YukonJack

For others' info, BW4485 is the "open differential" transfer case described here. RPO is NR3. Requires active braking by the EBCM to prevent torque from escaping one axle over the other due to the differential between the front and rear, and no clutches.

Automatic braking is what I thought was occurring at first, so I pulled the EBCM fuse to eliminate it trying to use the brakes to prevent slip. No change. I'm thinking of trying it with the ESC/ALC (elec susp ctrl/auto level ctrl) fuse removed, though I cannot find if the electronic shocks default to maximum or minimum dampening. I would think the max, but not sure. If that doesn't work, may have to try 1FastBrick's suggestion of limiting straps. Still awaiting warmer weather and un-salted roads.

Atomic

iTrader: (42)

You need to stiffen up the suspension, a lot, to dampen that out. Its pretty common with higher power 4wd stuff to do the row boat maneuver. Its from the weight transferring back, front tires loose traction, springs back forward, tires gain traction, repeat for a few cycles until you are going fast enough where it doesnt shift as much. Basically just not enough shock.

For instance, here is back in the day:

and here is with a lot more power and tighter suspension:

YukonJack

Getting back into this with the weather decent finally. I did pull the ESC/ALC fuse but no change, though I still don't know if the magnetic shocks default to full stiff. Regardless, I need to do something as it seems to be even worse now that I am dialing in the cal. Any suggestions? I have not found a lot in the aftermarket, most seems geared towards lowering the suspension. I just want to stiffen it up. It is a mostly daily driver, I am not trying to run xx.xx 1/4 mile times.

It is a 2013 Yukon Denali, stock motor (for now) with Whipple 2.3L. It is coil-over strut in the front(magnetic ctrl shocks), coil spring in the rear with air level control/magnetic shocks. But I have no problems ditching it.

randeez

they launch like mashed potatoes with the stock suspension/ride height control... need to figure out if you really want to go that direction to make it launch. the spring is pretty soft with air ride, if you want to ditch it and stay the same height you will probably want to look into the stock spring for trucks without it or the ppv spring but i think it drops 2" or so.

cause here's how it went for me:
- lowered mine just 2/3 stock air ride shock. spindles and rear spring stiffened up a little. but still launched like crap.
- swapped to a qa-1 adjustable in the back, measure what length shock you need at ride height (with out the air shocks as it will drop another 1" or so with out them.
- back was stiff, but it just accentuated how bad the front suspension was. even max'd out on the rear shock, front would still lift/spin. felt like the front was dancing around while rear was planted with just normal driving. and gets real harsh driving around with the shocks cranked way up finding a happy place for comfortable ride didnt launch well, find myself always adjusting.
- did sway bars next, wasnt quite ready to dump the money on coil overs up front, helped tighten up the front end some but launches werent any better
- front coilovers next, same thing...a nice ride doesnt launch well so plan on adjusting or bouncing around all the time. with the front set up right i do notice it allows me to leave the back shock a little softer and plant a little better
- i did the spohn rear bars, for me it was to center wheel back in the opening and adjust pinion angle (both not needed if youre stock height) but they dont use rubber bushings like the stock bars.

worth it? for me sure, i can adjust everything and still have a smooth ride or stiffen everything up.....its done 1.7x 60's @5900lbs with cam/bolt ons...still playing with new turbo but ive already bested that with some soft launches

YukonJack

Researching this further, it looks like the best way to control this is changing the Instant Center by adjusting the angles of the 4 link. I just did a swag measurement, and my upper control arm is aiming upwards at 3 degrees and the lower arm is aiming up at 1 degrees, so extending them out, they would NEVER meet. This was just sticking an angle finder in from the wheel well, with the wheel in my way, so not precise by any means. Need to set it on blocks and look around a bit. Either the upper control arm mount at the axle has to move up, or the front mount has to move down. And of course adjustable arms will be needed. For the older GM muscle cars QA1 makes “anti-hop” bars that do this. Everything I find on the net for trucks is geared towards leaf suspension.

RB04Av

That's the same situation the old A & G bodies (Chevelle) used to have.

Take a look at the old Edelbrock "no-hop" bars for an idea. Probably won't fit or even anything close, but should give you an idea of what is needed. There are other mfrs of them nowadays, somebody might even make em for our trucks. Check QA1 for example. Also, relocation brackets for the lowers might be a possibility; not too hard to build something like that yourself.