Jeep Wrangler PCM and module repair and replacement

Shuddering over every bump

AndyA

AndyA

2006 TJ X
Original poster
Supporting Member
Joined
Apr 30, 2023
Messages
584
Location
Tucson, AZ
For every small bump, road seam, reflective lane marker, etc. the whole Jeep shudders for half to one second. Having never driven another TJ or another vehicle with two solid axles, is this normal? If it is then good, I don't need to work on the suspension anymore :) But perhaps it isn't...

What I have done since I got the vehicle:
  • Replaced front track bar
  • Replaced front and rear sway bar bushings
  • Replaced all control arms
  • Replaced shocks (Ranchero RS5000X)
  • Replaced all tires, set to 28 PSI
  • Alignment
Stock (as far as I know) suspension with 1" body lift and 33" Goodyear Wrangler DuraTrac tires.

If I push down on each corner I get a single bounce from the shocks.

I haven't replaced the rear track bar, but the rear doesn't feel strange to me like it is moving around independent of the front.

It tracks in a straight line and I could drive with fingertips if I wanted to.

Thanks, Andy
 
AndyA said:
For every small bump, road seam, reflective lane marker, etc. the whole Jeep shudders for half to one second. Having never driven another TJ or another vehicle with two solid axles, is this normal? If it is then good, I don't need to work on the suspension anymore :) But perhaps it isn't...

What I have done since I got the vehicle:
  • Replaced front track bar
  • Replaced front and rear sway bar bushings
  • Replaced all control arms
  • Replaced shocks (Ranchero RS5000X)
  • Replaced all tires, set to 28 PSI
  • Alignment
Stock (as far as I know) suspension with 1" body lift and 33" Goodyear Wrangler DuraTrac tires.

If I push down on each corner I get a single bounce from the shocks.

I haven't replaced the rear track bar, but the rear doesn't feel strange to me like it is moving around independent of the front.

It tracks in a straight line and I could drive with fingertips if I wanted to.

Thanks, Andy
Click to expand...

Try jacking up your front end and grab the top and bottom of each front tire looking for any slop in the ball joints. Easy thing to eliminate.
 
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TJ4Jim said:
Try jacking up your front end and grab the top and bottom of each front tire looking for any slop in the ball joints. Easy thing to eliminate.
Click to expand...

I checked - no slop in the ball joints. Andy
 
Body lift looks ok. I measured my front springs at 11" and rear at 7" - see pics. Did I do that right? Could sagging springs cause a jarring ride?

Andy

IMG_7620.webp


IMG_7622.webp


IMG_7623.webp
 
Check the torque on everything, do a dry steering test and check the rear track bar and take a flashlight and check all control arm mount welds for cracks, and body mount bushings.
 
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I am 85% sure when I replaced the control arms I did the torquing with the wheels on the ground. To be sure tonight I loosen, rocked the vehicle around then retorqued. It has helped a bit for sure.

When I got the vehicle it had Goodyear Wrangler Duratracs on it of varying ages. Ride was horrible but I have gradually replaced all of the rubber bits underneath so a month ago it was finally time to replace the tires. One was 10 years old and cracking.

Went to Discount tire, got five new Duratracs and the ride was just as horrible. I then reduced the PSI to 28 then 24 and no improvement.

I went back to Discount tire for a rebalance and they told me the road force was too high, so they swapped me to Falken Wildpeaks. Those they could balance. I assumed they set them to 28 PSI... but no. Tonight I check and they were 40 PSI 😱

Reduced to 28 PSI and between that and the control arms it is quite a bit better.

Andy
 
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After letting it sit for most of a week I took it for a drive and it has stiffened up again!

Is it possible for the control arms (standard, Moog) to bind themselves up?

I torqued the lower ones to 107 ft-lb, couldn't get to 125 because I didn't have the strength. The uppers are torqued to spec.

Andy
 
I put some red grease on the top of the bump stops and drove it. The grease was transferred to the bottom on both of the fronts. Not on the rears.

So it seems I don't have enough clearance. I know the springs have sagged 1" but is that enough to cause this or do I have the wrong parts installed by the PO or a shock problem?

I took it to a local suspension shop with good reviews and they wanted to remove the body lift and put in new shocks and springs to lift it that way. I can do that myself if it is going to solve this problem. I am running 33" tires and I only drive on moderate dirt roads.

Am I going to damage the vehicle by driving it this way for a few thousand more miles?

Thanks, Andy

IMG_7783.webp
 
The suspension shop also said I had a 3" lift, but it looks like 1.5" to me?

Andy

IMG_7784.webp
 
usually if the suspension lift is, for example, 2", they will extend the bump stop 2", so you don't actually gain any travel, just the travel has been moved. if you started with a 3" lift, and had 3" bump stop extensions, they would reduce your compression range by 1" as the springs have sagged.

There could be other things, but it looks to me like there isn't enough space between that bump stop and the axle. I'm not sure that is the problem, but I'm pretty sure it is "A" problem.

What shocks are you using currently?
 
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Strizzo said:
usually if the suspension lift is, for example, 2", they will extend the bump stop 2", so you don't actually gain any travel, just the travel has been moved. if you started with a 3" lift, and had 3" bump stop extensions, they would reduce your compression range by 1" as the springs have sagged.

There could be other things, but it looks to me like there isn't enough space between that bump stop and the axle. I'm not sure that is the problem, but I'm pretty sure it is "A" problem.

What shocks are you using currently?
Click to expand...

Thanks. I have the Rancho shocks for 0" lift height. I don't have a suspension lift, only a body lift. Andy
 
Any luck dialing this in yet? I'm still getting used to my mostly stocky and am genuinely uncertain if I'm just not used to driving something with two solid axles and such a short wheelbase.
 
I am definitely hitting the bump stops - do the same test I did with the grease and see. I am going to put in new springs and also replace the rear trackbar. So far I have done the following:

  • New front track bar
  • New front and rear sway bars
  • New shocks
  • New control arms
  • New tires
In general, replace all of the 20+ year old rubber on the suspension.

Andy
 
AndyA said:
I am definitely hitting the bump stops - do the same test I did with the grease and see. I am going to put in new springs and also replace the rear trackbar. So far I have done the following:

  • New front track bar
  • New front and rear sway bars
  • New shocks
  • New control arms
  • New tires
In general, replace all of the 20+ year old rubber on the suspension.

Andy
Click to expand...

Hm, if this is the case for me as well, I'm wondering if getting larger springs may be in store...
 
That looks like a lot of bump stop. At ride height how much distance do you have for up travel before the bump stop bottoms out vs how much before the shock bottoms out? Your bump stop may not be letting your shocks cycle fully.
 
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What do you mean larger? As in longer? The stock springs are 12" and 8" tall so measure them. Mine are 11" and 7" so I know they have sagged.

Andy
 

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