ST XTA spring rates M vs nonM

It'sNotTurboTime · 05-21-2024, 10:26 AM

Does anyone know if the M3 version of this kit uses the same spring rates and valving as the non M?

I know non M e82/e90 ST XTA are using the same rates. M3 KW V123 uses something stiffer. And then M3 Clubsport has its own rates. The M3 XTA kit seems like the oddball. would it use the 7k or 10k front spring? and a regular M3 V3 rear spring? or a 14k club sport spring? Or the updated rear club sport spring?

I've tried contacting KW for some of this info but they never want to give it out.

Of course all this depends on if that little aluminum spacer can be popped off the struts so that they fit in the non M knuckle. TCKline website shows that spacer as removable so I wonder if it is on other coilovers too.

For some context:
I've basically decided on Redshift Motorsports Competition coilovers, but the XTA kit is still really tempting since I can get it for about $1000 CAD cheaper. And if I could buy the M version of the kit, it might have increased compression damping making it more appropriate for what I want. (Those KW camber plates look really really nice too)

ShocknAwe · 05-22-2024, 12:57 PM

Id hope not. Sway bars are a different rate on M cars contributing to a higher overall effective spring rate. Bearings are also used more heavily in the arms which reduces rate. Ohlins accounts for this. Not sure I'd buy a kit from a company that neglects differences in other parts of the suspension, but I'd hope that KW does.

It'sNotTurboTime · 05-22-2024, 01:18 PM

I found the TUV certificate for E90 M3 ST XTA this morning.

Front is 7k spring with helper spring, same as 128i kit.
Rear is 12k spring with helper spring.

The dampers all have different part numbers from the 128i kit.

If this kit can be installed on the 128i, it could be a good affordable way to get a more motorsports focused set up for a very good price. (Assuming the M version has more compression damping). Just keep the rebound on a softer setting and you'll be closer to a digressive compression, linear rebound race set up.

Maybe it's just too many unknowns though. The internet seems to be scrubbed free of KW dyno plots so it's a gamble if the M3 kit uses better valving for the goal.

05-21-2024, 10:26 AM	#1
It'sNotTurboTime New Member 0 Rep 7 Posts Drives: 2008 BMW 128i Join Date: Oct 2022 Location: Alberta iTrader: (0)	ST XTA spring rates M vs nonM Does anyone know if the M3 version of this kit uses the same spring rates and valving as the non M? I know non M e82/e90 ST XTA are using the same rates. M3 KW V123 uses something stiffer. And then M3 Clubsport has its own rates. The M3 XTA kit seems like the oddball. would it use the 7k or 10k front spring? and a regular M3 V3 rear spring? or a 14k club sport spring? Or the updated rear club sport spring? I've tried contacting KW for some of this info but they never want to give it out. Of course all this depends on if that little aluminum spacer can be popped off the struts so that they fit in the non M knuckle. TCKline website shows that spacer as removable so I wonder if it is on other coilovers too. For some context: I've basically decided on Redshift Motorsports Competition coilovers, but the XTA kit is still really tempting since I can get it for about $1000 CAD cheaper. And if I could buy the M version of the kit, it might have increased compression damping making it more appropriate for what I want. (Those KW camber plates look really really nice too) Last edited by It'sNotTurboTime; 05-21-2024 at 05:37 PM.. Reason: Clarity
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05-22-2024, 12:57 PM	#2
ShocknAwe 1Addict 3245 Rep 7,913 Posts Drives: E82 Mutt, M57 Truck Join Date: Jul 2012 Location: Charleston iTrader: (22)	Id hope not. Sway bars are a different rate on M cars contributing to a higher overall effective spring rate. Bearings are also used more heavily in the arms which reduces rate. Ohlins accounts for this. Not sure I'd buy a kit from a company that neglects differences in other parts of the suspension, but I'd hope that KW does. __________________ 2010 135i 6MT Jet Black N54/3 FE82 Mutt \| BUILD THREAD \| GARAGE SALE
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05-22-2024, 01:18 PM	#3
It'sNotTurboTime New Member 0 Rep 7 Posts Drives: 2008 BMW 128i Join Date: Oct 2022 Location: Alberta iTrader: (0)	I found the TUV certificate for E90 M3 ST XTA this morning. Front is 7k spring with helper spring, same as 128i kit. Rear is 12k spring with helper spring. The dampers all have different part numbers from the 128i kit. If this kit can be installed on the 128i, it could be a good affordable way to get a more motorsports focused set up for a very good price. (Assuming the M version has more compression damping). Just keep the rebound on a softer setting and you'll be closer to a digressive compression, linear rebound race set up. Maybe it's just too many unknowns though. The internet seems to be scrubbed free of KW dyno plots so it's a gamble if the M3 kit uses better valving for the goal.
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