[Frankenstein_135]

Hello

I am in search for coilovers for my E91 xDrive wagon, and for now my first choice are the ST XA coilovers. I am only looking for minor lowering and some autocrosses, and no track days. The ST is attractive because of its price and rebound adjustability. I have a few questions on the spring rates:

1. Anyone happens to know the spring rates on these coilovers? They have progressive springs - a main spring and a helper spring. When I asked an ST representative, he just said that it is progressive and therefore there is no straightforward measurement of spring rates. But I guess that the main and helper springs can be measured separately?

2. Anyone knows if the spring rate is different on wagons? I found a few posts on the stock spring rates for wagons, but few on coilovers, since very few people are modifying their wagons, which itself is fewer than other body types (so many "few"s). ST seems to offer different product for wagons and sedans, which leads me to think that the spring rate is specially tuned for wagons, but I do not have any proof. Anyone has more insights?

Thanks

[TyroneShoelaces]

Timely post! I have a wagon that was awd, now rwd and came with sport suspension. I'm in the middle of doing coilovers myself. I bought a lightly used set of BC's from someone who wrecked their car and destroyed the front right so I have to purchase a new one. My use is probably the same as yours. My wagon is daily with some spirited driving, occasional autocross (1st date in 2 weeks) and hopefully a fun track day tossed in (if I can keep this N54 out of limp mode)

So my coilovers came with 8k springs for the front and 12k for the rear. I installed the rears and am rolling with that for now. I need to buy a new front from BC and wondering if I should drop the spring rate down from 8k to something less for the front. This would be the time to do it if so.

You've probably read all the same threads as me here, and I don't have a definite plan. 8k and 12k rear is kind of the default from BC it seems but according to what I've read it should be like 5k and 12k ratio.

[Frankenstein_135]

Originally Posted by TyroneShoelaces

Timely post! I have a wagon that was awd, now rwd and came with sport suspension. I'm in the middle of doing coilovers myself. I bought a lightly used set of BC's from someone who wrecked their car and destroyed the front right so I have to purchase a new one. My use is probably the same as yours. My wagon is daily with some spirited driving, occasional autocross (1st date in 2 weeks) and hopefully a fun track day tossed in (if I can keep this N54 out of limp mode)

So my coilovers came with 8k springs for the front and 12k for the rear. I installed the rears and am rolling with that for now. I need to buy a new front from BC and wondering if I should drop the spring rate down from 8k to something less for the front. This would be the time to do it if so.

You've probably read all the same threads as me here, and I don't have a definite plan. 8k and 12k rear is kind of the default from BC it seems but according to what I've read it should be like 5k and 12k ratio.

It's been a couple month and I still haven't made up my mind...

I talked to ST customer service a couple more times and confirmed the following:
1. The XA series do not come with a camber plate.
2. The front springs have a conical shape so it my decrease wheel clearance.

These are not deal breakers, but not ideal. So I looked back at BC, which was my first choice until I found ST. The problem for BC is that, the I-59-BR fits AWD E90 and E92, and the I-17-BR fits RWD E91 and E93. But I have an AWD E91...

Since you have performed a conversion from AWD to RWD, did you notice any difference in the shocks? Also, what do you have installed now for your wagon?

P.S. I also looked at Bilstein and Fortune Auto. Bilstein does not have a camber plate, either, so that puts it in the same boat as ST - good but not ideal. Fortune Auto is a bit out of my budget.

[TyroneShoelaces]

Originally Posted by Frankenstein_135

It's been a couple month and I still haven't made up my mind...

I talked to ST customer service a couple more times and confirmed the following:
1. The XA series do not come with a camber plate.
2. The front springs have a conical shape so it my decrease wheel clearance.

These are not deal breakers, but not ideal. So I looked back at BC, which was my first choice until I found ST. The problem for BC is that, the I-59-BR fits AWD E90 and E92, and the I-17-BR fits RWD E91 and E93. But I have an AWD E91...

Since you have performed a conversion from AWD to RWD, did you notice any difference in the shocks? Also, what do you have installed now for your wagon?

P.S. I also looked at Bilstein and Fortune Auto. Bilstein does not have a camber plate, either, so that puts it in the same boat as ST - good but not ideal. Fortune Auto is a bit out of my budget.

