74 drum brake system tech

[rsbcruiser]

The SST method!

Let me see, gotta have one of these . That is for Coolerman. The first to expose me to the term SST. Thanks Coolerman. I like it! So, with the Master Cylinder pushrod in place and all of the stuff in the cabin set up correctly, just shove the Master Cylinder in place. Pay attention to that gap shown. If the pushrod is too long then you will feel it make contact and start depressing the Master Cylinder spring. Get it, it is that simple. If it is too long then turn that little nut on the pushrod back. Keep going at it until there is no more contact between the Master Cylinder and the pushrod. You can actually tell the difference between a few thousanths of an inch using this method. A thaousanth of an inch looks like this, 0.001". The FSM states that there should be a 0.004" to 0.020" gap between the Master Cylinder and the Master Cylinder pushrod.

 

[rsbcruiser]

The modified SST method

Sorta left you hanging back in the last post. So to achieve that .004" to .020" gap all you have to do once you found the point where there is no contact betwen the Master Cylinder and the Master Cylinder pushrod is to turn it back another 1/4 turn. Done! I used calipers to measure between adjustments. writing the numbers down each time. See the intervals? Most are from 1/4 turns of the Master Cylinder pushrod. A little less than 0.020". The red arrow points to the final length.

 

[rsbcruiser]

Fooled you!

This is an aside to the vets guys. Ha Ha! You guys thougth I was going to show them how to dead measure the whole thing didn't you? Heck no, why drag them through that! Back to you Newbies now. You can actually measure your way through the SST method. If you are handy with calipers.

 

[Coolerman]

Many times in your life, you will, or already have run into two of the paradigms predominant in the Industry. One I will call Old guy knowledge. The other is the text book said so knowledge. between the two somewhere lies the truth, seek it out!

Now ain't that the truth!

 

[Coolerman]

Sorta left you hanging back in the last post. So to achieve that .020" gap all you have to do once you found the point where there is no contact betwen the Master Cylinder and the Master Cylinder pushrod is to turn it back another 1/4 turn. Done! I used calipers to measure between adjustments. writing the numbers down each time. See the intervals? Most are from 1/4 turns of the Master Cylinder pushrod. A little less than 0.020" The red arrow points to the final length.

Hmmm, so adjust until the desired effects are obtained...

Good info on the 1/4 turn = about 0.020. The SST to do that job is made from unobtanium

 

[rsbcruiser]

Consider sticking close to home for a while

So, lets assume you have set up your brake system and are now ready to hit the road. As far as the brake actuator system goes....maybe you should stick close to home for a trip or two. Two things could happen. The first problem could occur if you set up the brake actuator system too long. Therefore, every time you step on your brakes you are building pressure in the brake system. If there is no freeplay in the system then the Master Cylinder can not return passed the port that opens to the resevoir. When this happens pressure will build in your system until the brakes are locked solid. If you try and drive the rig with this condition then you are destroying the brake shoes, polishing the drum surfaces and generally making a mess that will need to be adressed before any hope of attaining a well funtioning brake system can be achieved. Yep, you ruined the drum system, bummer! The other side of this coin is if you set up the actuator system too short. Then you will have a permanent lag in the brake peddle that will be a nuisnce. No drum adjustments will fix this problem.

 

[rsbcruiser]

replacing the brake hoses

I will start with the rear axle flexible brake line. The first step is to disconnect the fitting shown. Next you can go after the connection on the axle. Clean up around the fitting first. That one is a real knuckle buster.

 

[rsbcruiser]

Modify the rear flexible line bracket

You will have to modify the rear flexible brake line bracket in order to fit the new stainless steel brake line. when you install the back flexible hose you will need to use the clip shown. There is a c-clip provided to hold the opposite side in place.

 

[rsbcruiser]

Install in reverse order

Don't forget the copper washer that goes on here. Coat with antisieze and install the rear brake line in reverse order.

 

[rsbcruiser]

Now on to the fronts

same routine really as the back. Break this one first.

 

[rsbcruiser]

Now diconnect this one. check out the angle on the hose where the rubber was missing. Scary!

 

[rsbcruiser]

This front hose fits into the bracket with no modification. Make sure to clean the bracket up first. Note the rubber booty covering the hard line inlet to keep debri out of the system.

 

[rsbcruiser]

This picture shows the clip you will have to use here to secure the line. The other arrow points at the copper washer. Anti-sieze on all of the fittings.

 

[rsbcruiser]

The front flexible brake line from the frame to the axle installs like the back. So, we are done!

 

[PabloCruise]

Holy cow! This is an awesome resource!

Thank you for creating!!!