter poolguy
- Start date
I agree with checking the E brake. I had the same problem and after I thought I adjusted the rear brakes I had a soft pedal and the E barake wouldn't hold the truck while in drive. Made the adjustment and all is good.
DieselChemist
Registered User
I'm having a similar problem. Before leaving Chicago the brakes were soft but did not sink to the floor and the brake light was coming on. I adjusted the rear brakes until they dragged. Once this was done I had a stiff pedal and the e-brake worked. After driving 500 miles straight the rear brakes were loose again and the e-brake would not hold. Stopped at a meineke and they readjusted the rear brakes until they dragged and the pedal did not feel real different but the e-brake held, the brake light would still come on sometimes. What they told me, I had the rear brakes too tight and the brake fluid got too hot and the rear brakes got unadjusted. I know how tight I had those rear brakes and they were not that tight. It has new master, booster and pads/shoes. I checked the vacuum pump and it looked okay. Could this be the RABS thing. One other thing, when my foot is on the brakes at a stoplight and the truck is stopped the pedal slowly in a jerking manner sinks but not to the floor.
dwaymar
dwaymar
sounds like a booster leaking down or a vac leak in the system
Compu Doc
Full Access Member
I dont know how many times I posted the foloowing link but it has been a lot of times. Maybe this link should be posted in the tech section or people should print out the article and if they have a brake problem refer to it.
http://www.asashop.org/autoinc/dec99/techtips.htm
Even if your truck does not have a RABS valve you can still use part of the method for checking your master cylinder.
http://www.asashop.org/autoinc/dec99/techtips.htm
Even if your truck does not have a RABS valve you can still use part of the method for checking your master cylinder.
Jeff Dodson
Full Access Member
Well I have done ALL the above, replaced pads, replace booster, replace RABS valve, adjusted rear brakes etc... dadadad... I had a friend of mine, VERY KNOWLEDGABLE, I might add. He told me there was service bullitin from FORD stating that when the front calipers ( BTW, I replaced those as well) are replaced, rebuilt whatever, the original master cylinder does noes pump enough fluid to aal four brakes, therefore causes the mastercylinder to fade down. I fought with this for a year. Finally, I did what my friend said and ALSO what the service bullitin said to do. Install a mastercylinder from an F450. I got one from AUTOZONE for a 96, I believe they are the same for several years. Now if you dont buy the booster also ( as recommended ) then you will have to elongate the mount holes on the mastercylinder to fit it your booster, that will be the only modification need, everything else ghooks up the same.
Now when I did this, someone here told me that was not the right way to fix it, they said, I did not fix the problem, I eliminated it. OK its fixed. Then someone found the service bullitin and posted and it said the same thing.
I'm sure if you do a search you can find it, but its been awhile, 1 year I think, and the brakes are still working great. I did not change the booster, I wish I would have just for piece of mind, but as I said they are fine now and dont fade down. Good Luck with it and let me know if you have any further questions
Now when I did this, someone here told me that was not the right way to fix it, they said, I did not fix the problem, I eliminated it. OK its fixed. Then someone found the service bullitin and posted and it said the same thing.
I'm sure if you do a search you can find it, but its been awhile, 1 year I think, and the brakes are still working great. I did not change the booster, I wish I would have just for piece of mind, but as I said they are fine now and dont fade down. Good Luck with it and let me know if you have any further questions
Mont91
Full Access Member
Hi Jeff, you are talking about me.
Through you we found out that calipers are bored out when being rebuilt(apparently not all) thus screwing up the volume balance in the brake system. This creates an imbalance in the master cylinder and exceeds its ability to compensate. Read that minimal sizing by the engineer.
The larger master cylinder moves more volume thus restoring proper function.
When you replace a part with different specs that solves a problem and you do not know why, you have "covered up" the problem. The problem is fixed yes, but the reason is unknown and may return without warning.
