currently i have eibach prokit springs on my 86. i kept the stock iroc springs. now i am looking at an 84 formula to buy. i was planning on swapping all my camaro suspension mods(lca's, adj. panhard, all poly in stock front components, eibach prokit) over to the formy.

what i am trying to figure out is, are the formula springs the same as my stock iroc springs? which set of springs would be best for handling, street driving and the occasional drag strip pass with drag radials and removed front swaybar?

it seemed like the progressive rate rear spring of the prokit halped my car squat and launch better, but ive read many threads that say that the eibach kit is purely for looks and stock springs will perform better if cut for the same amount of drop. maybe i could run the progressives in the rear with the stock irocs up front trimmed a little?

ps- i wanted to run longtubes on the formula to let the (future) carbed nitroused 383 breathe better at 6500rpms.

 

The springs could be the same. Check the tags. There should be a yellow sticker tags on the springs themselves with a 3 letter code, the more common ones are BZW and BZX. If you can't find a tag on the spring itself, check the RPO codes. the numbers should be 6-- and 7--, the two letters after the 6 and 7 will tell what spring code they are.
Once you have that I can tell you which should be a stiffere spring.


If you still have the IROC springs and they are readily available I'd be interested in knowing what the size of them is ( height when uncompressed, number of coils, and outside diameter of coils, diameter of the wire ) and the three letter code.

I am trying to assemble a listing for the different springs that came on the cars since it seems you can get three different answers if you ask 3 people about what was available.

I just bought some Moog 5662 front springs because they are supposed to be the "stock replacement" and they are quite clearly not the same as what I took out.

 

sure ill whip out the tape sometime tomorow get some measurements on those. i have not yet purchased the formula so i cant get to the spring tags.

 

just to let you know they didnt make formulas in 84 they started in 87

 

i only got a measurement on the front springs and there is no longer a tag on either of them. but they are about 13.5" tall with 6 coils.

 

do you have the RPO code sticker in your console for the car they came out of?

 

i found the tag on the springs! they were caked under years and years of grime. the fronts say BZK and the rears say NNM. sorry i didnt find them earlier.

and correction about the firebird. it is an 83 trans am(same hood as the formie).

do you think it has the quicker ratio steering box that my IROC has?

 

my parts book doesn't list BZK. Maybe it's either BZY or BZX?

The NNM is stiffer than what's been on any of my 3 TPI cars, 87 IROC, 88 IROC and 92 Formula all had NNL which was a step below the NNM.

 

Jay --- its good to hear you are working on getting the spring info in one organized location, just one question, do you have a resource that lists spring rates for the letter codes ???