Installed #600 rear springs with my Motons

[8mywal8]

Installed #600 rear springs with my Motons. Changed out the #800. What a difference in the way the car rides. I will see what it does on the track in a few weeks. So far on the back roads feels pretty damn sticky.

 

[JonB]

The Fronts Matter!!!!

 

[mjorgensen Woodhouse]

Chances are the fronts are 500#, I have been experimenting with rate changes also and I find that the power on cornering with closer rates is a little better. Although at neutral throttle the car pushes more the trail braking and exit are better. Since I autocross these are helpful. Currently using 950 rear and 800 fronts. Changing to 850 rear this spring to try it, there is a lot of race data out there that supports the spring choices, but I feel that very aggressive driving (like I do) needs a different option. Also the rake of the car is a big tuning help when changing and trying different combos.

 

[NI-KA]

Can't wait to hear your conclusions. I want to track and autocross and am interested in finding out what the optimal set up may be.

Please keep us posted 1

 

[8mywal8]

Can't wait to hear your conclusions. I want to track and autocross and am interested in finding out what the optimal set up may be.

Please keep us posted 1

Went to Laguna Seca last weekend. Car handled very well after I got the tire pressure correct and set the Moton canisters set at 225 psi. Stayed right behind a ZR1. This was my first time and last time at this track.( explane later). Car rides so much better around town with the #600 rear springs and the canisters at about 110 psi. I think I may put the #500 from the front on the rear and try some #400 in the front. Next time I go to the track I will set the canisters at about 275-290 PSI. Lex at Moton said we could go to 300 psi. I am trying to get the best of both worlds. This may not be possible but hell we need something to work at.

As far as Laguna Seca butterfly chasing f--ks. They wanted to kick me out for the car being to loud. It is stock with a Corsa cat back. How could that be to loud? I will go to Thunder Hill from now on.

 

[mjorgensen Woodhouse]

What is your ride height and rake set at??? The reason I ask is that even with 950# rears my car has worn through the rear inner fender liners from hard cornering and accelerating, I can't believe yours has not.

Went to Laguna Seca last weekend. Car handled very well after I got the tire pressure correct and set the Moton canisters set at 225 psi. Stayed right behind a ZR1. This was my first time and last time at this track.( explane later). Car rides so much better around town with the #600 rear springs and the canisters at about 110 psi. I think I may put the #500 from the front on the rear and try some #400 in the front. Next time I go to the track I will set the canisters at about 275-290 PSI. Lex at Moton said we could go to 300 psi. I am trying to get the best of both worlds. This may not be possible but hell we need something to work at.

As far as Laguna Seca butterfly chasing f--ks. They wanted to kick me out for the car being to loud. It is stock with a Corsa cat back. How could that be to loud? I will go to Thunder Hill from now on.

 

[8mywal8]

What is your ride height and rake set at??? The reason I ask is that even with 950# rears my car has worn through the rear inner fender liners from hard cornering and accelerating, I can't believe yours has not.

I am set at about 3 fingers front and rear. (2") I did not here any rubbing. Once in a while when I hit a hard bump.I only have Invos on it so maybe they do not grip as hard as your tires. 220 tread where. Maybe I do not corner as hard as you. this is only my second track day in this car.

 

[2000_Black_RT10]

What is your ride height and rake set at??? The reason I ask is that even with 950# rears my car has worn through the rear inner fender liners from hard cornering and accelerating, I can't believe yours has not.

Heya Mark - Are there bump stops in the damper assembly (i.e. under the spring cap within the coil diameter)? Some neglect or are not aware of limiting spring compression with aftermarket dampers, because the suspension / control arms may not rely on external bump stops to limit suspension travel. OEM dampers can have internal bump stops (inside the damper) or on the shaft under the upper eye. Also, if a damper is fully compressed to the point of bottoming out internally (if this occurs before full coil compression length) this can damage the damper internals. If the spring is fully compressed before hitting the bumpstop, this can also damage the damper in the long run, in such that the caps will be taking hard hits.

