240Z/240K rear brake drums interchangeable?

[Alfadog]

I have a pair of rear brake drums that came spare with my 240Z when I bought it, but were lost in the deep dark cave known as the "garage" some time ago. I found them again the other day and thought why not swap them into the 240K? They look fairly identical except the Z has heatsink shims around the drum.

Before I go ahead and do it, is it ok??? I don't see how it could be a problem, but I thought I better ask.

Here are some pictures. Both are marked with MAX. DIA. 230.0MM, 9.055 as shown in the second image.

[sakijo]

It's a popular upgrade for the 510/Bluebird and Skylines of the era. I would get them checked for warpage, though. I had a set and the mechanic said they were warped so I couldn't use them. The finned aluminum is supposed to dissapate heat better than the cast iron.

[Alfadog]

Excellent information! Thanks Miles.

[Z Kid]

I know when putting them on the 1600 you have to grind off the outer lip of the backing plate to make then fit right down, or get the fins machined off the bottom 3mm of the drum to fit. I would suspect that the 240K would have more in common with a 1600 rear end than a Z. So yes they are the same size, but may require some trimming down.

[sblake01]

I have put them (finned aluminum drums) on a 510 in the past and on my 810. Both of those also required modification of the backing plate. I suspect that they would have to be modified to fit anything other than an S30.

[Alfadog]

Right on. I didn't notice that when I test fitted them :stupid:

Anyway, I've got them on now and they look nice (as nice as drums can look), but they don't work/b]. I don't know what I did wrong... The handbrake doesn't work and I can tell through the foot brake that they don't work too... When I pulled back into the driveway I gave it a BIT more pressure and the rear (right?) went something a little like "CLONK!"

I have to admit, I did apply the footbrake while the rear right was off. Could this have done something?

I'm so not cut out to be a mechanic

[dhoneycutt]

Sounds like you probably blew the wheel cylinder out. Time for a rebuild. When you applied pressure without the drum on there was nothing to keep the brake shoes from expanding more than normal causing the pressure to push the pistons in the wheel cylinders out and "blowing" off the rubber caps. If your lucky you didn't rip the rubber caps and maybe able to reuse them. However, I would probably rebuild them both for safety's sake.

[Alfadog]

Great. Looks like I need to get a loan.

[dhoneycutt]

Great. Looks like I need to get a loan.

It sounds alot worse than it is unless you are driving the car with it that way. It is a pretty simple task to do. Go buy a wheel cylinder rebuild kit for each rear wheel and brake fluid. Watch how you take it apart. Clean everything real good. Put the new parts on. Repeat for other side. Bleed the brakes. I may have missed a step or two but it really is pretty easy. Good luck. Gotta love these old cars!!!

[sakijo]

I have to admit, I did apply the footbrake while the rear right was off. Could this have done something?

You drove the car with only one drum on? Or was it parked and you stepped on the brake and one drum was off? I think David's right, you popped the wheel cylinder.

I'm so not cut out to be a mechanic

No, you just need more practice . . . .

[Alfadog]

No I didn't drive it without a drum, I was just too curious and had to see it working.

I'm learning - just so happens I'm learning the expensive way.

[440k]

Haha don't worry Lachlan - we've all made mistakes - some more expensive than others.

At least you're having a go - that's more than I can say about many people out there.

Considering the age of the car, it might be worth pricing new wheel cylinders. If they're really cheap, probably best to go that way, rather than try to rebuild the old ones.

They will be a ba$tard to replace (nothing too difficult - just a pain in the rear) but nothing's impossible. There are a series of interlocking shims that hold the assembly in place (on the back side of the backing plate) that are very fiddly to fit. Just make sure you note the order they come off, and make sure everything's clean, and it should be fairly straight forward (making sure you don't bend them in the process).