Mixing JB3 and JB5 brakes

[Ronno6]

I purchased an 84 C10 that has JB5 disc brake setup on front, and JB3 drums on the rear.
I have replaced every piece of hardware but cannot get the rears to stop locking up.
All calipers,pads,drums,shoes,wheel cylinders, master cylinder and proportioning valve have been replaced and bled,bled, and more bled.
Nothing helps.
Parking brake adjustment has been backed off. No help.
I have only read 1 post on a forum in which a guy had done this and had to upgrade rear brakes to JB5 in order to balance the system.

I know this would require drums,shoes, and cylinders, but what about the brake pivot and hardware?

Any resources available which I have not yet found?
thanks.

 

[4WDKC]

I dont see flexible hoses on the list. Could they be bad and either not letting pressure pass through the front only allowing rear brakes to work or not letting enough pressure return fro the rears causing lock up when applying the brakes?

 

[Ronno6]

I have not was of yet replaced hoses. Plenty of fluid gets thru when bleeding the brakes,tho.
Could be a possibility...

 

[4WDKC]

I have not was of yet replaced hoses. Plenty of fluid gets thru when bleeding the brakes,tho.
Could be a possibility...

Could be the issue, i know my truck does this but I put the JL7 or 8 calipers when I did the disc conversion on my 14bff.

 

[Charlie]

 

[bucket]

One option would be to install an adjustable proportioning valve to adjust the front/rear bias.

 

[Ronno6]

One option would be to install an adjustable proportioning valve to adjust the front/rear bias.

I have thought about that, but only as a last resort.
I have received a few suggestions that the rear hose may be acting like a check valve, so I a, going to replace it and see shat happens.
I have a set of JB5 rear brakes on the way. I'll upgrade when I pull the rear end to do my posy/gearing mods.

 

[dvdswan]

IMO, I would replace all 3 brake hoses at the same time. Fronts may be a little more worn than the back allowing them to expand/swell more and the pressure all goes to the back.

 

[chengny]

I purchased an 84 C10 that has JB5 disc brake setup on front, and JB3 drums on the rear.
I have replaced every piece of hardware but cannot get the rears to stop locking up.
All calipers,pads,drums,shoes,wheel cylinders, master cylinder and proportioning valve have been replaced and bled,bled, and more bled.
Nothing helps.
Parking brake adjustment has been backed off. No help.
I have only read 1 post on a forum in which a guy had done this and had to upgrade rear brakes to JB5 in order to balance the system.

I know this would require drums,shoes, and cylinders, but what about the brake pivot and hardware?

Any resources available which I have not yet found?
thanks.

It sounds as if you are all over this, but just in case:

Probably the most common cause of rear drum brake grab is that the shoes are reversed. IOW, the smaller leading shoe is in the back and the bigger lagging shoe is towards the front.

• Shoes/Linings incorrectly installed. Each side should have a leading and trailing shoe. The lining surface on the trailing shoe will be slightly larger than the lining surface on the leading shoe. The trailing shoes should be installed in the rear position on each side, while the leading shoes are installed in the front position on each side. If the shoe positions are reversed, the braking performance will be very grabby and prone to wheel lockup.

They should be installed as shown below:

You must be registered for see images attach

 

[Ronno6]

It sounds as if you are all over this, but just in case:

Probably the most common cause of rear drum brake grab is that the shoes are reversed. IOW, the smaller leading shoe is in the back and the bigger lagging shoe is towards the front.

• Shoes/Linings incorrectly installed. Each side should have a leading and trailing shoe. The lining surface on the trailing shoe will be slightly larger than the lining surface on the leading shoe. The trailing shoes should be installed in the rear position on each side, while the leading shoes are installed in the front position on each side. If the shoe positions are reversed, the braking performance will be very grabby and prone to wheel lockup.

They should be installed as shown below:

You must be registered for see images attach

I definitely had shoes installed correctly.

As a follow up, I finally got the truck back on the ground after installing 3.73i posi in place of the 2.73 open diff. I upgraded the rear brake system to JB5, same as on the front.
Rear skidding is OVER.....matching components did the trick.