On other cars, there may be a rubber bumpstop on the control arm or on the frame to limit suspension travel, so a bumpstop is not needed in the damper.

Just a comment.... adding a bumpstop (or a larger one) may cure the inner liner rubbing issue... yet I don't know the details of what damper, springs or the setup you have.... just a fyi suggestion to help.... but you may know all this.... no worries.....

Best regards,
Mike

PS.. here's an example image of a past ACR style damper with a bumpstop, and under full compression, the top of the damper body will hit the bumpstop limiting the compressed length of the damper before the springs (not shown) can fully compress.

You must be registered for see images

 

[mjorgensen Woodhouse]

Yes I do know about bump stops and the Moton has none. We use the 8" springs so there is no spring bind that you could get with a shorter spring. My shock has never run out of travel, but it will allow the tire to contact the liner.

I think there is a place for bump stops just not on my cars. The abrupt hit of the stop will greatly affect the handling (generally not in a good way) when you are traveling fast or cornering at the limit. They do make longer more progressive stops but what is the point? with only a couple inches of travel you would be on them all the time so just up the spring rates till you have what you really need.

I feel the same about cranking up the canister pressure and the bump adjustment to mask a soft spring. The handling is compromised and the shock is not meant to be a spring. I know it can be done though as it is very common practice in Solo while running in a stock class.

 

[8mywal8]

I would run a stiffer spring if I was racing all the time. But I drive my car all the time. I want it to be semi comfortable. It still handles better then most cars on the road.

 

[David Pintaric]

Mark,

Do you know what spring rates the ACRXs have?

 

[Boxer12]

The ACRX has KW suspension, and this issue being discussed isn't a problem with the KW. The ACRX has stiffer springs than the ACR, but even the ACR doesn't rub the fender wall, at least when its set up correctly and with 19" tires in rear and recommended rake.

 

[mjorgensen Woodhouse]

The ACRX has KW suspension, and this issue being discussed isn't a problem with the KW. The ACRX has stiffer springs than the ACR, but even the ACR doesn't rub the fender wall, at least when its set up correctly and with 19" tires in rear and recommended rake.

True the ACR and X all have more rake by almost an inch than the regular coupe to compensate for the aero at speed, along with much higher rates so no they would not rub.

 

[2000_Black_RT10]

I think there is a place for bump stops just not on my cars. The abrupt hit of the stop will greatly affect the handling (generally not in a good way) when you are traveling fast or cornering at the limit. They do make longer more progressive stops but what is the point? with only a couple inches of travel you would be on them all the time so just up the spring rates till you have what you really need.

I design cars for a living, including suspension systems for several OEMs. Your comments in conjunction with rubbing the wheel liners is a bit extreme from my perspective.

The max jounce height is controlled by a bump stop in practically every vehicle on the road, regardless of where it's located on the damper, strut, suspension component, control arm, leaf spring, straight axle housing or on the chassis or frame. In design, an additional offset clearance value (+ bushing compliance) disregarding the bumpstop (design considers that the bushing may deteriorate over time to be safe, sometimes called steel on steel contact) is given around the tire (i.e. 10 mm or more) and for cars that can use snow chains, the clearance can be much more (i.e. 30 mm or more) so let's obviously ignore snow chain clearance on a Viper.. Given that you are rubbing the liners, the jounce wheel travel is going beyond the OEM design if the OEM wheel and tire is utlized. Extreme situations would be a hard turn with body roll and hitting a *** hole or bump. A tire rubbing the chassis is not good, there are steel components on the other side of the plastic liner (typically 3 mm thick), and if the tire rubs thru the liner and makes contact with a component, this can be dangerous. The halfshaft is designed to the max jounce and rebound travel of the suspension. There is a telescoping portion of the halfshaft to accomodate suspension travel, whether it's a CV joint on one end that can plunge and has an angle limit or a splined shaft with U-joint. Going beyond the extended limit of the halfshaft may result in a shaft pulling apart or the CV joint going beyond the angle it can accomodate internally. I do not know the length and angle limit of the halfshaft being used on your car, yet I'm just sharing a bit of design insight. Another option to control the body roll is obviously addressing the sway bar.

