AST 4150

[Clipdat]

Congrats. Did you order it directly from AST?

Originally Posted by botbs

Great! I pull the trigger and ordered a set of AST5100 8k/8k with DDP. It will take around 4 - 6 weeks, I will let you guys know once I got it installed.

Cheers!

[botbs]

Originally Posted by Clipdat

Congrats. Did you order it directly from AST?

I ordered from Cygnus Performance and Geoff is an awesome guy!

I also spoke to AST regarding spring rate after I read your post and they also told me to order from Cygnus Performance as they are the Subie Rep for North America.

"[00:25] AST: We do not sell direct to consumers, but contact Geoff at Cygnus Performance and he can get them ordered and processed.
[00:26] AST: He is our go to dealer for Subaru AST sales."

[JoeCFRS]

I'm having a really bouncy ride with the AST 4100's from Mann engineering. I just got a set installed about a month ago and just daily driving around the ride is super bouncy to where i feel every bump in the road. Its so bad that if i rest my head on the headrest it will just bounce back and forth off it it at highway speeds. I'm not sure if i got a bad set or what. I'm going to contact Mann and possibly AST and see what the deal is.

I have the set custom valved to 5k/9k spring rates that i know several other people are running. Ive talked to another person who has the same set with valving and doesn't have the bouncy issue.

Ive tried adjusting the rebound several times to see if it helps and it doesn't so much of anything. Any ideas what could be the issue?

[botbs]

Originally Posted by Jive Turkey

here is how the car currently sits.

as of now the alignment specs are

front:
-1.9 camber
.04 toe out

rear:
-1.6 camber
.08 toe in

I noticed you are using Group N top hats, how did you get your -1.9 deg camber front or once you are lowered it is automatically at -1.9deg? Did you just reuse factory bolts?

Thanks!

[Jive Turkey]

used camber bolts too

[finch1750]

Originally Posted by JoeCFRS

I'm having a really bouncy ride with the AST 4100's from Mann engineering. I just got a set installed about a month ago and just daily driving around the ride is super bouncy to where i feel every bump in the road. Its so bad that if i rest my head on the headrest it will just bounce back and forth off it it at highway speeds. I'm not sure if i got a bad set or what. I'm going to contact Mann and possibly AST and see what the deal is.

I have the set custom valved to 5k/9k spring rates that i know several other people are running. Ive talked to another person who has the same set with valving and doesn't have the bouncy issue.

Ive tried adjusting the rebound several times to see if it helps and it doesn't so much of anything. Any ideas what could be the issue?

Did you get this solved? The 9k rear rate seems offly high even though you say others run it, everyone's tolerance is different. Valving changes are fairly noticeable imo. Mine is a little bouncy when soft but nothing crazy (i daily at 3 clicks from soft) It goes away when I stiffen it up to 8 clicks front/rear. Im on 5k/6k springs

[JoeCFRS]

Originally Posted by finch1750

Did you get this solved? The 9k rear rate seems offly high even though you say others run it, everyone's tolerance is different. Valving changes are fairly noticeable imo. Mine is a little bouncy when soft but nothing crazy (i daily at 3 clicks from soft) It goes away when I stiffen it up to 8 clicks front/rear. Im on 5k/6k springs

I kinda got it a little better with adjusting the rebound to 8 clicks. I think i can still mess with it a bit. With a higher rebound in the rear the bouncing is less jarring but still there.

On another topic regarding these coilovers. Does anyone have recommendations where to get a proper set of camber plates for these? I contacted AST directly and they think they have a set that will fit but arent 100% sure.

[botbs]

Originally Posted by JoeCFRS

I kinda got it a little better with adjusting the rebound to 8 clicks. I think i can still mess with it a bit. With a higher rebound in the rear the bouncing is less jarring but still there.

On another topic regarding these coilovers. Does anyone have recommendations where to get a proper set of camber plates for these? I contacted AST directly and they think they have a set that will fit but arent 100% sure.

I got the velox camber plates and will get it installed on Monday. People said racseng one works too.

See this youtube video, the whiteline coilovers is same as the AST.
[ame="http://www.youtube.com/watch?v=ekuiFYbbX9w"]http://www.youtube.com/watch?v=ekuiFYbbX9w[/ame]

[AFRichZC6]

Just stumbled upon this thread while doing some research, so I'm going to resurrect this as I have custom valved AST 5200 dampers on my BRZ used for autocross.

Originally Posted by finch1750

Did you get this solved? The 9k rear rate seems offly high even though you say others run it, everyone's tolerance is different. Valving changes are fairly noticeable imo. Mine is a little bouncy when soft but nothing crazy (i daily at 3 clicks from soft) It goes away when I stiffen it up to 8 clicks front/rear. Im on 5k/6k springs

I have the same spring rates as JoeCFRS. On the surface, the rates don't seem to make sense or seem way off compared to everyone else, but if you were to calculate what the ride frequencies are with those rates, the frequencies are appropriate for autocross and casual track duty and should have a flat ride. Most setups with similar front and rear spring rates like 8/8 or 6/7 or whatever on these cars will result in ride frequencies that can cause the car to pitch back and forth when hitting bumps or dips on the street or freeway.

Originally Posted by JoeCFRS

I kinda got it a little better with adjusting the rebound to 8 clicks. I think i can still mess with it a bit. With a higher rebound in the rear the bouncing is less jarring but still there.

On another topic regarding these coilovers. Does anyone have recommendations where to get a proper set of camber plates for these? I contacted AST directly and they think they have a set that will fit but arent 100% sure.

