[sglemans]

Looking for pics of how different front springs will sit on a 68-72 lemans/GTO. Hoping that there one out there that doesn't sit too high

Only want to see as-bought, not springs that have been cut etc. and if you could list the part number of the springs in the pic that would help a lot

[rustedgoat]

You may want to be more specific on the year, the weight difference of the front ends on those cars will make a difference.

[HWYSTR455]

I ran Global West springs in all my cars, in the LeMans and 442, the ones that worked the best for me, including stance, was:

In the 442:

Front S-19 - 560 lbs
Rear S-61 - 160 lbs


Used the same for a while in LeMans, but switched to:

Front S-34 - 680 lbs
Rear S-62 - 140 lbs


You can dig a little and find pics, but I liked the 680/140 combo in the LeMans because of how I drive (hard).

There's too many factors on stance, BUT, if you buy from GW, and you don't like them or the stance is wrong/undesirable, they will swap them for cost of shipping one way. They pay the other.

Not many places will do that for you, and they are not overpriced.

You can't do just the fronts and suspect to get the stance right. Remember, as the front rises, the rear drops.


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[sglemans]

Thx, if you could post those pics I'd appreciate it. My front springs are looking saggy and I would like to raise it but not too much

[HWYSTR455]

It won't help for me to post pics, my setups use the AFX spindles, so it wouldn't give you an accurate impression.

You're just going to at some point have to take a leap of faith and buy a set, install them, and see where you are. That will be your starting point.

And you HAVE to do both front and rear at the same time. You could look at 1000s of pics and it wouldn't matter, could still do the same thing and not get same results.




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[locomotivebreath]

Stock drum spindles , these are generic 2” drop springs from Jegs - 500lb rate . Love the look but it needs to come up an inch or run a tire taller than 26 . I’ll drag coming out of the driveway if I don’t cut it right .

[Shiny]

I replaced springs on front and rear a long time ago and just guessed. I guessed badly on the rear and may want to re-visit.

Because my rear is too high, I don't think my front would be a good example.

Where is there a table showing the original/stock spring dimensions and rates for different configs and options?

For example, I assume the weight of AC might have required a different front spring than a non-AC car. And "handling packages" might have used different springs, correct?

HWYSTR455 - does Global West or can you compare your numbers with stock? I assume these are rates (ie 560 lbs per inch), correct? This is part of the design, but free length would also be variable, correct?

[sglemans]

Lcmotivebreath, that's kind of what mine looks like now, might even be a bit lower than that. The ride is super-soft though, so I think it's just saggy original springs, not aftermarket ones.

[locomotivebreath]

It rides good , taunt but not harsh . This spring I’m going to install some spacers to raise it an inch in the front and call it good .

[HWYSTR455]

Originally Posted by Shiny

HWYSTR455 - does Global West or can you compare your numbers with stock? I assume these are rates (ie 560 lbs per inch), correct? This is part of the design, but free length would also be variable, correct?

Not sure what stock is, but they have a higher free height. The 'performance' springs that most sell are shorter.

Shorter springs are easier to install, can do it without a spring compressor.

I think the OE ones are like 450 or something? You can look it up, but it's pretty worthless because of the design of the system. And they used like 7 or more different types/specs of springs.

They didn't use different springs per side, they always used pairs of the same rate/length.

Once you go to aftermarket control arms or control arm bushings, the control arms articulate much better/easier, and that's why a higher rate is needed.

The control arm bushings have teeth, bite into the frame, and adds resistance. That's why you have to do OE bushings with the car on the ground at ride height. Shocks are different too for the OE suspension.

Once you have a free articulating suspension, and you get the spring rates dialed in, you can tune with shocks & bars.

Spring manufacturers that make quality springs are companies like Landrum and AFCO, but most of the time you need to provide specific specs. People who have been dialing in 64-72 GM A-bodies for a long time know what works.

Pretty sure Global West uses Landrum, but Doug uses his own specs. There might be one or two off the shelf ones he provides, but in general, think he uses his own numbers.

