Coilover Recommendation

[r4dr]

250#, these (mine) are swift springs, I wanted to stay with swift due to their reputation of being the best. my other option is to go down to 225#. I will mount them and do some physical measurements. but this will help others that want to change springs.

Gotcha. Eibach makes a 7", 275#, 2.5" ID spring (0700.250.0275) but that's as low as they go.

Edit: if you go 60 mm, I'd consider buying those Eibach adapters and Turner top hat adapters. PM me if that happens.

[maupineda]

What spring rate are you going for? I see Eibach makes 2.5" springs that are 7" long, am I missing something?

250#, these (mine) are swift springs, I wanted to stay with swift due to their reputation of being the best. my other option is to go down to 225#. I will mount them and do some physical measurements. but this will help others that want to change springs.

[r4dr]

The photo below also shows the shim stack (6.75mm) I am using to reduce preload, although I have come to realize is pointless as shimming or having preload end up in the same place based on my calculations, I fear I may need to go to a 7in spring, the issue is that the there are no standard size springs in 7in heights and will need to go to either 280 or 224 60mm springs, and buy again the spring seats as the 60mm springs won't fit with the 2.5 TMS items

What spring rate are you going for? I see Eibach makes 2.5" springs that are 7" long, am I missing something?

[maupineda]

For those interested, the H&R, KW and Bilstein can be made to work with linear springs and the OE hardware in combination with the TMS upper spring seat.

Bellow a few images showing the TMS upper spring seat (2.5in) mounted to the OE bearing and aluminum hat



The photo below also shows the shim stack (6.75mm) I am using to reduce preload, although I have come to realize is pointless as shimming or having preload end up in the same place based on my calculations, I fear I may need to go to a 7in spring, the issue is that the there are no standard size springs in 7in heights and will need to go to either 280 or 224 60mm springs, and buy again the spring seats as the 60mm springs won't fit with the 2.5 TMS items



Also, the upper spring pad can be modified (cut) to make it fit the TMS spring seat for an OEM look, and it provides protection to the bearing.



By the way, the M3 and Z4M share ALL hardware up top except for the aluminum hats, so this setup will be compatible with E46 M3's should you don't want or need to run camber plates (I don't, as I am after OEM+ experience) and don't want added NVH, plus the Z4M can add negative camber but shimming the strut and knuckle assembly

[maupineda]

I took my front struts off the car to take some measurements and prepare the coils for the new springs I got 080-250-250 swift springs, these are 8" long.

I also took the opportunity to take the bump stop out to learn how many bump travel the H&R struts have in total, and to my surprise, they do have 5" of travel, just 0.25 less than the OE strut



What I found was that the bump stop was pretty long, 70mm, the OE bump stop is 44mm long.



So what I did is I trimmed the bump stop to be the same length as the OE, ideally, I would have cut it to 40mm, but was difficult to be that precise.

The next picture shows how much travel there was before engaging the stop, with the car on the ground, my shocks compressed 2.1in or 53mm, so there was just a little bit of travel (~7mm), before engaging the stops. with the mod I did to the bump stop I literally gained about 25mm or 1in of travel.



No wonder why the car rode very stiff, and even so that I had set the ride height to be the same as OE! If I had set it at 1.0 drop per the H&R spec, I was literally riding well into the stops.

Now the issue I am finding is that with the perch set all the way down, my 8" spring is compressed to 7.1 when assembled to the strut, this means I am adding about 210# of preload, which will limit how much the car would drop on its own weight, my calculations indicate that the car would drop 2.75in with no preload, with the preload I have it means it would lower just 2", effectively raising the car a few mm from what I had before with no room to lower more at the perch. So to reduce preload, I am looking into how to space the top hat up to reduce preload and allow the car to drop more. I don't need much, perhaps 8-10mm. I will post what I end up doing.

Overall it has been very fun understanding deeply my setup, suspension travel, spring rates, etc. the cheery on the cake will be the FCM dampers, but first I need to get the baseline I want.

[r4dr]

That was fixed a decade ago :P

Durrrrr

Thanks, guess it's down to an all-out FCM setup or TCK DAs with flat ride spring rates.

[Obioban]

On a related note. Is the weird noise from TCK DA rears still an issue? Or did they fix that?

That was fixed a decade ago :P

[r4dr]

On a related note. Is the weird noise from TCK DA rears still an issue? Or did they fix that?

[maupineda]

Very cool thanks! I wonder if they have all the diameters that their camber plates can be optioned with.

