Need help on suspension fix

[ClawSS]

I have installed a 2" front and 1" rear Thuren combo with front trackbar and Fox shocks. Riding on 18" wheels with Falken 37's and 35lbs of air in the rear and 40lb front.
'22 Mega Hemi Limited w/ Ramboxes

The rear end jitters/bounces abruptly on sharp bumps like bridge approaches, manhole covers, or other quick hits. It's like a Chihuahua on Redbull the faster these bumps are experienced.
I don't know if its just the "soft ride" springs, the lack of dampening in the shocks, or maybe the stock rear trackbar at the wrong geometry. I do NOT remember it this bad on stock Transforce and OE springs.
The rear 1" springs only increased ride height in the rear by 1/2" due to Rambox weight and combined Megacab weight over a CC. The Hemi allowed a 2.25" total lift/level.

I've had the tires roadforce balanced and they are smooth if the road allows it and the front seems very planted without much steering wheel movement at all on the same bumps with no vibration.

Yes, it's a HD truck and I don't really expect a car-like ride, but I also wouldn't think that it'd vibrate/jitter over every road imperfection. Suggestions?

 

[Crusty old shellback]

First off,
Love the truck and the color.

Now on to the problem. If the springs are softer, then the shocks are probably not tuned right. Did you buy it as a tuned package from the same seller? Or did you mix and match springs and shocks?

My Power wagon with stock suspension, only larger tires does not do that. I run 37 PSI in the rear tires and 45 in the fronts.

You have 37's on 18's so about the same sidewall as mine 35's on 17's. Unless the sidewalls are super stiff, they should give some flex over the smaller bumps.

 

[ClawSS]

@Crusty old shellback ....Thank you. I love the look of the truck...Really happy with that.

The springs and shocks were direct from Thuren as a package. I am not sure if the Falken A/Ts are super stiff vs other 37's out there.

 

[Crusty old shellback]

OK. I'd call Thuren if you bought directly from them, or whomever you bought the package from and ask them. May be the rear track bar or it's angle.

are the shocks adjustable with a DSC?

Are they remote resi shocks. May be able to lower the pressure some in the resi. But then that might affect how they react on big bumps.

 

[ClawSS]

I have emailed Chris @ Thuren, but I am unsure if my description of the jitter I feel was communicated correctly. He wanted me to have a read about the rear trackbar and what it can help, but that really seems to be more for rear sway and the side to side motion during suspension travel and not multiple sharp rearend bounces when I hit an abrupt bump or break in the pavement. I mean, the truck is twerkin'.

I could have done something wrong on the install, but it seems so focused on the rear.

The shocks are not adjustable. They are the IFP Fox versions.

 

[Crusty old shellback]

OK. Take a second look at everything you did on the rear to make sure its correct. Double check the springs and make sure they got seated correctly.

 

[Crusty old shellback]

Also double check the part numbers and make sure you got the right springs and shocks.
Reread the instructions and make sure you followed the steps, ALL of them.

 

[hookedup2407]

I have emailed Chris @ Thuren, but I am unsure if my description of the jitter I feel was communicated correctly. He wanted me to have a read about the rear trackbar and what it can help, but that really seems to be more for rear sway and the side to side motion during suspension travel and not multiple sharp rearend bounces when I hit an abrupt bump or break in the pavement. I mean, the truck is twerkin'.

I could have done something wrong on the install, but it seems so focused on the rear.

The shocks are not adjustable. They are the IFP Fox versions.

Did you ever figure it out? I’m about to install a Carli 2.5” with possibly a 1” Thuren rear spacer.. (not coils) I’m just curious what the problem could be.. good luck and keep us posted.

 

[ClawSS]

Nothing has changed the situation, yet. I had to rebalance the 2 rear tires due to throwing a weight, but that did NOT fix the issue. I notice every imperfection in the road, but only in the back. Steering wheel remains smooth even on large jolts without an aftermarket steering stabilizer. Truck only has 9000 miles on it.

I checked the spring and shock install last night and it looks perfect. Thuren numbers right-side up and on the outside, rubber seats in place and springs clocked correctly. I don't get any noises, pops, or creaks from spring perches and the shocks are tightened at the top to the snug +2 turns recommendation.
Rear trackbar was loosened and retorqued when the truck was on the ground...and done again last night. The frame-side bolt is a bugger to get to with the stock Hemi exhaust.
I have not touched the stock trailing arms....I don't think I need to. Remember I only got .5" of lift from the soft springs.

Big bumps seem to settle out quickly, but the most minor of asphalt seams or dip will cause a jitter in the back. It's not constant enough to be tires but I do notice it amplifying at higher speeds. I need to throw about 500lbs in the back to see if it settles down. I may also put my OE Bilsteins back on just to verify shocks...I doubt the 1/2" is enough to matter...could make it worse.

