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Brakes and steering problem/ Vacuum booster issue?

 
  #1  
Old 11-09-2018, 04:08 PM
natira121
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Brakes and steering problem/ Vacuum booster issue?

Hey guys,

Several months ago, I installed a new master cylinder and vacuum booster in my farm truck. Everything was fine for a few months, but now I'm noticing that the brakes don't work well hauling heavy loads. (Towing 6000 lbs) Noticed the same to a lesser degree when hauling weight in the bed.

I've also noticed that the steering is super stiff when I start it up. Takes about 10 miles or so before it feels normal again.

What is up? Is it a vacuum leak? Bad booster? Something else?

1978 4x4 supercab 390 manual tranny

Thanks guys

Julie
 
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Old 11-09-2018, 04:20 PM
scottscott
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Its time to pull the wheels & check all the brakes. Particularly the rear drum brakes. I'll bet they are out of adjustment, at the least. They have self adjusters, those sometimes work, sometimes they don't.

Please post the year, model, & info on how the truck is equipped. That information will help others provide insight into what too check on your truck.
 
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Old 11-09-2018, 04:44 PM
natira121
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Scott,

I just had the rear wheels off a few weeks ago to fix a leaking axle seal. Everything looked fine, brake shoes look nearly new, the wear pattern was even,drums looked good, nothing looked amiss. There is no fried brake smell, and it brakes just fine... no pulling or noises. It's just with a load, it feels like brakes that haven't been bled. And of course they were when I replaced the master and booster.

Why would the brakes make the steering feel stiff? I'm not being sarcastic, I'd like to know. I may be a grandma, but I don't know everything!
 
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Old 11-09-2018, 05:04 PM
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Brakes & steering are two separate issues, not connected in any way. I don't have any good advice on the steering.

The rear brakes may look fine, & everything is in good condition, but they may be out of adjustment. When re installing the brake drum there should be slight drag between the shoes & the drum. If the drum slides right over the shoes without the slightest bit of contact, the adjustment is out.

See this very recent thread for a similar brake problem to yours, & what they are going to try to cure it: https://www.ford-trucks.com/forums/1...e-diagram.html
 
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Old 11-09-2018, 08:53 PM
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As Scott said, the brake situation is probably separate from the steering matter. Brakes with air in the lines often result in a soft "spongy" feel in the brake pedal. If you're getting this after lots of braking while pulling & hauling large loads there could be a bit of brake "fade" happening. Some lining material seem to be more prone to this than others. I'm wondering if it's manual or power steering. I'm also wondering what part of the World you're in. If it's Prudhoe Bay the cold air may make the steering stiff until it warms up some.
 
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Old 11-10-2018, 03:46 PM
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Originally Posted by Ozzie H. View Post
As Scott said, the brake situation is probably separate from the steering matter. Brakes with air in the lines often result in a soft "spongy" feel in the brake pedal. If you're getting this after lots of braking while pulling & hauling large loads there could be a bit of brake "fade" happening. Some lining material seem to be more prone to this than others. I'm wondering if it's manual or power steering. I'm also wondering what part of the World you're in. If it's Prudhoe Bay the cold air may make the steering stiff until it warms up some.
According to their profile, they're in WA
 
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Old 11-10-2018, 10:27 PM
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I'm not sure if this is the case natira, but if the power steering fluid is really old, and has some simple water build up inside, perhaps it's just not flowing through the system like it should until it warms up.
If the fluid has never been changed (as so many have not) then even if it's not the actual underlying problem, it's a good excuse to flush out the old and in with the new.

For brakes, how does the parking brake action feel? If you push a few clicks down, does it slow the truck down? Does one click practically stop the truck, or does it take many clicks to near the floor?
How far the parking brake pedal goes is often a good indicator of out of adjustment rear brake shoes.

When you say the brakes don't work very well when loaded, is this an issue with excessive pedal travel? Or is it just that they lack the power that they used to have?
It's possible that the front calipers are binding up a bit on rusty sliders. Is this an F150, 250 or 350? The brakes are designed similarly, but with some big differences.
Or it's possible like you said that the booster is going bad. Unfortunately this is not too out of line for a new booster. These days we learn to suspect ANY AND ALL new, or new-ish parts as possible culprits in crime. New stuff is crap!
And new things are even more likely to crap out when they're not used as much. Is your farm truck used every day? Or does it sit for extended periods until needed?

Good luck.

Paul
 
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Old 11-15-2018, 02:24 PM
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Hey guys,

My truck is a 1978 F250 Supercab 4x4, 390, manual tranny, with manual/vacuum assist brakes, and power steering

I'm is SW Washington, in the Gorge

I'm sure I need to do some lube on the steering components, and I'll change the fluid there as well. The truck sits a lot, it's my badass farm truck!

The brakes work fine with no load in the bed, or towed behind. With load, they are very mushy, travel nearly to the floor, and have very little stopping power. No funny noises, no shimmy, no pulling one way or the other. I first figured this out towing a huge old military trailer (with no brakes) that's all built of 1/4 steel, 16 feet long, with 3000 pounds of hay on it, downhill. My heart stopped before the truck did!

My parking brake isn't working at all.... and hasn't for years cuz I keep forgetting to adjust the damn thing.

I'm going to check for vacuum leaks, and bleed the brakes again.
 
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Old 11-15-2018, 02:37 PM
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Sounds like the rear brakes need to be adjusted. Your emergency brake won't work if the brakes are way out of adjustment also.
 
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Old 11-15-2018, 07:47 PM
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The rears might even be leaking or low on fluid. If your truck is equipped with one of the variable-height proportioning valves (rear loaded height activated) then when empty the front brakes do most of the work. When loaded down the rear brakes take a more prominent role.
But definitely need to physically check and adjust them no matter what.
Mushy pedals and long stopping distances are not worth putting off at all.

Paul
 

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