Question about installing coilovers

[Matt_337]

I was inquiring about getting an alignment done for my car (just installed coilovers) and a local place who does work on cars that see track time asked me if I floated the suspension prior to installing the coilovers. He said that doing an alignment was a waste of money if I didn't do this previously.

Now, what he means by floating the suspension (based on my understanding of his explanation) is loosening up all of the pivoting parts that have bushings (control arms, etc) and then setting it down (with the wheels on) and then re-torquing all of those parts on. He said this would prevent the bushings from stretching and tearing once the coilovers were put on and the ride height changed.

I have had many cars and coilover installs previously and have never heard of this. I don't doubt what the man is saying because of the specialty work he does. What I am asking the experts here is, is this needed for a car that will see track time maybe once or twice a year? The shop that installed my coilovers said it wasn't necessary for the NSX. He said for certain Porsches it would be.

Sorry for the long post.
Thanks in advance

Matt

 

[Daedalus]

I assume your ride height is changing with the coilovers. If not, then the procedure is not necessary.
Without re-torquing, regardless of how much you'll be driving the car, the torsional bushings will always be stressed. As designed, they're neutral when parked and stressed only as loads/ride height change. Not sure how much more stress is involved, but if you wanted to take the measurments, you could calculate the shear. You would still need to translate the data into useful knowledge regarding life expectancy, which I'm unfamiliar with. At the very least, it would give biased pre-load values that would be different from the original design.
Keep in mind that a lot of these bushings are not easily replaced. They are integral to the suspension members; replacing the bushings requires replacing the (very expenive) members, unless you want to cut/burn them out and replace with poly. Doing so loses whatever benefits their torsional properties give, properties that were considered during the design phase.
That said, I disagree that an alignment would be a waste of money. Correct alignment is still important. Perhaps what he meant is that it would be a waste in that it would have to be re-aligned if you chose to loosen/retorque the suspension later.

 

[LJSB]

The best way is to do as your alignment shop suggested. With what it takes to do this (should of been installed that way anyway) and considering the subject (NSX:smile it's worth it to do it right. After all the hallmark of the NSX is precision.

 

[fkong777]

I dont think it is necessary with NSX suspension design. For BMW's there is Thrust bushing that needs to be tighten at static height... I dont see anything like that on the NSX.

 

[LJSB]

Well here's one more opinion. It's from the NSX service manual.
Repeatedly throughout the section where the "dampers" are removed/replaced/installed it states that the vehicle should be on the ground(suspension loaded) before they are tightened or torqued to spec.
For example:
"The bolts and nuts should be tightened with the vehicle's weight on the damper". Section (18-28)

"The vehicle should be on the ground before any bolts or nuts connected to rubber mounts or bushings are tightened."(18-29)

This procedure is nothing new in suspension work and it's the way it should be done.

 

[Matt_337]

Thanks for all of the feedback.

I will go with what the service manual says to do.