OMG! - ACR guys

[MtHam ACR]

When asked for a ride, is your first response to your wife/girlfriend, "Honey are you wearing your sports bra tonight?" Or have they just quit asking? Have you been known to bang your head on the headliner at a good dip on the freeway? Do you do the expansion joint-shuffle?

We've been suffering through bouncy and uncomfortable suspension for too long -- this is an issue woefully unaddressed on this board.

This is a fix for post-Koni ACRs only, I believe DC changed-over from the Koni's tot he Dynamic Suspension Gas reservoir shock mid-year 2000. But the factory decided 1100lb rear springs were about right ("for what?" I want to ask). Actually it depends on how you want to use the car, different tracks and applications should require different springs, but we don't all drive like that.

I just had 800 lb hypercoils springs put in a*s-end of the car:
http://www.hypercoils.com/text/catalog.htm

You want part number 7A0800, for a 7" long 2.25" ID 800lb rate. The springs are $75/ea and they will ship them direct to you.

People, you NEED this this mod if you drive at all on the street. The ride is still firm, but the bouncy-bounce is gone, absent, void, nada, zip. The car sets into the corners nicely, there is better weight transfer going on under braking, which is going to help the understeer thing a bit (at least in theory - I haven't actually had any more time in the car than picking it up from the shop and a spirited freeway on-ramp or two).

Anyway, I will give them a shake-down at Buttonwillow this weekend and so I should have a better reference for comparison. Bottom line is street ride quality has been elevated from tolerable to pleasant.

Behind the rims, in terms of quality of change, this is a very close second.

 

[Vic]

Eric, What rate of springs do you have on the front?

 

[safireviper]

Yes, let us know how your ACR does at the track. I too, cannot believe how rough the ride is in my 2002 ACR on the street. I know one problem is we basically sit on top of the rear wheels. ( along with that 1100 lbs. spring rate ! ) I too, have been giving serious consideration to changing my rear springs also.

How difficult was it to do to swap the springs?

 

[monnieh]

NO WAY! I love the ride of my ACR. I am not sure if my 2000 got the shock change or not though.

The racing suspension is one of the things that is great about the ACR. (besides the BBS wheels)

 

[THEMASH]

I dont think i would change the springs on my car either. The ride does get bumpy sometimes, but i thought by adjusting the suspension settings, it would take care of it. have not tried it though.

 

[MtHam ACR]

Vic wrote <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>What rate of springs do you have on the front?<HR></BLOCKQUOTE> You know, I haven't taken them out to look, but I've heard 600 lbs. Whatever the stock setup for the 01 is.

Safireviper wrote <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>How difficult was it to do to swap the springs?<HR></BLOCKQUOTE>

It's basically two bolts that hold the shock in, an upper and a lower that go through a heim-joint. Pull the wheel and access is right there, two wrenches will drop the shock; slide the old spring off (its not under compression when the car is off the wheels) and slide the new spring on. I actually had a shop do it (Custom Alignment in Mt View, Ca - these guys are awesome, BTW), because I ran out of time before the event this weekend. They estimated 2.2 hrs, and charged me for 1.2 hrs, which was probably a bit fat. They also checked the corner weights and alignment while they were under there. Anyone with a half a mechanical aptitude could do it.

One other benefit I was noticing on the way home tonight was the weight transfer under acceleration. The car digs out of the hole way better. You get on the gas, the rear end actually dips a bit and stays down instead of just popping right up, so the car bites harder. Impressive change. With those big springs, you'd get none of that, the car would just sort of skip along with just a tad of depression in the rear end under initial acceleration. Now its a very noticable difference. Can't wait to come hard out a few of the slower corners on the track.

 

[safireviper]

Thanks, Matt. I am really considering about changing my springs in the rear. Since the replacement cost is minimal, I just might try it.

I know another problem we may have that some other ACR guys don't have to deal with is California roads. They're terrible. I took my ACR to Four Corners and the highways of Arizona and Utah were much, much nicer.

 

[JonB]

The Year matters....discussion is for 2000.5 and newer:

As many know, I just bought a new yellow ACR in June. I found the overly-stiff rear end 'almost dangerous' on washboardy roads. Race tracks have no washboard, but rural asphalt does!
A downhill, off-camber wasboard could end your drive, in my opinion. Scary-bad.

I spent 3 test-and-tune sessions at PIR-Portland TRYING to get the 2000.5 - 2002 ACR DSI rear shocks to 'work' and I could not. I was very frustrated, along with 2 other track rats here onsite.

The 500-lb sprung front shocks are very adjustable, but the rear 1100 springs simply overpower the shock valving. After 5 more test-tune sessions, adding weight, etc and even taking a PVO engineer for a test ride, I have settled on 850 lb springs for the rear as the best match for PIR, T-Hill, SIR, and street.

