E9X Swift Spec-R springs

[Brian_]

For anyone else looking to get a higher/stiffer rate lowering spring, the still available E9X 335i Swift Spec-Rs (4X905R) work out decently well installed on E82s. Springs rates are advertised as front: 224 lb/in (4.0 Kg/mm) rear: 616 lb/in (11 Kg/mm) with a 1" front and .8" rear drop for E90/E92/E93 . Rates are linear front and rear, with a very soft rate upper section that goes coil bound at ride height acting as a helper spring to keep everything seated in full droop.

I decided to try them hoping they’d be close enough in ride height front to rear and less slammed than all the other E82 specific springs out there, and I'm pretty happy with the result so far. There was a little more forward rake than I wanted at first so I ended up installing some thicker E30 upper spring isolators (31331128522) up front as well as some 034 Motorsport spring isolators (034-404-Z001) on the soft "helper" portion to both protect the spring and give a small addition to the block height when coil bound. That’s got me at ~.25” forward rake with a little extra front ground clearance as well making steep driveways a bit easier. Still have the option to toss in some extra 5mm spring spacers (33536769473) for the rear if I decide I want to try out more rake, but I'm satisfied with the handling balance it has for now with the slight rake.

Car is a lighter spec’d 128i (slicktop, manual, manual seats), so YMMV with an N54 car. Some pics below with current ride height and showing the thicker upper isolators and 034 spring sleeves as installed.

[sibanez]

Great find. Any idea what the spring rates are? Which shocks and struts are you running?

[Brian_]

Originally Posted by sibanez

Great find. Any idea what the spring rates are? Which shocks and struts are you running?

According to Swift:

Front: (224 lb/in) (4.0 Kg/mm)
Rear: (616 lb/in) (11 Kg/mm)

Puts the front/rear wheel rates both at ~205 lb/in and feels pretty balanced.

Running off the shelf Koni yellows for now with trimmed OEM bumpstops.

[HP Autosport]

Excellent find and springs!

[roninsoldier83]

How is the ride on the street with those rates and Koni’s?

[Brian_]

Originally Posted by roninsoldier83

How is the ride on the street with those rates and Koni’s?

Feels entirely daily drivable to me for the roads in my area. Still comfortable and with plenty of rear travel that I’m not worried about bottoming out driving to/from track days with the trunk loaded down with tools and spares.

Probably wouldn’t recommend it for any commutes with real rough roads or lots of pot holes though as the front height is pretty low for how soft the spring rate is so large bumps can get pretty crashy

[Daydream Garage1]

Great find, thank you.

[ShocknAwe]

This is sticky worthy. Nice job. Please update your post with all the parts part numbers and a photo of what you did with the front isolators to get it to work!

I wonder if we have a moderator...

[PureE92]

Would these be lower than the tein s tech springs? The specs seem very similiar, 190lb front and 590lb rear

[Brian_]

Originally Posted by PureE92

Would these be lower than the tein s tech springs? The specs seem very similiar, 190lb front and 590lb rear

No idea on height, but the listings I saw had all the Tein variants at 168lbs front & 560lbs rear.

https://www.tein.com/srch/us_search....lt&item=S.TECH

[Brian_]

Originally Posted by ShocknAwe

This is sticky worthy. Nice job. Please update your post with all the parts part numbers and a photo of what you did with the front isolators to get it to work!

I wonder if we have a moderator...

I’ll grab some pics next time I take the wheels off.

[PureE92]

Originally Posted by Brian_

No idea on height, but the listings I saw had all the Tein variants at 168lbs front & 560lbs rear.

https://www.tein.com/srch/us_search....lt&item=S.TECH

Oh wow, thanks. I saw it being posted on the spring rates page on the e90 forum. In that case it definitely makes more sense to go swifts. Thanks again!

[Brian_]

Originally Posted by PureE92

Oh wow, thanks. I saw it being posted on the spring rates page on the e90 forum. In that case it definitely makes more sense to go swifts. Thanks again!

