KW Coilover install

3X3=5 · 09-23-2010, 12:26 PM

Not getting a reply at the bottom of my other thread so I'll start a new one asking this question directly. For those who have installed KW (or any similar) coilovers, did you reuse the OEM nut/washer/foam pad assembly for the rear upper shock (the one you tighten from inside the trunk, part #7 on the diagram below) or did you use the KW supplied nut?

The reason I ask is that I'm experiencing some seesaw front to back bouncing when I stop since installing the coilovers. I'm wondering if the OEM nut, which I did reuse, is allowing some play and causing the bounce. I'd like to know if changing nut might fix it before I tear the trunk apart again. Thanks.

stratplaya06 · 09-23-2010, 03:37 PM

That seesawing is normal with coilovers. It is from your rear subframe bushings. I had the same issue until I got M3 bushings out back.

3X3=5 · 09-23-2010, 09:54 PM

Could you explain why this would happen with coilovers but not the OEM suspension? If anything I'd think coilovers would reduce bounce (if it were present with OEM, which I don't think it was) because the stiffer springs and stiffer-valved shocks are more responsive.

Also, would this also be present with a spring/shock upgrade? I didn't notice it when I had H&R sports on the car, but I had OEM sport shocks. Thanks.

kevin@bavarianx · 09-23-2010, 10:06 PM

Did you hand tighten the rear mounts with two wrenches? I believe its a 6mm and a 11mm as the nut will just spin with just a ratchet.

3X3=5 · 09-24-2010, 12:53 AM

Yes, it was tightened using a 6mm socket on the pin and a wrench on the nut. I'm sure it was fully tightened.

3X3=5 · 09-24-2010, 06:03 PM

OK, I did some investigating to see if I can resolve this. Took the trunk apart and looked at how the rear shocks mount to the car. It turns out you can't possibly used the KW supplied nut - it wouldn't be tightening to anything but the threaded shock itself (not the frame of the car). Because the opening where the shock enters the car is so large, you must reuse all of the stock hardware both in the fenderwell and in the trunk. I really don't understand this set up, it seems very loose because you're basically tightening two washers against each other with a layer of foam on either side of the frame. I took some pictures to illustrate. Has anyone replaced their rear mounting hardware completely? My guess is that the seesaw effect I'm experiencing is caused by the foam pads allowing the suspension to move a little after I stop.

If I can't resolve this I don't think I'll keep these coilovers because it's annoying. Yes, I'm aware that I can change to M3 bushings but that's more expense time and a harsher ride, so I won't be doing that.

And can someone please explain why the coilovers produce the seesaw effect while the OEM suspension (or an upgraded spring/shock combo) does not? I really don't understand what the difference would be.

3X3=5 · 09-26-2010, 11:41 AM

Bump for the question: can someone please explain why the coilovers produce the seesaw effect while the OEM suspension (or an upgraded spring/shock combo) does not? I really don't understand what the difference would be.

stratplaya06 · 09-26-2010, 10:37 PM

The car doesn't dampen the movement as well, because of the stiffer shocks/springs. This puts more lateral force on the subframe bushings, making their sloppiness more evident. They are really weak laterally, I was able to flex mine by hand once they were off the car. I am by no means a suspension expert, but that's what I personally think it is.

3X3=5 · 09-27-2010, 11:22 PM

I have no doubt that changing out the OEM bushings will help, but I took the car to Tru-Line (highly regarded alignment/suspension shop here in Seattle) and had them take a look. The tech said the install all looks good. But the dampers just aren't matched on these coilovers - the fronts are a lot stiffer than the rears. This was demonstrated by pushing the frame down in front - the majority of pressure was transferred through the tire which flexed a bit. However the body didn't move much at all (meaning the suspension is very stiff and the tire gives before the shock). However in the rear the opposite was true. With the same pressure applied, the body of the car would bounce up and down with minimal flex in the tire. He suggested that this mismatch in stiffness is what's causing the seesaw at a stop and bouncing on the highway.

nicks3 · 09-28-2010, 08:21 AM

Wow, thats not good....puts me off coilovers now. perhaps BMW Performance is the better option?

ajsalida · 09-28-2010, 09:03 AM

Are you sure the fronts were installed correctly? Some folks here were reusing the factory bump stops and that was wrong apparently, the kit has its own stops. Also if there is too much preload dialed into the front they are essentially solid (no give). What you're describing about the tires flexing before the front suspension does means the SPRING is somehow too stiff, not the shock.

If the fronts are not working/installed right then of course the rears will bounce around as the forces have to go somewhere.

3X3=5 · 09-28-2010, 10:35 AM

Yes, I installed myself (pretty knowledgeable when it comes to suspension install) and the tech at Tru-Line confirmed it looks correct. I used the bump stops that came with the coilovers (they're very short, and the car isn't slammed by any means so I don't believe the bump stops should be engaged at all). Also, based on the driving feel of the front damping feels correct.

