Truck pulls while braking

[vince72]

Hi everyone
So the truck pulls to the left when the brakes are applied, we replaced the right caliber as it looked to be the issue and unfortunately it is not. The master cylinder does has a minor leak, could this be the cause? (I’m debating on upgrading to the newer type eventually) what else can cause the pulling issue?

 

[df2x4]

I would replace all the soft rubber brake lines if you're not sure how long they've been there. They can look OK visually but have internal failures that cause intermittent restriction.

 

[Erik the Awful]

The master cylinder does has a minor leak, could this be the cause?

Yes. If it's leaking fluid out, you're leaking air in. Get air in that right front line and it'll have less braking power than the left.

 

[vince72]

Any good places to get stainless braided lines for obs trucks?
I ordered the newer master cylinder this morning

 

[Erik the Awful]

There's no reason to spend extra money on stainless braided lines for a daily driver. I would only consider them if the truck's main purpose was competition. They also require more care in routing. If one rubs on a tire it will eat through it in short order.

If you spend the money to get quality Raybestos hoses from RockAuto, you're still under $30, including shipping.

 

[Schurkey]

WHAT VEHICLE? WHAT BRAKE OPTION CODE?

So the truck pulls to the left when the brakes are applied, we replaced the right caliber as it looked to be the issue and unfortunately it is not.
The master cylinder does has a minor leak, could this be the cause? (I’m debating on upgrading to the newer type eventually)

Probably not. The master cylinder supplies pressure to both front brakes equally. The ABS and/or the combination valve splits the front into left and right sides. It'd be unusual for one side to get air and the other side doesn't.

"Newer type" master cylinder? Please tell me you're not considering converting to the so-called "NBS" master cylinder if you have low-drag front calipers.

what else can cause the pulling issue?

How are the rear brakes? Adjusted properly? Linings and drums in good condition?

Have you EVER bled the (1990 or newer) ABS using a scan tool to activate the solenoid valves? Does the ABS still have original fluid in it because it's never been properly bled?

Have you looked at the tie rod ends, idler arm, Pitman arm, ball joints, and control arm bushings? Upper control arm bushings have been a known problem on these trucks, and all the other items including lower control arm bushings are a known problem on...everything.

Any good places to get stainless braided lines for obs trucks?

I bought Russell brake hoses, they're not made like OEM with solid metal sections to keep them from rubbing the control arms. I did not know about the better style at that time.

If I were doing that upgrade again, I'd get these:
www.summitracing.com/parts/cst-sbh6055

Classic Tube SBH6055 Classic Tube StopFlex Brake Hose Kits | Summit Racing

Free Shipping - Classic Tube StopFlex Brake Hose Kits with qualifying orders of $109. Shop Brake Hoses, Sets at Summit Racing.

www.summitracing.com

I ordered the newer master cylinder this morning

If this is the so-called "NBS" master cylinder, this is a gigantic mistake if you have low-drag calipers. It's a potential mistake if you screw-up the bore diameter of the new master cylinder vs. the old master cylinder, with non-low-drag calipers. Either way, the "NBS" master cylinder serves no real purpose on these trucks.

All the 1500 trucks have low-drag calipers. (JN, JB or JD, 1, 3, 5, or 6. Examples: JN3, JB5)
The 6-lug 2500 trucks probably have low-drag calipers (JN, JB or JD6) unless ordered with heavy-duty brake option (JN, JB or JD7).

8- or 10-lug trucks don't have low-drag calipers. (JN, JB or JD7, or higher numbers, 8 or JF9)

 

[vince72]

@ erik
I was only thinking of replacing the hoses because of the age, they have no leaks just look worn out. The truck is a driver only for now lol

@ schurkey
Is brake option code on the glove box label?
We double checked the rear brakes last night and they are in good working order.
I will do some research on the ABS bleeding and scanning-that i have not done myself, after this it might be time to begin to budget for the front end overhaul they are worn from age but none seem torn or broken only worn.

Thanks for all the pointers !

 

[vince72]

I drove the Sierra last week & while driving it the brake pedal stayed slightly depressed, enough that I would have to give it throttle to move. I removed & re installed the brake valve, could it be a bad valve or booster?

 

[RichLo]

I'd replace the other caliper as well. Try to always replace brakes and components in pairs, if 1 is bad chances are the other isn't far behind.