What would be normal ride height measured at the top of the wheel arches? Front and rear. Reason I ask is my front fender lip at wheel CL is 25 1/4" and the rear is 27 1/4". Which seems too high to me. I know the factory gives specs measured at the rockers.

 

Paul,

The 1970 CSM (Chassis Service Manual) calls out ride height for your 442 as follows...

Trunk empty, front seat back, fuel tank full, correct tire pressures, doors closed
Put car on a level surface
Measure clearance at 1" rearward of front door opening, the spec is 9 5/8" from rocker panel to ground
Measure clearance at 3" forward of rear wheel opening, the spec is 9 1/2" from rocker panel to ground

Gary

 

Ok.....and thanks but I know all that. What I'm asking is what all that translates to produce X hight measured at the top of the wheel arches.

Those specs are far inboard from the wheels, so a tiny bit of change there make a bigger difference at the wheel arches.

 

I happen to be working on this as well. For reference-9" per the rear is 27 1/4 at the wheel lip. 7 3/8" in the front equals 24 3/16 at the wheel lip. I am measuring to the body line on the wheel lips above the wheel opening molding.

Based on this I think the factory ride height at the wheel lip would be about 27 3/4" in the rear and 26 1/2 in the front.

My gas shocks, which are not in right now raise the ride height 1/4"

I am way too low in the front with 1" drop springs. I want to get the front up to at least 25.

My understanding is that a spacer under the front spring will raise it double the spacer thickness and the rear spacer will raise it equal to the spacer.

Good luck!

Pat

 

Be aware that the factory ride height measurements are with factory diameter tires, and those sizes are difficult to find today.

 

If you already know two points on one line then extend that same line through the wheel well and measure the height above the center (focal) point of the wheel well to the top of the wheel arch.

 

Z = Stock Ride Height (assuming tire pressure, springs, shock absorbers, blah, blah, blah are stock equivalents)

 

Out of curiosity, if you're nose high how do you drop it?

 

Shorter springs is one way.

 

but I've got the correct springssprings..at least according to ESPO. I told them what I had (442, 400 w/AC) and thats what they sent me.

OP, not trying to threadjack. I'll take this elsewhere.

 

The reason the factory specified ride height at the bottoms of the rockers are because those are hard points that don't vary very much. The wheel openings vary considerably just due to manufacturing tolerances (particularly on the front fenders) and as such are a very poor choice for measuring ride height. Any bumps or bodywork mucks that up even more. And obviously tire size plays a huge part in this. The factory ride heights assume the OEM standard equipment tires.

 

True but the dimensions of the OEM tires are readily available, then it's just math.

One thing that a lot of people don't realize is that the OEM bias ply tires had stiffer sidewalls than today's radials. As a result, the effective rolling radius of the radial will be slightly less than for a bias ply of the same nominal outside diameter. This also effects right height.

 

Like this? Data derived from the 1970 PIM. I considered it unnecessary to plot X vs. Y for the discussion. The OP only needs to find the exact distance to derive the answer. Reserving comment on the utility of such a discussion, but the question (none-the-less) asked the ride height above ground at the top of the wheel well fender arches (involves math).

Example: If the distance were extended (from PT.Z) to the focus of the wheel well along a line with given slope, the (above ground) ride height at the focus of the wheel well is 9.675" (9.48" + 0.195") - a total rise of 0.195" over a total distance of 96.15"

 

Thanks all.
The front I am assuming has sagged a little. The rear appears to be all stock and no air shock or spring spacers. Just surprised how high it sits. Is there a way to shorten rear coils a bit? Either cutting or de arching (I know, leaf spring term) to get it 1" lower?

 

Unfortunately it is not easily possible to cut the rear springs since both ends have reduced diameter coils. Usually these cars have a "tail down" appearance in stock form, so perhaps someone previously installed taller or stiffer rear springs?

 

I'd be interested in viewing a profile of your vehicle if you have a picture to share.

 

Profile of my '71 CS (FWIW) - may or may not assist you. Pretty certain my car was dinged (not seriously) by a PO. This picture is after I rebuilt the suspension a couple years ago.

 

Those factory numbers - it says bottom of rocker - does that mean the lowest point of the pinchweld?

 

I put hotchis 1in lowing springs. Shock package. Same hight as the old settled springs. Fit a rear 15x10 295 tire out back.26in front 27in. BackFloor to fender
my other 442 I put "correct " springs.its 31/4 higher....deffenetly probably like yours....an inch too high

 

I provided this information in Post #13. The PIM diagram (Page 27) demonstrates location of the rocker panel measuring points (Y & Z) relative to the pinch weld.

 

This is current. I swapped rear coils and that dropped the rear to 9-1/2" at the rocker. Front is also 9-1/2 at the rocker at front of door.
And yes I know the stripes are too wide over the wheel arches - will tackle that this Winter

 

Considering the distance ('X' dimension) is called out @ 9.48" I'd say you did satisfactory.

Nice job, good stance.

 

As noted in the PIM the variance is 0.40" from what is posted. Well done both front & rear.

 

Lookiing good!

So which springs did you install? I'm sure there are many folks who could benefit from this information.

 

An original set from my 70 GTO coupe. Same uninstalled height but much small diameter wire. Wish I had more info and part # but was a set sitting here and I tried them. Honestly I would expect convert to need a more robust spring than a coupe but they seem to work fine

 

Here is the car outside, drove it for the first time Saturday - kinda looks a little low

 

You may be a little low, but until you measure it according to the chart in Post #20, you won't know. If you look at the illustration in Post #20, you'll see the rocker panel bottom between the front and rear wheels is BELOW the center line of the front and rear wheels. This is pretty much true of any car.
If you see the rocker panel bottom line near the center line of the wheels or above, the suspension has been altered.

 

I agree, you need to measure to know if it's at the proper height or not.

But it doesn't really look that low to me. Here's a comparison to my car.

 

One thing that could make a difference in the rear ride height is a full tank of gas vs almost on empty. The rear goes up and down as much as an inch. Also those with the full spare tire setup in the trunk will sit lower then the same car w/o. One thing I did on my 71 convertible was install air bags in the springs. These can be used for drag race launching for preload to launch straight but also work great if you have rear seat passengers on long trips. Put 2 adults in the back seat and watch how low the rear will go!! Bottoming out is not fun.

Joe

 

some pics of the air bags:
InCUdrG.jpg
I'm running 18" wheels but here are my springs in case it helps anyone:
SPC front coil springs 1.2" drop 14 1/8 inch 550 rated
SPC rear coil springs 1” drop 14 ¼ inch 135 rated
some side pics - sorry it's so ugly finally got the car in for some paint and body work:
Ep7LETr.jpg
fDXByC9.jpg
mkuW1KP.jpg