 

[ROCKET62]

110 psi on the street - seems low, especially with the softer springs? This thread has turned out to be a great discussion on the moton set-up. I need to get nadar's fill kit so that I can see where my motons are set (still at factory fill with 2 years on them).


2000 Black RT10 - On the SRT there really isnt a metal chassis behind the liner - just a lot of empty space. I am amazed that more people that lower their Vipers are not rubbing thru the liner? My Viper is not slammed like some I have seen and there is one bump in town that if I hit it at speed, I can hear the tire (and smell) the tire hitting the liner.

Went to Laguna Seca last weekend. Car handled very well after I got the tire pressure correct and set the Moton canisters set at 225 psi. Stayed right behind a ZR1. This was my first time and last time at this track.( explane later). Car rides so much better around town with the #600 rear springs and the canisters at about 110 psi. I think I may put the #500 from the front on the rear and try some #400 in the front. Next time I go to the track I will set the canisters at about 275-290 PSI. Lex at Moton said we could go to 300 psi. I am trying to get the best of both worlds. This may not be possible but hell we need something to work at.

As far as Laguna Seca butterfly chasing f--ks. They wanted to kick me out for the car being to loud. It is stock with a Corsa cat back. How could that be to loud? I will go to Thunder Hill from now on.

 

[mjorgensen Woodhouse]

I can fully appreciate your comments as I would view it this way if I did not experience something different. Anyone that lowers the rear of a SRT 1" will be making contact with the liners under hwy speed bumps or rolling humps. I would be willing to bet that if these people would check the liners at the top front intersection of the two parts will find some rubbing. This is the exact reason we only lower the rear of a Viper for the street 3/4" with the Motons unless the owner understands the possibility and will accept it.

With the 1050# rears of the ACR they only set the ride height to 5 1/2". The stock SRT shocks have bump stops to help the travel with only 550# rears, the Moton does not and that is part of the reason they ride so well, but need stiffer springs to stay high enough during jounce. People that lower the SRT with springs and the caps are on the stops even more! The Moton will not bottom with this setup before contacting the liners. The front has no real issues and I have run the front as low as 3.8"

I just swapped to 600F and 850R and have been happy so far at the 5.25" rear height. I will get a better read for this after my first event. I also set rears at 120psi and fronts at 100psi for now. This lets me use more of the available adjustments for rebound and compression on the shock.

I design cars for a living, including suspension systems for several OEMs. Your comments in conjunction with rubbing the wheel liners is a bit extreme from my perspective.

The max jounce height is controlled by a bump stop in practically every vehicle on the road, regardless of where it's located on the damper, strut, suspension component, control arm, leaf spring, straight axle housing or on the chassis or frame. In design, an additional offset clearance value (+ bushing compliance) disregarding the bumpstop (design considers that the bushing may deteriorate over time to be safe, sometimes called steel on steel contact) is given around the tire (i.e. 10 mm or more) and for cars that can use snow chains, the clearance can be much more (i.e. 30 mm or more) so let's obviously ignore snow chain clearance on a Viper.. Given that you are rubbing the liners, the jounce wheel travel is going beyond the OEM design if the OEM wheel and tire is utlized. Extreme situations would be a hard turn with body roll and hitting a *** hole or bump. A tire rubbing the chassis is not good, there are steel components on the other side of the plastic liner (typically 3 mm thick), and if the tire rubs thru the liner and makes contact with a component, this can be dangerous. The halfshaft is designed to the max jounce and rebound travel of the suspension. There is a telescoping portion of the halfshaft to accomodate suspension travel, whether it's a CV joint on one end that can plunge and has an angle limit or a splined shaft with U-joint. Going beyond the extended limit of the halfshaft may result in a shaft pulling apart or the CV joint going beyond the angle it can accomodate internally. I do not know the length and angle limit of the halfshaft being used on your car, yet I'm just sharing a bit of design insight. Another option to control the body roll is obviously addressing the sway bar.

