[HP Autosport]

This is from one of the Hotchkis engineers:


This shows how we came up with the 95% stiffer than stock.

"Front OE Bar
- The front bar has 2 diameters depending on the sections you consider. We chose the larger of the 2 since it makes up for most of the torsional section of the bar.
O.D. = Ø26.7mm
Wall thickness = 4.29mm
I.D. = Ø18.12mm

Polar moment of inertia for this cross section = 39310 mm^4

Hotchkis Bar
O.D. = Ø31.75mm
Wall thickness = 4.78mm
I.D. = Ø22.19mm

Polar moment of inertia for this cross section = 75961 mm^4

Percentage stiffer than Stock=> (75961/39310)-1 = 0.93 or rounded up to 95% stiffer than stock"

[Mr. 5]

Thanks for explaining that Harold.

Originally Posted by HP Autowerks

This is from one of the Hotchkis engineers:


This shows how we came up with the 95% stiffer than stock.

"Front OE Bar
- The front bar has 2 diameters depending on the sections you consider. We chose the larger of the 2 since it makes up for most of the torsional section of the bar.
O.D. = Ø26.7mm
Wall thickness = 4.29mm
I.D. = Ø18.12mm

Polar moment of inertia for this cross section = 39310 mm^4

Hotchkis Bar
O.D. = Ø31.75mm
Wall thickness = 4.78mm
I.D. = Ø22.19mm

Polar moment of inertia for this cross section = 75961 mm^4

Percentage stiffer than Stock=> (75961/39310)-1 = 0.93 or rounded up to 95% stiffer than stock"

[stressdoc]

Orb's original point that the Hotchkis sways -- in particular the front -- is a stiff mofo still holds. My guess is that it is well suited to autoX and best fitted with relatively stiff coilovers, a LSD, and chassis & strut tower braces. A very tight ride with little roll. Not user friendly at high speeds on the street, things will happen very fast with little warning. Much closer to a race set-up, great for experienced drivers.

But c'mon Harold, tell us what your opinion of the feel is. What is it like riding around in a Hotchkis car?

[HP Autosport]

Originally Posted by stressdoc

Orb's original point that the Hotchkis sways -- in particular the front -- is a stiff mofo still holds. My guess is that it is well suited to autoX and best fitted with relatively stiff coilovers, a LSD, and chassis & strut tower braces. A very tight ride with little roll. Not user friendly at high speeds on the street, things will happen very fast with little warning. Much closer to a race set-up, great for experienced drivers.

But c'mon Harold, tell us what your opinion of the feel is. What is it like riding around in a Hotchkis car?

We are currently using the Hotchkis front anti-roll bar only and using for very fine tuning of the handling of our project 335i.

Most of our suspension tuing is done with spring rates and damper settings. We only added the Hotchkis front anti-roll bar to reduce front body roll and lessen the effect of roll induced camber changes, thus keeping us from running more than -3 degrees of front camber. The end result is much less understeer.


The increase in roll stiffness up front is barely noticeable after the installation, probably because of our particular suspension combination. Ride qualty did not change by adding the Hotchkis front anti-roll bar.

Harold

[Mr. 5]

Originally Posted by Orb

It is still a stiff bar no matter what but far less than what I was expecting and the biasing remains the same as stock. That setup will excel in flat autocross with no LSD but I wouldn’t want to drive on my local mountain run with it which uses all the travel.

Knowing that the stock bar is hollow opens up a lot more options now especially for the track guys. You can see the Stock front + H&R rear is very scary indeed.

Orb

This was why I was confused with your earlier explanation because based on what I was told by other members and what I've read, the Hotchkis bars seemed to be a great option since it was still proportional to stock.
No matter what, I think that upgrading to the 14mm rear bar is a good start for my first so called aftermarket sway bar.

[AV9]

Originally Posted by Mr. 5

This was why I was confused with your earlier explanation because based on what I was told by other members and what I've read, the Hotchkis bars seemed to be a great option since it was still proportional to stock.
No matter what, I think that upgrading to the 14mm rear bar is a good start for my first so called aftermarket sway bar.

be sure to let us know how it works out for you!

[Chowbow]

A side note, may be related. Hotchkis' 335i has PSS9s and was shown testing at some SoCal autocrosses...

With my shocks and springs, I found no need for aftermarket sway bars. I actually had them in my garage ready to install, but ended up selling them since I felt the car was already neutral and had less roll than stock. I wanted to maintain some body roll and compliance on the street. On bumpy mountain roads, it's already "itchy" enough... I'm not sure too many people with stiffer suspension setups will want to also add sway bars, particularly on a primarily street driven vehicle.

