acr ride question

[BennyBad]

for you acr owners, ive had (2) gen.3 vipers and at the track all were smooth in the triple digit speed range. ive had my acr at 2 hpde and the car is smooth until the 105 plus and the ride seems rough or harsh.. no vibration or anything like that just not smooth like my previous vipers. is this because of the adjustable suspension? the softer tires? cars settings have not been touched still with factory settings. just asking if this sensation is normal or not.. any input would be great. thanks benny

 

[SquadX]

I ve heard you need to adjust the suspension because its not set to its best for track use from factory. Again just from what I've heard. Also, the downforce may pay a part in it when you get in the triple digit numbers.

 

[fireball]

Well... I have an '04 Vert and an '08 ACR and I've been to the track with both. Additionally, I'm an expierenced road racer, so I may have some worth while input.

The ACR rides WAY harder then the Vert all the time - that's a given. I agree, there may be something to this and I expect it's the dual rate spring. Does the downforce collapse the first spring leaving us with a stiffer spring for the remainder of the suspension travel? I think this is the case.

Interesting.

Greg

 

[ACRBruce]

The ACR comes with adjustable shocks and it is meant for you to adjust them properly before getting on track. Now go find your ACR Owner's Manual or download it from this site (search for it). Adjust the car properly before you get out on track again, the car deserves to be setup properly.

 

[ACRBruce]

Well... I have an '04 Vert and an '08 ACR and I've been to the track with both. Additionally, I'm an expierenced road racer, so I may have some worth while input.

The ACR rides WAY harder then the Vert all the time - that's a given. I agree, there may be something to this and I expect it's the dual rate spring. Does the downforce collapse the first spring leaving us with a stiffer spring for the remainder of the suspension travel? I think this is the case.

Interesting.

Greg

The helper springs are always compressed all the way on my car and I did talked to a KW engineer at SEMA and was told that the helper springs are supposed to be compressed all the way and it is there to help the regular springs from fully extended beyond its range when fully extended. So I guess these helper springs aren't there to help the ride of the car.

 

[BennyBad]

have manual and agree car will need to be set up, just looking for a base line comparison with other owners if there having similiar ride feel as i am. could be as suggested above the aero dynamics starting to push down. long back straight at PBIR speed were up to 130 to 150. tracks in s. fla. are all flat and smooth, no real elevation changes and PBIR is new asphalt versus homestead (older and much rougher)were i first noticed this ride sensation. keep it coming guys. thanks benny

 

[Grant]

BennyBrad,

I was the guy at the HoD event with the red/black ACR. I was hitting 153-155 every lap on the back straight, and felt no unusual roughness. The factory settings on the dampers are very soft, meaning the suspension is very under-damped. I suggest setting the dampers a bit stiffer, maybe to the recommended track settings, and trying it out on a smooth road.

 

[trojewski]

Guys:

I have just 500 mi on my ACR at this point and I agree with the previous posts re: ride harshness. I've owned each generation, but don't find this ride objectionable (on the street) compared to the earlier cars. OBTW, I also have road race experience.

What I do find a problem, though, is the "dartiness" on crowned or patched surfaces. It's downright scarey at times! I've held off doing a full alingment because we want to lower the car and bring the suspension to "rough track" set-up this winter (I'm in Ohio).

Has anyone else dealt with this situation?

Tom Rojewski

 

[fireball]

Guys:

I have just 500 mi on my ACR at this point and I agree with the previous posts re: ride harshness. I've owned each generation, but don't find this ride objectionable (on the street) compared to the earlier cars. OBTW, I also have road race experience.

What I do find a problem, though, is the "dartiness" on crowned or patched surfaces. It's downright scarey at times! I've held off doing a full alingment because we want to lower the car and bring the suspension to "rough track" set-up this winter (I'm in Ohio).

Has anyone else dealt with this situation?

Tom Rojewski

I agree. If there's a ride issue I don't notice it but the instability on the street with uneven pavement is severe. I've only done 4 track days since I got my car and only one (on a very wet unfamiliar track) with the car lowered so there's still lots to learn about set-up.

Since I'm parked for the winter it'll be a few months before I get to it.

 

[Boxer12]

This is why all the other car manufacturers use nanny tech...turn a knob, or push a button, track ready. The ACR sounds too complicated to set up for the average HPDE guy, which is contradictory to its stated objective. They should sell shirts that say "Going to the track? RTFMS."

It also makes no sense that you void your warranty by making suspension setting changes. If you build a track ready car, stand behind its intended purpose and warranty its up to the harder use standard. Just my 2c.

 

[tiger6]

The ACR comes with adjustable shocks and it is meant for you to adjust them properly before getting on track. Now go find your ACR Owner's Manual or download it from this site (search for it). Adjust the car properly before you get out on track again, the car deserves to be setup properly.

Benny,
ACRBruce is correct. Set your car up as recommended in VCA magazine Summer 2008, and the only thing you will feel at 150 mph is the GIANT HAND shoving your car down on the track. No vibration-just rock steady.

