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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, Aug-15-2019, 08:18:44 PM   #11
hbalzanya69
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Default Re: Broken Ground Control Coilover springs

By looking at that spring I would say it's possible that spring might have been coil binding (which is where the spring coils all contact each other before the damper/strut bottoms out), especially if both springs broke at the same time, or close to it. Coil bind can not only cause a spring to break, but it can also cause corrosion (like the corrosion seen in the picture) that weakens the spring because the paint usually gets damaged when the coils make contact with each other.

If you want to verify whether that was happening or not, measure the spring perchs (top and bottom perch) then measure from the damper seal/cap to the base of the bumpstop (not the stop itself, the metal portion it sits against). Then subtract the distance between the damper/bumpstop base from the distance between perches. This difference will give you the perch gap when the damper/struck is bottomed out. If that gap is the same or less than the spring's "coil bind" or "coil stack" height (which in your case is 2.38"), you are coil binding the spring.

That said, ANY time you change the perch to perch distance this should be checked, especially if the car is being raised. Also, when it comes to springs, they are not equal especially when it comes to coil bind. For example HyperCo springs use higher grade metal and as such, have a shorter coil bind height than the equivalent Eibach, so they are generally a better spring for applications where the spring must operate near coil bind.
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Old Thu, Aug-15-2019, 08:29:08 PM   #12
TboneM3
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Default Re: Broken Ground Control Coilover springs

^ true, though Eibach has a barrel solution to allow for a shorter coil stack for the same total spring height.

Those Eibach barrel springs have part #s just like their normal ERS springs, but end in an "S".

Good solution for those wanting flat ride with a 250lb-400lb front spring, but in a shorter package like 6" for a lower ride height which is generally desirable. I'm able to run a 7" spring and avoid coil bind issues, but only because I reduced the strut to mount stack height so significantly, lest I wish for 14.5' 4x4 ride height lol
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/// 2004 SilberGrau M3 Coupe 6MT slicktop zero options ~3200lbs JOURNAL
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Evolve-R Alpha N Evolve CSL CF Airbox Eventuri Scoop Supersprint V1 stepped 2.5" SS V1 S pipes 2.5" + 200 cell HFC OE sect 2 SCZA 2.5" sect 3 Besian RE pullies fan/SAP/washer delete CSL battery

Bilstein HD B6 + GroundControl/Eibach 325/550lb + GC "tall" RSMs Hotchkis front sway (med) rear strut bar TMS camber & subframe plates Eibach alu rear camber arms RE trans mounts AKG poly subf/diff 95a SDW RTAB OE weighted ///M knob + ZHP alcantara boot + UUC DSSR + delrin bushing

OE CSL trunk Cobra Nogaros + BK + manual OE bases TMS black pedals Sportline 8S 18"x 8.5/9.5" MPSS 245/275 APEX 75mm Studs Brembo 996 4 pot 36/40 345mm CSL & 28/30 328mm CSL ZHP "712" rack Pioneer/CDT/Eclipse/Kicker
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Old Thu, Aug-15-2019, 09:20:59 PM   #13
hbalzanya69
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Default Re: Broken Ground Control Coilover springs

Quote:
Originally Posted by TboneM3 View Post
^ true, though Eibach has a barrel solution to allow for a shorter coil stack for the same total spring height.

Those Eibach barrel springs have part #s just like their normal ERS springs, but end in an "S".

Good solution for those wanting flat ride with a 250lb-400lb front spring, but in a shorter package like 6" for a lower ride height which is generally desirable. I'm able to run a 7" spring and avoid coil bind issues, but only because I reduced the strut to mount stack height so significantly, lest I wish for 14.5' 4x4 ride height lol
The part numbers ending in "S" are just silver color versions. The barrelled springs have a "3" in the middle of the part number so instead of 0600.250.0600 it would be a 0600.2530.0600.

