Metalcloak Thread
05-21-2013, 01:25 PM
#111
05-21-2013, 01:34 PM
#113
JKred,
I agree with most of what you say.
From the little information I gave, it may look like a contradiction. Well, I did not create, or try to create, a perfect system.
The idea was experimenting adjustable air springs with 0" to 4" lift, while being aware that a 4" lift range wouldn't deliver consistent proper geometry.
My main interest was in improving capability on steep slopes, by individually controlling each spring.
For DD I used 0"~1". Most of the offroading was at 3"~4" lift.
Extreme lift, such as in the case of that step, was not the purpose of using air springs (and they became too hard by the added 50% pressure – just like the change in tire feel with 26psi vs 39psi). The possibility of more lift was there, so I tried it... (Wouldn't you?
)
8"~9" was used only briefly, the Jeep was lowered right after climbing a short distance.
This is it, including the stock arm, at max' lift:
Up to 4" lift, the air springs behavior was superior to everything else we compared them to – various coils/shocks, lifts, and both short and long arms. (We didn't compare to coilovers.)
I developed a way to soften them at max' lift/pressure, and tested the idea as a static pilot. It worked.
The decision against further developing of the system came partly because of some of the reasons you pointed to, and partly because it would have made the system too complicated and therefore less reliable.
It also became clear that there would be too many things to operate 'all at once' while crossing tough obstacles, diverting attention from the driving itself.
Developing electronic automation to take care of all the variables was a 'non-starter'.
So... my current Jeep has a regular 4" coils lift…
I'm very happy with the Full Traction lift, but, if the MC was available AND regularly imported and serviced in my country, I might have preferred it.
Obviously this isn't the only factor, but hard coil/shock combination moves the body more than a soft combination does. In fast offroading, a hard combination doesn't allow the suspension to move enough to comply and prevent body movements. If we stretch this to the extreme and make the coils much harder, they wouldn't compress and the body would move stiffly with the axles.
The theoretical parameters you point to are valid. However, in actual use, the felt influence is negligible at up to 4" lift. I compared similar jeeps on which the only difference was short vs long arms, and compared again after I got the Rubi. There was no improvement on a bad road, and no improvement on a trail, slow or fast. That was the impression of 3~4 people – the Jeep owner(s), the owner of a 4x4 modding shop and myself. I didn't compare challenging rock crawling.
With a lift taller than that, I could feel the difference.
I agree with most of what you say.
GJeep
Long arm are good, in fact necessary , for 6" lift or more. Up to about 4" lift, long arms have no advantage.
The Jeep, in the picture on the left, has air springs lift. In the picture, the lift is at its max', about 8"~9". At the time, except for the air springs and Fox shocks, everything was stock, including the arms, wheels and tires (245/75/17).
The Jeep climbed that step quite easily, just touching the right side-step.
Without that much lift, it would have sat on its belly.
Long arm are good, in fact necessary , for 6" lift or more. Up to about 4" lift, long arms have no advantage.
The Jeep, in the picture on the left, has air springs lift. In the picture, the lift is at its max', about 8"~9". At the time, except for the air springs and Fox shocks, everything was stock, including the arms, wheels and tires (245/75/17).
The Jeep climbed that step quite easily, just touching the right side-step.
Without that much lift, it would have sat on its belly.
JKred
Rather strong contradiction there, but I see what you were getting at.
Rather strong contradiction there, but I see what you were getting at.
From the little information I gave, it may look like a contradiction. Well, I did not create, or try to create, a perfect system.
The idea was experimenting adjustable air springs with 0" to 4" lift, while being aware that a 4" lift range wouldn't deliver consistent proper geometry.
My main interest was in improving capability on steep slopes, by individually controlling each spring.
For DD I used 0"~1". Most of the offroading was at 3"~4" lift.
Extreme lift, such as in the case of that step, was not the purpose of using air springs (and they became too hard by the added 50% pressure – just like the change in tire feel with 26psi vs 39psi). The possibility of more lift was there, so I tried it... (Wouldn't you?
) 8"~9" was used only briefly, the Jeep was lowered right after climbing a short distance.
This is it, including the stock arm, at max' lift:
Up to 4" lift, the air springs behavior was superior to everything else we compared them to – various coils/shocks, lifts, and both short and long arms. (We didn't compare to coilovers.)
I developed a way to soften them at max' lift/pressure, and tested the idea as a static pilot. It worked.
The decision against further developing of the system came partly because of some of the reasons you pointed to, and partly because it would have made the system too complicated and therefore less reliable.
