What is the factory ride height? Back Yard Shock settings

[nomac]

I cannot find the stock/factory ride height. My new 91 has 100mm under the jacking points and 110mm under the front lugs. I see I have Back Yard NSX shocks with 2 rings above the perch in the back and 3 rings in the front.
Moving to the highest ring would add 20mm, making a ride height of 120mm (4"). Is this the factory setting?
Thanks

 

[nsxtasy]

I cannot find the stock/factory ride height.

Then apparently you can't figure out how to search for topics with "Ride Height" in the title. Otherwise you would have found this one, which answers your question:

Ride Height

 

[nomac]

Thanks, nsxasy for the link. I was searching for "stock ride height" and "factory ride height". I will learn more. I have only been on this site for 2 weeks and trying hard.
I see wrote the ride height reply in 2006. You say your stock setting is 4.5 to 4.74 and the factory setting is 5.3. Why the difference?

 

[Honcho]

The only correct way to measure the ride height is to use the method described in the service manual. "Finger gap" and measuring the jack points will not give you a reliable number. You need to measure the height to the middle of the front lower arm bolt and the height to the middle of the rear toe arm bolt. For a stock 1991 NSX on OEM 15/16 tires at factory pressures, the range is:

Front: 170 to 180 mm
Rear: 213 to 223 mm

 

[nsxtasy]

You say your stock setting is 4.5 to 4.74 and the factory setting is 5.3. Why the difference?

(but see below)

The only correct way to measure the ride height is to use the method described in the service manual. "Finger gap" and measuring the jack points will not give you a reliable number.

You are correct, this is the proper way to measure according to the manual. However, measuring using the bottom of the jacking tabs should also be reasonably reliable and consistent from one measurement or car to another. It's also much easier to do it that way because the jacking tabs are much easier to reach, without any need to crawl under the car. Plus, it's a shorter distance so the measurement itself is likely to be more accurate.

Finger gap is inaccurate because it does not involve a vertical line between easily recognizable points.

Regardless of method, all measurements of ride height depend on tire make/model, tread depth, and inflation. Different make/model tires labeled as the same size may in fact be slightly different sizes. The difference in tread depth between a new tire and one that is worn and needs replacement can be .25" or so. And pressure in the tires has an effect as well. So all measurements need to be considered approximate, not precise.

 

[Wild Turkey]

I cannot find the stock/factory ride height. My new 91 has 100mm under the jacking points and 110mm under the front lugs. I see I have Back Yard NSX shocks with 2 rings above the perch in the back and 3 rings in the front.
Moving to the highest ring would add 20mm, making a ride height of 120mm (4"). Is this the factory setting?
Thanks

My first post is to a 7 year-old thread. Shouldn't be too controvercial.

I'm trying to figure out if my new (to me) NSX is lowered. It has Bilstein shocks and Zanardi springs, which I found out from other threads is not supposed to be lowered. All of my jack points are within a 1/16th 4" (Note this is 101.6 mm, not 120mm!) I'm on stock tires, with new tread on the fronts and about 50% wear on the backs.

My best guess is that I'm at stock height.

 

[Honcho]

My first post is to a 7 year-old thread. Shouldn't be too controvercial.

I'm trying to figure out if my new (to me) NSX is lowered. It has Bilstein shocks and Zanardi springs, which I found out from other threads is not supposed to be lowered. All of my jack points are within a 1/16th 4" (Note this is 101.6 mm, not 120mm!) I'm on stock tires, with new tread on the fronts and about 50% wear on the backs.

My best guess is that I'm at stock height.

Welcome to Prime! Make sure to post pics of your new ride in the new owner section.

The "stock" ride height depends on whether you are using OEM wheels/tires at the factory pressures. For cars on the original 15/16 Phat Fives with 205/50 F and 225/50 R tires, or cars with the 16/17 7-spokes with 215/45 F and 245/40 R tires, the correct height measured to the center lower control arm bolt is:
Front: 170 - 180 mm
Rear: 213 - 223 mm

See below, which shows you where to measure. Make sure you're on a level surface.

The Zanardi springs lower the car about 10 mm in the front and 5 mm in the rear, so even if your springs are on the top perch of the Bilsteins, you should be a little lower than stock.

 

[Honcho]

*** MODERATOR NOTE ***

Moved to correct forum.

 

[Wild Turkey]

That's what I was getting at. As NSXTACY noted, there should be a fixed relationship between the control arm bolts and it's also difficult to measure to the center of a bolt, so there should be be a corresponding measurement to the jack points that would would be easier to use. But I guess not.