Also, are you assuming they'll fit our stock mounts or were you able to confirm? I would assume they'd only fit their camber plates, but their camber plates do use the stock (yellow/black) trust bearing.

I guess as long as there's enough room between the trust bearing and top mount, you'll be fine. I was just thinking, ya the diameter is correct, but what about their depth. it's probably fine.

Yes, ECS sells the 2.5in and the 60mm. which are the two options available with the TMS plate kits. I have made some guesses primarily based on the fact that their kits work with the OE spring perch as well the OE bearing, so the depths should be compatible, once I receive them I will document the fitting.

Also, on the strut side, my OE BMW Z4M Struts have 5in of travel, I will measure and compare the H&R coil struts when I take them off to install the new spring set this weekend, but my rough measurements with them still on the car indicate that they are about an inch shorter, being Euro cars, I am almost sure the actual difference is 20mm, so it will be 130mm vs 110mm (~4in).

To that travel we need to subtract the bump stop, the OE bump stop is 45mm sharp.

My car at the moment is set to the OE ride height (607mm from the bottom lip of the wheel to the fender), this means that my strut/spring assembly compresses about 2.1in (53mm), which leaves me with another 2.1 (53mm) of bump travel

If I extrapolate this to the OE strut and spring, the car will compress a further 20mm, or 73mm total, to maintain the stock ride height. This leaves bump travel at (130 - 73 = 57mm) or a little more than 2in, so it seems that OE would have between 4-5mm more travel to the H&R struts.

However...

Considering the bump stop, with the stock setup I have 57-45=12mm of travel before engaging the stop, if I assume the stop compresses almost all the way to 20mm, it means that actual bump travel is more in the range of 37-40mm before the suspension bottoms out completely. I have read that the H&R stop is shorter (40mm long), if this is true, then the bump travel is close to stock should I maintain the OE ride height (53-40=13), or about 33mm before bottoming out.

Lower the car a little (12mm actually) and then the car now rides on the bumps stops all the time with very little travel left, no surprise why all these coilover kits ride like shit!!!!

I am aiming to maintain the OE height and travel with my swift springs, I will also open the struts up to check if the H&R stops are 40mm. If not I will modify them. BTW, the Bilstein PSS10 has 40mm stops according to their TUV certificate

It will be interesting to see E46 M3's measurements, as seen above the Z4M is very limited in travel already from the factory.

[Tbonem3]

Very cool thanks! I wonder if they have all the diameters that their camber plates can be optioned with.

Also, are you assuming they'll fit our stock mounts or were you able to confirm? I would assume they'd only fit their camber plates, but their camber plates do use the stock (yellow/black) trust bearing.

I guess as long as there's enough room between the trust bearing and top mount, you'll be fine. I was just thinking, ya the diameter is correct, but what about their depth. it's probably fine.

[maupineda]

I believe the 2.5" spring ID will fit because my 2.5" springs do have a little wiggle room on my 2.5" perches.

Do you have a link to the TMS 2.5" top perches? never have seen them other than what came with the camber plates.

I found them as stand-alone items in ECS, Turner has them as add ons to their hybrid and street camber plates kits.

https://www.ecstuning.com/b-turner-motorsport-parts/25-spring-perch-for-turner-e46-m3-street-camber-plates-pair/tsu4680777~tms/

[Tbonem3]

I believe the 2.5" spring ID will fit because my 2.5" springs do have a little wiggle room on my 2.5" perches.

Do you have a link to the TMS 2.5" top perches? never have seen them other than what came with the camber plates.

[maupineda]

For what it is worth, the H&R and Bilstein coils use a 60mm perch in the front, which drives the use of 60mm ID springs only, for which there are not as many rate options in the Swift catalogue. So I bought some adapters from Eibach to mount 2.5in springs to a 60mm perch. These are made off aluminum and are fairly cheap ($20 each)

These may even work with KW coilovers as their perches are 61mm



I hope the springs are not an exact 2.5 (63.5) or it will be a very tight fit :P



Not much is added to the stack height



These will go with turner 2.5in spring perches up top to seat on the OE top mounts

[Tbonem3]

Oh ya nvm lol

[r4dr]

Ya, looking at it now, I think you're right. That said, now you'd only need to buy 1 pair of linear springs for the rear. So just add another $50-100 (easily find sets of race coils on ebay, etc). Run the FCM calculator with the 571 front + figure out the rear + chose a coil close to that = profit?

It takes 1000 lbs/in in the rear just to get up to a 1.01 ratio. You would probably want something like 1200 back there which is insane, and probably way beyond the damping capabilities of that shock. Crazy.