Back story:

1971 240z. Believed to be very stock and has sat in storage since early 80's.  Being put back together by me. Has sat on jacks since Oct of 2015.  Was driven/rolled into the garage by me at that time. Did light driving and seemed okay, but nothing at speed where the suspension would go through a large travel range.  Since then the relevant work I have done to this area is changing the rear differential fluid (Red Line 75W90NS) and serviced the rear brakes: new cylinders, new hardware, new hard and soft lines at the corners. rebleed. Reused existing shoes and drums. Checked function of parking brake.

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So, I put the wheels back on last night, and went to roll the rear passenger tire.  For one it was hanging very low in the corner.  2, it did not want to roll forward easily.  If I put enough rotational force on the tire, the corner would actually lift up and then roll over maybe 90 degrees and would then fall back down. If I keep doing this it will keep spinning and lifting, as if going over a hump.

If I jack the corner up enough (to roughly where the rear drivers side corner sits when in the air) it will roll freely.

Interesting note, when the corner is dropped down to its currently (lowest) resting position, when I roll the rear passenger tire the rear drivers side spins.  If i jack the tire up to a more reasonable resting position and roll it (which can now be done more easily) the drivers side tire does NOT spin.

Can anyone explain what is happening if something is not working as intended?  Very confusing.  The half shafts are hooked up and bolted properly, and the strut appears to be connected at the corner and to the frame.

 

Edited July 20, 20168 yr by DaveR

Looks like the rubber insulator at the top of the strut broke, letting the wheel drop.  You can probably see the remains above the tire with a light.  There's room to get your head in there now.  The dropped wheel is causing the u-joints in the halfshaft to bind, that's where the bumpy rotation comes from.

34 minutes ago, DaveR said:

the strut appears to be connected at the corner and to the frame.

Just saw this part. If you're looking at the studs on the top, the rip has happened below, tearing the studs from the rest of the rubber, in the strut.fender well.

If stored on jacks for long time strut can over extend.

Also, because the wheel has dropped so low it looks like the parking brake cable is holding it all up.

The cable is fine, it`s the cover/sheath that breaks easily then needs replacing.

Some more info for you guys.  It definitely seems to be the strut or something related to it. Attached are some photos that may shed some light.

I wasn't super excited to find the little custom plates on top of the struts, not really sure why they are there and what was removed/done prior to them. Seems like some metal was knocked off in that area, although i couldn't tell you why. Maybe to get more access to the nut at the top of the strut?

If i had some spring compressors I would have taken the strut out and taken a look up top, but that will have to wait.

I really want to get this car on the road and driving, if only to test stuff.  I assume it would be no go for me to ride on this strut temporarily? 

Thanks all

 

 

 

 

 

 

Also looking into how I can service this thing.  Trying to take apart as little as possible to get access.

Edited July 21, 20168 yr by DaveR

Are those pictures with the car on jacks or with weight sitting on the wheel?

You can remove the strut without removing the spring.  Disconnect the brake parts and the halfshaft.  Described in the Rear Axle chapter of the FSM.

Car will always be on jacks for these photos.  That last picture is with the wheel removed (i believe I am remembering correctly), so there is no additional hanging weight from the wheel, but i assume the spring is what is pushing it apart.

Seems likely that the strut is simply hyper extended. It doesn't look like the rubber bits are ripped up. Guess I'll be looking into new struts....  Since I don't have air tools I may attempt to get the spindle nut out of there so I can bring the entire assembly somewhere. Or disconnect the entire control arm and replace the bushings while I am at it.

and yes, unfortunately I think that cable has been loaded like that for quite some time in my garage.

Edited July 21, 20168 yr by DaveR

BGM was probably on it then.  I don't know how the extension stops work inside the shock but yours looks way over-extended.  Might be damaged in other ways also.  Should be okay to drive but don't catch any air.

Copied a picture of what grannyknot was talking about.  That's not good.

Seems like its the last thing I want to do... to tackle that spindle nut or those control bushings...  So I suppose now I look at how to replace the strut while its flopped over on the car.

I forgot about the FSM recommendation to remove the spindle pin.  You don't have to do that.  Remove the control arm with the strut instead, leave the spindle pin intact.  Four bolts.per side.  Take the whole thing out, replace the struts, leave everything else alone.  

The flop it out method would probably work, except that your strut is over-extended.  The other side might flop out while on the car though.  It's been described.

So I'm trying to wrap my head around the strut replacement options. Obviously the struts control the maximum travel, and the springs set the height... so is it safe to assume that any of the major strut options will work with stock springs? I know some struts specifically say not to be used with lowering springs, but I have never seen a strut say that it REQUIRED different than stock springs.

And while I realize its a good time to also do a spring swap... this strut failure was unexpected so I would prefer to not go down the spring path right now if I can help it.

Edited July 21, 20168 yr by DaveR