Manual to power brakes

[Old_iron]

I have most of the swap done, now I need to hook up the brake lines to the master cylinder prop valve. Which line goes into which port and do I have to install new ends on the lines?

[68 P.O.S.]

Not sure if the routing matters or not. There's other threads on here discussing this and it seems the lines were routed either way. I'd say do it the way the factory service manual shows. Hopefully someone will chime in with better info.

[Mbeef61]

What year? Drum/drum? Or disc/drum?

[AussieinNC]

Your pic shows a proportioning valve so I am assuming your truck now is disk/drum...if so...see pic for pipe routing...

If drum/drum, you dont need a proportioning valve, you need a distribution block...see pic of booster and master attached....

[randy500]

Another conversion not well thought out and probably mismatched parts.....

Your proportioning valve is for disc front drum rear....i assume you have converted that truck to disc?

Your brake lines are for drum brakes, disc brake trucks have a 3/16 front line and a 1/4” rear line, your lines both look like 1/4”
On the proportioning valve the front line is 3/16 standard fitting and thread size
the rear line fitting size i think is 9/16-18 threads, a special fitting.

Brake lines exiting the proportioning valve are front fitting to front brakes, rear fitting to rear brakes.

[AussieinNC]

One more consideration ....

If you have changed from drum/drum to disc / drum, did you relocate the front brake metal lines from behind the cross member to the front of the cross member?

As randy500 mentioned, the brake lines themselves are different sizes and fittings are different sizes, the routing of the lines themselves is different....

[Old_iron]

Truck is now discs up front, drums in the rear. So I need to run some new smaller line for the front? What do I need to know to get this working. It does not have to be original.

[randy500]

I believe the brake lines are smaller in the front with discs for a reason and i believe that reason has to do with proportioning the pressure to the front vs. the rear, its a system.

Since your current lines are too short and the fittings are not correct you should just buy a new set of lines. The long line to the rear is the same so you could use your existing line, i believe the disc lines connect at the same location and same fitting size.

As someone said before the hard lines connect to the rubber lines at the rear of the front tire so you also need a bracket there, someone posted a pic last week of this, maybe sold by CPP?

[randy500]

Post a picture of your booster...kind of looks like its a 3/4ton booster....is your truck 3/4ton too?

[randy500]

Now is see your truck is a probably a k20 with 2wd exhaust manifolds....whatever i said previously about brake lines was to apply to a 2wd truck.

72-2 4wd brake lines go down and follow the outside if the frame rail, crossing over at the front crossmember where the front lines T’s off to each side at left front of crossmember, rear line goes across then back

[Old_iron]

I am reviving this thread now that the snow is gone - I need to get my brakes working.

The situation: This '68 truck is a 3/4 ton 4wd. Originally it had drums front and back, manual brakes. I have replaced the front diff with a '72 to get the power brakes, etc and installed the brake booster/mc from the same donor (3/4ton 4wd - same).

This truck is a farm truck. It does not need to be original, it just needs to work and stop safely and reliably. I need to get the brakes working with minimal $$ and time.

The Question:
Do I need to buy a whole new brake line set/kit? Or can I just bend the lines so that they match up? Or just buy new front lines for a 72 3/4 4wd?

[Old_iron]

(pictures attached)

[demian5]

CPP sells the fittings to adapt the front and rear factory lines to the combination valve.

[Old_iron]

Originally Posted by demian5

CPP sells the fittings to adapt the front and rear factory lines to the combination valve.

I looked all over their site and can't find it. Do you happen to have a link?
So is it ok to use the original front lines even though they are the same size as the rear?

[kwmech]

Yup, as long as all the air is out of them.