[subieworx]

AST coilovers are something I have used for quite a while on my subarus and given their heritage decided I would try them on my 335. For some reason I don't see much talk of them. The 4100's are not much more than KW or some of the others that I have seen and have some cool features that others don't and the performance to boot. Since this is primarily a street car for me with limited track use I went with the off the shelf setup from AST. This includes single adjustable rebound damping, 8k front/15.5k rear springs with helpers in the front.

Here is how they came from my chosen vendor, Turn in Concepts.



And here they are unpacked.

Fronts



Rears



There are a couple cool features on these that I really like and have not seen on other coilovers in this range. The first is the adjustable endlink mounting tab on the front dampers. This allows the ability to remove any sway bar preload during corner weighting and also replaces the need for adjustable endlinks due to running the car very low. All around it's a pretty cool design.

Here's a pic of the collars.



The other feature that I REALLY like is the fact that these actually have MORE travel than the stock suspension. This allows the car to ride very well and actually absorb bumps better than the stock suspension at times.

Check out the difference. Stock (sport suspension) is on the left.



There are also some extended adjusters for the rear so I don't have to remove any interior bits to adjust the rear shocks.



Couple other random pics.

[subieworx]

Driving impressions:

AMAZING! I have been through a couple different setups on this car so far. The H&R sport springs I started with were terrible. Much less control than the stock springs and struts and horrible over large bumps. It was also terrible at the track as anything other than perfectly smooth surfaces caused the car to be quite bouncy. I then swapped the front springs back to stock with the supreme power lowering perches. This was a definite improvement over the H&R, but still not where I wanted it to be.

The AST's are very nice on most surfaces. At the worst times it is no worse than what I had and better in 95% of all other cases. The ride is supple over imperfect roads due to the increase in travel. It is obviously much more controlled in corners as well. Can't wait to get it out on track.

For those interested they have quite a height range as well. You could go from higher than stock to absolutely slammed with these. Where I am set (about where the H&R sports put the car) there is still almost three inches of bump and droop travel in the front.

More to come as I put more miles on them, but so far I love them!

[just4kickz]

aren't these like 2.5k? if not more?

[subieworx]

Retail is like 1899 or so. Similar in price to kw v3 or pss10.

[subieworx]

So far the valving is feeling pretty good. I have been very happy with them and can't stop driving the car.

[itsbrokeagain]

Good to see you are enjoying them. I've been pushing these or conies on my customers and they have been very satisfied with the results.

Try swapping them out to Swift Springs. You might notice an even better ride quality.

[zsapphire7]

wow rear adjustment extenders ???? i didnt know they had those! i could use some... ive been driving without the rear trunk lining for the longest time now...

[subieworx]

Originally Posted by Matt@Camber-Toe

Good to see you are enjoying them. I've been pushing these or conies on my customers and they have been very satisfied with the results.

Try swapping them out to Swift Springs. You might notice an even better ride quality.

In the works. I already have the swifts here, just wanted to see how they felt out of the box first.

[subieworx]

Originally Posted by zsapphire7

wow rear adjustment extenders ???? i didnt know they had those! i could use some... ive been driving without the rear trunk lining for the longest time now...

The adjustment extender is pretty nice. I had to cut a slit in the trunk lining to allow them to poke through, but once installed the slit cannot be seen.

[zsapphire7]

Originally Posted by subieworx

The adjustment extender is pretty nice. I had to cut a slit in the trunk lining to allow them to poke through, but once installed the slit cannot be seen.

did u get em straight from the AST site?

[pits200]

This is killing me, I want to get the 4100s so bad for my xi but they don't make them. I heard that maybe in a few months they'll be available.

Crossing my fingers.

And congrats on the purchase.

[UltraRacer13]

Originally Posted by pits200

This is killing me, I want to get the 4100s so bad for my xi but they don't make them. I heard that maybe in a few months they'll be available.

Crossing my fingers.

And congrats on the purchase.

I am with you! I have been bugging the guys at AST mercilessly. They say they are coming soon. I live in Plano, TX where AST-USA is based. I am about to show up at the shop and not leave until I get some 4100's!