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[Shiny]

I tried to click an answer and struck out on finding "original" spring specs, although I'm sure they are out there somewhere.

Reading all these posts (and locomotivebreath's earlier thread), I feel it is tricky territory. If I ever decide to change mine, sounds like going to a "custom" supplier will improve chances of a good ending.

Originally Posted by HWYSTR455

Not sure what stock is, but they have a higher free height. The 'performance' springs that most sell are shorter.

Shorter springs are easier to install, can do it without a spring compressor.

I think the OE ones are like 450 or something? You can look it up, but it's pretty worthless because of the design of the system. And they used like 7 or more different types/specs of springs.

They didn't use different springs per side, they always used pairs of the same rate/length.

Once you go to aftermarket control arms or control arm bushings, the control arms articulate much better/easier, and that's why a higher rate is needed.

The control arm bushings have teeth, bite into the frame, and adds resistance. That's why you have to do OE bushings with the car on the ground at ride height. Shocks are different too for the OE suspension.

Once you have a free articulating suspension, and you get the spring rates dialed in, you can tune with shocks & bars.

Spring manufacturers that make quality springs are companies like Landrum and AFCO, but most of the time you need to provide specific specs. People who have been dialing in 64-72 GM A-bodies for a long time know what works.

Pretty sure Global West uses Landrum, but Doug uses his own specs. There might be one or two off the shelf ones he provides, but in general, think he uses his own numbers.

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HWYSTR455 - thanks for the education. Your explanation of bushings and springs makes sense.

A MOOG "partfinder" I found online says their 5372 front and 5401 rear are standard for a 70 LeMans without AC but I don't trust it since they didn't list any options where I was looking.

Here are some specs for these two PNs that someone else claimed are from MOOG catalogs:



So these are not stiff at all - front is 289? lbs/in. This is a lot softer than 500, so the "clamped rubber" stock bushings must add significant stiffness.... at least assuming these Moog springs are anywhere near stock...

Originally Posted by locomotivebreath

Stock drum spindles , these are generic 2” drop springs from Jegs - 500lb rate . Love the look but it needs to come up an inch or run a tire taller than 26 . I’ll drag coming out of the driveway if I don’t cut it right .

locomotivebreath - do your control arms use aftermarket bushings or the stock "clamped rubber" type as HWYSTR455 explains?

Originally Posted by sglemans

Lcmotivebreath, that's kind of what mine looks like now, might even be a bit lower than that. The ride is super-soft though, so I think it's just saggy original springs, not aftermarket ones.

sglemans - as you work through this, please post what you learn and end up doing. If the spring rate I found online is anything close to stock, maybe they would feel "super soft" by original design?

Would obviously be helpful if someone could post all the original spring options for 68-72 Tempest, GTO, handling packages, AC, etc. I found some discussion about this for 64 GTOs here in the forum (linked here) and it sounded quite complicated.

Mike

[locomotivebreath]

I use the energy suspension polygraphite - and they don’t squeak . I grabbed the jegs springs because of the sale price at the time . I wish I knew who made them because I’d say 2” drop from stock was pretty accurate . I wish they had 1 inch . I don’t run headers so I wasn’t to concerned - then I smacked my crossmember on a stretch of road that’s rutted up by dump trucks . I have edelbrock ias shocks front , bilstein rear .

[HWYSTR455]

You will drive yourself crazy trying to figure out the 'OE springs'. And even if you do, it will still only be 'stock', not what you want for a suspension with upgraded handling.

Then you have to deal with IF the factory documented changes thru a model year. Like they could change a supplier mid-production, and not 'tell' anyone. Same with replacement parts, which legally have to be made available for 7 years after the cars' production.

A change in production doesn't mean the parts suppliers made a change to their' parts either. And going thru time, they could make changes to make parts that are 'acceptable' for more models, to reduce cost and warehouse space.

Say for example the part manufacturer only made springs in 50lbs increments. So a 289lbs spring could be a 300, or a 250. Then stack the 'accepted' tolerance of 10-15%, for 300, that would be 270 at one end, and 330 at the other end.