So I appreciate your data, experience, and plan to install 850s if I can find them. This setup is still stiffer front and than the more manageable 1999-2000.4 ACR.

 

[monnieh]

OK, how can you tell if your 2000 is .4 or .5?

 

[Frank Parise]

I just purchased an '01 ACR as a street car. I thought I would check the ACR Dynamic shock manual that came with the car. I found some very interesting information.

First of all, it said that the factory ride heights were set to 5-1/8" in the front and 5" in the rear (measured from the frame to the ground at the axle centerlines). That seemed strange to me, since it implied that the car was delivered with a 1/8" negative rake! It also seemed strange since I had understood that factory ride heights on a normal GTS were 5" front and 5-1/2" rear.

So, I figured I would check my ride heights. I found them to be at 5-1/8" in the front and between 5-5/8" - 5-3/4" in the rear!

Then, I thought I would check the shock settings. The manual doesn't indicate where the shocks are set from the factory. I jacked up the car and pulled off the wheels. I found that the rebound and the bump adjustment screws were still sealed with strips of metal tape that had lettering to the effect that the shocks were set to factory specifications.

I checked and recorded each shock setting. All four shocks had different compression and rebound settings. The compression was set relatively soft, but not to full soft ( and it was different on each corner). The rebound was set relatively stiff, but not to full stiff ( and it was different on each corner). Just as a flying guess, I reset my shocks to where I would normally set my Penske shocks on the race Viper. This means medium stiffness on compression and very stiff on rebound. Both fronts were set the same and both rears were set the same. The rears were also set 2 clicks softer than the front on both compression and rebound. While the car wasn't bad to begin with, it was much stiffer in feel than a normal street car. But, that's what you would expect from a race option package. My car feels better after the adjustments I made.

We need to keep in mind that the ACR, although a street car, was set up to be road raced. Therefore, it is much more stiffly sprung and at a greater ride height so that the car can stay off the bump stops during high-G cornering. Learning how to adjust the shocks for optimal handling takes more than several track sessions, although you should see some improvement over three weekends. It's the most misunderstood part of chassis set-up that I have experienced. Just when you think you have it figured out, track conditions change and it's back to the drawing board. I have volumes of shock setting notes from six seasons of racing my Viper with adjustable shocks. It's part of the mystery that makes racing so fascinating.

 

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by monnieh:
OK, how can you tell if your 2000 is .4 or .5?

<HR></BLOCKQUOTE>

Konis will say KONI at the bottom of the black shock bodies and 2 adjusters will be visible in the window at the top shock eyes. Dynamics are anodized blue and gold. They have a remote nitrogen accumulator reservoir off to the side of the damper bottom.

 

[SERPENT INDIANA]

Had both of mine adjusted as harsh as they can be set and much of the bounce is gone....before the adjustments is was easy to "get air" in the seats.....like them fine now that I am used to them.....both are street cars...had a "Final Edition" GTS and a 2000 GTS....both rode like luxo cruisers compared to these ACRs.but I love it !!!

 

[Mark 00 RT10]

I'm looking to buy a set of front and rear ACR shocks (adjustible).
If anybody is interested please e-mail.
[email protected]

 

[GTS Dean]

Adelberg had a set of Koni 2812s for sale the other day.

 

[Toronto_ACR]

My first ACR was a 2000 before it got written off. now that i have the 2002 ACR I find that the ride is way to bumpy. yes they are not as nousy but who cares. i found the 2000 to be much more safe than the 2002. Does anybody know which car handles better. The 200 koni shocks or the 2002 Dynamics. Which one has better performance on the track. Also I have not read anyone saying that the bumpy ride can be fixed in the 2002 without changing shocks. What is the answer because I do not like it. What the hell did Chrysler do with these things

 

[GTS Dean]

Toronto,

Please re-read the very first post in this thread and try to understand its implications.

 

[Frank Parise]

Toronto, where do you have your compression and rebound adjusters set to? Your shocks may simply be adjusted too stiff for your liking.

 

[Toronto_ACR]

Frank I do not want to take my ACR to the dealer. I am not happy with his work. Where do I find out how to adjyst these things. I want to know everything. I also would like to know which cars are better suited to the track. The 2000 ACR which i think had a better ride or the new 2002 ACR's which jump up and down like a rabbit. No wonder we got beat real good by the GT2 in the last sports car edition.

 

[Toronto_ACR]

MTHam ACR

How did things go at the track during the weekend with your new springs. I am curious to know

Thanks

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by MtHam ACR:
When asked for a ride, is your first response to your wife/girlfriend, "Honey are you wearing your sports bra tonight?" Or have they just quit asking? Have you been known to bang your head on the headliner at a good dip on the freeway? Do you do the expansion joint-shuffle?

