[BrianMN]

Suspension Review

So I have had a set of Bilstein PSS9 coilovers on my car for almost two years, and was very pleased with how the car drove, rode and performed on the street and track. I couldn’t have asked for a better-responding track setup while still being manageable on the street.


However, Minnesota potholes became too much for one of my front coilovers to handle and blew the crap about it a couple weeks ago. It was somewhat of a strange blowout. Every time I’ve worn out or had a failed high-pressure shock it has been simply lost all strength and dampening….you could literally push it up and down with your pinky. However, this was MUCH different. The shock would compress a couple inches then almost hit an internal obstruction and come to an instant stop. I noticed this when I had taken the coilover apart to examine the shock. Because my stock parts were at a previous house and the new suspension wasn’t here yet, I had to re-install the broken coilover for another week.

Here’s where it gets interesting- when I went to install the new suspension, the PSS9 inner tube had separated from its race and the shock was EXTREMELY pressurized, forcing the shock to expand as much as the control arms would allow. See picture below: it normally only extends out 4 inches or so, but it had broken off the race/holder so it was being pushed out 10 inches, or as far as it could.



Needless to say, this made removing the shock very difficult. I literally could not compress it to get it out of the spindle. My plan was to resort to removing the tie rod and both control arms, letting the entire spindle come out. When I removed the first control arm, BOOM!!


The shock exploded in my face..I got very lucky that I didn’t get fluid in my eyes. I’ve never had this happen to a shock before on any car, motorcycle, truck, etc. Very strange.

So, Harold at HP Autowerks had gotten some AST 4100 coilovers coming my way FAST! I chose them based on quality: price ratio. I would have loved to get a set of JRZ coilovers with external reservoirs, but it’s just a bit out of my price range at the moment. The AST system with the swift springs and thrust washers fit the bill perfectly. You can immediately tell the quality of the AST suspension is far superior than the other competing shocks with the exception of JRZ, Moton and a few others, and I like the adjustability of the sway bar link.

Install went straight-forward, however the top side of the front AST shocks protrude up too far and won’t clear the factory strut brace. I got a little creative and used a couple valve springs to make a spacer, and it works great! It clears the shock and hood just fine! Hahahaha



My impressions of the AST are phenomenal. Along with any type of motorsport vehicle, suspension is THE most important upgrade you can make to your car/motorcycle/donkey/whatever. I have logged quite a few miles in a Time Attack Evo X with the top of the line JRZ setup, and know what an amazing suspension should feel like. The Bilstein PSS9s were a good budget coilover, but of course there are superior systems. That said, I couldn’t be more impressed with the AST 4100s!!! The suspension, on full hard OR full soft felt great; extremely plush, balanced and smooth. Long story short, these AST shocks are top of the line quality at an affordable price.
Definitely will be recommending these!
Special thanks to Harold @ HP for getting me hooked up very fast! They are a truly professional operation, and nobody knows more about E9x suspension than those guys

Thanks for reading!

Brian

[pits200]

Nice job on the install. I just installed the 4100s on my xi and had the same issue with the tower brace.

How easy do your adjustment knobs turn? Mine don't seem to have a solid "notch" feeling when turning the knob.

Also, did you go with the 400/800 spring rates?

[Fraggy]

Why do they come up so far?? That seems odd, do all other AST 4100 owners get this problem too? Ive not heard of it yet.

Congrats tho, thats what am planning to save up for so long as the excessive protrusion is not the norm.

[UltraRacer13]

Originally Posted by Fraggy

Why do they come up so far?? That seems odd, do all other AST 4100 owners get this problem too? Ive not heard of it yet.

Congrats tho, thats what am planning to save up for so long as the excessive protrusion is not the norm.

yes. Best solution is m3 tower brace.

[BrianMN]

Originally Posted by pits200

Nice job on the install. I just installed the 4100s on my xi and had the same issue with the tower brace.

How easy do your adjustment knobs turn? Mine don't seem to have a solid "notch" feeling when turning the knob.

Also, did you go with the 400/800 spring rates?

Thanks, I assume you went with Vorschlag camber plates as well? I think the protrusion can clear the strut brace when the stock pillowball mount can be used, however when you have camber plates and have a bit of negative camber, that's when it gets in the way.

