R20 burb pulling left under brakes

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

shanegtr

Full Access Member
Joined
Sep 29, 2018
Posts
313
Reaction score
267
Location
Perth, Australia
First Name
Shane
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
Hi all, still learning thomgs about my burb - got an issue with it pulling left under brakes. Just wondering if there's any common issue to these trucks that cause this? At this stage I suspect the right front calliper may not be doing its job and also has a bit of a squeal from that side when brakes are applies, has plent of brake material left
 

idahovette

Full Access Member
Joined
Aug 7, 2016
Posts
6,451
Reaction score
13,784
Location
Weiser Idaho
First Name
Perry
Truck Year
1975-1979
Truck Model
K20-K10
Engine Size
350
When it pulls does your steering wheel noticeably turn or does it just drift. defines front or rear brake problems
 

dvdswan

Full Access Member
Joined
Mar 11, 2014
Posts
2,366
Reaction score
2,024
Location
Port Orchard, WA
First Name
Dave
Truck Year
1978
Truck Model
K10
Engine Size
350
Several things can cause a brake pull; sticking caliper, corroded slides, bad cut on rotor, dirty pads or shoes, brake cylinder leaking, worn out brake hose, just to name a couple of things.

What I'm getting at is inspect both front and rear brakes.
 

Obwonkonobe

Full Access Member
Joined
Feb 21, 2017
Posts
531
Reaction score
116
Location
AZ
First Name
Ethan
Truck Year
78
Truck Model
C10 custom deluxe
Engine Size
350
When it pulls does your steering wheel noticeably turn or does it just drift. defines front or rear brake problems
Which problem means front or rear? I’m having the same issue but mine pulls the wheel to the left like I’m steering the truck
 

shanegtr

Full Access Member
Joined
Sep 29, 2018
Posts
313
Reaction score
267
Location
Perth, Australia
First Name
Shane
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
When it pulls does your steering wheel noticeably turn or does it just drift. defines front or rear brake problems
It's a noticeable turn left, the harder you jump on the brakes the more it will pull left. I think it will be something not right with the right hand front
 

idahovette

Full Access Member
Joined
Aug 7, 2016
Posts
6,451
Reaction score
13,784
Location
Weiser Idaho
First Name
Perry
Truck Year
1975-1979
Truck Model
K20-K10
Engine Size
350
Which problem means front or rear? I’m having the same issue but mine pulls the wheel to the left like I’m steering the truck
If the steering wheel physically moves against your grip it usually means something in the front brakes, pulling in the direction of the least applied. If it just "drifts "one way with brake application it is usually the rear. A fairly good rule is grease (of some sort) pulls and brake fluid slips, meaning if you have grease on the lining it should pull or bind up on the side with the grease and the opposite for brake fluid contamination.. YMMV
 

shanegtr

Full Access Member
Joined
Sep 29, 2018
Posts
313
Reaction score
267
Location
Perth, Australia
First Name
Shane
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
Gave the brakes some attention today. Flushed the brake fluid and checked out the front brakes, all seems ok there. Left rear brake is locking before the rest so that could be a possible cause (either left rear is coming on to hard or the right rear too soft). But the rear seems willing to lockup long before the fronts do. I noticed what looked like a load proportion valve under the back - as this truck is lowered is it possible that the valve needs a tweak?
 

skysurfer

Full Access Member
Joined
Oct 23, 2010
Posts
2,643
Reaction score
1,995
Location
west coast
First Name
John
Truck Year
1989 Suburban
Truck Model
V2500
Engine Size
5.7/TH400/NP241C
The LSPV affects pressure to the rear brakes but equally side to side, so a pulling issue can't be pinned on that. Adjusting it to prevent rear lockup before the fronts is pretty easy. Clean off the end of the stem that sticks out of the round part of the proportioning valve and make a dot at 12:00 with a Sharpie so you have a point of reference. Remove the nut and short arm that are attached to the stem. Rotate the stem a few degrees clockwise to reduce braking pressure. It doesn't take much to notice a difference. Reattach arm and nut then test drive. Repeat as necessary.

GM issued a tsb instructing mechanics to bypass the LSPV on vehicles with braking problems. See post #5 here. https://www.gmsquarebody.com/threads/the-brakes-breaks.5984/
 

shanegtr

Full Access Member
Joined
Sep 29, 2018
Posts
313
Reaction score
267
Location
Perth, Australia
First Name
Shane
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
The LSPV affects pressure to the rear brakes but equally side to side, so a pulling issue can't be pinned on that.
Wasnt trying to pin the LH rear early lockup on the LSVP. It looks like the RH rear is not doing its job fully. Had a weird issue a couple of times today where the brake pedal dropped to the floor. Cant see any leaks at any of the lines or at the wheels so I may also have a leaking master cylinder.....
 

shanegtr

Full Access Member
Joined
Sep 29, 2018
Posts
313
Reaction score
267
Location
Perth, Australia
First Name
Shane
Truck Year
1989
Truck Model
R2500 Suburban
Engine Size
454
I've had a search around the forum, are there any tech write ups on adjustment of the 13" drum?
 

Stewy

Junior Member
Joined
Dec 10, 2012
Posts
4
Reaction score
7
Location
Pacifi Northwest
First Name
Scott
Truck Year
79
Truck Model
k25
Engine Size
454
When it comes to the front, don't forget, the rubber flex hose that connects to the caliper, over time, will collapse internally over time. I know 1st hand because I have had both sides on mine do it on my 79 GMC.
 

WHEELMAN

Full Access Member
Joined
Aug 9, 2011
Posts
136
Reaction score
11
Location
HICKORY TAVERN SC
First Name
BILL
Truck Year
1986
Truck Model
C10
Engine Size
454 v8
Bad calipher..bad brake hoses.change the two front hoses first.then if it's pulling.change out the caliper.the problem is some of the older vehicles.we can't get new parts.dont buy.autozone.
 

idahovette

Full Access Member
Joined
Aug 7, 2016
Posts
6,451
Reaction score
13,784
Location
Weiser Idaho
First Name
Perry
Truck Year
1975-1979
Truck Model
K20-K10
Engine Size
350
Bad calipher..bad brake hoses.change the two front hoses first.then if it's pulling.change out the caliper.the problem is some of the older vehicles.we can't get new parts.dont buy.autozone.
Looks like you got your PERIOD ?
 

Latest posts

Forum statistics

Threads
41,851
Posts
903,510
Members
33,365
Latest member
rossivey
Top