[unruhjonny]

Originally Posted by poncho-mike

I work for Eaton in the Electrical Power Division. I'm on medical disability right now due to hip replacement and can't log into my work computer. After I go back to work in mid-August, I should be able to get you the specs on any Eaton springs.

Mike

sounds great!!

I am not in any rush, it may be some time before I need them... I may buy more dependant on exchange rather than getting to the point where I need them...
I just finished disassembling, and blasting my subframe, and I have young kids that have a great habbit of eating up time where i might otherwise want to be tinkering in the garage... but it's all good

[Formulabruce]

I would HUMBLY recommend the Eaton 1973 rear springs. Like the factory did, they are the same number. Why you ask?
1. Radial tires
2. Road Crown compensation
3. RTS ( Offset Camber bar on factory cars.
I always order the base model spring, lowest load, like 115? Or you car will be jacked in the back.
Make SURE you are getting the 4 Leaf version, not the common 5 leaf camaro spring.
The new springs form Anyone are so stiff and ride a bit high that many on here will buy lowering springs right off. ( Norwood's car is a Great example of a handling look 1970 T/A)

[unruhjonny]

ok, I am all ears for suggestions.

I am wondering if I aspire to bring my Formula to the PSMCD if the "bias ply 14" tire" springs aren't maybe better for traction?

[72projectbird]

I have some pretty stiff Hotchkis front springs, new stock replacement rear leafs, Competition Engineering tractions bars, and subframe connectors. The car actually handles pretty well, even with the 15" wheels. I bolted on a set of 18s from another car, and the handling improved dramatically.

I personally don't like the rear sitting lower than the front.

[Formulabruce]

Even Trans Am's sat lower in the rear. This was for traction, for flush and dry rockers, and for stability in corners especially where a anti sway bar was in use.
Keep a car "Up" in the rear, and wash it, guess where the water goes? Bottom of the "Air horn" just at the bottom rear of the fenders...and stays there, inside the rocker.
But Alas, people like to look at "stance"

[unruhjonny]

ok, so I just went through different model years, and different engine options on the Eaton link from my post and cross referenced them to the GM part numbers.

It looks like this is what the Eaton application guide does:
(side)-(weight rating) = (GM part numner)/(Eaton part number); (application)

• RH-#89 = 482545/ML3661; 1970 & 1971 Firebird's w/350
• LH-#88 = 480878/ML1991; 1970 & 1971 Firebird's w/350
• RH-#103 = 482546/ML3595; 1970 & 1971 Firebird's w/400; 1972 & 1973 standard duty (both sides) w/350
• LH-#126 = 482548/ML231; 1970 & 1971 Firebird's w/400
• RH-#126 = 482547/ML559; 1970 & 1971 Trans Am's
• LH-#126 = 481612/ML1147; 1970 & 1971 Trans Am's; 1972 & 1973 heavy duty (both sides) w/350
• RH/LH-#126 = 481132/ML231; 1972 & 1973 standard duty w/400 & Trans Am

If I only focus on the differences for Formula an Trans Am models my MPC shows some small differences from the Eaton guide:
1) It shows that the 1973 Formula 400 & Formula 455 w/o Y99 used 'PR' 482548 as the service part for both sides, while the 1972 chart still shows in the same application used 482546/482548 just like 1970 & 1971 Formula's.
2) It shows that 1972 Y99 equipped Formula 350/400 cars and any car with a 455HO received 482547/481612.
3) It shows that 1973 Trans Am's & Y99 equipped Formulas used 'PJ' 481132 as OEM & SR parts for 1973.

So it looks to me like Bruce, you're suggesting I essentially opt for the 1973 'PJ' 481132 springs which are a number not used prior to 1973;
Wasn't the logic of different rate springs because this would aid in traction?

I'd like my car to launch like this when I get it done:

[Formulabruce]

Then THIS>> is what you want
RH-#103 = 482546/ML3595; 1970 & 1971 Firebird's w/400; 1972 & 1973 standard duty (both sides) w/350
BOTH sides.
Trans Am, as built was a road race car, so the stiffness is not the best for a Launch with traction.

[bird72]

TA springs will "launch" the worst