Originally Posted by Fraggy

Why do they come up so far?? That seems odd, do all other AST 4100 owners get this problem too? Ive not heard of it yet.

Congrats tho, thats what am planning to save up for so long as the excessive protrusion is not the norm.

I don't see any way to avoid it protruding up so high with the top hats supplied...it's just the way it is. Not a big deal if you have some valve springs! haha

[David1]

But now your strut brace is useless since it will now flex.

[Blk07335i]

Upgrade to the M3 strut brace and you won't have the clearance problem.

[pits200]

Originally Posted by David1

But now your strut brace is useless since it will now flex.

Eh, the OEM strut brace is pretty useless to begin with.

[specE30Dude]

Originally Posted by pits200

Nice job on the install. I just installed the 4100s on my xi and had the same issue with the tower brace.

How easy do your adjustment knobs turn? Mine don't seem to have a solid "notch" feeling when turning the knob.

Also, did you go with the 400/800 spring rates?

I have a 335d and just installed the Swift/AST setup a few days ago. Due to the extra weight of the diesel, I went with 450/800 with the 4100's. I did not have the clearance limitation with the adjustment knob but it was certainly a tight fit.

Regarding the solid "notch" feel, I had the same problem, contacted AST and they are sending me a new adjustment component. You will notice a small brass nut on top of the strut..Mine was defective. There is a little bearing in there that allows one to count each notch while turning. I will know if that replacement fixes the issue upon receiving the part. Not the happiest with AST's turnaround time as they promised it would ship Monday so I could have it fixed prior to my 4-day road trip but it will not leave their shop until Wednesday.

I am still getting a feel for the damper adjustments and have not driven much as of yet. Also, I have no idea what the front setting is because it spun indefinitely in both directions. I am also playing with the height a bit. It appears that the rear dampers like to be 2 notches from the stiffest setting, but then again my ride height was initially slightly lower in the back. In a week or so, my full review will be here: http://www.e90post.com/forums/showth...ht=335d&page=2

[longdiyu]

why didn't you use your bilstein lifetime warranty??

[Bimmer-Bob]

Originally Posted by longdiyu

why didn't you use your bilstein lifetime warranty??

This. It sounds like you got an upgrade anyway, but you should at least have the Bilstein strut fixed so that you could sell the set.

If it's not covered under warranty for some reason, they rebuild PSS9 dampers for $125/apiece. Just need to get them to their facility in San Diego.

[Fraggy]

Originally Posted by Bimmer-Bob

This. It sounds like you got an upgrade anyway, but you should at least have the Bilstein strut fixed so that you could sell the set.

If it's not covered under warranty for some reason, they rebuild PSS9 dampers for $125/apiece. Just need to get them to their facility in San Diego.

A bit OT, but that office is about a mile from my house LOL.

[pits200]

Originally Posted by specE30Dude

I have a 335d and just installed the Swift/AST setup a few days ago. Due to the extra weight of the diesel, I went with 450/800 with the 4100's. I did not have the clearance limitation with the adjustment knob but it was certainly a tight fit.

Regarding the solid "notch" feel, I had the same problem, contacted AST and they are sending me a new adjustment component. You will notice a small brass nut on top of the strut..Mine was defective. There is a little bearing in there that allows one to count each notch while turning. I will know if that replacement fixes the issue upon receiving the part. Not the happiest with AST's turnaround time as they promised it would ship Monday so I could have it fixed prior to my 4-day road trip but it will not leave their shop until Wednesday.

I am still getting a feel for the damper adjustments and have not driven much as of yet. Also, I have no idea what the front setting is because it spun indefinitely in both directions. I am also playing with the height a bit. It appears that the rear dampers like to be 2 notches from the stiffest setting, but then again my ride height was initially slightly lower in the back. In a week or so, my full review will be here: http://www.e90post.com/forums/showth...ht=335d&page=2

That would be great if you would let me know about the knob. It is very frustrating. Two of them are solid feeling and turn properly but then the other two have sloppy play and after the first click it's very hard to determine what level you're set at.

[BrianMN]

Originally Posted by longdiyu

why didn't you use your bilstein lifetime warranty??