 

[Wild Turkey]

Finally got out and measured my ride height and confirmed that my Zanardi springs seem to have lowered my ride height by 25 mm.

I also took my wheels off and jacked the front and rear to exactly the spec for the Lower Contol Arm Bolt and the [FONT=Inconsolata, monospace, arial, sans, sans-serif]Toe Contol Arm Bolt. I then measured the height at the Jack stands at 5 5/16". With a tolerance of +/- 5 mm, that would work out to +/- 3/16".[/FONT]

[FONT=Inconsolata, monospace, arial, sans, sans-serif]But that works only if the car is level, with both front and back out by the same amount. Otherwise a lever effect could occur where the jack point spec looks says one thing, but the ride height is out by more because the correct measurement points are further from the center of the car.

As Honcho said, you have to measure at the correct locations, which aren't that hard to access.[/FONT]

 

[Honcho]

Finally got out and measured my ride height and confirmed that my Zanardi springs seem to have lowered my ride height by 25 mm.

I also took my wheels off and jacked the front and rear to exactly the spec for the Lower Contol Arm Bolt and the [FONT=Inconsolata, monospace, arial, sans, sans-serif]Toe Contol Arm Bolt. I then measured the height at the Jack stands at 5 5/16". With a tolerance of +/- 5 mm, that would work out to +/- 3/16".[/FONT]

[FONT=Inconsolata, monospace, arial, sans, sans-serif]But that works only if the car is level, with both front and back out by the same amount. Otherwise a lever effect could occur where the jack point spec looks says one thing, but the ride height is out by more because the correct measurement points are further from the center of the car.

As Honcho said, you have to measure at the correct locations, which aren't that hard to access.[/FONT]

25 mm is a lot for the Z springs. Did you check to see if the springs are mounted on the lower perch of the shocks?

 

[silver2002]

My question: can you measure rake by comparing front jack point height to rear jack point height?

 

[Wild Turkey]

My question: can you measure rake by comparing front jack point height to rear jack point height?

Seems to me you should be able to, since I measured them as equal at 135 mm when I had jacked the front and rear to exact specs. That agrees with the diagram in my service manual.

If you want the rake angle, tan-1 of the difference/the jackpoint midpoint distance of 1270 mm.
If you want the rake in terms of how much lower the front end is than the back end in mm, just double the difference you measured, since the wheelbase (2530) divided the jackpoint midpoint distance (1270) is almost exactly 2.
I'd love someone else more experienced to confirm my measurements.

 

[Honcho]

My question: can you measure rake by comparing front jack point height to rear jack point height?

I think the problem with this method is that sometimes the body is not fully settled on the springs. Maybe measuring height at the top of the shock bolt front-to-rear would be better?

 

[silver2002]

Seems to me you should be able to, since I measured them as equal at 135 mm when I had jacked the front and rear to exact specs. That agrees with the diagram in my service manual.

If you want the rake angle, tan-1 of the difference/the jackpoint midpoint distance of 1270 mm.
If you want the rake in terms of how much lower the front end is than the back end in mm, just double the difference you measured, since the wheelbase (2530) divided the jackpoint midpoint distance (1270) is almost exactly 2.
I'd love someone else more experienced to confirm my measurements.

Ok, I think I'm getting it.. My rake jack point to jack point is 1/4 inch, I set it that way - but if you extend the line in space [sort of wheel to wheel], that probably means I have too much rake, maybe a half inch.

 

[LJSB]

I think the problem with this method is that sometimes the body is not fully settled on the springs. Maybe measuring height at the top of the shock bolt front-to-rear would be better?

The issue I have with measuring ride height from the jack point is that it is not a manufacturer control point.

It is not precisely placed and can be different from car to car. It's not a control point.

I can't see a good reason not to measure the way the manual outlines. You're measuring suspension geometry not body dimensions, or rather rocker dimensions.

The manual shows how and where to measure ride height. Why not do it right? It's not a taxi.

(and measuring with fingers over the tire to fender is not the way either)

 

[Honcho]

The issue I have with measuring ride height from the jack point is that it is not a manufacturer control point.

It is not precisely placed and can be different from car to car. It's not a control point.

I can't see a good reason not to measure the way the manual outlines. You're measuring suspension geometry not body dimensions, or rather rocker dimensions.

The manual shows how and where to measure ride height. Why not do it right? It's not a taxi.

(and measuring with fingers over the tire to fender is not the way either)

I have the same issue as you, which is why I measure using the factory method.

 

[Wild Turkey]

Agree, as above. After measuring it both ways, absolutely go with the factory method as Honcho suggests. It's really no more difficult.