 

[2000_Black_RT10]

Imagine if you had a set of these to play with (high tech and very expensive, used in F1, ALMS, FIA GT series, etc..).

Dynamic Suspensions

That's good to hear Rocket62, some just assume.. I just wanted to generally highlight some stuff to be aware of.

Cheers,
Mike

 

[2000_Black_RT10]

I just swapped to 600F and 850R and have been happy so far at the 5.25" rear height. I will get a better read for this after my first event. I also set rears at 120psi and fronts at 100psi for now. This lets me use more of the available adjustments for rebound and compression on the shock.

Does the damper manufacturer suggest an optimum psi range, depending on the valve design and internals, sometimes a higher psi is suggested to prevent cavitation. I don't know if this is the case with your dampers.. just suggesting a question / inquiry to help out.. if not.. no worries..

Cheers,
Mike

 

[mjorgensen Woodhouse]

Yes cavitation can occur at lower pressures than 100, but for short events and or autocrossing I will be fine. After about 200 miles at this set up I decided I will probably go up in 10 psi increments till I get the sweet spot for my tastes. We generally use 175 psi front and rear for the Clubsport set ups.

 

[Viper X]

Installed #600 rear springs with my Motons. Changed out the #800. What a difference in the way the car rides. I will see what it does on the track in a few weeks. So far on the back roads feels pretty damn sticky.

IMHO, 600lb rear springs are too soft for the rear of a Viper on the track. I've followed several of our members around a local race track (Willow Springs) and in turn 8, a high speed turn, the car rolls excessively and hops / skips around this turn at speed, losing traction.

I'd suggest going to minimum 750 - 800 rear springs for the track.

Adding a bunch of pressure to the Motons to make up for lighter springs is not a very good idea, safety wise. When you increase pressure in the shocks, you gain compression (spring rate) but you also lose rebound capability (control of the upward motion of the car).

Dan

 

[NI-KA]

Excellent thread.

Can any of you experts recommend a good technical reference book that would help someone with a technical background get a better understanding of this subject?

 

[2000_Black_RT10]

We can go thru the basics using this software tool, first thing to understand is the natural frequency reviewing 1 corner of the car (ignore front and rear and other dynamic situations, anti roll bars, inertia, pitch, downforce, compression and rebound, etc.. for the time being).

Here's a link to a frequency tool that you can install on your Windows PC called Motorsports Natural Frequency Software :

Dynamic Suspensions

The natural frequency (Hz) can illustrate response, higher the number, quicker the response and Wheel Deflection being the static deflection in frequency (think of a frequency wave), and basically, looking for a frequency to be compatible with maintaining contact on road conditions at speed.

Once you start the software (hit Accept at the top right corner). All the values below are being keyed in the right column entry fields / boxes.

1) Checkmark the same velocity for spring and damper on, key in 800 lb/in for a Spring Rate, 1.0 for Damper Velocity Ratio and 800 lb for Sprung Corner Mass (mass at one corner of the car).

Result = The Hz (at the corner of the car) calculated should be 3.127 and the Deflection at the Wheel is 1.0 inches.

2) If you reduce the Spring Rate to 550 lb/in.

Result = The natural frequency number drops to 2.593 and the Deflection at the Wheel increases to 1.455 inches.

Note we have been using 1.0 for the Damper Velocity Ratio (1 to 1, not damped). Valve adjustments, valves and changing the gas psi charge is going to increase / decrease the velocity & volume transfer of the fluid (then there's viscosity and changes as the fluid heats up during use, but let's also ignore that).

3) Change the Damper Velocity ratio to 0.3 (can be a common passenger car with a plush shock).

Result = The Hz dropped to 0.778 and the Wheel Deflection increased to 16.16 inches (big waves). Less chances to stay connected to the road...

