School me on mid-arms

The key to understanding control arm geometry (regardless of it being short, mid or long) is to understand the concept of the instant center and how the instant center influences antisquat. Antisquat is the behavior of the axle to push against or pull away from the ground while under load from the engine. If you can get past the common fixations on arm length and instead focus on the control arm mount locations and how they define the instant center and influence the antisquat, then you will be thinking in the right direction.
 
jjvw said:
The key to understanding control arm geometry (regardless of it being short, mid or long) is to understand the concept of the instant center and how the instant center influences antisquat. Antisquat is the behavior of the axle to push against or pull away from the ground while under load from the engine. If you can get past the common fixations on arm length and instead focus on the control arm mount locations and how they define the instant center and influence the antisquat, then you will be thinking in the right direction.
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You also need to consider how the geometry will act once engine load is significantly reduced such as at speed through woops. You want to keep that tuneable.
 
Brianj5600 said:
Is on-road stability diminished with a triangulated 4 link? Lower roll center?
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All by itself, a 3/4 link will have more body roll than a stock 5 link. The inherent bind is significantly reduced and the resulting moments are much faster. The best that I can describe it is the difference between the stock front antisway bar and an Antirock. This creates a new baseline for how you might want to tune your shocks and sway bars.

FWIW, I have been daily driving the Savvy kit for more than 2 years.
 
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jjvw said:
All by itself, a 3/4 link will have more body roll than a stock 5 link. The best that I can describe it is the difference between the stock front antisway bar and an Antirock. This creates a new baseline for how you might want to tune your shocks and sway bars.

FWIW, I have been daily driving the Savvy kit for more than 2 years.
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Do you run a rear sway bar?
 
Brianj5600 said:
Do you run a rear sway bar?
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Factory rear with 12" travel shocks, Antirock front on the middle setting with 10.75" travel shocks.

Sway bars on both ends are important to have for performance and stability.
 
To add to this, I drove a Savvy mid-arm (3/4 link) across the country. Over 3k miles and I never once said to myself that I wish the geometry was different. In and of itself, it's very streetable.

Towards the start of the trip I did a hill climb in 2wd, stock TJ wheelbase, and street pressure in the tires that a lot of people would hesitate to do in 4wd. It went right up with 2 passengers. Amazing.

In the sandy desert, 2wd was also fine through the sand flats or climbing dunes. I spent a week driving across the sand with street pressure and didn't dig a hole once. Other people were getting stuck in 4wd on the dunes.

I understand that there's a lot of other factors going on too, but so far the geometry just works.
 
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To further add... ;)

I just drove 800 miles round trip pulling a 5x8 u-haul trailer between Denver and Moab with the mid arm, outboarded shocks, Antirock, etc... My only complaint was the diminished braking ability from the added weight of the trailer.
 
I’m in support of savvy’s mid arm in this, as I would never, ever, run a mid arm system with the factory link mounts. The proper geometry just can’t be achieved by having longer lowers and the same mounts on the upper. If the mid arm isn’t including new mounts to correct geometry for anti squat and dive then I wouldn’t put it on my rigs. I’ve been building linked trucks for 6 years now in prerunning and daily driving and feel 100% comfortable with a linked daily driver. To me if it handles well going fast off road, it’s gonna handle well on the street!
 
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really apreciating sme of the hands on knowledge of the savvy setup but does anyone actually have hands on knowledge of the rokmen system?
so far almost everyone has commented that the rokmen system uses factory upper frame mounts which if you bothered to even look at the link posted for that system you would see that it comes with new link mounts for front and rear, upper and lower. now that we have a bunch of savvy info can anyone actually attest to hands on time with the rokmen system just to get a little balance in the discussion? trying to learn differences and functionality doesnt work well with one sided information.
 
4speedhandler said:
really apreciating sme of the hands on knowledge of the savvy setup but does anyone actually have hands on knowledge of the rokmen system?
so far almost everyone has commented that the rokmen system uses factory upper frame mounts which if you bothered to even look at the link posted for that system you would see that it comes with new link mounts for front and rear, upper and lower. now that we have a bunch of savvy info can anyone actually attest to hands on time with the rokmen system just to get a little balance in the discussion? trying to learn differences and functionality doesnt work well with one sided information.
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Looking at the pics, we can see that the rear upper frame side mounts are set further back than the lowers. One thing that will do is push the pinion down as the axle drops. That would be very problematic with my build. I also don't see anywhere near the amount of frame side vertical separation as Savvy which suggests an IC that is closer to the AS line. My feeling is that there is more AS than Savvy. If accurate, I would expect the Rokmen kit to sink the rear during a climb and encourage the front to lift off the ground.
 
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Something to consider with the Rokmen setup is that it is designed around a premise of LCoG. An issue with that premise is that the short arm geometry doesn't become a meaningful problem until lift heights above what would be considered LCoG. So what problem is the Rokmen kit correcting?

If a typical LCoG suspension is biased towards down travel, then perhaps the significant benefit of the longer arm at a lower lift height is to reduce axle jacking/wheel walk exacerbated by the massive down travel. Whether or not one feels that this is a sensible way to build a rig will depend on what your ideas of a functional build are.
 
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jjvw said:
Something to consider with the Rokmen setup is that it is designed around a premise of LCoG. An issue with that premise is that the short arm geometry doesn't become a meaningful problem until lift heights above what would be considered LCoG. So what problem is the Rokmen kit correcting?

If a typical LCoG suspension is biased towards down travel, then perhaps the significant benefit of the longer arm at a lower lift height is to reduce axle jacking/wheel walk exacerbated by the massive down travel. Whether or not one feels that this is a sensible way to build a rig will depend on what your ideas of a functional build are.
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I'm entirely unfamiliar with Rokmen's design but it could be to prevent rear steer.
 
Rear Rokmen control arms Upper and Lower.
By the length I could tell that the Upper mount has to me relocated as the Lower one. May be not included as the upper mount is pretty easy to cut and re use.

81504
 
I am considering the Savvy mid arm on my build and am going back and forth because of my front Dana 30. There is a trutrac in the front and an elocker in my rear Dana 44. Wondering if the geometry change will get me up and over the steeper tough rock climbs that much better and reduce the need for a Dana 44 w/ true definitive locker on a front? I’m sure the answer lies somewhere in between. Yes better performance but a front locker even better.

What front differentials do you guys have with your mid arm lifts?
 
Honeybadger said:
I am considering the Savvy mid arm on my build and am going back and forth because of my front Dana 30. There is a trutrac in the front and an elocker in my rear Dana 44. Wondering if the geometry change will get me up and over the steeper tough rock climbs that much better and reduce the need for a Dana 44 w/ true definitive locker on a front? I’m sure the answer lies somewhere in between. Yes better performance but a front locker even better.

What front differentials do you guys have with your mid arm lifts?
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I wouldn't hesitate to run the Dana 30 up to 35s. The locker can be upgraded in the future, or even the entire axle by either carefully cutting the truss off or buying a new truss.

I have the mid-arm on a RJ60VXR and on a 44.
 
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