How to slow down the 80 from rocking so much while wheeling - body control (1 Viewer)

[alia176]

Too bad the Slee 4” HP aren’t in stock. Which coils are you choosing @alia176

 

[Shoredreamer]

I see that coil. Your lift height should be good in that they spec that rear coil at 4” lift, which relates to a 24” hub to flare. 24” h-f correlates to a 15.75” coil height. Free height of that coil is 19.3” meaning the coils compresses 3.55” at ride height. The weight needed to compress that based on the 411# spring rate is 3.55x822 (411x2 coils) which equals 2918#. Add in the unsprung weight of about 600# for axle and wheels and you get a scale weight of 3518#. Subtract from stock rear axle weight of ~2500# and you come to 1000# over stock. That’s kinda the backing in way to figure the Ironman specs. Your scale weight of 3800# should put you slightly below the 24” h-f which I think you were shooting for.

The spring rate of 411# is the highest I have seen for our trucks. Definitely will be stiffer than your previous 320# of the 171 coils. Not sure how that will play out. May be hard to stuff the rear during articulation? Definitely should feel not so loosey goosey obviously. The coil height is also pretty short for a 4” lift spec so coil may unseat when fully drooped depending on the shocks you got (4” vs 6” MRR).

I run 1000# heavier than you on the rear axle and run a tall coil with 375# rate and overall pretty happy with those. Overall curious to see your new setup.

 

[alia176]

I see that coil. Your lift height should be good in that they spec that rear coil at 4” lift, which relates to a 24” hub to flare. 24” h-f correlates to a 15.75” coil height. Free height of that coil is 19.3” meaning the coils compresses 3.55” at ride height. The weight needed to compress that based on the 411# spring rate is 3.55x822 (411x2 coils) which equals 2918#. Add in the unsprung weight of about 600# for axle and wheels and you get a scale weight of 3518#. Subtract from stock rear axle weight of ~2500# and you come to 1000# over stock. That’s kinda the backing in way to figure the Ironman specs. Your scale weight of 3800# should put you slightly below the 24” h-f which I think you were shooting for.

The spring rate of 411# is the highest I have seen for our trucks. Definitely will be stiffer than your previous 320# of the 171 coils. Not sure how that will play out. May be hard to stuff the rear during articulation? Definitely should feel not so loosey goosey obviously. The coil height is also pretty short for a 4” lift spec so coil may unseat when fully drooped depending on the shocks you got (4” vs 6” MRR).

I run 1000# heavier than you on the rear axle and run a tall coil with 375# rate and overall pretty happy with those. Overall curious to see your new setup.

That is an EXCELLENT calculation of how the body height relates to coil free height/capacity. Thank you for typing all that in and making it straightforward for us to digest.

Edit: I may not have a lot of down travel due to F+R Whiteline swaybars and I'm running the 4" MRR shocks.

 

[alia176]

It's been a while so it's time for an update. I was able to meet up with David from Dobinsons and Dave from Delta VS at the Overland Expo. We discussed my shocks/springs/etc and I came away with more knowledge and a plan of attack on the MRR adjustments.

Yesterday, my GF and I finished up a 1500 mile trip through the North Rim of Grand Canyon, AZ strip and the Vermillion Cliffs in the 80. I played with the high speed compression primarily on this trip and this improved the body control by a large margin. Some trails required couple of clicks this way or that way on the front shocks in order to understand what's happening. On the road, the high speed knob was all the way tightened and the body wallowing was very manageable.

Sitting on the pass seat made me feel the ride more as I wasn't holding on to the steering wheel. We needed to be back home by a specific time so that my GF could meet her patients so she set the cruise control at 85 heading East on I-40. The cross winds at times made the 80 a tad bit twitchy and watching her play with the steering wheel was a tad unsettling. We made it from Flagstaff, AZ to Albuquerque, NM in little less than 4.5 hours. The 80 with the turbo really likes to hum along at 2750 rpm which translates to approx 82 mph (4.56+315s) This is the power band for this engine and she can pull hills w/o downshifting.

My plan is to remove everything off the roof and drive her around for a while to see what she feels like.

I'll be ordering the 145VT springs for the rear from Delta VS this week and see what happens.

Some random pics.

New item by A. Ali

photos.app.goo.gl

New item by A. Ali

photos.app.goo.gl

New item by A. Ali

photos.app.goo.gl

 

[alia176]

Alright, the 145VT springs are in and what a mothafucka experience that was Them sumbitches are tall and of course not easy to "slide" into their homes. Had to force the axle housing with a bottle jack as low as possible then used a pry bar to slide the new springs in. Net gain on both sides 1 3/4" but haven't gone for a drive yet. While the tires were off the rig, I went to check my MRR shock adjustments and one of the shock has 70 clicks max clockwise where the other one goes up to 23 clicks. This is the high speed compression large dial. An email went to David Otero to see what I did wrong and what needs to be done.

Also, the Whiteline sway bushings are done. Bumper the Whiteline sway bar thread for a replacement option.

Recap: i'm running Dobinsons C59-170 3" springs up front, VT145T 3.5" springs in the rear with MRR shocks all around, plus Whilteline sway bars F+R.

Pics below are after the new rear springs.

 

[alia176]

More pics

 

[baldilocks]

Did you mean to say that you are running 3” front and 3.5” rear? I was unaware that they made the VT line in those heights. I was always 2.5/2.0 and 3.5/3.0 front/rear respectively. Is that photo post new spring installation?

 

[alia176]

Updated the post above with clarification. Lmk if you got more questions.

 

[Outsane]

How do you like the new springs?

 

[alia176]

How do you like the new springs?

I like the height gain from the VT springs but the vehicle hasn't been driven since the installation. I need to remove one of the MRR shock and send it in for inspection.

 

[coues7]

Great info here. This forum is amazing.

 

[sxp]

I may have missed it, but have you tried driving without the rear swaybar attached yet?

 

[alia176]

I may have missed it, but have you tried driving without the rear swaybar attached yet?

No I haven't. I drove with the front SB detached and do that often for technical stuff where lots of articulation will be had. I have two Whiteline SBs in order to maintain excellent hwy manners given how much weight I have up top.

 

[sxp]

No I haven't. I drove with the front SB detached and do that often for technical stuff where lots of articulation will be had. I have two Whiteline SBs in order to maintain excellent hwy manners given how much weight I have up top.

I removed my rear sway bar which greatly reduced the body snap from rough roads and trails. The body still wallows around (not bad though, 90 mph is fine on the highway), but the the neck snapping motion is gone.

 

[alia176]

I removed my rear sway bar which greatly reduced the body snap from rough roads and trails. The body still wallows around (not bad though, 90 mph is fine on the highway), but the the neck snapping motion is gone.

Good info, thanks bud!