It also became clear that there would be too many things to operate 'all at once' while crossing tough obstacles, diverting attention from the driving itself.
Developing electronic automation to take care of all the variables was a 'non-starter'.
So... my current Jeep has a regular 4" coils lift…
I'm very happy with the Full Traction lift, but, if the MC was available AND regularly imported and serviced in my country, I might have preferred it.
GJeep - "too bouncy" ….. how level it stays with a lot of articulation (or how much/little does the center of gravity move)"
Both of those^ points have a little to do do with coil/spring matching
The theoretical parameters you point to are valid. However, in actual use, the felt influence is negligible at up to 4" lift. I compared similar jeeps on which the only difference was short vs long arms, and compared again after I got the Rubi. There was no improvement on a bad road, and no improvement on a trail, slow or fast. That was the impression of 3~4 people – the Jeep owner(s), the owner of a 4x4 modding shop and myself. I didn't compare challenging rock crawling.
With a lift taller than that, I could feel the difference.
Last edited by GJeep; 05-21-2013 at 02:36 PM.
05-21-2013, 02:20 PM
#114
So, what does this mean? –
"Your lift would do nothing to help you climb that over any other bolt on short arm."
Theoretically, yes. According to my experience with different Jeeps, the difference is too small to be noticeable.
The MC arm joints look good, but "even" my Full Traction short arms move freely all the way up to full flex.
The coil/shock combination, my friend, make most of the difference between suspension systems. The MC dual-rate coil, in combination with the 6Pak shock, seems to work better than many others, probably better than mine too.
"Your lift would do nothing to help you climb that over any other bolt on short arm."
A properly set up long arm even at 2" will out perform a bolt on short arm mainly in its climbing ability and rock crawling where you have massive articulation going on. Its all in the geometry.
.....it was stated that the mc lift somehow gives a jeep greater abilities then other lifts out there. A statement like that shows the lack of knowledge of how a suspension works. Those mc arms just hold the axle in place, that is it.
The coil/shock combination, my friend, make most of the difference between suspension systems. The MC dual-rate coil, in combination with the 6Pak shock, seems to work better than many others, probably better than mine too.
Last edited by GJeep; 05-21-2013 at 02:24 PM.
05-21-2013, 05:46 PM
#115
JK Jedi
I stated bolt on short arm because if you really want to optimize your set up moving brackets should be included in the design. The factory brackets were designed and are engineered for the stock ride height. When you lift it, you throw all that engineering out the window and are just making compromises with bolt on equipment. Shocks and coils are only a small part of the whole suspension system that should be designed with more then just the two in mind.
Last edited by TheDirtman; 05-23-2013 at 05:10 AM.
05-23-2013, 02:08 AM
#118
The factory brackets were designed and are engineered for the stock ride, when you lift it you throw all that engineering out the window and are making compromises with bolt on equipment. Shocks and coils are only a small part of the whole suspension system that should be designed with more then just the two.
(The front driveshaft would have 'suffered' from the lift, so it was replaced with J.E. Reel 1350)
Shocks and coils are only a small part of the whole suspension system
The shock/coil combination determines the nature of the compliance with the terrain, a key factor in offroad capability.
The air springs I had, with the shocks valved to suit them, and with stock arms, felt and behaved better than a similar Jeep with properly adjusted long arms, at the same lift height. I think that this proves the point. Nothing determines the characteristics of the Jeeps' behavior on a trail more than the coil/shock combination.
The differences between coils (spring coefficient and possibly some progressiveness) are relatively small vs the large valving range between shocks. Therefore, in the coil/shock pair, the shock is the most influential part.
BTW, the MC idea of the dual rate coils is great. It also shows that a coil can't be made much softer.
The softer part of the coil is too soft to hold the weight, so it's normally compressed and doesn't participate most of the time. It opens only when a wheel moves down far enough, and then softens the drop of the Jeep, by compressing before the harder part of the coil begins to compress – sort of an "upside down spring bump stop".
That's why the MC coils allow faster sprints than can be done with 'regular' coils, including the relatively softer ones such as my Full Traction coils. I didn't have a chance to try it, but the dual rate coils should provide better offroad handling whenever there's a lot of flex – regardless of the arms.
"you throw all that engineering out the window and are making compromises….. designed and are engineered for the stock ride"
(And why, after 70 years of the Jeeps' evolution, I pay for a Rubicon and find a back seat that's so uncomfortable because it's too upright? – and add a bracket to slant it back to the angle it should have had in the first place?... I certainly wouldn't "throw all that engineering out the window", I'd just throw a few engineers…
) Suspension example:
With the up or down movement, the live axle also moves sideways. The sideways movement, especially of the rear axle, throws the Jeep a bit off course and undermines directional stability (this is even more pronounced in 2-dr than in a 4-dr).
