wheel cylinders

[ggdad1951]

ok quick question. In my notes I have the wheel cylinders with the larger bore piston forward and the small towards the rear.

While I was out getting some parts, my friends assembled the rear axle with the large bore to the rear. This isn't "right" per my notes, and I'm wondering how much of a problem this is?

Please advise!

[KJ's Dodge]

The small bore is always towards the front. I asked the question a couple of months ago. So, take a look at the following tread for the answer.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=23324&highlight=stepped+wheel+cylinders

[ggdad1951]

well ok then, I will assemble accordingly.

[TodFitch]

I don't have step bores on mine (they came later), but I believe that KJ's Dodge is correct.

The leading shoe will "self-energize" (i.e. the rotating drum will pull the shoe out some) and so it needs less force from the wheel cylinder to get the same braking effect as the rear shoe.

The amount of force applied by the wheel cylinder piston to the shoe is proportional to the pressure (same for both bore diameters) and the area of the piston (which goes up with the diameter). So there is more force applied to the shoe on the large side of the cylinder and you want that to be the trailing shoe so that both shoes have equal total force (wheel cylinder + self-energizing).

[Merle Coggins]

Yup, I just looked in my shop manual again. Small piston to the front, large piston to the rear.

Merle

[ggdad1951]

the why the H-E-DOUBLE hockey sticks do my old ones have an "L" and "R" cast into them opposite of that? Good news is the rear is together right and I can continue with the front brakes with some confidence.