Truck pulls to the right.

shotrod69 · Mar 26, 2024

1987 R20 Suburban.
What’s causing my braking issue?

When ever I hit the brakes the truck pulls to the right. The harder I hit them the harder it pulls. To the point of needing to counter steer with some effort to avoid going in the ditch. Had to “panic” stop in the rain a few days ago, only right tire locked up. Usually both lock up.
Did not find any fluid on rotors or pads. Brakes also seemed (could be wrong) unusually tight when trying to turn hub. Calipers and rotor was also too hot to touch, but not excessive enough to indicate overheating. Temp seemed equal on both sides and cooled enough to touch before I finished my cigarette. Fluid level is good. Hoses look to be in good condition. Both brakes work when pedal is pressed. Pulled calipers and pushed pistons in. Pressed brake 10-15 times to seat pads. Left side was noticeably looser then right.
New parts 32k miles ago.
Master cylinder
Calipers
Hoses
1 rusted brake line
Completely new fluid.
Pads have enough meat left to not need changed.

MidneightReider · Mar 26, 2024

Will be very difficult to diagnose this digitally so as the suggestions come you'll have to inspect and try different things.

I'll start it off by saying don't completely rule out the rear brakes malfunctioning. Even though they are separated in the master, the system all works together because if the rears lock up early or late it can affect the way the front engages. I know that most will focus on the front as a separate system.

That said, it's probably something in the front. I would start by bleeding or re-bleeding both sides at the caliper and bleeding the master which is often overlooked.

dd1990 · Mar 26, 2024

Sounds like an air pocket or clog somewhere in the system...bleed them

Redfish · Mar 26, 2024

My bet would be a bad caliper. Getting quality replacement parts these days is a hit and miss proposition. When I replaced my front calipers I returned 2 left side calipers before I got one that worked properly.

Ricko1966 · Mar 26, 2024

Are the hoses new or relatively new. What happens is a the hoses swell shut on the inside,not visible. Your master and power brakes can force fluid through the restricted hos,but the caliper seals don't have the power to push the fluid back through,so you have residual pressure there and then you put more fluid in and the side that already has pressure locks. Take off the front wheels,pump the brakes a few times then go crack your right bleeder. I'm guessing you're going to get a big squirter of brake fluid,which means there's pressure on the caliper even when the brakes aren't applied. Another thing that can cause a bad pull is stuck caliper slides. So if you don't fi d residual pressure,verify your calipers slide easy.

fast 99 · Mar 26, 2024

Get a cheap heat gun they are about $20. Make a few harder stops. Jump out and check rotor or drum temps. Whatever is cooler than the rest is the problem corner.

Does sound more brake related but also be aware loose steering/suspension parts can create a pull very similar to uneven brake action. Parts shift under the load.

https://m.media-amazon.com/images/I/614ohKW2HRL._AC_SX522_.jpg

Grit dog · Mar 26, 2024

Left side caliper not working as well as the right side (pulling right). If one was hanging up it would be noticeably hotter and pull to that side when not braking.
That’s my internet guess.
Unless there’s some **** in the lines that got pushed to the left. Although I’d think it would have dislodged at least temporarily after you pushed the fluid back to the Mc.

squaredeal91 · Mar 26, 2024

Not sure of R designation.
But 2wd trucks will pull to the right with bad idler arm.

TotalyHucked · Mar 27, 2024

squaredeal91 said:
Not sure of R designation.
But 2wd trucks will pull to the right with bad idler arm.

'87-up trucks are R/V, for 2wd and 4wd. The C/K designation moved to the GMT400 platform.

OP, I hope you get it figured out. My truck has done that very thing for the 4 years I've owned it, I have to counter steer when coming to a hard stop. Whole new front end (including idler and pitman arms), 2 sets of calipers (second being Wilwood D52s), all new lines (stainless braided up front now), 3 sets of wheels/tires, new steering box and it still does it. Only thing left is the proportioning valve I guess

greyghost · Mar 27, 2024

my guess is caliper on right side locking up, due to excessive wear either from pads or rotor or both. cud also be dirty piston,seal allowing debris into chamber, wore out cylinder where piston gets jammed up at end of its travel n wont return back into caliper to free up rotor to spin. caliper repair kit, brake hone, couple cans brake cleaner. lil lithium grease on mounting bolt sliders, measure rotors for thickness there is a spec for excessive wear replace if worn past spec.

hwyix · Apr 1, 2024

Don't over look your suspension. If you have a blown bushing on side and then step on the brakes that tire is going to pull.

shotrod69 · Apr 1, 2024

squaredeal91 said:
Not sure of R designation.
But 2wd trucks will pull to the right with bad idler arm.

It might be an idler arm. However, it’s a moog part and it’s got less then 20k on it.

shotrod69 · Apr 1, 2024

hwyix said:
Don't over look your suspension. If you have a blown bushing on side and then step on the brakes that tire is going to pull.

I can check it, but it’s all got less than 20k miles on it. Replaced the entire front suspension and steering.

JBswth · Apr 1, 2024

shotrod69 said:
1987 R20 Suburban.
What’s causing my braking issue?

When ever I hit the brakes the truck pulls to the right. The harder I hit them the harder it pulls. To the point of needing to counter steer with some effort to avoid going in the ditch. Had to “panic” stop in the rain a few days ago, only right tire locked up. Usually both lock up.
Did not find any fluid on rotors or pads. Brakes also seemed (could be wrong) unusually tight when trying to turn hub. Calipers and rotor was also too hot to touch, but not excessive enough to indicate overheating. Temp seemed equal on both sides and cooled enough to touch before I finished my cigarette. Fluid level is good. Hoses look to be in good condition. Both brakes work when pedal is pressed. Pulled calipers and pushed pistons in. Pressed brake 10-15 times to seat pads. Left side was noticeably looser then right.
New parts 32k miles ago.
Master cylinder
Calipers
Hoses
1 rusted brake line
Completely new fluid.
Pads have enough meat left to not need changed.

You might have a flex hose that is coming apart on the inside, so that the separated section(s) is acting like a baffle that allows fluid to move toward the wheel cylinder, but then blocks it from returning, causing a tight brake applies harder than the opposite one. If you are in a traffic jam, it might eventually lock up and for awhile refuse to release.

J.B.

backwoodsman · Apr 3, 2024

shotrod69 said:
When ever I hit the brakes the truck pulls to the right. The harder I hit them the harder it pulls. To the point of needing to counter steer with some effort to avoid going in the ditch.

I had the same problem on my '83 K1500 Suburban last year. Both front calipers worked fine as far as I could tell. But when I had both removed from the rotors and fully compressed, then pressed the brake pedal, the left one moved only about half as much as the right one. Over the course of a couple hundred miles it had somehow developed enough internal resistance that the other caliper got a lot more of the pressure. Replacing it solved the problem.

Truck pulls to the right.

shotrod69

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