In this case a part that, unknown to us, had non original specs(caliper)and caused the malfunction of an original spec part(master cylinder). This was corrected by adding a second non original spec part(MC) to eliminate the problem caused by the first non original spec part.
Warning,,,,, if you replace your calipers and have the sinking pedal after properly checking the other components the master cylinder may be the problem.
Does anybody know if the caliper specs can be checked at purchase and what the original specs are?
Through you we found out that calipers are bored out when being rebuilt(apparently not all) thus screwing up the volume balance in the brake system. This creates an imbalance in the master cylinder and exceeds its ability to compensate. Read that minimal sizing by the engineer.
The larger master cylinder moves more volume thus restoring proper function.
When you replace a part with different specs that solves a problem and you do not know why, you have "covered up" the problem. The problem is fixed yes, but the reason is unknown and may return without warning.
In this case a part that, unknown to us, had non original specs(caliper)and caused the malfunction of an original spec part(master cylinder). This was corrected by adding a second non original spec part(MC) to eliminate the problem caused by the first non original spec part.
Warning,,,,, if you replace your calipers and have the sinking pedal after properly checking the other components the master cylinder may be the problem.
Does anybody know if the caliper specs can be checked at purchase and what the original specs are?
Mont91
Full Access Member
WJB
Sounds like your adjuster lever is worn and letting the adjusters back off. Have you checked them?
Sounds like your adjuster lever is worn and letting the adjusters back off. Have you checked them?
There's no chance in hades any parts house is going to let you disassemble a caliper before buying. only thing I look for is that the caliper has the replacement steel pistons in place of the factory plastic ones. I have the piston sizing specs buried in my parts catalogs, at one time you could buy rebuild kits but not anymore.
DieselChemist
Registered User
Mont
When I opened up the drivers side to adjust them in Chicago the adjuster had completely fallen off and was ground quite a bit so I replaced it, however the passenger side was never replaced but it adjusted very well.
My main question is why the rear wheels are unadjusting themselves, I had a stiff non-fading pedal when I had adjusted them. The parking brake set high and now it sets very low.
When I opened up the drivers side to adjust them in Chicago the adjuster had completely fallen off and was ground quite a bit so I replaced it, however the passenger side was never replaced but it adjusted very well.
My main question is why the rear wheels are unadjusting themselves, I had a stiff non-fading pedal when I had adjusted them. The parking brake set high and now it sets very low.
Mont91
Full Access Member
wjb
By adjuster are you talking about the threaded part or are you talking about the lever the cable pulls on? If that little lever is worn or not engaging the threaded adjuster the threaded adjuster will back off in a hurry. When adjusting the rear shoes you should be able to hear a solid click as the lever moves from notch to notch. And you should not be able to back off on the adjustment. If the adjusting in chic. eliminated the sinking pedal, stopped the light from coming on and made the e-brake function properly I would have to believe you are still dealing with an adjustment problem. The brake shop apparently did not adjust them quit far enough, a little bit of extra travel makes a big difference in these trucks. Could your e-brake cables be sticking? If they are this holds the adjusting lever up letting the adjuster back off and the pedal might not return to the top.
By adjuster are you talking about the threaded part or are you talking about the lever the cable pulls on? If that little lever is worn or not engaging the threaded adjuster the threaded adjuster will back off in a hurry. When adjusting the rear shoes you should be able to hear a solid click as the lever moves from notch to notch. And you should not be able to back off on the adjustment. If the adjusting in chic. eliminated the sinking pedal, stopped the light from coming on and made the e-brake function properly I would have to believe you are still dealing with an adjustment problem. The brake shop apparently did not adjust them quit far enough, a little bit of extra travel makes a big difference in these trucks. Could your e-brake cables be sticking? If they are this holds the adjusting lever up letting the adjuster back off and the pedal might not return to the top.
icanfixall
Official GMM hand model
The rear brakes adjusters are sold for each side IIRC. Thats a left and right part.