We've been suffering through bouncy and uncomfortable suspension for too long -- this is an issue woefully unaddressed on this board.

This is a fix for post-Koni ACRs only, I believe DC changed-over from the Koni's tot he Dynamic Suspension Gas reservoir shock mid-year 2000. But the factory decided 1100lb rear springs were about right ("for what?" I want to ask). Actually it depends on how you want to use the car, different tracks and applications should require different springs, but we don't all drive like that.

I just had 800 lb hypercoils springs put in a*s-end of the car:
http://www.hypercoils.com/text/catalog.htm

You want part number 7A0800, for a 7" long 2.25" ID 800lb rate. The springs are $75/ea and they will ship them direct to you.

People, you NEED this this mod if you drive at all on the street. The ride is still firm, but the bouncy-bounce is gone, absent, void, nada, zip. The car sets into the corners nicely, there is better weight transfer going on under braking, which is going to help the understeer thing a bit (at least in theory - I haven't actually had any more time in the car than picking it up from the shop and a spirited freeway on-ramp or two).

Anyway, I will give them a shake-down at Buttonwillow this weekend and so I should have a better reference for comparison. Bottom line is street ride quality has been elevated from tolerable to pleasant.

Behind the rims, in terms of quality of change, this is a very close second.

<HR></BLOCKQUOTE>

 

[GTS Dean]

http://www.dynamicsuspensions.com/

 

[Frank Parise]

Toronto,
The ACR has adjustable shocks that profoundly influence the handling characteristics of your Viper. All you have to do is remove the wheel from your car and look at the shock absorber.

At the top of the shock just below where it is attached to the frame of the car you will see a little red wheel. Turn it clockwise to stiffen your rebound setting and turn it counterclockwise to soften the rebound setting.

To the side of the main shock body you will see a separate tube that is shorter than the main shock body. On its side you will see a blue colored adjustment knob. Clockwise turns will stiffen the compression setting of your shock. Counterclockwise turns will soften the compression setting.

Both the rebound and the compression adjustment knobs should have taped seals on them which, if not broken, indicate the shocks are still set at the original factory settings. Simply remove the tape and make your adjustments.

When you move the knobs, do it slowly and pay close attention to what you are doing. As you move the knob, you will feel it "click". There are a total of 24 clicks of adjustment in your rebound and 12 clicks of adjustment in your compression settings. Keep track of where the shocks were (they are probably different on each wheel) before you adjust them. This way, you can always get back to where you started if you don't like how the change feels.

With the dynamic shock, you are supposed to always make your adjustments from the fully closed "stiff" position. Count how many clicks they are off of a full stiff setting. Then, make your adjustments.

Call me at 520-906-6844 if you want me to walk you through this. Once you see how easy it is, you will have a good laugh!

 

[toddt]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by MtHam ACR:
I have not started to mess with compression and damping too much. To me those shock settings are like trim-tabs, the spring is the big gross adjustment. <HR></BLOCKQUOTE>

Man, are YOU in for a surprise!

 

[JonB]

Frank, please know that I seriously respect your suspension experience, and driving expertise. readers should be thankful for your input. That said,

On 2000.5 and newer ACRs all with the DSI shocks, the OE 1100lb rear springs OVERPOWER all 12 compression settings. Those settings just dont matter. 4-6 clicks of the rebounds have any effect. After that, the spring "RULES" what's happenin' back there.

I feel that the 500lb fronts are very adjustable thru the entire range. But adjusting the rears made virtually no difference, unless I had a full tank of gas, a full cargo load, and 2 large adult occupants. Also, a REAR WING with 600-1200 lbs downforce would benefit from those springs, but not an empty ACR.

As Frank noted, once you get dialed, you either get a) new survace ie RAIN or B...go to a new track! I fear NW RAIN with virtually un-dialable rears at 1100lbs. Scary bad.

Your comments will be gratefully read and used..........but my 850lb Hypercoils are on the way !

 

[Toronto_ACR]

frank i will call you this week and get some info from you. It sounds like from what everyone is saying the best thing to do is replace the springs to get it perfect and completely get rid of the bumpy jack rabbit ride. Personally i liked my 2000 ACR in handling compared to my 2002 ACR.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Frank Parise:
Toronto,
The ACR has adjustable shocks that profoundly influence the handling characteristics of your Viper. All you have to do is remove the wheel from your car and look at the shock absorber.

At the top of the shock just below where it is attached to the frame of the car you will see a little red wheel. Turn it clockwise to stiffen your rebound setting and turn it counterclockwise to soften the rebound setting.

