[kern417]

Originally Posted by skier_du

Interesting you bring up the sealing of the SPL arms. I saw a recent post where someone mentioned they claim those bushings will last years. I brought this up with Tony at VAC. He said they would make arms like that if someone wants them. But it would be with sealed, factory style bearings similar to their monoballs (both tension and LCA) they are now making. That's because they use the same type of ball joint as SPL on their race cars. Those joints often don't even make it through 1 race season without needing to be replaced. Let alone a street car with all the dirt (and salt if you live in the north)

That was probably my post. I'm still waiting for them to release the arms. That will really help front end grip by correcting the roll center.

There are some F8x guys that have had the arms for a while, but mostly in the rear. There are some long term reviews in their forums.

[skier_du]

Originally Posted by kern417

That was probably my post. I'm still waiting for them to release the arms. That will really help front end grip by correcting the roll center.

There are some F8x guys that have had the arms for a while, but mostly in the rear. There are some long term reviews in their forums.

I see. I asked Tony at VAC how long it would take him to make arms like that. He said he had just about everything needed so just a few days. If you called them and ask about making those roll center correction arms, they'd do it and with whatever bearing type you want. I'd say that's quick turn around fire a custom part. You could test out the arms for them.

[pkiledj]

Can someone explain why the monoball on the tension strut is beneficial as far as turning goes? What exactly does switching out the hydrobearing for the monoball do? And why the replace the bushing in the tension strut vs the lower control arm (which I thought were the same thing)? Here are some resources I found for reference:


Close Look at F30 328i Suspension by Insideline! https://f30.bimmerpost.com/forums/sh...d.php?t=648418

And


https://www.realoem.com/bmw/enUS/sho...diagId=31_0993

Granted the first link is RWD and I am more interested in the switch for my xdrive. Someone shed some light on this!

[Jvac]

Originally Posted by pkiledj

Can someone explain why the monoball on the tension strut is beneficial as far as turning goes? What exactly does switching out the hydrobearing for the monoball do? And why the replace the bushing in the tension strut vs the lower control arm (which I thought were the same thing)? Here are some resources I found for reference:


Close Look at F30 328i Suspension by Insideline! https://f30.bimmerpost.com/forums/sh...d.php?t=648418

And


https://www.realoem.com/bmw/enUS/sho...diagId=31_0993

Granted the first link is RWD and I am more interested in the switch for my xdrive. Someone shed some light on this!

Hey bud, it's easy to confuse the parts on the front suspension. I was in your shoes a short while ago when researching this topic. The lower control arm or LCA is the smaller, straighter one with the 90 elbow at one end. The tension strut (aka thrust arm, aka trailing link, and other names that bmw and other manufacturers have used interchangeably) is the larger arm with a zigzagging shape and a bigger bushing in the joint at one end.
Both can be replaced to make adjustments to the suspension geometry - there are bushings for the LCA which can increase front camber, and there are solid rubber bushings or monoballs (sealed bearings) available for the tension strut. Hopefully I got them all sorted out this time. It's a confusing jumble of names up front.
To your second question - the hydro bushings are designed for a comfortable ride. They're soft and squishy to go along with the general design philosophy of the f30 chassis, which is to isolate the driver from the feel of the road and give it a plush, floating type of ride. Unfortunately this also results in a vague and imprecise steering experience since all of these soft parts sit between the wheels and the steering components, in a way. They allow a lot of deflection or movement (slop) which is not really ideal in a high performance driving scenario.
Most of the folks on these forum threads are doing these mods to reduce the vague/numb feel. The solid bushes resist the deflections resulting in a more precise steering. Sharper turn in, easier to place the car on the desired line, increased feedback from the road. The increased negative camber improves the front tire grip during high speed cornering. All result in more predictable handling and increased driver confidence.

[pkiledj]

Originally Posted by FaRKle!

What were your final alignment specs?

There are a couple of reasons you may be feeling the way you do:
1) Alignment not set up to take advantage of parts, or out of cal alignment rack so you don't have what you think you have.
2) Other limiting factors on your car, so the headroom the bushings provide can't be reached.
3) You're just numb, and can't feel the difference, in which case no other bushings/monoballs will help you either.

If you really think that a degree of camber change doesn't have much effect when the suspension is properly aligned, well there's plenty of evidence to the contrary...

What does "out of cal alignment" mean?

[FaRKle!]

Originally Posted by pkiledj

What does "out of cal alignment" mean?

Uncalibrated alignment rack. So the rack says you have x measurement, but you really have something else.

For example, I went to a place once that said they aligned my toe to 0.05deg in each side, but when I went to a properly calibrated rack it was more like 0.35deg each side.

[pkiledj]

Originally Posted by FaRKle!

Uncalibrated alignment rack. So the rack says you have x measurement, but you really have something else.

For example, I went to a place once that said they aligned my toe to 0.05deg in each side, but when I went to a properly calibrated rack it was more like 0.35deg each side.

@FaRKle!, I just watched your video on the front sway bar - thanks for making that!

About the KMAC tension strut monoball - how did you determine the amount of caster to run? And how did you match the left/right caster? Did you literally just put the left and right tension struts side by side and eyeball the monoballs to get them to be symmetrical? My mechanic is talented but I can't speak to his knowledge of suspension performance. My point is, when he installs the monoballs what should I tell him as far as "put the hole at ______ o'clock"

[FaRKle!]

Originally Posted by pkiledj

@FaRKle!, I just watched your video on the front sway bar - thanks for making that!

About the KMAC tension strut monoball - how did you determine the amount of caster to run? And how did you match the left/right caster? Did you literally just put the left and right tension struts side by side and eyeball the monoballs to get them to be symmetrical? My mechanic is talented but I can't speak to his knowledge of suspension performance. My point is, when he installs the monoballs what should I tell him as far as "put the hole at ______ o'clock"

I want as much caster as I can without anything rubbing. For this platform that's about 8-8.5deg (you may rub at 8.5deg if lowered). To do this you need to adjust it while on an alignment rack. During initial install you can estimate it a bit though by measuring the distance from the bolt hole to the ball joint on the OE arm, and then setting the distance with the KMAC bushing a bit greater (like 1/4" or so).

[pkiledj]

Originally Posted by FaRKle!

I want as much caster as I can without anything rubbing. For this platform that's about 8-8.5deg (you may rub at 8.5deg if lowered). To do this you need to adjust it while on an alignment rack. During initial install you can estimate it a bit though by measuring the distance from the bolt hole to the ball joint on the OE arm, and then setting the distance with the KMAC bushing a bit greater (like 1/4" or so).

Maybe I'm misunderstanding how the KMAC bushing adjusts caster. I thought caster is adjusted by the way the bushing is pressed into the tension strut (where the hole is placed). So are you saying the caster can be adjusted after installing the bushing?

If you are just changing the angles that the wheels turn, why/where would it rub. I am lowered on Dinan springs but the drop is very minimal, especially in the front.

Can you explain the idea of adding caster from a handling perspective. Sorry for the newb questions!