The result is that constant small steering corrections are necessary. This is annoying on long trips, and it's something that Jeep could/should have solved long ago.
I installed a Full Traction CRC Link which replaces the radius arm and totally eliminates the sideways movements of the rear axle. The steering improvement was very noticeable from the first 100~200 yards on a road.
Last edited by GJeep; 05-23-2013 at 02:13 AM.
05-23-2013, 04:53 AM
#119
JK Super Freak
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OK, forget about the long arms…
If I "threw all that engineering out the window", my 4" lift, bolted on the factory brackets, wouldn't have delivered better handling than the stock suspension. Nothing is stressed at max' flex. That's what adjustable arms are for – readjusting.
(The front driveshaft would have 'suffered' from the lift, so it was replaced with J.E. Reel 1350).
If I "threw all that engineering out the window", my 4" lift, bolted on the factory brackets, wouldn't have delivered better handling than the stock suspension. Nothing is stressed at max' flex. That's what adjustable arms are for – readjusting.
(The front driveshaft would have 'suffered' from the lift, so it was replaced with J.E. Reel 1350).
All you've changed with the arms is axle geometry (not to be confused with suspension geometry). With 4 inch of lift and ALL factory brackets still in use, you have quite a few bad angles that play a lot into the way the suspension handles. I'll get more into this in the end of my post...
"Small part"? – the shock/coil, is the most noticeable thing while driving. We don't feel a slight change of the arm angle, but we immediately feel the difference between coil & shock sets.
The shock/coil combination determines the nature of the compliance with the terrain, a key factor in offroad capability.
The air springs I had, with the shocks valved to suit them, and with stock arms, felt and behaved better than a similar Jeep with properly adjusted long arms, at the same lift height. I think that this proves the point. Nothing determines the characteristics of the Jeeps' behavior on a trail more than the coil/shock combination.
The differences between coils (spring coefficient and possibly some progressiveness) are relatively small vs the large valving range between shocks. Therefore, in the coil/shock pair, the shock is the most influential part..
The shock/coil combination determines the nature of the compliance with the terrain, a key factor in offroad capability.
The air springs I had, with the shocks valved to suit them, and with stock arms, felt and behaved better than a similar Jeep with properly adjusted long arms, at the same lift height. I think that this proves the point. Nothing determines the characteristics of the Jeeps' behavior on a trail more than the coil/shock combination.
The differences between coils (spring coefficient and possibly some progressiveness) are relatively small vs the large valving range between shocks. Therefore, in the coil/shock pair, the shock is the most influential part..
BTW, the MC idea of the dual rate coils is great. It also shows that a coil can't be made much softer.
The softer part of the coil is too soft to hold the weight, so it's normally compressed and doesn't participate most of the time. It opens only when a wheel moves down far enough, and then softens the drop of the Jeep, by compressing before the harder part of the coil begins to compress – sort of an "upside down spring bump stop".
That's why the MC coils allow faster sprints than can be done with 'regular' coils, including the relatively softer ones such as my Full Traction coils. I didn't have a chance to try it, but the dual rate coils should provide better offroad handling whenever there's a lot of flex – regardless of the arms..
The softer part of the coil is too soft to hold the weight, so it's normally compressed and doesn't participate most of the time. It opens only when a wheel moves down far enough, and then softens the drop of the Jeep, by compressing before the harder part of the coil begins to compress – sort of an "upside down spring bump stop".
That's why the MC coils allow faster sprints than can be done with 'regular' coils, including the relatively softer ones such as my Full Traction coils. I didn't have a chance to try it, but the dual rate coils should provide better offroad handling whenever there's a lot of flex – regardless of the arms..
With all due respect to all the Jeep engineers ever since 1941... The Jeeps' suspension isn't perfect or free of built-in issues.
(And why, after 70 years of the Jeeps' evolution, I pay for a Rubicon and find a back seat that's so uncomfortable because it's too upright? – and add a bracket to slant it back to the angle it should have had in the first place?... I certainly wouldn't "throw all that engineering out the window", I'd just throw a few engineers…)
Suspension example:
With the up or down movement, the live axle also moves sideways. The sideways movement, especially of the rear axle, throws the Jeep a bit off course and undermines directional stability (this is even more pronounced in 2-dr than in a 4-dr).
The result is that constant small steering corrections are necessary. This is annoying on long trips, and it's something that Jeep could/should have solved long ago.