[Mr. 5]

Originally Posted by Chowbow

A side note, may be related. Hotchkis' 335i has PSS9s and was shown testing at some SoCal autocrosses...

With my shocks and springs, I found no need for aftermarket sway bars. I actually had them in my garage ready to install, but ended up selling them since I felt the car was already neutral and had less roll than stock. I wanted to maintain some body roll and compliance on the street. On bumpy mountain roads, it's already "itchy" enough... I'm not sure too many people with stiffer suspension setups will want to also add sway bars, particularly on a primarily street driven vehicle.

I appreciate your input but I really don't want to mess with my springs or the way it feels when driving in a straight.
This is why updating the rear sway looks like a good alternative for making turns.

BTW, I just received my BMW Performance Strut bar yesterday and it's going to be dropped off today at a Metal refinishing shop to get anodized black.
IMO, the silver look in that engine bay is fugly!
I'll take some pics when I get it back.

[Chowbow]

Originally Posted by Mr. 5

I appreciate your input but I really don't want to mess with my springs or the way it feels when driving in a straight.
This is why updating the rear sway looks like a good alternative for making turns.

BTW, I just received my BMW Performance Strut bar yesterday and it's going to be dropped off today at a Metal refinishing shop to get anodized black.
IMO, the silver look in that engine bay is fugly!
I'll take some pics when I get it back.

No worries. I think that sway bars make sense for a lot of people. But for those guys who are already running stiff 600+lb/in springs and have a generally stiff setup, I don't think they would like it that much with too little compliance especially on a road course. At least for me, my preference is to have some good compliance and a tiny bit of understeer for a n00b safety net.

The swaybars also makes the car feel a lot more planted with less lean in the corners, and for a softly sprung car, it probably makes it a bit faster (although I haven't tested any of this).

[stressdoc]

The 14mm rear M-sport is nice because it changes the over/understeer balance towards neutrality without upping the overall amount of roll resistance by too much. Springs and dampers are key, and for track work, camber adjusters. My guess is that lowering also changes the roll-resistance dynamics a bit.

[seccsc]

Originally Posted by Mr. 5

I appreciate your input but I really don't want to mess with my springs or the way it feels when driving in a straight.
This is why updating the rear sway looks like a good alternative for making turns.

BTW, I just received my BMW Performance Strut bar yesterday and it's going to be dropped off today at a Metal refinishing shop to get anodized black.
IMO, the silver look in that engine bay is fugly!
I'll take some pics when I get it back.

Mr. 5,
I appreciate you starting this review and just wanted to add my .02 cents, which doesn't mean much.

I'm looking to upgrade my suspension also but with Hotchkis Sways.
Since it was explained in detail earlier, the stock shocks/struts with Hotchkis would probably be in nightmare during bumpy turns at high speeds.
My thoughts were to go with Koni FSDs and Stock Springs with Hotchkis Sways due to its better rebound dampening. This was detailed in ORB's Review from 8/16/07, but has since then he has changed his suspension. These characteristics were what I was looking for....

Originally Posted by Orb

The third upgrade was the Koni FSD. Although the stock shocks are fairly good they are harsh on small ripple bumps and way way too soft in low speed compression. The rebound dampening is just to soft and tends to make the shock overshoot that static ride height under all condition. The Koni FSD worked well beyond what I expected and contradictory to other reviews posted here. The rebound dampening is just absolutely flawless and no matter what the condition the shocks returns there static ride height without harshness or packing. The low speed compression dampening is about 25-30% stiffer than the stock shocks which contradiction what many have said here. The real difference is that the stock shock tend wallow and oscillate with small bumps complete out of phase (typical for twin tube design) which transmits harshness to the driver while the Koni FSD simple do not respond in the same manner so the road feel is smooth (not soft). It is far from diminished and is simply different, with a bit more road time it becomes obvious it is superior. The high speed compression dampening is perfect and stiffer than the stock shocks but no near as harsh. My overall ride impression is at high speeds the car is completely planted and feels like a go kart which is firm but not harsh. The first thing I really noticed was the lack of any pitch the car has now which is very noticeable while body roll has been reduced further. Some of the annoing traits of the rear end are gone. Rapid lane changes are a night and day difference as the car no longer pitches and rolls.

My thoughts of the stock springs is they are not soft at all. In fact, the stock springs are fairly stiff.....

Orb

I hope this helps.....

Maybe Orb can expand his thoughts on this setup.

[Mr. 5]

Wow, that was a nice read.
Thanks for posting that.
I was curious why the FSD shocks were so expensive but now I know.
I was thinking that the BMW Perfpormance Dampers were 555 and the FSDs were about 730, so I was curious what the big difference was.
Again, I'm sure I'll be happy with the BMW Performance dampers but then again, I'll just wait and find out.

