1975 280z front struts

[Dave WM]

I decided to remove the front strut after noticing that the passenger side was weeping a good amount of oil and the bounce test seemed iffy when pressed down on that corner. It seemed fine when bouncing the middle front but not so much on the corner.

after getting the strut out and the spring off I found little to no damping action at all in compression or rebound. It was the orig strut hardware (not a cartridge). I decided to try replacing the oil (after some research I ended up with some 15wt fork oil from a motorcycle shop, belray IIRC), 310ml, put a new o ring in as the old one seemed a bit deformed, reassembled and cycled thru a few times (much better now), then installed the spring. I reused the old glan nut, the rubber wiped seemed ok so I greased up and reused. I have to replace the boot (it tore in the disassembly process, should have been more careful) so I left it off for now, better to see if the seepage is gone. I do see some seepage after driving for a while, I suspect the glan nut wiper/seal is not working very well. The is a local hyd seal place near by so the plan is to take it to the guy and let him look and see if there is something that will work. If not I have a spare glan nut with a use seal that I may try.

As far as the process to remove the strut, could not have been simpler, jack up front, remove wheel and brake caliper (use a plug to stop the brake fluid from leaking out of the hard line), unclip the brake line and fish it up thru the holder that is mounted to the strut. loosen the sway bar top nut and the control arm bushings to make it easier to move the control arm down. remove the 17mm bolts from the bottom of the steering knuckle and the strut will be free on the bottom, remove the 3 top mount nuts on the insulator (while holding the strut so it does not drop) and its out. I did NOT remove the brake hub/rotor as could not see a reason to do so. It is heavy with all that stuff but not too much to make it worth the effore IMHO.

Used a BF adjustable wrench the remove the glan nut, no problem at all just brace up the wheel hub with on foot and crank on the BFAW and it came right off. putting back together was just as easy, just have to remember to re  torque the control arm nuts (19mm) with the suspension settled under load. I used a HF coil spring compressor, its almost too big for the spring but easily compressed it. I used a air ratchet to speed things up (not an impact, not needed as the Z springs are not that stiff). I am not sure why the recommend no air tools so do at your own risk. It was all very easy, again just make sure you loosen up the bottom of the boot and slide it up as far as you can before starting the process and make sure your spring compressor stays clear of it.

I know there are cartridges out there but I am a stock kind of guy and would prefer to keep it original. Not racing it so no need for the added performance of a gas shock.

 

[S30Driver]

I don't know Dave ... but these may be in your future :   https://zcardepot.com/suspension/shocks/kyb-front-shocks-struts.html    (you just might be the only member on this site running the original non cartridge struts)

It is also likely if the rears are the same age, they will be bad as well,  and will make the biggest difference.

[Dave WM]

one quick question, while I did mark the strut insulator I was wondering if there is a "right" way to install in. I noticed that the flat is pointing back a little toward the inboard nut. I wonder since the insulator seems to wobble when spun on the spring mount, indicating that the flat metal part of the insulator that rest on the bearing is not plumb with the centerline of the hole. there is also 3 molded rubber nibs on the bottom of the insulator rubber part, perhaps for orienting correctly? It would seem possible that changing this could effect the castor or camber depending on how its installed.

do me a favor all, pull the front rubber plug on your struts and see which way the flat of the threaded rod is facing please. I don't recall any mention of this in the FSM.

Edited May 31, 2017 by Dave WM

[Zed Head]

27 minutes ago, Dave WM said:

do me a favor all, pull the front rubber plug on your struts and see which way the flat of the threaded rod is facing please. I don't recall any mention of this in the FSM.

You'd have to find somebody with factory installed struts, never removed.  Mine were, seven years ago, but I can't remember the oprientation

The insulator rubber is compressed unevenly when installed and it will take a set.  I've noticed it on all of mine.  If you get both sides installed the same way you'll probably be fine until the rubber "resets".  I think that nubs are vents or sprues for casting.

Could be wrong but I don't think that that giant chunk of rubber is a precision part.

[Dave WM]

had not thought about it taking a set. I have some new ones on the way, will check to see if they have the same wobble.

[Dave WM]

finally  had a chance to try out the strut repair (new o ring and replaced the lost oil) wow what a diff 90mph with none of that floating feel like a disconnect from the steering. Very happy. will have to pull the strut again t replace the torn boot, and add another 30ml of oil (shb 340 I did 310). After that will do the other side just so I know they are matched. will get to the rears soon as well.

[Dave WM]

new strut insulators came in, do not have the same wobble so looks like the old ones do take a "set" with age. New ones will go in later this week.

[Dave WM]

passenger side I replaced the torn boot, added some more oil (340ml not 310ml), installed new insulator.

driver side, turns out the damping was pretty shot on that one too, not as bad as the passenger was but still not very good.

new O ring, new oil (340ml 15wt fork oil belray), new insulator, boot was ok. This time I did not remove the brake caliper, just unhooked the hard line from the strut and disconnected at the brake caliper, capped it to prevent fluid loss. 2 17mm nuts on the steering knuckle, loosen the control are at the frame mount, take off the top nut on the sway bar and it ready to come out. Leaving the brake parts on make the strut heavy but not impossible. the BFAW handled the gland nut no problem. put it all back on, set car down and tighten up the control rod bushings under load. Got to clean up the garage to night then take it out for a test ride. The front has no bounce at all a hard push down it just sinks and then comes up with out a hint of bounce after the rebound.

[Dave WM]

I don't know if its just my imagination or not but it sure seems like the road noise has gone down with the new insulators, or maybe I just think so since they cost 120$, whatever it sure seems better. I can tell now the rear struts have to be done as they def has more bounce than the front have now that I have put in fresh oil and new o rings.

On the rear can't buy new insulators though (tall ones) so will have to re use them or some other used ones I bought if the orig are in sad shape. I recall seeing a spacer that is being sold though that would allow the short ones to be used. Anyone have any feed back on that?

Edited June 11, 2017 by Dave WM