I never drove the vehicle as an awd car. I bought it as a crashed awd auto N52. The first time I drove it was as a RWD manual N54. I test drove a rwd N52 and it was just a cruiser feeling to me and seemed to drive well.

I am currently running sport springs with B4 shocks up front and the coilover rears. The ride is OK. I have M3 arms up front and I find the ride a bit darty and rough which is odd for a car with such squishy shocks. I just bought a set of 18" wheels to get off the 19" 35 series tires . I need to order the coilover for the front to finally swap them on. I am going to order a 6k spring to be at 1:2 ratio.

Ordering struts for an AWD E90 will fit your wagon fine. You just have to decide on spring rates for the rear, which for BC is an included option when ordering.

[Frankenstein_135]

Originally Posted by TyroneShoelaces

I never drove the vehicle as an awd car. I bought it as a crashed awd auto N52. The first time I drove it was as a RWD manual N54. I test drove a rwd N52 and it was just a cruiser feeling to me and seemed to drive well.

I am currently running sport springs with B4 shocks up front and the coilover rears. The ride is OK. I have M3 arms up front and I find the ride a bit darty and rough which is odd for a car with such squishy shocks. I just bought a set of 18" wheels to get off the 19" 35 series tires . I need to order the coilover for the front to finally swap them on. I am going to order a 6k spring to be at 1:2 ratio.

Ordering struts for an AWD E90 will fit your wagon fine. You just have to decide on spring rates for the rear, which for BC is an included option when ordering.

I think I'll pull the plug on the BC coilovers for AWD E90. I looked up RealOEM, and the E90 and E91 have the same part number for the front shock, but different for the rear. My guess is that it is just different damping rate to match the spring rate. I tried to reach out to BC to confirm but wasn't able to.

The Fortune Auto 500 series suspension I looked at has a 8k front / 11k rear, compared to the 6k front 12k rear from BC, which was surprising to me. It seems that Fortune Auto is universal to E90/E91/E92, which kinda confirms that a shock for E90 can also be installed on E91.

Wow the history of your wagon amazes me. Great work and I hope it brings you a lot of good memories.

[TyroneShoelaces]

Originally Posted by Frankenstein_135

I think I'll pull the plug on the BC coilovers for AWD E90. I looked up RealOEM, and the E90 and E91 have the same part number for the front shock, but different for the rear. My guess is that it is just different damping rate to match the spring rate. I tried to reach out to BC to confirm but wasn't able to.

The Fortune Auto 500 series suspension I looked at has a 8k front / 11k rear, compared to the 6k front 12k rear from BC, which was surprising to me. It seems that Fortune Auto is universal to E90/E91/E92, which kinda confirms that a shock for E90 can also be installed on E91.

E91 uses a different rear spring than an E90 from the factory, so yes likely a heavier duty damper as well. E90 and E91 are mostly all interchangable vs an E92 body/interior wise. But suspensions are the same across the platform, except M cars.

8k/11k sounds like a bad ratio unless you're tracking your car from my research. The out of the box default setup from BC is 8/12k. I doubt most people care if they're just slamming their car. I just want low and rides well with the occasional autocross /track. Much like a good performance spring shock combo, but a little lower.

[Frankenstein_135]

Pulled the plug on the I-59-BR from BC Racing. The website says it is for AWD E90/E92 but I was finally able to get hold of a tech support and was told that it fits AWD wagons as well. Will update when installed.

[TitanLH8]

I'm on the fence between the I-59-BR BC Racing and Bilstein B14 PSS for my E91 AWD. Would love to hear your experience with the coilovers once it's installed

[Frankenstein_135]

The coilovers arrived. Will be a slow install as I have a pretty busy work schedule abd very limited free time.

I do have one question. When removing and installing the front strut, the spindle needs to be at a very steep angle. That makes the CV shafts at a very steep angle as well - almost feels like they are popping out. I watched several videos on coilover installations on xDrive cars, and they all had this. When everything is buttoned up, all the geometries go back to normal.

Can anyone confirm that there is no special procedures for the CV shafts? Just want to have a peace of mind.