[DieselDiner]

Originally Posted by subieworx

In the works. I already have the swifts here, just wanted to see how they felt out of the box first.

Subie, what is different about the Swifts? Spring rate?

You have piqued my curiousity with this setup. I would like to go lower on my 335D with sport suspension (I'm running 19's), but I like the ride quality, and won't give that up for a lowered look accompanied by a ride like you attributed to the H&R's. I've been wondering if my best solution is to find a coilover setup with spring rates that are the same or very close to what my sport suspension has. Is that what you are trying to do?

[subieworx]

Originally Posted by DieselDiner

Subie, what is different about the Swifts? Spring rate?

You have piqued my curiousity with this setup. I would like to go lower on my 335D with sport suspension (I'm running 19's), but I like the ride quality, and won't give that up for a lowered look accompanied by a ride like you attributed to the H&R's. I've been wondering if my best solution is to find a coilover setup with spring rates that are the same or very close to what my sport suspension has. Is that what you are trying to do?

Swift springs use a specific kind of metal for the construction of their springs which make them lighter, have more travel, and a more consistent springs rate throughout the range of travel. They are considered the best barrel springs on the market for the most part.

You won't find a coil over system with spring rates anywhere near the BMW sport suspension. BMW uses very low spring rates then relies on bump stops for roll resistance which. Coilovers, good ones, will allow the spring to do it's job of supporting the car and the dampers and bump stops are left to control the spring. The spring rates on these coil overs are 3x stiffer than that of the factory sport suspension, yet still ride very well.

[subieworx]

Originally Posted by zsapphire7

did u get em straight from the AST site?

Turn in concepts. Ast wholesale distributor.

[DieselDiner]

Hey Subie, thank you for the explanation of the swifts! Looks like I need to make another list for my next big mod. How were you able to swing a buy with a wholesaler (TIC)? I found their website, and they don't even list the AST's for the BMW. You must have favored nation status with them!

P.S. Did you source the swifts through TIC as well?

[subieworx]

Call them. They have/can get anything from ast and can custom valve them for race applications. They also have swift springs.

[subieworx]

quick pic I took of the car to show where it is sitting height wise. Sorry for the craptastic photo.

[IN54NITY]

These look very nice. IMO KW will need to drop their xi prices when the 4100 comes out for xi.

>There are also some extended adjusters
>for the rear so I don't have to remove
>any interior bits to adjust the rear shocks.


I'm interested in hearing more experiences with Swift springs.

[subieworx]

Been on these for a couple months now and have really liked them. Was talking to the guy at Turn in Concepts in charge of custom valving dampers and told him about a couple things I didn't like in relation to the way the car felt over certain bumps. We came up with a plan to revalve the front and rear AST dampers for better performance and ride quality.

All I can say is AMAZING! I am even more impressed with these now than I was before. The ride more comfortably and handle bumps better mid corner when being pushed.

Figured you guys would like some pics of the internals since you don't get to see them very often.

First one is of the front dampers (all pics of the front) on the bench after degassing. The one on the right has the shaft out of it in this pic and can be seen on the left side of the picture.



Pic of the tooling from AST. I think they are one of just a handful of companies in the US who have the tooling and knowledge to custom valve AST shocks.



Shock piston. The upper cylinder is a guide cylinder to prevent side loading. The lower is the actual piston doing the work. Just above the larger nut in the bottom of the pic you can see the shim stack for rebound damping. There are quite a few little shims in there to control the flow of oil through the piston above it. This is a drastically different design from a twin tube like KW's that don't use shims.

Close up of rebound shim stack.



Bottom of adjuster mechanism. That allen headed set screw is the adjuster for determining the number of clicks of adjustment the shocks have.



Rebound shim stack removed. The oil flows through the holes in the piston and then is forced around the shim stack. The number and size of shims determines the rate of flow and hence the damping profile of the shock.



Rebound shim stack layed out. There are quite a few and remember this is only half of them. There is still a compression shim stack.



Piston removed, compression shim stack showing.



That's all I took. Can't believe at how much different and better the car feels. Amazing!

[ninesixtwo]

Hey, thanks---cool stuff.

[ninesixtwo]

Let me ask: why not go with M3 rear shocks and lower control arms?