I installed a Full Traction CRC Link which replaces the radius arm and totally eliminates the sideways movements of the rear axle. The steering improvement was very noticeable from the first 100~200 yards on a road.
(And why, after 70 years of the Jeeps' evolution, I pay for a Rubicon and find a back seat that's so uncomfortable because it's too upright? – and add a bracket to slant it back to the angle it should have had in the first place?... I certainly wouldn't "throw all that engineering out the window", I'd just throw a few engineers…
) Suspension example:
With the up or down movement, the live axle also moves sideways. The sideways movement, especially of the rear axle, throws the Jeep a bit off course and undermines directional stability (this is even more pronounced in 2-dr than in a 4-dr).
The result is that constant small steering corrections are necessary. This is annoying on long trips, and it's something that Jeep could/should have solved long ago.
I installed a Full Traction CRC Link which replaces the radius arm and totally eliminates the sideways movements of the rear axle. The steering improvement was very noticeable from the first 100~200 yards on a road.
You also now have terrible roll centers. Roll center being the theoretical point at each axle by which the moment of force due to the center of gravity rotates about. It is measured by measuring the average height of the trackbar (center between height of the uppr and lower mount). This will cause more body roll in coreners and changes in road/trail pitch, causing axle steer. The shorter the control arms, the more axle steer, the less predictability.
Since we are keeping stock brackets, none of this can be addressed, however if we change brackets...
Raising AXLE SIDE trackbar brackets and flipping the drag link raise roll centers and significantly reduce bump steer. The closer the roll center to the CG of the jeep, the more stable, period. By reducing body roll you reduce axle steer. Some companies, however, use frame drop brackets and drop pitman arms, lowering roll center, making handeling even worse.
Now, the CRC link... All this is, is a Watts link, and is an effective way of keeping the axle constantly centered, AND raising the roll center quite a bit. However, it takes up quite a bit of space, add ANOTHER link, and some elaborite bracketry, which is why you will never see it out of the factory. It does the same thing as triangulated 4 links, which are superior in every way, as they are constant centering, high roll center, AND no axle steer.
My point, bolt on lifts are just that.... and factory brackets should be thrown out the window when you lift a vehicle. Springs and shocks help, as well as arms like MC's that use a joint the has both a high deflection angle and good NVH characteristice, but a vehicle with proper suspension geometry will always be superior both on and off road.
05-23-2013, 04:54 AM
#120
JK Jedi
I highly doubt your 4" lift handles better then stock unless you have a front axle with caster correction built in, have raised your roll center, and are running stiffer sway bars. The sport model rides terrible from the factory mainly due to the crappy shocks they use. Just installing a better shock valved for what you are doing will greatly improve the ride. If you think you have a nicer ride now I would credit the shocks not the lift. All coils do is hold up the weight of the jeep the shock valving is what is important for ride quality.
I never said the jeep engineers did a perfect job on the factory suspension but they did engineer it to the ride height with the constraints of the JK frame and body clearances. I understand the axle shift during articulation and if you do, you would understand that a long arm minimizes that shift. Changing the mount locations on a short arm will also minimize the axle shift. Triangulating the control arms will also eliminate the axle shift and allow you to run without the track bar or your crc link.
Not sure why you are now talking about rear seats? When loosing the debate, change the subject?
If you think shocks and coils are all the shit on the suspension talk to some of the guys running ori's They run neither shocks or springs. From your posts it looks like you know very little about suspension geometry and how to set up a suspension without it being a bolt on product.
If you want to learn about suspension design I am glad to help but if you want to quote me and spread mis-information I am done with this thread.
A 1350 driveshaft is not needed and a JK and actually limits your articulation more then a 1310 joint does.
I never said the jeep engineers did a perfect job on the factory suspension but they did engineer it to the ride height with the constraints of the JK frame and body clearances. I understand the axle shift during articulation and if you do, you would understand that a long arm minimizes that shift. Changing the mount locations on a short arm will also minimize the axle shift. Triangulating the control arms will also eliminate the axle shift and allow you to run without the track bar or your crc link.
Not sure why you are now talking about rear seats? When loosing the debate, change the subject?
If you think shocks and coils are all the shit on the suspension talk to some of the guys running ori's They run neither shocks or springs. From your posts it looks like you know very little about suspension geometry and how to set up a suspension without it being a bolt on product.
If you want to learn about suspension design I am glad to help but if you want to quote me and spread mis-information I am done with this thread.
A 1350 driveshaft is not needed and a JK and actually limits your articulation more then a 1310 joint does.
Last edited by TheDirtman; 05-23-2013 at 05:05 AM.