[necdb3]

Originally Posted by Bentwheelbob

Can you post a copy of your build sheet?

Here's mine. I'm not sure if the springs are actually different or if the PN is reflective of the assembly with the front spring perches on them.

[njsteve]

You know, that could be the actual explanation! I never thought of that.

Here's the page in my old mega thread where Lloyd mentioned that the 1977 MPC shows the same part number for both sides:

http://forums.maxperformanceinc.com/...=481612&page=9

Also, the interesting observation was that my car had the 481612 on the side of the car that should have had the 482547 spring.

It's hard to believe that that thread was over 12 years ago!

[Judge273]

Originally Posted by Judge273

So, in 70-71 had different part number. Early 72 Jan-March had same part numbers.



After that different...do the Judges know this?



Pontiac was in turmoil...

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[4birds]

I don't recall if the Black car had the Handling Package as one of its many options. If so, the springs would be the same as the Trans Am's.

Also, Eaton springs chart shows a definite difference between the left and right rear leaf springs for the 1972. Not sure if the spring rate was different or the arch was different between the two sides.

Here are pictures of the original leafs on my second 12A built 1972 Trans Am. The left is obviously a 481132 PJ, but the right is not quite legible. It looks like 482*** PM. I can't tell.


Hopefully with everyone's help, Bob can get the correct part numbers and codes stenciled on his rear springs.

[njsteve]

HOLY PALIMPSEST, BATMAN!

I think I just solved the mystery!!! Look closely at the photo and you can see that the partially hidden, underlying stenciled part number is 482547 !!!!

I guess the suppler was painting over the existing numbers to comply with the running change????

[eaglesan13]

Can the stencil be seen with the spring in the car?

[njsteve]

Yes, it was on the top side, near the front spring eye.

[necdb3]

Originally Posted by 4birds

Bob, here is my 03A built 72 T/A sheet showing PL and PJ for the rear springs.

Pretty cool the differences between the 2 build sheets. You can see the differences in ft springs, hoses, etc, because one having A/C and one not.

[Bentwheelbob]

So I think I have pretty much decided to go with the same part number (481612) on both springs, but one with the PL prefix and one with the PJ prefix. The PL stencil is done, now I need to cut out the PJ. I think I'll just do the "J" and piece it in the same stencil.




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[Formulabruce]

Originally Posted by 4birds

Also, Eaton springs chart shows a definite difference between the left and right rear leaf springs for the 1972. Not sure if the spring rate was different or the arch was different between the two sides.

Pontiac Firebird DS spring "rate" was determined at a greater arc than the Pass side at the same deflection due to higher perceived Driver weight.
Note. This was PRE "Cross slope" paving ( crown in middle of road), and Pre Radial Tire, and these cars had a Straight Upper "A" arm mount in front , which got changed for crowned roads to an offset for this reason. At the same time Pontiac made the Rate at the same deflection as the other side in mid 1972 Calendar year. This made both rear springs identical by 73 production. The difference was about 15 lbs at a greater arch, not much, and therefore Pontiac allowed substitution till they ran out, just like a parts change pick order, except for the Sub assembly area. ( hope this wasnt too big a side track of this thread)

[njsteve]

There goes FormulaBruce channeling his inner Cliff Clavin! ;-)

(Very cool info)


(I corrected the pselling...Darn thumbs gettin in the way again! SPELLING)

[Norwood]

Cliff Clavin

[bird72]

Originally Posted by Formulabruce

Pontiac Firebird DS spring "rate" was determined at a greater arc than the Pass side at the same deflection due to higher perceived Driver weight.
Note. This was PRE "Cross slope" paving ( crown in middle of road), and Pre Radial Tire, and these cars had a Straight Upper "A" arm mount in front , which got changed for crowned roads to an offset for this reason. At the same time Pontiac made the Rate at the same deflection as the other side in mid 1972 Calendar year. This made both rear springs identical by 73 production. The difference was about 15 lbs at a greater arch, not much, and therefore Pontiac allowed substitution till they ran out, just like a parts change pick order, except for the Sub assembly area. ( hope this wasnt too big a side track of this thread)

I have noticed my 72 (and prior 72) had a better (IMO) stance than my 71 I had. Meaning not as low in back. I was going to change rear springs in my 71 to raise a bit (I like level) but my 72 sits perfect are fine. Your info may help explain. My 72 is very late build car BTW.

[Bentwheelbob]

Thanks for all the help on the springs. They got finished up today, and the pinion and crush sleeve got set. A bunch of other stuff got done as well, not the least of which was cooking a 14lb prime brisket, but these were the big things.

MPD made a up a cool tool to help set the pinion preload. We strapped the axle to the workbench and everything worked great. Today was his 70th birthday, and he said he couldn't think of a better way to celebrate it. I wholeheartedly agree. Life isn't about numbers or inanimate objects. It's about spending time with people who make you laugh, smile and give off positive energy.

I've had two great weekends in a row... The TA Nats were great spending time with old friends and making new ones. This weekend I went to to the wedding of my boss, friend and owner of the company, and partied my a_s off without getting in too much trouble. Today I got to hang out in the garage with my best friend on his birthday. What more could you ask for?

Life is good.







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[Red Goat]

Everything looks great, Bob!

And a Happy F'n Birthday to MPD!!!

Cheers,
Tim

[Norwood]

Happy Birthday Dave

[ladytata]

b day cheers

[Bentwheelbob]

I'll be sure to pass these well wishes on to MPD. It will mean a lot to him. He hated missing the TA Nats, but is doing much better now and is counting the days for MCACN.

BTW - the brisket was the best ever. I sent some home with him for his celebration. MiniMe and her man JakisBack enjoyed it also.





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[OVERULD]

Great time with family and friends Bob! Glad you had a great weekend. Got any good pictures of you line-dancing at your boss' wedding? Tell MPD I said Happy Birthday!

I took the Formula to a nice local car show today - had a perfect day for it.

Back at the shop afterwards, had a little fun in the truck court with the 455 and the Vette. I'll let you figure out which marks belong to which car. Yes...life is good!




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[Formulabruce]

Thanks for sharing Bob !
I cant Wield the big Breaker bar to set the crush sleeve, so I have been using one that only needs about 150 lb ft to set it. I forget who makes it, but it makes the "out of car experience" a bit better for those of us with back/ leg troubles. Looks great, and Happy B-Day MPD! I hope to meet the "Man behind the missions "!