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Stock 240 / 740 / 940 spring rates

Alright, back to square one. We have two guys saying the front, spring rates on a 240 are 80 lbs and 120 lbs. Forget which model(standard, diesel or GT) that is a 50% difference! They both can't be right.

I think it was reasonably clear from Mike's post that there is some variation in the front spring rate. The wire diameter for my measurements was without paint and undercoating. These springs (the 120 lb ones) were from my 1981 GLT. I also ran them with my spring rate gauge because you'll get yelled at around here if you just use MATH/Physics to do the calculation. The two number agreed in case anyone cares. As the GLT was a carry forward car from the GT (I've never measured a set, but they are known to be different for various years), they most likely are ever so slightly stiffer than a stock DL.

Whatever the number, they are as soft as cheese.
 
If your 120 lb springs are softer than cheese then Mike's 80 lb springs have to be softer than yogurt. What stands out to me is Mike's front springs(80 lb) we're softer than his rear springs(91 lb). Highly unlikely don't you think, considering the weight of the engine? My guess is someone did an extreme hatchet job cutting those springs.
 
Given the motion ratios involved, it's a bit weird as those offsets would have ride frequencies messed up front to rear. The 240 front corner weights (my car is a turbo, so take that into account) are around 800 lbs per side. I now run 400 lb/in springs and it's firm but not brutal. The standard 244 is around 2850 lbs total. So lighter than many think.
 
Given the motion ratios involved, it's a bit weird as those offsets would have ride frequencies messed up front to rear. The 240 front corner weights (my car is a turbo, so take that into account) are around 800 lbs per side. I now run 400 lb/in springs and it's firm but not brutal. The standard 244 is around 2850 lbs total. So lighter than many think.

I can see now why there's so much variation. I forgot about suspension geometry and how that affects spring action, the same spring in different cars can have a different ride(not necessarily rate). Then add each person's own interpretation of "ride quality" and it's enough to tear your hair(what's left). Anyways, thanks for the enlightenment.
 
If your 120 lb springs are softer than cheese then Mike's 80 lb springs have to be softer than yogurt. What stands out to me is Mike's front springs(80 lb) we're softer than his rear springs(91 lb). Highly unlikely don't you think, considering the weight of the engine? My guess is someone did an extreme hatchet job cutting those springs.

The RATE is soft, but stock the front springs are under at least 6 inches prelaod...possibly more.

All the Xratties strewn around my place back in Sleezattle have stock rate of 97 lb/in...and they allegedly a "sproty" ish car.. Their Euro big brother the various Cosworth Sierras/Sapphires have front springs around 110 lb/in.

Guessing is bad. No place for guessing when talking suspension. Measurements of actual parts, not calculations, not guessing.
 
I agree. But you can only measure if you have em in your hands. And that can get expensive...if you measure em all.

As usual with a question such as this - the answers bring even more questions !:omg:

Here's my solution, I will get my hands on a couple of OEM springs and take them to our [ RAMSHOX ] spring makers for testing and evaluation.

Not only will they do the math testing - but they have a rig that will test them in the real World.

This may take a little time as funds are tight and it means I have to purchase springs for testing - but I will do it.
 
As usual with a question such as this - the answers bring even more questions !:omg:

Here's my solution, I will get my hands on a couple of OEM springs and take them to our [ RAMSHOX ] spring makers for testing and evaluation.

Not only will they do the math testing - but they have a rig that will test them in the real World.

This may take a little time as funds are tight and it means I have to purchase springs for testing - but I will do it.

Thank you, myself and others will greatly appreciate that.
 
As usual with a question such as this - the answers bring even more questions !:omg:

Here's my solution, I will get my hands on a couple of OEM springs and take them to our [ RAMSHOX ] spring makers for testing and evaluation.

Not only will they do the math testing - but they have a rig that will test them in the real World.

This may take a little time as funds are tight and it means I have to purchase springs for testing - but I will do it.


Test them in the real world!???

OH NOEZ!!! NOT THAT!!!!!!


If it hasn't been done until now, think of the repercussions!

THINK OF THE CHILDREN!!!!!

How will the servers handle the enormous instant drop off in traffic if the spring rates are actually known?

Oh I fear the end of TB!!
Woe iz us'n.
 