 

[F8L SNK]

The suspension comes in the full soft setting both compression and rebound. At high speeds my car would start to buck over uneven pavement and elevation changes that were sharp. It was actually pretty scary. But that was almost all due to no rebound settings and the car would get light and then no compression setting and it was bottoming out. After setting the suspension to the recommending 6/6 Front and 5/5 rear it feels totally different.

The ride is much more sharp (hard) but car control is MUCH better and I feel in control instead of the feeling I had of being on a roller coaster.

 

[SoCal Rebell]

OK, all decent replies. I've had the ACR up to 150 mph at Willow Springs many times and it is rock steady. I've driven that track in probably 3-4 dozen differnet Vipers in my time and I say go with the KISS rule, check your tires' balance, probably something as simple as that. That being said the ACR is not a difficult car to set up yourself, read the manual.

 

[cheryl mccally]

I live in the country in Texas where all roads are bumpy at best and I don't find the ACR darty or hard to drive at all. My ACR is lowered and set up for the track and I leave it that way. I did get better times on our tracks around here with the suspension set at 6 compression, 7 rebound in front and 5 compression and 6 rebound in the rear.

 

[mjorgensen Woodhouse]

Changing the suspension ride height and doing a "proper" track alignment is the only way to remedy the dartiness you have been describing. The factory "street alignment is not much different than the normal SRT cars and as you know they exhibit the same feeling without an alignment change. We have set up about 30 of the ACR's now and all but 2 have left with a proper corner weighting and track alignment as Cheryl did. I can help any of you with the starter settings if you need just call or drop me an Email.

The reason the shock warranty is voided after adjustments is because of the stress the valving adds, this as with any racing shock will shorten the life cycle of the shock. This is the reason race teams have multiple sets available and have them re valved very often. The bumpiness is because the spring rates especially in the rear for the down force reasons are very high. The shocks will need to be stiffer to control the extra energy the spring has to smooth the ride but not make it softer riding by any means.

This is the reason the Moton Clubsports ride so well, they are mated very well with the spring rates and valving creating a very smooth forgiving ride well beyond the factory offerings but at the added cost of admission.

 

[Grant]

I think we need to define some terms here. If by "dartiness" you mean tramlining (or the tendency for the front wheels to follow ruts and gradients in the road), then its normal. All cars with wide, sticky front tires (and especially aggressive front camber) will tramline, with varying intensity.

Tramlining is most noticeable on back roads where ruts have been worn into the asphalt. My ACR (set up by Mark J. and great in every other respect) does it, as does every other performance car I've owned. My car can also sometimes feel "darty" before the tires (and their pressures) have come up to temperature on cold days. PS Cups really don't like the cold.

 

[BennyBad]

ok from what im reading here is that i should set the car to its softest settings on the compression and rebound all around and then do the suggested 6 clicks harder and 5 clicks harder or vise versa from the stiffist setting and 6 clicks down and 5 clicks down in the rear ??? or are there numbers on these shocks have not been under the car yet. hey to you grant you are very fast and smooth out there, should have taken up your offer that night to do the adjustment..

 

[Grant]

Benny, thanks. I just wish I could have gotten clearer traffic for more laps, to shave some more time off. I don't remember if it was you who was asking me about my DAQ and lap timer, but if you want to see what it recorded and a video, go here.

As far as adjustments go, the ACR Owner's Manual probably spells it out best. They have you go full hard, then 6 clockwise clicks in front and 5 in the rear. I have mine set 9/9 front and 10/10 rear for street use; I found the street settings to be too under-damped for my driving style.

 

[BennyBad]

by under damped for your driving style??? i drive mine on the street for little trips to check my jobs not aggressive and try and do a hpde at least once a month. what do you recomend?thanks

 

[BennyBad]

update. had the factory settings checked which are suppose to be front comp. 13 and rebound 18 and the rears 13 comp. and 17 rebound. car was rt. front 15 and 20, lft. frt 10 and 16. rear rt. 13 and 16 and rear lft. 13 and 17, one for four not bad. adjusted full stiff and did the recommended 6 and 6 up front and 5 and 5 rear. also lowered car to smooth track setting of 4 " in front and 5 3/8" in rear, well almost gave up at 4" and 5 1/8". car feels much tighter now but do to local law enforcement step do to holiday weekend no high speed maintained runs. so you acr owners that havent touched the suspension, its as loose and sloppy as dodge could have ste it from the factory. go figure a car with adjustable suspension and warning decals on them to prevent you from touching them. they peel back real easy and just put them back on.. thanks B

 

[BennyBad]

update car is much stiffer and the sensation is definitely the downforce resistance. still trying to adjust the rake correctly according to manuel. thought i had it right and checked the car with person in it and its at 5 1/4"(133.87) rear and 4 1/2" (114.75) in front manuel says 136 rear and 102 front for smooth track.. im i close enough to even notice??? thanks for all your help people..

hpde at morosso on the 14th of dec.love to see some more vipers..