I'm in the process of replacing rear brake shoes and cylinders on a 1966 122s. I've got the drum off one, working on another. This is my first brake job on a car. No doubt I'm making mistakes as I go. Here are my questions. The first one reveals my ignorance of basic knowledge about drive-train engineering on cars:

1. If the car is in gear (& obviously up on jacks) should the rear axle turn? In working to get the drum off, I found that the axle was spinning. (I used a pry bar to stop the motion when banging on the drum puller.) What's the engineering principle in play that allows the axle to move when the car's in the air but in gear? (I thought the engine compression/being in gear would create resistance, like on a BMW motorcycle). Also, should the car be in gear when banging away on the drum puller? Could I damage the drive train in banging on the drum puller if the car is in gear? Maybe already have?

2. Does somebody know the diameter of the nut on the brake line fitting where it attaches to the rear brake cylinder. I want to get a flare wrench that fits. Thanks in advance.

E;

If the entire rear axle is lifted, as I suspect you have, doing a brakejob on both sides, you'll find that when you turn a rear wheel while in gear, the other side rotates in the opposite direction due to the differential...if fact, this is one way to check if you have a locking dif...they'll turn in the SAME direction if you do...

Because of the forces involved, I do not leave the trans in gear...I don't feel good about subjecting everything to those forces either (hell, people leaving the trans in gear is probably the cause of timing gear hub failure!!!!). The impact will work just as well against the intertia.

3/8" nuts are used brakelines.

More notes on brakes here: http://sw-em.com/service%20notes.htm#Braking%20System

Cheers

Ron, Thanks. I've read quite a bit re doing the brakes and never got a tip whether or not to put the transmission in gear (I've a 4-speed) when pulling the drums. So I decided to put it into 1st. After pulling the one drum (and really having to beat on the puller to do it) it occurred to me how much force I might be transfering through the entire drive train. I guess I'll see if any damage was done once I get the brakes in & car down off the jacks.

I take it from your response that once the car is up on jacks (yes, I am using two jack stands under the rear axle) even if the car is in gear (e.g., 1st) the axles will spin rather freely. This, I take it, has something to do with how the differential works.

This may seem obvious, but be sure to only work on one set of shoes at a time so you'll have the other side to use a reference during reassembly.

On the line fittings: give them a good soaking in PBlaster or Liquid Wrench if they appear rusty. If turning the fitting appears to be turning the line as well, STOP and let it sit for awhile longer. Maybe give the fitting some mild taps with a drift to break it free from the line. It is rather easy to twist and break the line.
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(2) '73 1800 ES 'projects', g/f's '73 1800 ES