4) Change the Damper Velocity ratio up to 0.8.

Result = The Hz increases to 2.04 and the Wheel Deflection is 2.273 inches.

5) Increase the Spring Rate back up to to 800 lb/in.

Result = The Hz increases to 2.502 and the Deflection at the Wheel decreases to 1.563 inches.

In summary, increasing the Damper Velocity ratio or the Spring Rate will increase the frequency, yet working with reduced Wheel Deflection at that frequency. The frequency is a target, depends on the track (dynamic situations), front and rear are typically tuned individually. Hz in ballpark terms, typical passenger cars can be around 1.0 +/- 0.5, weekend track cars 2 +/-0.5, and 4.0 +/-1.5 for race cars.

Regards,
Mike

 

[ROCKET62]

Is there a "Translate Button" for those of us that dont have a clue what the heck 2000 Black RT 10 just posted?

I have the moton Clubsports. 500/750 springs. Set Rebound at "3". Do not know what my pressure is (factory fill, 2 years old). From the Moton Website:

ADJUSTING PROCEDURE FOR DOUBLE ADJUSTABLE

CLUB SPORT DAMPERS ​

COMPRESSION ADJUSTER
[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]The compression adjuster is located on the top of the canister. It has a range of 7 positions (0 – 1 – 2 – 3 – 4 – 5 - 6 ). To adjust the shock or strut turn the knob one click at a time. [/FONT][/FONT]
[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]([/FONT][/FONT]clockwise "-" softens; counter clockwise "+" stiffens[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]) [/FONT][/FONT]​

(softest setting is position "0" – stiffest setting is position "6")

PROCEDURE

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]When installing the shock or strut on the car for the first time, the compression adjuster should be set at 2 clicks from "0". [/FONT][/FONT]

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]Turn the adjuster knob clockwise until it stops. This is the "0" position. From this position turn the knob counter clockwise 2 clicks. The compression is now adjusted. [/FONT][/FONT]
REBOUND ADJUSTER ​

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]The rebound adjuster is located on top of the piston rod. It has a range of 7 positions. [/FONT][/FONT]
[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma](0 – 1 – 2 – 3 – 4 – 5 - 6). To adjust the shock or strut turn the brass hex knob (or orange alloy rebound knob) 1 click at a time. [/FONT][/FONT]​

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]([/FONT][/FONT]Clockwise "-" softens; counter clockwise "+" stiffens[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]) [/FONT][/FONT]

(softest setting is position "0" – stiffest setting is position "6")

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]The shock or strut should be in the "0" position ([/FONT][/FONT]full clockwise[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]) and should be adjusted to a basic setting from which you can establish a base line for adjustment. The "0" position on the rebound is achieved by turning the brass hex knob or rebound knob clockwise until you cannot turn it any further. ([/FONT][/FONT]CAUTION: once it stops turning DO NOT force it any further[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]). [/FONT][/FONT]​

PROCEDURE

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]When installing the shock or strut on the car for the first time, the rebound adjuster should be set at 3 clicks from "0". [/FONT][/FONT]

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]Turn the adjuster counter clockwise to position "0" and then adjust it 3 clicks counter clockwise. The rebound is now adjusted. [/FONT][/FONT]

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma](NOTE: the rebound adjuster opens or closes small orifices, this restricts the flow of fluid in small increments. Each click will have an effect on the handling characteristics so do not adjust more than 1 or 2 clicks at a time).[/FONT][/FONT]

BEGINNING SETTINGS
[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]FRONT:[/FONT][/FONT]
[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]COMPRESSION = 2 REAR: COMPRESSION = 2 [/FONT][/FONT]​

[FONT=JHKMGF+Tahoma,Tahoma][FONT=JHKMGF+Tahoma,Tahoma]REBOUND = 3 REBOUND = 3 [/FONT]

[FONT=JHKMGF+Tahoma,Tahoma]GAS PRESSURE (canister): [/FONT]

