I installed my Hotchkis springs over a year ago, and I have a question about my installation method.

I've done suspension spring/strut installs on both my DD and the Z, and each time I have just performed the install while the car was up on jack stands (using factory torque specs). I just recently saw in my service manual for the Z that they recommend that a final torque of suspension bolts be done with the tires on the ground and the vehicle unladen. I've drive about 10k with the Hotchkis' on the Z, and about 50k or so with the suspension on the BMW with no problems at all.

I guess I could just go back and do a torque check on a lift, but that'll have to wait til spring when I take the Z back out and actually have access to the drive-on type lift.

All the DIYs I've ever seen for either car never mention on-ground off ground torquing.

Just want to get some thoughts on when it's important to consider unsprung weight and stuff like that.

 

when you torque the bolts at the normal ride height the rubber busings are in a neutral position...

but when you torque them down with the suspension fully extended, then let the car down, it twists up the rubber busings the whole time the car is on the ground. its not the end of the world, but doing it the way the manual says will let the bushings last longer.

 

+1 if you tighten all the bolts in full droop the bushings will have preload on them when you put the car back onto its wheels.

either use ramps to loosen everything then tighten everything back up or if it's on jack stands put a jack underneath your lower control arm, raise it until your car lifts slightly off the stands, then tighten everything again.

same thing applies to installing a sway bar.

 

Why isn't this technique more widely covered?

I've been driving like this for 15k miles.

Is that safe to loosen everything and then re-tighten w/ the suspension compressed?

 

I was just thinking you don't pre-load the wheels with the weight of the car when attaching the lug nuts, so why should I pre-load the suspension in the same fashion. Both are susceptible to immense stress + the weight of the car.
So it's not a situation where the bolts are going to loosen and whatnot (i'd think not since i've done a lot of driving since the install), it's only a method to help the bushings?

Thanks for the response btw.

 

You dont preload a wheel, because the conical shape of the lug helps center the wheel. Its alot tougher to do if the wheel is preloaded. I always bring it up snug and do the final torque once the wheel has been centered. At this point it can be preloaded. Good info though, this year I want to do the drop

 

I dont think you have anything to worry about at all. This recommendation is scientifically accurate, but I have yet to see any issues with trqing things down in the air. The bushings we are speaking of, are not made of soft rubber...they are extremly rigid.

In fact, every race team I have worked around, or been around, trqs things down in the air. It's just not practical to do otherwise.

 

Thanks for the response, Sharif.

 

A little update: The manual actually says to do the "final torque" of the points in the front and rear suspension that use rubbing bushings with the wheels on the ground. So you are applying the initial torque while the car is still in the air, and then the final torque once you lower its weight back on the wheels. Doesn't that still mean you are pre-loading the bushings?

 

Another question: When installing my springs last year, I re-used the nylok lock nut threaded to the top of the shock absorber shaft that secures the mounting insulator, upper spring seat, and spring itself to the actual shock absorber.

In my service manual, I was looking up something unrelated, and realized that Nissan says that you must replace this nut after each disassembly. They also say to replace a shi*load of other stuff when you do any disassembly on the car, too (e.g. the plenum gasket, exhaust gaskets, the nuts used to attach the cats), all of which I have reused with no problems. That ok?

Anyway, I've driven 10k+ miles since the install, and I was (up to this point) totally pleased with the coils and my install. The suspension is noise free, and feels very tight.

But now I'm concerned because I do corner my car hard very often, and the last thing I need to happen is to be up in Vermont driving up or down a mountain and lose a shock assembly, then it's bye bye Blackfairlady.

I feel as if this is one of those posts that I am going to do my own thing anyway for piece of mind, since it's my life and all, but I thought I'd throw it up here so others don't make such a trivial mistake in the future.

 

i keep my bolts loose then torque them down with the weight on the suspension.

yes, if you torque them tight in the air then it defeats the purpose. so the initial torque in my case: loose. ha

i wouldn't worry about the nylock nut coming loose. i don't know the specifics of the z's mounting, but on a miata the nut on the shaft doesn't really keep the shock on the car anyway. it's the three bolts that bolt the shock to the body sheetmetal.