09-23-2010, 12:26 PM	#1
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	KW Coilover install - reuse the OEM nuts or KW supplied nuts? Not getting a reply at the bottom of my other thread so I'll start a new one asking this question directly. For those who have installed KW (or any similar) coilovers, did you reuse the OEM nut/washer/foam pad assembly for the rear upper shock (the one you tighten from inside the trunk, part #7 on the diagram below) or did you use the KW supplied nut? The reason I ask is that I'm experiencing some seesaw front to back bouncing when I stop since installing the coilovers. I'm wondering if the OEM nut, which I did reuse, is allowing some play and causing the bounce. I'd like to know if changing nut might fix it before I tear the trunk apart again. Thanks. Attached Images
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09-23-2010, 03:37 PM	#2
stratplaya06 Captain 46 Rep 967 Posts Drives: 2008 E92 335xi-SOLD 5.0 Miata Join Date: May 2008 Location: Maryland iTrader: (10)	That seesawing is normal with coilovers. It is from your rear subframe bushings. I had the same issue until I got M3 bushings out back. __________________ \| PROcede Rev3 \| Vishnu Meth \| DCI \| BMW Perf. Exhaust \| AR Coated/Catless \| CP-E FMIC \| Quaife \|
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09-23-2010, 09:54 PM	#3
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	Could you explain why this would happen with coilovers but not the OEM suspension? If anything I'd think coilovers would reduce bounce (if it were present with OEM, which I don't think it was) because the stiffer springs and stiffer-valved shocks are more responsive. Also, would this also be present with a spring/shock upgrade? I didn't notice it when I had H&R sports on the car, but I had OEM sport shocks. Thanks.
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09-23-2010, 10:06 PM	#4
kevin@bavarianx Banned 33 Rep 812 Posts Drives: E36 M3 Join Date: Jul 2010 Location: Brea, CA iTrader: (3)	Did you hand tighten the rear mounts with two wrenches? I believe its a 6mm and a 11mm as the nut will just spin with just a ratchet.
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09-24-2010, 12:53 AM	#5
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	Yes, it was tightened using a 6mm socket on the pin and a wrench on the nut. I'm sure it was fully tightened.
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09-24-2010, 06:03 PM	#6
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	OK, I did some investigating to see if I can resolve this. Took the trunk apart and looked at how the rear shocks mount to the car. It turns out you can't possibly used the KW supplied nut - it wouldn't be tightening to anything but the threaded shock itself (not the frame of the car). Because the opening where the shock enters the car is so large, you must reuse all of the stock hardware both in the fenderwell and in the trunk. I really don't understand this set up, it seems very loose because you're basically tightening two washers against each other with a layer of foam on either side of the frame. I took some pictures to illustrate. Has anyone replaced their rear mounting hardware completely? My guess is that the seesaw effect I'm experiencing is caused by the foam pads allowing the suspension to move a little after I stop. If I can't resolve this I don't think I'll keep these coilovers because it's annoying. Yes, I'm aware that I can change to M3 bushings but that's more expense time and a harsher ride, so I won't be doing that. And can someone please explain why the coilovers produce the seesaw effect while the OEM suspension (or an upgraded spring/shock combo) does not? I really don't understand what the difference would be. Attached Images
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09-26-2010, 11:41 AM	#7
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	Bump for the question: can someone please explain why the coilovers produce the seesaw effect while the OEM suspension (or an upgraded spring/shock combo) does not? I really don't understand what the difference would be.
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09-26-2010, 10:37 PM	#8
stratplaya06 Captain 46 Rep 967 Posts Drives: 2008 E92 335xi-SOLD 5.0 Miata Join Date: May 2008 Location: Maryland iTrader: (10)	The car doesn't dampen the movement as well, because of the stiffer shocks/springs. This puts more lateral force on the subframe bushings, making their sloppiness more evident. They are really weak laterally, I was able to flex mine by hand once they were off the car. I am by no means a suspension expert, but that's what I personally think it is. __________________ \| PROcede Rev3 \| Vishnu Meth \| DCI \| BMW Perf. Exhaust \| AR Coated/Catless \| CP-E FMIC \| Quaife \|
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09-27-2010, 11:22 PM	#9
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	I have no doubt that changing out the OEM bushings will help, but I took the car to Tru-Line (highly regarded alignment/suspension shop here in Seattle) and had them take a look. The tech said the install all looks good. But the dampers just aren't matched on these coilovers - the fronts are a lot stiffer than the rears. This was demonstrated by pushing the frame down in front - the majority of pressure was transferred through the tire which flexed a bit. However the body didn't move much at all (meaning the suspension is very stiff and the tire gives before the shock). However in the rear the opposite was true. With the same pressure applied, the body of the car would bounce up and down with minimal flex in the tire. He suggested that this mismatch in stiffness is what's causing the seesaw at a stop and bouncing on the highway.
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09-28-2010, 08:21 AM	#10
nicks3 First Lieutenant 31 Rep 309 Posts Drives: 335d Xdrive Msport Plus Join Date: Oct 2006 Location: Midlands, United Kingdom iTrader: (0)	Wow, thats not good....puts me off coilovers now. perhaps BMW Performance is the better option? __________________ 335d Xdrive Msport Plus, ACS springs and lots of toys Range Rover Evoque Dynamic Lux VW Touran 1.9Tdi, 18" wheels, superchipped and lowered!
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09-28-2010, 09:03 AM	#11
ajsalida Colonel 226 Rep 2,387 Posts Drives: 95 M3, 02 R1150GSA, 09 335xi Join Date: Aug 2010 Location: SW USA iTrader: (2)	Are you sure the fronts were installed correctly? Some folks here were reusing the factory bump stops and that was wrong apparently, the kit has its own stops. Also if there is too much preload dialed into the front they are essentially solid (no give). What you're describing about the tires flexing before the front suspension does means the SPRING is somehow too stiff, not the shock. If the fronts are not working/installed right then of course the rears will bounce around as the forces have to go somewhere.
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09-28-2010, 10:35 AM	#12
3X3=5 Lieutenant 117 Rep 557 Posts Drives: in a lot of traffic Join Date: Jul 2010 Location: Seattle iTrader: (8)	Yes, I installed myself (pretty knowledgeable when it comes to suspension install) and the tech at Tru-Line confirmed it looks correct. I used the bump stops that came with the coilovers (they're very short, and the car isn't slammed by any means so I don't believe the bump stops should be engaged at all). Also, based on the driving feel of the front damping feels correct.
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