ISC N1 Coilover Question

[Gooz]

Hey guys, so the M3 I purchased recently came with the ISC N1 coilovers. On the freeways it basically rolls into dips and throws the car back up so bad I almost hit my head on the roof every time. I also canyon the car and mid turn bumps upset the car so much I'll rather not canyon it at all. I've tried finding anything bad about these coilovers but everyone says they're great and they have no issues. I will be getting Ohlins soon but I wanted to know if anyone has experienced this with these coilovers and if there's a fix so I can enjoy the car for a few months until I switch. I've tried playing stiffness settings but they don't help the bounciness.

[Onefastsicilian]

did you preload the fronts? How low are you sitting? Whats your dampening setting?

I had these and loved them.

[Gooz]

did you preload the fronts? How low are you sitting? Whats your dampening setting?

I had these and loved them.

I'm not sure if the PO installed them with the correct amount of preload or if any. I'll be taking it to the shop this week to check that and maybe raise the rear a little. Damping is set to 5 clicks from soft in the front and 8 in rear. This is how it sits now

[mrgizmo04]

This sounds like the anti flat ride / very high front rate situation where the car just can't settle because the front end is so nervous.

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[T.J.]

I would try going full soft and see how feels. Sounds like they’re just too stiff. Are they the street kit or track kit?

[Arith2]

This sounds like the anti flat ride / very high front rate situation where the car just can't settle because the front end is so nervous.

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[Onefastsicilian]

Just sell them, and buy my ohlins

[Chas3n]

They’re over dampened in the front combined with a stiffer front spring. The chassis isn’t able to level out quick enough on their dampers and you thus get the issue you’re having.

A bandaid would be to contact swift and get the appropriately sized spring with a softer rate!

[DJAM3]

What are your spring rates?

[Gooz]

What are your spring rates?

They’re over dampened in the front combined with a stiffer front spring. The chassis isn’t able to level out quick enough on their dampers and you thus get the issue you’re having.

A bandaid would be to contact swift and get the appropriately sized spring with a softer rate!

560/672 according to Bimmerworld😬😬

[Tbonem3]

560 oooof.

If you end up going down to like 300-400 or whatever, keep in mind you may need a taller spring, if the adjustment threads don't allow enough range. Due to more sag.

[r4dr]

560/672 according to Bimmerworld😬😬

How much do you want to spend? If you get these sorted out, would you want to stick with these?

I'd throw 280-350# front springs on there and get some flat ride. Those rates have pretty bad pitch per FCM's spreadsheet.

[mrgizmo04]

Find out what the dampers' spring rate range is before throwing 280-350 springs on there. That is 40-50% reduction... Normally dampers can handle +/-20% or so. So even if you run dampers on full soft with 280 springs, you might still experience subpar ride quality. It's not just about getting the right spring rates to achieve flat ride, dampers have to be valved appropriately also.

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[Suspension Decoder]

It's safer to go softer on springs (and deal with a bit of overdamped behavior) than to go stiffer. As several people suggest, the softer spring route is worth considering.

Spring length matters, as also mentioned.

Run the dampers at a softer setting, and make sure you aren't bottoming onto the bump stops being too low.

May need to stiffen the front bar and/or soften the rear to maintain neutral handling.

The situation ought to improve. G/L.

[maupineda]

560 oooof.

If you end up going down to like 300-400 or whatever, keep in mind you may need a taller spring, if the adjustment threads don't allow enough range. Due to more sag.

That is if you have enough room to fir the spring, I have found this to be a challenge, is difficult to match the ride height you want with the rate you need to achieve the goal in mind, on top of this the spring still needs to have enough travel to match the bump travel of the strut assembly. I just went through all this and the lowest height I could dial in was stock (in fact 4mm taller). I could have gone one rate lower for a ~0.25in drop from where I am now, I could of also remove the locking ring but I felt that that could put too stress on the spring perch. I fought against using camber plates as I want the ride as good as it can be, but if lowering was a higher priority, then a camber plate would allow for some more drop without affecting the geo or travel.

is all a compromise, you choose what meets your priorities. I went with ride and suspension travel over lowering the car.