Rear drum locked up on 1971 240Z

[ZG240Z]

Hello all, and Happy New Year...

I'm having an issue with my car that I hoped would have a simple resolution, but so far I haven't been able to hit upon it. The last time I drove my car, a few weeks ago, I noticed that the driver's side rear drum seemed to be dragging pretty good. I put the car up on jackstands, pulled the rear driver's side wheel, and was unable to get the drum off easily. So I did what we've all probably had to do at one time or another, and I spent about an hour whanging on it with a rubber mallet...until I was finally able to pull the drum off.

This car has an original master cylinder, relatively new front calipers with Hawk pads, stainless steel braided lines all the way around, aluminum drums and Akebono shoes in the rear.

I pulled the shoes and springs and replaced them with a brand new set from MSA (I will do the other side as well). My process was this -- I cleaned everything up with brake cleaner, adjusted the 'star wheel' all the way down, installed the new shoes and springs, applied brake lube where the FSM says to do so, put the drum back on, and then adjusted the shoes with the emergency brake (and a few clicks on the star wheel). I bled the brake at that corner and added MOTUL fluid -- I haven't done all four brakes yet -- and all seemed to be well, and perfectly adjusted.

When I tested the brake pedal to see if I had a good firm pedal, I did. I also noticed that the rear driver's side wheel would no longer turn easily, if at all. So I appear to be right back where I started.

My observation is that when I stepped on the brake pedal, I locked up the drum again. What would cause this? Do I need to replace the wheel cylinder?

It's my understanding that the wheel cylinders for a 1971 model are pretty expensive ($319.87 for the driver's side cylinder at Motorsport Auto). Is there another source? I used to buy parts from Riley Curtis at Lynchburg Nissan; is he still the go-to guy here? Am I totally on the wrong track?

Any help or ideas are appreciated.

Thanks!

Brian in Asheville NC

 

[grannyknot]

How is $56.00? https://www.rockauto.com/en/catalog/nissan,1971,240z,2.4l+l6,1209158,brake+&+wheel+hub,wheel+cylinder,1952

It does sound like the wheel cylinders, so gummed up with crud the pistons don't want to retract. Do yourself a favor and replace both sides while your at it.

[ZG240Z]

My understanding was that the stock brake line wouldn’t work with the aftermarket wheel cylinders. Can anyone confirm?

[siteunseen]

I had to bend my short hardlines to use the newer ones. Wasn't too much trouble for the price difference.

https://www.classiczcars.com/forums/topic/58728-early-late-wheel-cylinders/

 

[Av8ferg]

I had a terrible time getting my drums off when I redid my brakes. After looking for a large puller hi and low on both line an locally I decided to devise my one and it worked perfectly. Had the drums off in under 10 mins.

I bought two large c-clamps at Lowes and placed a 2x2 wooded board between them with a large socket taped to the middle that would pass through the drum.
Here’s a pic, way better than beating the drums and breaking a cooling fin off. The only trick is to the turn each c-clamp a small amount and in sequence with the other one or the device will pope off due to becoming uneven.




Sent from my iPhone using Tapatalk

[Av8ferg]

I had a terrible time getting my drums off when I redid my brakes. After looking for a large puller hi and low on both line an locally I decided to devise my one and it worked perfectly. Had the drums off in under 10 mins.

I bought two large c-clamps at Lowes and placed a 2x2 wooded board between them with a large socket taped to the middle that would pass through the drum.
Here’s a pic, way better than beating the drums and breaking a cooling fin off. The only trick is to the turn each c-clamp a small amount and in sequence with the other one or the device will pope off due to becoming uneven.




Sent from my iPhone using Tapatalk

[ZG240Z]

4 hours ago, siteunseen said:

I had to bend my short hardlines to use the newer ones. Wasn't too much trouble for the price difference.

https://www.classiczcars.com/forums/topic/58728-early-late-wheel-cylinders/

 

Thanks, this is really helpful. Did you cap off the brake lines to preserve the brake fluid that was in the system, or did you let it run dry?

And Av8ferg, that drum brake puller is brilliant — I will try that if the drum really is stuck fast again. I’m finding that it’s getting harder and harder to work on these cars after you turn 50.

[siteunseen]

I don't rember capping anything and it seems like only a small amount of fluid came out, just leave the reservoir cap on.

I bled the air out for sure afterwards. I would use the dot 3 fluid too. The newer dot 4 doesn't play well in older cars/motorcycles from what all I've read.