 

[Crusty old shellback]

Putting the stock shocks back on will at least tell you if its a shock tuning issue. I doubt the 1/2" will matter.

Try calling CJC Offroad and see what they have to say. They do a lot of testing of the Thuren suspension on RAM's. Maybe they have some info that might help.

 

[Rockcrawlindude]

Beautiful truck.

The rear geometry is a little wonky on these trucks based on my reading. I think every company that makes quality suspension for these trucks has a rear trackbar relocation kit for this reason. There are videos about thurens kit on YouTube for sure

 

[hookedup2407]

Nothing has changed the situation, yet. I had to rebalance the 2 rear tires due to throwing a weight, but that did NOT fix the issue. I notice every imperfection in the road, but only in the back. Steering wheel remains smooth even on large jolts without an aftermarket steering stabilizer. Truck only has 9000 miles on it.

I checked the spring and shock install last night and it looks perfect. Thuren numbers right-side up and on the outside, rubber seats in place and springs clocked correctly. I don't get any noises, pops, or creaks from spring perches and the shocks are tightened at the top to the snug +2 turns recommendation.
Rear trackbar was loosened and retorqued when the truck was on the ground...and done again last night. The frame-side bolt is a bugger to get to with the stock Hemi exhaust.
I have not touched the stock trailing arms....I don't think I need to. Remember I only got .5" of lift from the soft springs.

Big bumps seem to settle out quickly, but the most minor of asphalt seams or dip will cause a jitter in the back. It's not constant enough to be tires but I do notice it amplifying at higher speeds. I need to throw about 500lbs in the back to see if it settles down. I may also put my OE Bilsteins back on just to verify shocks...I doubt the 1/2" is enough to matter...could make it worse.

You did the sway bar extensions? Don’t remember if you said this earlier in your posts. Sounds like you’ve been pretty thorough. I just remember that there are a few extras to add with the rear springs due to their extra travel..

 

[ClawSS]

Sorry. Left out those, but they also came in the rear spring kit. Rear shock specific for the Thuren rear springs as well.

 

[hookedup2407]

Sorry. Left out those, but they also came in the rear spring kit. Rear shock specific for the Thuren rear springs as well.

So I’d have to say that might be your problem.. they specifically say that you can’t just install the springs.. this is from the Carli 1” springs.. if you ‘left them out’ this might be your problem.. i almost got the rear springs but when i saw all the extra work and costs associated i decided not to.. for now

 

[H3LZSN1P3R]

Are the shocks adjustable? What you describe is typical of failing shocks or adjustable being set to “soft”

 

[G Mcpherson]

Install the rear links. They are designed for the Travel of the Rear Coil. Also the Factory shocks are not designed for the increased travel.

 

[ClawSS]

no I mean I left them out of my list of things installed. I did not leave them "off". They are installed.

 

[ClawSS]

Update....Things are better with no wrench turning required. It is very drivable and comfortable even.

After I visually inspected everything....again....I went out and "cycled" the shocks on what I would consider full compression and extension using a nice gradual earthen bank I have off of my driveway. (Read this as a redneck RTI ramp) Driver front first riding up the slope until I had the passenger rear stuffed and driver rear extended. I then turned around and did the same, but opposite stuff and extension. I then took off across the farm with some decent terrace ditches (those in central KY would know what I mean) to cycle the suspension even more, but less desert-like and more redneck-ish.

Got her back on the road and went to town on the same roads I've been on since the upgrade, and she was smooth(er). Much less jitter in the rear. Front was still as perfect as ever. Quite livable and more as I would have expected a 3/4 ton coil sprung truck to be with 37's on 18's and "softer springs". Before it was like a 70's model empty 2.5ton leaf sprung truck (FYI I have one of these).

The other thing is that I did force the suspension to do stuff in the field that you probably don't get to do on pavement (my first 9000 miles). That is unless you live in <insert your crappy roaded city here>. These actions could have also self-aligned, relieved tension on bushings, etc. etc.

I can now actually tell what is occurring in the rear that could warrant the rear track bar. I couldn't get past the twerking to notice anything else.

 

[ClawSS]

Ok, I'm back on this thread.

Suspension is good. The suspension is cycling well and the shocks dampen the larger bumps softly and successfully...BUT, there is still the jitter/shake/bounce on the seams in the blacktop or bridge approaches, etc.

I am learning to live with it, I guess, but not having vast relational knowledge to coil-rear suspensions, I am fishing for community agreement that even on 37's w/ 35lbs of air & softer Thuren rear springs, that the jitter (about 3 jiggles) is normal for the 2500 suspension when unloaded and encountering a bridge approach, road seam, piece of old gum, or partially decomposed green bean.

 

[LateToTheParty]

I'd suggest looking into either an adjustable rear track bar or a relocation bracket as already suggested. Getting that rear axle re-centered should allow it to cycle closer to how it was originally designed.