Unfortunately the reps at Bilstein haven't been the friendliest, and think this must be related to abuse because they've never seen this before. Kinda BS, but whatevs.

Originally Posted by Bimmer-Bob

This. It sounds like you got an upgrade anyway, but you should at least have the Bilstein strut fixed so that you could sell the set.

If it's not covered under warranty for some reason, they rebuild PSS9 dampers for $125/apiece. Just need to get them to their facility in San Diego.

Yep, I'll be sending it down there. Even though the PSS9s were decent and did the job, the ASTs are SOOOO much better! Kinda like tunes hahaha had to throw that in there.

[Hotcoupe]

Brian, I've just read about your experience with the Bilstein kit.

Did you get any prior warning signs before the shock gave out?

I've got the kit and I have a knocking noise that has developed on the nearside front, and my dealer has said the shock absorber is *ucked!

Not good as the kit has only been on just over a year and the cars only covered about 5-6k miles since being fitted!

[BrianMN]

Originally Posted by Hotcoupe

Brian, I've just read about your experience with the Bilstein kit.

Did you get any prior warning signs before the shock gave out?

I've got the kit and I have a knocking noise that has developed on the nearside front, and my dealer has said the shock absorber is *ucked!

Not good as the kit has only been on just over a year and the cars only covered about 5-6k miles since being fitted!

Yep, I did hear some distinct noises that got potentially worse. Like I described in the OP, it wasn't the "usual" way the shock blew. The shock actually had a problem with allowing it to go down past halfway. So it would go compress a couple inches then bind, or stop abruptly. I was able to feel it 'hit' hard on the street. It was more of a strong clunk feeling than a noise.

If the shock is blown in the traditional way, (not having any pressure/absorption) then you'll hear it also, more of a loose clinkity noise. It should be pretty easy to tell if your shock is having the usual problem by lifting the wheel off the ground and checking for free play.

Hope this helps!

[Hotcoupe]

Thanks for the response Brian, it's much appreciated

[bimmertt]

I am guessing the spring rates are pretty high for this setup. How is everyday driving? I am sure for the track this setup is perfect.

[BrianMN]

Originally Posted by bimmertt

I am guessing the spring rates are pretty high for this setup. How is everyday driving? I am sure for the track this setup is perfect.

Ya know, they actually aren't all that stiff. It's hard to describe...but basically it's much more 'plush' The very small bumps and sharp changes are completely soaked up and barely noticeable...which is something that you wouldn't expect from such high spring rates. All-around it feels much more planted as well.

So long story short: I'm very pleased with the ride comfort for daily driving.

[ajsalida]

Did the rod break or the piston come off inside the strut? Curious as to failure mode here on the Bilstein. Also were you in an accident or hit a pothole or something prior to this failing?

[BrianMN]

Originally Posted by ajsalida

Did the rod break or the piston come off inside the strut? Curious as to failure mode here on the Bilstein. Also were you in an accident or hit a pothole or something prior to this failing?

The inner shaft/piston/top tube didn't break...it simply became unnattached from the inside of the shock. Very strange.

No accident, no huge potholes, just the usual Minnesota winter roads. Many small bumps and cracks. However, there wasn't any huge pothole that I hit or anything...nothing notable, it just progressively got worse.

[ajsalida]

Originally Posted by BrianMN

The inner shaft/piston/top tube didn't break...it simply became unnattached from the inside of the shock. Very strange.

No accident, no huge potholes, just the usual Minnesota winter roads. Many small bumps and cracks. However, there wasn't any huge pothole that I hit or anything...nothing notable, it just progressively got worse.

So the rod either broke off or came unscrewed at the bottom inside the strut housing? This is hard to picture but this is what one looks like inside, on the left. That big tube on the upper part in your pic is just a guide tube (like a sliding bearing), the shock body is inside that tube. The piston rod attaches to the base of the lower housing near the spindle/hub. If you look down inside the strut housing (near the hub), there may be a rod stub. Or look up into the upper part, there should be a piece of shaft left sticking out. If neither I don't know WTF could have happened:

edit: I guess the piston + part of the rod could have come off inside the shock, that might explain it jamming. You'd have shock oil everywhere though.