Now apply that same scenario/formula to the bushings, and, just to say, there were multiple offering for different durometer specs for bushings. An example would be 2nd gen trans ams, which go different ones than say the camaro.

Now again, apply that scenario/formula to shocks. Might as well also apply that to tires too, going from bias ply to radial.

If by some miracle, the planets align, and you happen to have the actual spring rate. You end up having to deal with today's accepted tolerance, and whatever 'book' the manufacturer got it from.

Like I said, the spring rate is worthless info, and at some point you have to take a leap of faith/best guess. Even then, chances are maybe 50/50 that you will get the results you are looking for.

You take the exact same car, give it to 2 different people and ask for the opinion of the suspension, one will say 'compliant', the other 'harsh', throw that on the pile too.

My advice:

* Make the suspension as free-articulating as possible
* Select a spring manufacturer that has (or uses) a <5% tolerance spring
* Use double adjustable quality shocks
* Use the same durometer sway bar & end link bushings as the control arms (if possible)

If you're lucky, you might get an acceptable setup first shot. It's hard not to compare it to the suspension you had on before, but it's a good starting point. Once you drive it a number of miles, you may find what you thought was 'perfect' only acceptable, and still have to change it to get the original results you were after.

Don't get 'locked in' on any setup, not only may you find better along the way, but your taste may change too.

EDIT: If a spring manufacturer says 'We make to exact OE specs' you immediately know they are full of crap.


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[HWYSTR455]

Here's a useful comment on coil springs in general:

The longer the piece of 'wire' used in a coil spring, the more linear the rate is during compression.

And that's why you don't use coilover setups on the street, especially with 'heavy' cars.

Ever see a rate curve for a 'progressive spring'? it gets to a certain point and spikes.

And that's why you never use a progressive spring on the street.




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[HWYSTR455]

Here's the 442 with GW springs:


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[Shiny]

Thanks both for taking the time to explain all this.

Sounds like a total crap-shoot so having access to a forum like this will save a lot of grief.

Beautiful Cutlass for sure!

[HWYSTR455]

Originally Posted by Shiny

Thanks both for taking the time to explain all this.

Sounds like a total crap-shoot so having access to a forum like this will save a lot of grief.

Beautiful Cutlass for sure!

Thank you! My daughter loves it, it's hers, and she has over 200 hours helping on it.

That has the AFX Speedtech spindle on it, and the springs are 'factory' ride height, so technically, it's a 1" drop.

I don't have a good side shot of the LeMans, not with 18s and factory spindles anyway. So it wouldn't be a very good example.


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[locomotivebreath]

Is the 442 stock height but a higher spring rate ? I bit off on the “ we have the factory specs/ blue prints “ from Eaton years ago . I just wanted a factory height . It wasn’t even close ! Ehhh hindsight lol I wish I would’ve just called GW . Jegs had these on sale for like $249 for all 4 and it was too tempting . I bought 1/2 spacers to raise it 1” . A taller tire would even b better , but i wasn’t sure if they would rub - lots of different experiences with 68 & 69s on front tire fitment .

[HWYSTR455]

Yes, the springs on the 442 are 560 rate, and honestly, they are a little soft for my liking. But, it's my daughter's car, so didn't want to slam it or make it as ridged as I like.

The last set I bought from GW, think the fronts were like $160 for the pair, and $140 for the rears. They are like $190/$150 now I think.


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[bodee21]

Here's my 72 Lemans hardtop. The front suspension has, Eaton Detroit Spring # MC1308+ 2" Raise. Monroe Load Leveler Shocks #58273. Offset upper control arm, Raybestos. #5951016. Wheels are 15x6 Rally II with P215/70R15 BFG tires.
On the rear, Eaton Detroit Spring #MC1305+ 2" Raise. Monroe air shocks #MA762 @ 25 PSI. 15x7 Rally II with P255//60R15 BFG tires. I hope this helps.
I also have a 72 Lemans convertible with similar suspension modifications, but with 15x6 Rally II's and P215/75R15 BFG's on all 4 corners, that I could post pictures, let me know.