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-   -   2nd Gen Firebird Measurement (https://forums.maxperformanceinc.com/forums/showthread.php?t=879983)

Elarson 04-18-2025 05:23 PM

2nd Gen Firebird Measurement
 
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I got the 2" drop rear leaf springs from Detroit Speed. I finally got the car on the ground and it doesn't look much different than stock ride height to me. Maybe it's an optical illusion from the short tires??

Anyway, if a few of you would be so kind as to measure your 2nd Gen's from axle centerline up to fender lip, so I can compare. See attached picture. Mine measures 16"

Thanks in advance!

Eric

jpg69bird 04-18-2025 06:29 PM

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Car is still away, but this is the stock ride height as measured from the underbody, out of the 76 assembly manual.

PAUL K 04-19-2025 10:36 AM

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I don't normally measure from the center cap up but understand why your are. The white car is all original low mileage. The blue one seems to sit correct. The white car has a 235/60 the blue car a taller 255/60.... Hopefully these pictures are helpful.

Tellyshavilli 04-19-2025 11:31 AM

My 70-73 rear measurements from ground to wheel well lip are around 27 1/2 to 28 inch. Those measurements are from TAs with original springs.

76TA462 04-19-2025 01:33 PM

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For my second gen (1976) I used the Hotchkis Sport Suspension Lowering Leaf Springs Package - 2409C designed to lower 1.5 in. With the OEM rear leaf shackles my wheel center to fender was 14.5 inches. On dips etc. my exhaust was hitting the road a lot. In the pictures my spacing is now 15.25 inches. I raised the car 0.75 inches by fabbing up longer shackles (the difference in the shackles isn’t even obvious and still tucked under. Not like those foot long shackles of the 70-80s LOL.) Running 285 40 18.

76TA462 04-19-2025 01:37 PM

Mine seems to match Paul's measurements.

PAUL K 04-19-2025 01:50 PM

Quote:

Originally Posted by 76TA462 (Post 6561007)
For my second gen (1976) I used the Hotchkis Sport Suspension Lowering Leaf Springs Package - 2409C designed to lower 1.5 in. With the OEM rear leaf shackles my wheel center to fender was 14.5 inches. On dips etc. my exhaust was hitting the road a lot. In the pictures my spacing is now 15.25 inches. I raised the car 0.75 inches by fabbing up longer shackles (the difference in the shackles isn’t even obvious and still tucked under. Not like those foot long shackles of the 70-80s LOL.) Running 285 40 18.


Nice looking car!

76TA462 04-19-2025 02:11 PM

45 years of ownership and changes, and still having an awesome time with it. Thanks.

Elarson 04-19-2025 03:09 PM

Thanks for all the replies. That tells me a lot.
I need to look into those Hotchkis springs....sounds like they may be better for road courses than what I have now.

Eric

PAUL K 04-19-2025 04:50 PM

Eric have you looked a Landrum? ..... We used a lot of the springs for drag racing and they worked great. They also made us several pairs of "custom" street/strip springs. I believe their specialty was circle track.

srmmmm 04-19-2025 06:17 PM

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I'm running a five leaf spring assembly that was designated for the 1975 Chevy Nova police suspension option. No special additional curvature, just a stiffer rate.

Distance from axle centerline to wheel opening lip is 15.75"

Elarson 04-20-2025 08:04 AM

Quote:

Originally Posted by jpg69bird (Post 6560933)
Car is still away, but this is the stock ride height as measured from the underbody, out of the 76 assembly manual.

I measured my rocker panel height last night. I'm right at 8" so that double confirms all the other observations. I have "2" drop" springs and tires that are 2" shorter than stock and I'm only 1/2" lower than stock. Grrrrrr.....

Thanks....everybody was a big help.

Eric

JLMounce 04-20-2025 10:47 PM

This is for your road race second gen, correct? They are a bit spendy and I don't know your budget, but I'd talk to Global West about their Cat5 leafs.