[whyzee125]

Mr. 5 has an awesome thread from way back with all the afermarket spring rates for our cars. If the XA's are similar to V2's, here are KW's spring rates for this chassis

Aftermarket

KW v1-v3 (non M3)
Front: 190-256 lb/in (progressive average)
Rear: 545-570 lb/in (progressive average)

KW Street Comfort
Front: 286 lb/in
Rear: 572 lb/in

KW Clubsport (non M3)
Front: 400 lb/in
Rear: 570 lb/in

M3 KW v3
Front: 285 lb/in
Rear: 630 lb/in

[whyzee125]

Originally Posted by TyroneShoelaces

Timely post! I have a wagon that was awd, now rwd and came with sport suspension. I'm in the middle of doing coilovers myself. I bought a lightly used set of BC's from someone who wrecked their car and destroyed the front right so I have to purchase a new one. My use is probably the same as yours. My wagon is daily with some spirited driving, occasional autocross (1st date in 2 weeks) and hopefully a fun track day tossed in (if I can keep this N54 out of limp mode)

So my coilovers came with 8k springs for the front and 12k for the rear. I installed the rears and am rolling with that for now. I need to buy a new front from BC and wondering if I should drop the spring rate down from 8k to something less for the front. This would be the time to do it if so.

You've probably read all the same threads as me here, and I don't have a definite plan. 8k and 12k rear is kind of the default from BC it seems but according to what I've read it should be like 5k and 12k ratio.

I would go to 6k up front, 8k is pretty stiff especially for how BC's are valved (fairly stiff). 6k/12k is a good proven combo as is 5k/15k but depending on the coilover, height, and spring rate, 5k comes with some added complications. I think 6k is a good compromise.

[TyroneShoelaces]

Originally Posted by whyzee125

I would go to 6k up front, 8k is pretty stiff especially for how BC's are valved (fairly stiff). 6k/12k is a good proven combo as is 5k/15k but depending on the coilover, height, and spring rate, 5k comes with some added complications. I think 6k is a good compromise.

That's what I ended up ordering from BC. Waiting on them to come in. 6 week lead time

[Frankenstein_135]

Finally installed the coilovers. From factory settings, the front wheel gap is about half finger width and the rear is about two with the optional spacer installed. I adjusted front and rear to about one and a half finger width (didn't want my car too low). Keep in mind that the wagon is more rear-heavy, so the rear will sit lower compared to a sedan at the same settings.

I have 18x9 ET31 wheels and 255/35 R18 tires, and the front strut clearance is very tight. There may be 1/4" to 1/2" of clearance when static.

Driving slowly on residential roads, the tiers do not rub and the springs do not feel harsh at all. Will report highway driving and AutoX when I get alignment done next week.

[Frankenstein_135]

Originally Posted by Frankenstein_135

Finally installed the coilovers. From factory settings, the front wheel gap is about half finger width and the rear is about two with the optional spacer installed. I adjusted front and rear to about one and a half finger width (didn't want my car too low). Keep in mind that the wagon is more rear-heavy, so the rear will sit lower compared to a sedan at the same settings.

I have 18x9 ET31 wheels and 255/35 R18 tires, and the front strut clearance is very tight. There may be 1/4" to 1/2" of clearance when static.

Driving slowly on residential roads, the tiers do not rub and the springs do not feel harsh at all. Will report highway driving and AutoX when I get alignment done next week.

I have been driving the wagon for a while now and attended an AutoX event. Here is what I can report:

1. Expect settlement after installation. I adjusted them a few times to compensate for the settlement.

2. About 20 turns towards hard is too harsh on the streets. It doesn't bother me, but it does bother the car - it knocked the adjuster balls out of the automatic headlight once. I now have it about 8 turns front and 12 turns rear, which seems good.

3. Running full hard at AutoX with my spring rate, square tire set up and factory spec alignment, the car is definitely balanced towards understeer. Safe for the streets and since it will be a street car mainly, I'm good with this.

4. I have maxed out headlight adjustment and it is still pointing lower than my liking. Still figuring this out. Main thread:
https://www.e90post.com/forums/showthread.php?t=1954297

[LarrCarter1231]

Pulled the plug on the I-59-BR from BC Racing!