To the side of the main shock body you will see a separate tube that is shorter than the main shock body. On its side you will see a blue colored adjustment knob. Clockwise turns will stiffen the compression setting of your shock. Counterclockwise turns will soften the compression setting.

Both the rebound and the compression adjustment knobs should have taped seals on them which, if not broken, indicate the shocks are still set at the original factory settings. Simply remove the tape and make your adjustments.

When you move the knobs, do it slowly and pay close attention to what you are doing. As you move the knob, you will feel it "click". There are a total of 24 clicks of adjustment in your rebound and 12 clicks of adjustment in your compression settings. Keep track of where the shocks were (they are probably different on each wheel) before you adjust them. This way, you can always get back to where you started if you don't like how the change feels.

With the dynamic shock, you are supposed to always make your adjustments from the fully closed "stiff" position. Count how many clicks they are off of a full stiff setting. Then, make your adjustments.

Call me at 520-906-6844 if you want me to walk you through this. Once you see how easy it is, you will have a good laugh!

<HR></BLOCKQUOTE>

 

[monnieh]

Well, JonB just answered my question today about which shocks I have on my 2000. (I ordered the Mopar car cover, instead of killing my neighbors ***** cat) My motor had to be rebuilt by Arrow due to the cylinder sleeve problem which only happened the first of the 2000's.

I looked but could not see any markings on the shocks though like GTS Dean was talking about. ???

 

[MtHam ACR]

The track weekend was great. Viperdays ran Buttonwillow config 13 counterclockwise.

I was concerned that I might have gone to a too soft spring, the 00.5+ ACR rear springs are 7" vs. 8" for a stock GTS, so the question in my mind was do I run the risk of bottoming the shorter/softer spring.

What I found was the handling and manner of the car hasn't changed that much. The car is still stiff, but as I mentioned above, the big benefit is the weight transfer under acceleration -- the car digs out of the hole a whole lot better with a slightly softer spring. There are immediate benefits at corner exits, the car just plants better.

The part that I learned a ton about this weekend was throttle-steering the car through Buttonwillow's big, high speed sweeper. I'm not saying the springs were critical in this, but they certainly inspired a lot more confidence -- with the 1100 lb springs, the car felt more on-edge (loosing the rear end was always just a minor wrong input away). The softer springs are more forgiving, so it felt like it took more extreme inputs to have the same effect. Now, holding the steering wheel steady and fine-tuning the line with the throttle is just a joy.

There was one very rough corner that I could bottom the left rear shock on if I drove right through the conventional line. The surface is just torn up here and there is a big dip right at the apex. But I found a slightly faster and a whole lot less upsetting line, so abstinence was the right solution.

Disclaimer: I have not started to mess with compression and damping too much. To me those shock settings are like trim-tabs, the spring is the big gross adjustment. Like GTSDean, this is something that takes lots of time and effort and data collection to properly tune. I also think if you get into it very seriously, you will find you need different spring rates and shock adjustments (as well as brakes, tire pressures, gears etc) per track.

Jon B mentioned 850s, I think this solution is pretty close to what I stumbled-upon, and a pretty nice validation. I drove this track 4.5 seconds faster than I ever have, if that's any measure. My conclusion is, the new springs are providing better street ride without much of a sacrifice of performance at the track.

 

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by monnieh:
Well, JonB just answered my question today about which shocks I have on my 2000. I looked but could not see any markings on the shocks though like GTS Dean was talking about. ???

<HR></BLOCKQUOTE>

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This is from Koni's website - your actual colors may vary. Look at the top shock eye in the picture. Just below the heim joint and above the spring retainer cap is a rectangular opening. Inside this opening you should be able to see 2 round discs. The discs are stacked one atop the other and have holes in them so you can insert a small punch to rotate the adjusters. I assume that on the Koni, the top adjuster is rebound, the bottom is for bump. Dynamics have only one adjuster (rebound) in the top eye.

 

[MtHam ACR]

toddt wrote
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> Man, are YOU in for a surprise! <HR></BLOCKQUOTE> Todd, you have the Konis on your car, right? I think they're pretty different from the Dynamic Shocks. The literature says they are set at their most moderate (softest) settings from the factory (but that has been questioned in this thread, so I've got some investigation to do). I just couldn't imagine adding a harsher input with the larger springs. Now, I feel like I have a reasonable platform from which to begin trying new things. I hope they do have surprisingly positive results.

 

[THEMASH]

Just ordered the same 800lb springs, got them for $70 each

, thanks Eric.

 

[ACR Larry]

If you have an early 2000 Viper, here is a couple pics of the koni shocks

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