78w72 04-21-2025 09:37 AM

PTFB has some nice 1.5-2" drop springs, priced better than the other big suspension companies. I have had them on my 72 firebird along with some of their other parts, been in use for 10+ years & sits very nice, lower than my stock other suspension 2nd gens using factory size tires at about 27-27.5" tall.

The Champ 04-22-2025 10:56 AM

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Eric

Your post got me to go measure my wife's '72 Camaro that still has the original 53 year old leaf springs in the back. 13.5"! My short (25.7") 275/40/17's fill the wheel well as shown in photo below.

I've been contemplating getting new rear springs to alleviate the rear end sag, but have been hesitant on what springs to get to lift the rear .75 - 1" in the rear.

Front springs are 2" drop Eibach coils installed back in 2001.

I talked to PTFB and he thought their GT Pro leaf kit springs would be my best bet and they come with shackles that have two positions to give me easy adjustability if I needed more lift:

https://static.wixstatic.com/media/8...e2413a~mv2.jpg

I might cheap out as I need to replace the 7 year old tires this spring anyway. Currently running 275/40/17's (25.7") and go with 255/50/17's (27.2") to get the .75" that I'm looking for. Fronts are currently 235/45/17's (25.3"), but looking at 245/45 or 225/50/17's this time to gain maybe .25" up front.

Speed bumps and highly crowned rodes are a b!tch....

srmmmm 04-22-2025 01:56 PM

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These are 235/55R17 with what should be, stock height springs on mine.

Steve C. 04-22-2025 03:46 PM

When I obtained a copy of the AMA specifications for my 1970 2nd Gen they stated this as the factory ride height. These are height dimensions from the rocker panel to the ground in two places. The forward point on the rocker panel is located 36.3 inches from the front wheel centerline and it is supposed to be 6.5 inches off the ground. The rear point is 16.1 inches from the rear wheel centerline and is supposed to be 5.5 inches off the ground.


.

srmmmm 04-22-2025 04:21 PM

Quote:

Originally Posted by Steve C. (Post 6561463)
When I obtained a copy of the AMA specifications for my 1970 2nd Gen they stated this as the factory ride height. These are height dimensions from the rocker panel to the ground in two places. The forward point on the rocker panel is located 36.3 inches from the front wheel centerline and it is supposed to be 6.5 inches off the ground. The rear point is 16.1 inches from the rear wheel centerline and is supposed to be 5.5 inches off the ground.


.

Did it indicate the tire size for that? Seems a bit low, but considering that might be the spec with the base F78/14 tires, then correct.

yahooskidoo 04-22-2025 07:53 PM

Quote:

Originally Posted by Elarson (Post 6560927)
I got the 2" drop rear leaf springs from Detroit Speed. I finally got the car on the ground and it doesn't look much different than stock ride height to me. Maybe it's an optical illusion from the short tires??

Anyway, if a few of you would be so kind as to measure your 2nd Gen's from axle centerline up to fender lip, so I can compare. See attached picture. Mine measures 16"

Thanks in advance!

Eric

Have you driven it some to settle those new springs?

jhein 04-22-2025 08:16 PM

Quote:

Originally Posted by jpg69bird (Post 6560933)
Car is still away, but this is the stock ride height as measured from the underbody, out of the 76 assembly manual.

Quote:

Originally Posted by Steve C. (Post 6561463)
When I obtained a copy of the AMA specifications for my 1970 2nd Gen they stated this as the factory ride height. These are height dimensions from the rocker panel to the ground in two places. The forward point on the rocker panel is located 36.3 inches from the front wheel centerline and it is supposed to be 6.5 inches off the ground. The rear point is 16.1 inches from the rear wheel centerline and is supposed to be 5.5 inches off the ground.
.

There's a pretty big discrepancy between the numbers in these two posts. Below is what I found in my 1970 assembly manual. The car they show is a 1st gen but if you look in the bottom right area of the page it says it's for 1970.

https://i.imgur.com/BMVfdBOh.jpg


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