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Old 03-02-2021, 02:21 AM   #1
sloopy
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Default wagon springs or ambulance springs with koni sport dampers?

I'm looking to buy koni sport dampers for my 240 wagon and want to know which rear spring would be a better match for my system. Currently I have lesjofors 4095801 on the front and lesjofors 4295816 on the rear. I took some measurements by measuring suspension compression with a known added weight of two friends over the axle.

I measured an effective spring rate of about 118 lbf/in in the front, which probably puts me in the ballpark of a 125 lbf/in spring. My camber is set all the way negative with the stock plates, although I didn't do the math and assumed a rough 0.95 motion ratio to get the 125 lbf/in rate. This makes me think these are basically gt springs.

In the rear, I measured an effective spring rate of about 222 lbf/in. With a motion ratio of 1.5, that puts me at almost 150 lfb/in for the rear springs, which seem more like ambulance springs than normal wagon springs.

Dave posted specs on the konis here: https://www.240turbo.com/suspension.html

koni sport yellow: rebound / compression (newtons at a peak velocity of 500 mm/s)
front strut: 950-1900 / 700
rear shock: 2200-4400 / 1150


My gut reaction is that I should ditch the ambulance rear springs and get normal wagon rear springs, but I figure there should be an objectively better choice based on the data.
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Last edited by sloopy; 03-02-2021 at 08:47 PM..
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Old 03-02-2021, 04:41 AM   #2
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I've ran the ipd springs with yellow Koni dampers with succes on my 745 wagon. Redblockpowered has done a suspension sheet that you should be able to find here:
https://docs.google.com/spreadsheets...t?usp=drivesdk

It has some suggestions as to the ideal rates, the koni's are stiff compared to OEM, and therefore best matched to a higher spring rate. From memory the IPD is quoted as either 20 or 40% stiffer, so from the stock setup you should be able to calculate if your springs work. Given that I had to switch to a softer rear sway bar to make the rear hook up, I'd try the wagon springs

Just realized this is for a 240, derp haha
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Old 03-02-2021, 02:50 PM   #3
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I think they still sell 242GT front springs, which are some 40% stiffer than normal later 240 springs without losing travel. That plus no rear sway bar, bigger front sway bar, something like that with the stock wagon springs will probably get you in the ballpark.
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Old 03-02-2021, 09:07 PM   #4
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I agree. Stock wagon springs are the way to go for what I'm going for. I am a bit confused about which part to order though. Rockauto lists lesjofors 4495801 as the rear spring for a wagon. However, that part number is not in lesjofors catalog. Consulting the lesjofors catalog, they list 4295803 as the normal wagon rear spring, and 4295816 as the "reinforced version" or ambulance spring. I ended up with the ambulance springs in the first place because this is the only stock replacement spring fcp euro lists for a 1992 wagon. I searched 4295803 and they stock this spring, but their fitment table looks pretty strange, listing mostly 1985 and earlier cars. I'm not sure what's going on here.
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Old 03-03-2021, 10:58 AM   #5
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Alright! I called Sweden and they told me that 4495801 is the part number for a pair of two 4295803 springs, which are the normal wagon springs. So if you're buying nornal wagon rear springs, the pair from rockauto is significantly cheaper than buying the two springs separate from fcpeuro.
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Old 03-07-2021, 02:18 PM   #6
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From related experience with my 9 sedan, the KONI sports need 250 to 325 lbf/in rate up front. I don't know how the motion ratios compare between 7/9 rear and 2 series rear....but I'm running 250 front and 175 rear.... to the pleasure of the KONI Sport dampers.

2 series GT springs are nowhere near that rate.... I made the calculations here almost 10 years ago, and I believe the GT front were in the neighborhood of 170 lbf/in, and perhaps less.
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Old 03-07-2021, 03:44 PM   #7
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Interesting. I wonder how different the valving is for the koni sports between the 240 and 740. I hear people report the bilstein hd rides well in the front with gt springs. And according to the specs Dave posted, the koni sports are softer in compression compared to the bilstein hd (in the front): 700 vs 750
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Old 03-14-2021, 11:03 AM   #8
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I'm not a suspension expert at all but I have B&G springs on my 245 with Koni sport shocks/struts and slightly negative camber front wheels. Feels awesome. Absorbs the little bumps/cracks in the road but way less roll whilst hammering through long fast turns. Feels like a sportY modern car like a VW Golf. Comfortable but solid in turns. Of course you are thinking stock springs so please disregard my thoughts.
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