[FONT=JHKMGF+Tahoma,Tahoma]Dampers with 22 mm outside diameter piston rod (struts) = 12 bar or 185 psi[/FONT]
[FONT=JHKMGF+Tahoma,Tahoma]Dampers with 14 mm outside diameter piston rod = 18 bar or 275 psi [/FONT]​

[/FONT]​

MOTON Suspension Technology Phone Europe: +31 413 259838 USA: (770) 886 8777 ​

 

[2000_Black_RT10]

Regarding the knob / adjusters... today, a Moton 3 way damper (1 rebound adjuster on top of the shaft / rod and 2 speed compression adjusters on the canister) that was used on a race car was put on our damper dyno at work. This dyno can control force, velocity and time and output the results, connected to a computer. Here's some example results..

You must be registered for see images

The graphs (2 different runs) illustrate force over time and the associated force over displacement. Basically, adjust the damper and run it, each colored curve represents a selected damper adjustment.

The graph below illustrates bump and rebound adjustments and at different speeds (up to 300 mm/sec). Adjustments were made, one extreme position to the other (closed to open) in each graph. In bump (the top half of the graph), the high speed knob (on the canister) is very sensitive when cracked opened, an abrupt change then gradually changes. There's overlapped lines (dark blue and brown) in the middle which ilustrates the impact of adjusting the secondary low speed knob (on the canister) at 2 of the high speed adjustments shown in the time graph. 5 adjustments (top of the shaft) were made for rebound.

You must be registered for see images

The graph below also illustrates bump and rebound, but with 6 iterations of adjusting rebound (top of the shaft) and 6 for high speed bump. Rebound adjuster controls one speed, hence one line for each adjustment click from closed to open and between (6 adjustments of rebound are shown).

You must be registered for see images

This illustrates that adjusting the knobs is not linear. Basically, once the orifice opens, the first few clicks have more of a change compared to the comparing the change of the last few clicks. We use this dyno to adjust the internals (shims or..) of a damper, to create match sets of dampers. In other words, if the damper on the left side of the car is set to specific knob clicks / adjustments, you want the damper on the right to have identical results at the same knob clicks / adjustments.

Accommodating speed depends on the application. For instance, for WRC applications, when the car is airborne and lands, high speed damping limits (very fast compression with long travel) is needed, whereas for this type of road racing, less high speed limits are needed.

We can chat more if needed.. hope it basically helps illustrate what happens when you make adjustments.

Cheers,
Mike

 

[mjorgensen Woodhouse]

Nice, thanks for the detailed work!

 

[CCBrian]

Yes cavitation can occur at lower pressures than 100, but for short events and or autocrossing I will be fine. After about 200 miles at this set up I decided I will probably go up in 10 psi increments till I get the sweet spot for my tastes. We generally use 175 psi front and rear for the Clubsport set ups.

I have found that a 155/165 set up works pretty well-200+ is just to high.

 

[2000_Black_RT10]

I could propose this at work and to the VCA board, may be able to entertain doing a complete dyno analysis (much more info is available) and make any adjustments on fairly new set of dampers (not worn out needing a rebuild) for 1 car that's most commonly used amongst the member's cars, in order to make a full report for the VCA members illustrative guide section, match set tune the dampers for the car (need to know details, front and rear springs, weight, aero, sway bars, type of racing, etc.) including videos. Perhaps if a VCA (race) member wanted to contribute to this proposed effort, send us their dampers, you pay for shipping and get your dampers back tuned, charged, and a copy of the dyno results.

Cheers,
Mike

Here's an example of the results the dynamometer can provide (look under the Dyno Specifications and DynoSoft Software section inc. "Select a Project" pull down menu for more info):

Dynamic Suspensions

PS Mark J., under the Dyno Specifications, "Bump Rubber Testing" can be available in this dyno report...

If you don't know who Multimatic / Dynamic Suspensions are, here's an example customer (noted under the Suspension section):

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