I don't get what the mystery is? I've put up corner weights, spring rates (measured) and motion ratios have been computed. Literally every detail of this suspension is known. Redwood Chair has posted enough detail to compute the rates. The 78-80 GT's all were a bit different. What exactly needs to be worked out? The stock springs are not particularly stiff and they don't really need to be depending on what you're doing or what you want to use your car for. Driving on roads and enjoying the ride...stock works. Horses for courses - what is the question? Do we think there is some magic going from 109 to 120 lbs/in when the front corner weights are around 800 lbs (assuming turbo)? I've also measured the common lowering springs (Lesjofors) and the fronts are 150 lbs/in.

Here are the corner weights again (measured at the Canadian Autocross Nationals last year. 3/4 tank fuel. No driver, race trim).

 
MY question is ............................"WHAT ARE THE STOCK RATES FOR A 940 TURBO ESTATE".

The answer should be in two definitive numbers.

That's all the info I require.

Then I can go to my spring man and get suitable rated springs for the rear coilovers and at least know where to start [ my driving style etc. ] for my fronts.
 
MY question is ............................"WHAT ARE THE STOCK RATES FOR A 940 TURBO ESTATE".

The answer should be in two definitive numbers.

That's all the info I require.

Then I can go to my spring man and get suitable rated springs for the rear coilovers and at least know where to start [ my driving style etc. ] for my fronts.

It would be a lot easier to just find a set or remove the ones you have and simply measure them than fishing around this forum for definitive answers. The tendency is to work out what fits and might be stiffer and is available for almost free at the local junk yard or cut them...that would be my summation of most of the threads I've seen for 240/740/940 suspensions. With a few exceptions of course - and those guys just went and changed things until they got what they were after and very few went back to the junk pile and measured the stock springs (making a wild assumption that I'm reasonably sure is absolutely correct).

If you're looking for a specific ride/handling quality (ride frequency), then you need motion ratios, weights and a few other things then the spring rates are computed from these values. It won't be perfect, but it will get you in the ball park pretty fast.

This is how I ended up with the data for the 240 stuff that I've posted. I was trying to sharpen up the handling of my 242 for autocross and was working data collected for my car, then did the calculations, then worked out the frequencies based on what I know works for that style of driving. I then compared this to what the guys here run and low and behold, they are the same (give or take 25 lbs) - you can read their early threads (from the early 2000's) and see how they empirically worked this out.
 
^what he said.

And like I always say, find what works. Lots of people here have found good numbers that work for specific applications.

Granted, the 240z is a sports car, but I'm sure a Volvo weighs a lot more than that. So, wouldn't Volvo stock rates be higher than 92?
The 240Z handles nice stock, the 240 Volvo, NOT.

Given the motion ratios involved, it's a bit weird as those offsets would have ride frequencies messed up front to rear. The 240 front corner weights (my car is a turbo, so take that into account) are around 800 lbs per side. I now run 400 lb/in springs and it's firm but not brutal. The standard 244 is around 2850 lbs total. So lighter than many think.
Yep, definitely odd frequency front to rear, but it is what it is.
I mesured how much pressure it took to compress each spring, and retested each run. Then I increased the pre-load, so I got numbers starting at 40, 50, 60, 70, 80lbs. That's TEN tests per spring.

MY question is ............................"WHAT ARE THE STOCK RATES FOR A 940 TURBO ESTATE".

The answer should be in two definitive numbers.

That's all the info I require.

Then I can go to my spring man and get suitable rated springs for the rear coilovers and at least know where to start [ my driving style etc. ] for my fronts.
I will have turbo wagon (US) from the junkyard as soon as I have the money to pay for the front suspension. Until then, nobody has offered to let me test any springs at all. I do what I can.
I'll test another mid-80s sedan soon, and also a non-turbo 940 wagon.
 
^what he said.

And like I always say, find what works. Lots of people here have found good numbers that work for specific applications.

The 240Z handles nice stock, the 240 Volvo, NOT.

Yep, definitely odd frequency front to rear, but it is what it is.
I mesured how much pressure it took to compress each spring, and retested each run. Then I increased the pre-load, so I got numbers starting at 40, 50, 60, 70, 80lbs. That's TEN tests per spring.


I will have turbo wagon (US) from the junkyard as soon as I have the money to pay for the front suspension. Until then, nobody has offered to let me test any springs at all. I do what I can.
I'll test another mid-80s sedan soon, and also a non-turbo 940 wagon.

Mike, sticky somewhere?
 
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