Another option that I have seen are the Megan racing E92 springs (MR-LS-E92) which they list as having 372lbs/in front & 694lbs/in rear, but even after confirming the listed rates with them via email I’m still sceptical as it’s drastically different than their E90 springs and lists a 1.5” front drop vs the swifts 1”.

Will probably still order a set to test out if I decide to stay in my same time trials class (no coilovers allowed) again for next year.

[PureE92]

Originally Posted by Brian_

Another option that I have seen are the Megan racing E92 springs (MR-LS-E92) which they list as having 372lbs/in front & 694lbs/in rear, but even after confirming the listed rates with them via email I’m still sceptical as it’s drastically different than their E90 springs and lists a 1.5” front drop vs the swifts 1”.

Will probably still order a set to test out if I decide to stay in my same time trials class (no coilovers allowed) again for next year.

Would those be the stiffest springs on our platform?

[Brian_]

Originally Posted by PureE92

Would those be the stiffest springs on our platform?

Highest advertised rates I’ve seen, but given it’s Megan racing I’m assuming they start slammed with no travel and just get worse as they sag.

[mkeiser]

Originally Posted by Brian_

Another option that I have seen are the Megan racing E92 springs (MR-LS-E92) which they list as having 372lbs/in front & 694lbs/in rear, but even after confirming the listed rates with them via email I’m still sceptical as it’s drastically different than their E90 springs and lists a 1.5” front drop vs the swifts 1”.

Will probably still order a set to test out if I decide to stay in my same time trials class (no coilovers allowed) again for next year.

i'd be curious how the koni yellows perform with that high of spring rates.

[Brian_]

Originally Posted by mkeiser

i'd be curious how the koni yellows perform with that high of spring rates.

They don’t seem to be having too much trouble with the swifts set to right about the middle of their range.
They can still easily keep the car jacked down on the bump stops if you crank them up to like 75% or more on our bumpy Texas tracks so they should still have some high speed rebound headroom to handle stronger springs.
Main issue I would expect is a lack of front bump travel with such a big drop.

[PureE92]

Originally Posted by Brian_

Highest advertised rates I’ve seen, but given it’s Megan racing I’m assuming they start slammed with no travel and just get worse as they sag.

Thanks, I figured for the cost I’d try them out before going to Swifts. The Megan’s cost me 100 vs the 400 needed for swifts, hopefully the drop isn’t that much more. I love how your car is sitting right now.

[Brian_]

Updated the first post with a little more info.

[mkeiser]

Any updates on Megan springs or Swift springs? Im wanting to get rid of the H&RSports im running right now to gain a little bit of ground clearance and increase spring rate.

Don't have the cash to go full blown motorsport coilovers yet.

[PureE92]

Originally Posted by mkeiser

Any updates on Megan springs or Swift springs? Im wanting to get rid of the H&RSports im running right now to gain a little bit of ground clearance and increase spring rate.

Don't have the cash to go full blown motorsport coilovers yet.

Hey, I am not the OP but I did end up getting the Megan springs but I didn't like the frequency and drop of the MR-LS-E92.

I ended up using the MR-LS-E90 front springs and the MR-LS-E92 rear springs to get the perfect amount of drop and stiffness. I was going for a 1:3 ratio vs the 1:2 ratio offered by megan. It cost a little more but the car feels much more planted and complaint on the road. 260lbs front & 690lb rear

[mkeiser]

Originally Posted by PureE92

Hey, I am not the OP but I did end up getting the Megan springs but I didn't like the frequency and drop of the MR-LS-E92.

I ended up using the MR-LS-E90 front springs and the MR-LS-E92 rear springs to get the perfect amount of drop and stiffness. I was going for a 1:3 ratio vs the 1:2 ratio offered by megan. It cost a little more but the car feels much more planted and complaint on the road. 260lbs front & 690lb rear

this is good intel, exactly what I was looking for, thank you!