When I did my E36 M3 front springs I ran 0600.250.0600 but I had to take the stock spring perch and run it upside-down to keep them from coil binding. How did you reduce the stack height on the E46?
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Old Thu, Aug-15-2019, 09:41:55 PM   #14
M3 dude
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Default Re: Broken Ground Control Coilover springs

Quote:
Originally Posted by hbalzanya69 View Post
By looking at that spring I would say it's possible that spring might have been coil binding (which is where the spring coils all contact each other before the damper/strut bottoms out), especially if both springs broke at the same time, or close to it. Coil bind can not only cause a spring to break, but it can also cause corrosion (like the corrosion seen in the picture) that weakens the spring because the paint usually gets damaged when the coils make contact with each other.

If you want to verify whether that was happening or not, measure the spring perchs (top and bottom perch) then measure from the damper seal/cap to the base of the bumpstop (not the stop itself, the metal portion it sits against). Then subtract the distance between the damper/bumpstop base from the distance between perches. This difference will give you the perch gap when the damper/struck is bottomed out. If that gap is the same or less than the spring's "coil bind" or "coil stack" height (which in your case is 2.38"), you are coil binding the spring.

That said, ANY time you change the perch to perch distance this should be checked, especially if the car is being raised. Also, when it comes to springs, they are not equal especially when it comes to coil bind. For example HyperCo springs use higher grade metal and as such, have a shorter coil bind height than the equivalent Eibach, so they are generally a better spring for applications where the spring must operate near coil bind.
agree. i'd say root cause are flogged bump stops, letting the shaft over travel and result in coil bind.

please replace those as well as fitting 1" longer springs
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Old Thu, Aug-15-2019, 09:53:13 PM   #15
TboneM3
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Default Re: Broken Ground Control Coilover springs

Quote:
Originally Posted by hbalzanya69 View Post
The part numbers ending in "S" are just silver color versions. The barrelled springs have a "3" in the middle of the part number so instead of 0600.250.0600 it would be a 0600.2530.0600.

When I did my E36 M3 front springs I ran 0600.250.0600 but I had to take the stock spring perch and run it upside-down to keep them from coil binding. How did you reduce the stack height on the E46?
Ah that's right, got them switched. Point is, there's a solution from Eibach if you need short springs but more travel.

I reduced stack height via TMS plates and removal of TMS spacer and BMW spacer for 13/16" total reduction. I use taller RSMs to reduce droop and bring the shock shaft higher up in its stroke, though to be fair, I'm not positive how much it matters where the travel is happening in the shaft's stroke - from what I've read, you want it higher up, not lower, but again I'm not positive.

here's more info on the fronts from my journal:
http://www.m3forum.net/m3forum/showp...&postcount=482
__________________
/// 2004 SilberGrau M3 Coupe 6MT slicktop zero options ~3200lbs JOURNAL
_


Evolve-R Alpha N Evolve CSL CF Airbox Eventuri Scoop Supersprint V1 stepped 2.5" SS V1 S pipes 2.5" + 200 cell HFC OE sect 2 SCZA 2.5" sect 3 Besian RE pullies fan/SAP/washer delete CSL battery

Bilstein HD B6 + GroundControl/Eibach 325/550lb + GC "tall" RSMs Hotchkis front sway (med) rear strut bar TMS camber & subframe plates Eibach alu rear camber arms RE trans mounts AKG poly subf/diff 95a SDW RTAB OE weighted ///M knob + ZHP alcantara boot + UUC DSSR + delrin bushing

OE CSL trunk Cobra Nogaros + BK + manual OE bases TMS black pedals Sportline 8S 18"x 8.5/9.5" MPSS 245/275 APEX 75mm Studs Brembo 996 4 pot 36/40 345mm CSL & 28/30 328mm CSL ZHP "712" rack Pioneer/CDT/Eclipse/Kicker

Last edited by TboneM3; Thu, Aug-15-2019 at 09:58:05 PM.
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Discussing Broken Ground Control Coilover springs in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)