Right front brake caliper always dragging-- ive changed everything!

[The_Josh_Bear]

Ugh. That's not making me feel all warm and fuzzy.
Given the incredible failure rate of master cylinders, I'm not excited about going that route either.

 

[The_Josh_Bear]

I think I finally have a line on this one. After said smoke from yesterday on the passenger side, I pulled both sides and poked around. Low and behold, BOTH sides were scorched and melted the dust boot on the calipers.

Which means pushrod after all!! Still don't know why it only pulls right but that's a start. How far to adjust it for the first go? This is the same master and booster that's been on it for years and years... but I think it didn't show up cause I didn't keep my rears adjusted very well. Just a thought.

 

[KansasIDI]

I think I finally have a line on this one. After said smoke from yesterday on the passenger side, I pulled both sides and poked around. Low and behold, BOTH sides were scorched and melted the dust boot on the calipers.

Which means pushrod after all!! Still don't know why it only pulls right but that's a start. How far to adjust it for the first go? This is the same master and booster that's been on it for years and years... but I think it didn't show up cause I didn't keep my rears adjusted very well. Just a thought.

Thats lo and beer hold not low and behold lol

Could be one caliper is weaker than the other. The 89 I was working on has a caliper that was just worn out and didn’t apply as much pressure. Pulled to the left.

Adjusting your push rod is a drive adjust drive adjust drive adjust drive type deal

 

[franklin2]

You can make a tool out of a cereal box and a set of calipers. Though 1 inch would be pretty darn close.

You must be registered for see images attach

 

[Old Goat]

Here is this nifty Booster/Master Cylinder rod adjustment tool.
I bought one a few years ago, and used it last week when I was doing my
87 - 91 Master cylinder mod on the 86.
pretty cool how it works.
Here is one site selling and explaining how it works.
Do your searching, they are cheaper and pricyer depending who is selling them.

The Benefits of Booster Pin Depth Gauges | Master Power Brakes

The booster pin depth, which is often overlooked when installing a new master cylinder, can drastically affect the comfort and efficiency of your driving experience.

techtalk.mpbrakes.com

EDIT:

Just noticed back in post#7 I already posted this, with a YT Vid
from another vendor....OH Well...

Goat

 

[The_Josh_Bear]

Turns out the booster rod was a touch too long! I'd say only a mm, but I'm sure that makes a difference.

Thanks for the tip on the tool, got me one and for one thing it's way bigger than I thought, but also terribly useful! It was only about a 20 minute process including finding the right tools. That adjustment nut was TIGHT.

Test drive to work in the morning!

 

[franklin2]

There are tiny holes in the bottom of the reservoir of the master cylinder. Those are the ones that spit up brake fluid if you hit the pedal fast with the master cylinder cover off. This is less apparent on the plastic reservoir models. Those are called "compensation ports". When the brake pedal is up, those ports lead to the brake lines and the calipers and wheel cylinders front and rear. So the whole system is "open" to the reservoir when the brake pedal is not pressed. This allows for expansion of fluid in the system and gives it somewhere to go.

When the brakes are applied, the very first thing that happens, these ports are covered up so pressure can then build and apply the brakes. If the rod is just a little too long, it will cover up these ports. All you have to do is take it for a drive and it doesn't take long for the fluid to warm up and start expanding, and since it can't go back in the reservoir, it will start applying the brakes slightly.

 

[Rdnck84_03]

I need to check this out on my 83. I installed a new booster a couple years ago, everything has worked perfectly until I put new pads on the front last weekend.

Now they are both dragging, right side worse than the left. I'm hoping the rod adjustment is my issue. If not I guess my next step is to blow the pistons out of the calipers and polish them.

James

 

[franklin2]

I need to check this out on my 83. I installed a new booster a couple years ago, everything has worked perfectly until I put new pads on the front last weekend.

Now they are both dragging, right side worse than the left. I'm hoping the rod adjustment is my issue. If not I guess my next step is to blow the pistons out of the calipers and polish them.

James

90% of the time that is the calipers sticking. The pads get thinner and thinner and the pistons move on out to compensate. All that old dirty fluid in the caliper starts creating rust behind the piston. When you put new pads in and take a c-clamp and squeeze the piston back in the caliper bore, it rides right over all that rust and gets stuck.

Do you know a place that sells the seal for the piston? Polishing it like you said and a new seal is probably all you need. But no one seems to sell diy parts to rebuild anything.

 

[IDIBRONCO]

Rock Auto sells them. They're called a caliper repair kit. I just typed in a 1990 F250 with a 7.3 for a quick, generic search so maybe they're available for other models, maybe not. I would guess probably so.

 

[Rdnck84_03]

I have had good luck in the past with not replacing the seals after re assembly.

James

 

[The_Josh_Bear]

What the heck. I know it's been a while but I just can't figure this thing out.

Test drive after booster pin adjustment made for a better feel, less brake drag for sure. Still pulls right, not quite as bad.

So to sum up:
1. Brakes pull to the right when driving. When you stomp on the brakes they don't really pull anymore.
2. Pulled passenger front wheel off and verified it's the caliper being too tight when nobody is on the brakes.
3. Cracked the bleeder and sure enough there is pressure in that caliper.
4a. Changed passenger caliper, no positive change.
4b. Changed flexible brake hose at front right.
4c. Checked both sides for bearing or alignment issues, good to go.
5. Whined on here a few times.
6. Changed passenger caliper AGAIN, just incase the reman was crap. No change. (OB member suggestion)
7. Changed DRIVER's caliper in case it was under-performing, no change. (OB member suggestion)
8. I adjusted the push-rod length using a tool from amazon, works a treat. (OB member suggestion)
9. Decided to do a compression test on engine since I've never done that before. And I'm not driving it much. (unrelated)

I can't get over how consistent this thing is. Oh and when I got to bleed the brake or push the piston back in, it flows just fine like normal-- nothing I can feel that's impeding flow in the slightest.

At this point I'm thinking it's a pinched hard line or corrosion but like I said fluid flows just fine both ways. Or maybe a bad flex hose from the factory. GAH! There is pressure built up in the front right caliper, regardless of what caliper is there. But it can't be the master because it would be pinching both sides, no? I hate throwing parts at stuff. I'm already quite annoyed that I can't figure it out.

Thanks guys,
Joshua

 

[Rdnck84_03]

@The_Josh_Bear have you replaced the master cylinder? My dad's 82 f150 4x4 did this on the passenger front years ago. I have no idea how the master cylinder had any effect on just the one front side, but it fixed it after replacement.

Prior to the master we replaced all the front brakes (calipers, rotors, pads,flex lines) then thought that maybe the rear was doing something crazy and causing issues with the front so we went through them (turned the drums, new shoes, wheel cylinders, hardware kit, flex line). Then swapped the proportioning valve, adjusted the booster rod. Still no change.

We actually used the truck for about 6 months with a nail between the steel and flex line on that side to block the fluid to that side so it was drivable. Finally on the recommendation of a mechanic my dad knew we changed the master and it fixed it. If you have a spare laying around or want to spend the money on a gamble it could be worth a shot.

I still cannot wrap my mind around what in the master could possibly cause only 1 side to lock up when they work off of the same line.

James

 

[KansasIDI]

Yes, try master cylinder next. Inexpensive and will help braking performance if nothing else

 

[KansasIDI]

Did wonders for my truck…