Originally Posted by Mr. 5

I appreciate your input but I really don't want to mess with my springs or the way it feels when driving in a straight.
This is why updating the rear sway looks like a good alternative for making turns.

BTW, I just received my BMW Performance Strut bar yesterday and it's going to be dropped off today at a Metal refinishing shop to get anodized black.
IMO, the silver look in that engine bay is fugly!
I'll take some pics when I get it back.

Originally Posted by seccsc

Mr. 5,
I appreciate you starting this review and just wanted to add my .02 cents, which doesn't mean much.

I'm looking to upgrade my suspension also but with Hotchkis Sways.
Since it was explained in detail earlier, the stock shocks/struts with Hotchkis would probably be in nightmare during bumpy turns at high speeds.
My thoughts were to go with Koni FSDs and Stock Springs with Hotchkis Sways due to its better rebound dampening. This was detailed in ORB's Review from 8/16/07, but has since then he has changed his suspension. These characteristics were what I was looking for....

Originally Posted by Orb

The third upgrade was the Koni FSD. Although the stock shocks are fairly good they are harsh on small ripple bumps and way way too soft in low speed compression. The rebound dampening is just to soft and tends to make the shock overshoot that static ride height under all condition. The Koni FSD worked well beyond what I expected and contradictory to other reviews posted here. The rebound dampening is just absolutely flawless and no matter what the condition the shocks returns there static ride height without harshness or packing. The low speed compression dampening is about 25-30% stiffer than the stock shocks which contradiction what many have said here. The real difference is that the stock shock tend wallow and oscillate with small bumps complete out of phase (typical for twin tube design) which transmits harshness to the driver while the Koni FSD simple do not respond in the same manner so the road feel is smooth (not soft). It is far from diminished and is simply different, with a bit more road time it becomes obvious it is superior. The high speed compression dampening is perfect and stiffer than the stock shocks but no near as harsh. My overall ride impression is at high speeds the car is completely planted and feels like a go kart which is firm but not harsh. The first thing I really noticed was the lack of any pitch the car has now which is very noticeable while body roll has been reduced further. Some of the annoing traits of the rear end are gone. Rapid lane changes are a night and day difference as the car no longer pitches and rolls.

My thoughts of the stock springs is they are not soft at all. In fact, the stock springs are fairly stiff.....

Orb

Originally Posted by seccsc

I hope this helps.....

Maybe Orb can expand his thoughts on this setup.

[Ray]

I am very impressed with the pairing of the FSD with the and the OE Sport springs. Koni offers pieces that feel custom valved to those springs, which is surprising from a mass production company.

These improved shocks offer an improved rebounding compared to OE Sport, yet maximizes the stiffness of the E90/92 chassis.

[Gen_E92]

The Performance shocks will make handling better at the cost of rougher ride since they're likely the same design. FSD makes both handling and ride better

Mr. 5 Im not sure where you got your FSD price, but when i got mine it's like $800 shipped with eibach springs...

[Mr. 5]

Originally Posted by Gen_E92

Mr. 5 Im not sure where you got your FSD price, but when i got mine it's like $800 shipped with eibach springs...

Right here man.

http://www.tirerack.com/suspension/s...036&perfCode=P

[stressdoc]

Any more info on the yellow BMW performance springs?

[Mr. 5]

Originally Posted by stressdoc

Any more info on the yellow BMW performance springs?

I know this is speculation, but I truly believe that they are the same exact spring as the sport spring, but since they are now selling these with the "BMW Perf Suspension" they are coloring them yellow to match the other perf stuff.

The Perf dampers are the same dampers as the M package in europe and the M package in europe uses the same springs as the sport package.

[stressdoc]

From a hi-res photo, they appear to have some differences from the OEM springs. But whether there are functional differences remains to be seen.

[Mr. 5]

Originally Posted by stressdoc

From a hi-res photo, they appear to have some differences from the OEM springs. But whether there are functional differences remains to be seen.

Could you post that because I didn't see that pic.

[Mr. 5]

This might be a funny question, but is there any way that a set of shocks can change the ride height?
I saw that somewhere and I tought that this was only determined by the springs.

[Chowbow]

Originally Posted by Mr. 5

This might be a funny question, but is there any way that a set of shocks can change the ride height?
I saw that somewhere and I tought that this was only determined by the springs.

Springs determine ride height.

However, if you have really really really crappy shocks and replace them with new high quality ones, the ride height could go up a bit since the old shocks were so fatigued.

[Mr. 5]

Originally Posted by Chowbow

Springs determine ride height.

However, if you have really really really crappy shocks and replace them with new high quality ones, the ride height could go up a bit since the old shocks were so fatigued.

That's what I thought.