Touchy rear brakes, locking up

[shortchevy]

Not original rear? If the slave cylinder is not the same size as the original then the master cylinder/prop valve may be sending too much pressure to the rear brakes, causing them to lock. Big slaves work slower/small work faster.

DING DING DING! worse case scenario you could throw an adjustable prop valve on the line going to the rear.

 

[Jorge6.5]

Not original rear? If the slave cylinder is not the same size as the original then the master cylinder/prop valve may be sending too much pressure to the rear brakes, causing them to lock. Big slaves work slower/small work faster.

I thought the slave cylinder only has to do with the clutch? The slave cylinder is original to the truck.

The problem with the rear brakes locking only started recently, I've had the rear in the truck since October.

 

[Jorge6.5]

DING DING DING! worse case scenario you could throw an adjustable prop valve on the line going to the rear.

I have heard in the past about something to do with the proportion valve when I was researching the rear end swap. Honestly, I didn't give it much thought.

Where can I source an adjustable proportioning valve?

EDIT: just did a search and found some adjustable prop valves

Also, the brakes on this 14bolt sf are much bigger then the brakes from the original 10bolt rear. Basically my rear brakes are a bit overkill for my lighter smaller truck compared to a 3/4 ton truck.

 

[shortchevy]

I have heard in the past about something to do with the proportion valve when I was researching the rear end swap. Honestly, I didn't give it much thought.

Where can I source an adjustable proportioning valve?

EDIT: just did a search and found some adjustable prop valves

Also, the brakes on this 14bolt sf are much bigger then the brakes from the original 10bolt rear. Basically my rear brakes are a bit overkill for my lighter smaller truck compared to a 3/4 ton truck.

when IOWNJUNK says slave cylinders he is referring to the wheel cylinders, they are the "slave" cylinder of the braking system. if the wheel cyl is a different size on the 14bolt than the 10 bolt then your master cylinder is giving the wrong amount of pressure to the wheel cylinders which could cause your wheels to lock up.

 

[TylerZ281500]

when IOWNJUNK says slave cylinders he is referring to the wheel cylinders, they are the "slave" cylinder of the braking system. if the wheel cyl is a different size on the 14bolt than the 10 bolt then your master cylinder is giving the wrong amount of pressure to the wheel cylinders which could cause your wheels to lock up.

could but i havent had a single issue swapping to a sf on my yukon

 

[Jorge6.5]

when IOWNJUNK says slave cylinders he is referring to the wheel cylinders, they are the "slave" cylinder of the braking system. if the wheel cyl is a different size on the 14bolt than the 10 bolt then your master cylinder is giving the wrong amount of pressure to the wheel cylinders which could cause your wheels to lock up.

When I bought the new wheel cylinders, I got the ones specifically for the 14 bolt rear and I matched them to the old ones, they appeared to be identical.

Thanks for all the replies guys.

 

[98_k1500]

Try pulling the drums and just cleaning everything up. Simple fix and alot of the time it will resolve this issue. Another auto manufacturer that we must not speak of here had major problems out of this in the mid 90s and excessive brake dust build up was the culprit. If it only locks the rear wheels the first couple times you use the brakes, then they operate properly, this is your problem. If they lock every time, I'd look into the mis-matched master/wheel cylinders. I think the light duty trucks that the sf 14 bolt came out of have a regular 1/2 ton master cylinder. I am not sure if the proportioning valve is different or not.

 

[Jorge6.5]

So I can clean the drums with brake kleen. How do I go about cleaning the brake shoes?

 

[Alljackedup408]

Mine were locking up about a month ago. I had ridges on my drums.. had them turned and the problem is gone.

Might want to check that out too.. and give everything a good cleaning.

 

[98_k1500]

brake cleaner is safe to use on the shoes. just pull the drums and give everything inside them a good cleaning. I'm betting you will be suprised at the amount of brake dust build up on everything. Chances are this will fix the issue.