I'm not 100% sure, but the 5100's shaft might be larger than the non-inverted 4100/4150's 14mm shafts, which is common for most aftermarket dampers (KW, RCE, etc.). My 5200 are not quite off-the-shelf models, and they have 16mm shafts. If you happen to have 16mm shafts, either Ground Control or Raceseng will be able to help you out, as their camber plates use bearings with a large inner diameter, and they both can machine a sleeve so the bearing fits our girthy shafts.

I contacted Velox about their camber plates before. Their bearing won't fit 16mm shafts.

[finch1750]

Originally Posted by AFRichZC6

I have the same spring rates as JoeCFRS. On the surface, the rates don't seem to make sense or seem way off compared to everyone else, but if you were to calculate what the ride frequencies are with those rates, the frequencies are appropriate for autocross and casual track duty and should have a flat ride. Most setups with similar front and rear spring rates like 8/8 or 6/7 or whatever on these cars will result in ride frequencies that can cause the car to pitch back and forth when hitting bumps or dips on the street or freeway.

Yeah, I have since messed around trying to understand ride frequency and realize that is pretty close to ideal. I have contemplated jumping to a 5/8 set-up to compare. Just gonna wait for a set of swifts in the right specs to pop up for sale used I think lol

[Lincoln Logs]

Originally Posted by AFRichZC6

I have the same spring rates as JoeCFRS. On the surface, the rates don't seem to make sense or seem way off compared to everyone else, but if you were to calculate what the ride frequencies are with those rates, the frequencies are appropriate for autocross and casual track duty and should have a flat ride. Most setups with similar front and rear spring rates like 8/8 or 6/7 or whatever on these cars will result in ride frequencies that can cause the car to pitch back and forth when hitting bumps or dips on the street or freeway.

I've been running my Whiteline Coilovers (AST5100) with 5kg/5kg and I have not noticed this pitch. If anything, for competition use, they are just a little soft. I think the pitch is just a function of the short stroke these cars have and all of the GT86s I've driven do the same thing, independent of rates, when bottoming out at speed. I notice it mostly when the front hits a bump and bottoms. You can feel the car get upset mid corner and just have to wait before getting the car to react again.

Regarding ride quality, I'd like to see the shock dyno for my struts/shocks. My seat of the pants feeling tells me these have a lot of rebound force or high gas pressure because even on full soft they have a touch of bounce. Not uncomfortable but it's there if you really tune in. The camber plates, I run Verus, have been the worst offender in terms of reducing ride quality. Grooved concrete freeways make the entire car buzz.

I have a bunch of Swift springs sitting in my garage for testing. I am going to first bump it to 6kg square to see how the car handles the bumps in our local autocross lot before changing anything else.

[AFRichZC6]

Originally Posted by Lincoln Logs

I've been running my Whiteline Coilovers (AST5100) with 5kg/5kg and I have not noticed this pitch. If anything, for competition use, they are just a little soft. I think the pitch is just a function of the short stroke these cars have and all of the GT86s I've driven do the same thing, independent of rates, when bottoming out at speed. I notice it mostly when the front hits a bump and bottoms. You can feel the car get upset mid corner and just have to wait before getting the car to react again.

Regarding ride quality, I'd like to see the shock dyno for my struts/shocks. My seat of the pants feeling tells me these have a lot of rebound force or high gas pressure because even on full soft they have a touch of bounce. Not uncomfortable but it's there if you really tune in. The camber plates, I run Verus, have been the worst offender in terms of reducing ride quality. Grooved concrete freeways make the entire car buzz.

I have a bunch of Swift springs sitting in my garage for testing. I am going to first bump it to 6kg square to see how the car handles the bumps in our local autocross lot before changing anything else.

There's pitching when the car prematurely hits the bumpstops, but pitching can be caused by the front and rear of the car having frequencies that take an excessive amount of time to zero out. I've had other spring rate combinations before on the same dampers on my car, and in my case, the pitching wasn't due to hitting the bumpstops in ride.

I think the Whiteline coilovers for the twins come with a dual spring setup using helper springs in the front, which would reduce the effective spring rate until the helper spring is fully compressed. This is probably why you don't feel any pitching while driving on the road where the range of damper stroke isn't enough to fully compress the helper.

A dual spring setup with 5 kg/mm with, say, a 2 kg/mm helper spring would create a spring rate of only 1.43 kg/mm. (Ride frequencies 1.1/1.7 Hz)

If the front had either a zero-rate/tender spring or only the 5 kg/mm main spring, then you would probably experience more pitching. (2.0/1.7 Hz)

When you swap to 6 kg/mm springs, try running the front without a helper and see if you notice a difference in ride.

[Lincoln Logs]

Originally Posted by AFRichZC6

I think the Whiteline coilovers for the twins come with a dual spring setup using helper springs in the front, which would reduce the effective spring rate until the helper spring is fully compressed. This is probably why you don't feel any pitching while driving on the road where the range of damper stroke isn't enough to fully compress the helper.

The helper is full compressed at static and under load, it's length is much shorter than the main spring, and in reality it spends most of it's time compressed and does not contribute the helper's rate to the total spring pack. The helper comes into play during droop travel and helps keep the tire on the ground. Given a set up with and without helpers, I'll take the helpers.

The Whiteline coilovers only have a helper up front, don't recall the rate off hand but it isn't zero. I'd like to add a helper to the rear at some point too.

[botbs]

Here is my AST5100 and some odd reason they threw in the rear helper springs for me as a bonus!

I have to say compared to my KW RCE Tarmac 1 on my previous Legacy GT Wagon, this coilover is more comfy when it is at full soft even I am with a set of R comp (Nankang AR1) on the BRZ. I am quite surprised that it is not harsh at all with the 8k Front and 8k Rear spring on the street.

I will definitely buy AST over the KW (purely based on my personal experience). Unless this AST coilovers breakdown within 50,000km; otherwise, I would definitely buy it again within this price range.