Rear Suspension Bad???

[MATT0404]

I am trying to diagnose a problem that has been driving me nuts for a couple of months. I think that I have narrowed it down to the rear suspension. Here's the situation.

Symptom #1 - When driving at speeds over ~40mph the truck seems to "do it's own thing". It felt like a steering problem at first, because it wouldn't drive straight consistently. I am constantly needing to make steering corrections in order to keep it between the lines. It's typically not as noticeable when driving through town at speeds under ~30mph.

Symptom #2 - When coming to a stop, more noticeably on an incline, I can feel the back end raise and then bounce as I complete the stop.

Symptom #3 - When hitting bumps in the road the back end seems to want to "skip" over them. It almost feels like the back end slides to one side a little, requiring a steering correction to bring it back straight.

Symptom #4 - The truck just feels floaty in the back end on the highway. Wind causes body roll and a feeling of instability.

Symptom #5 - Last one, I promise! Plain and simple, any sort of cornering is a chore.

Suspension:
Fabtech coilovers in the front. LC coils/Fabtech shocks in the back. 1" 4crawler BL. Unknown mileage on all suspension components, except BL.

Recent Preventive Maintenance
Replaced tires
Replaced front brakes
Poly front sway-bar busings
Steering rack bushings (Not installed yet)
Replaced passenger side inner/outer tie-rod

So, what do you guys think? This issue is driving me crazy! At this point, I am contemplating replacing the rear shocks and springs with OEM LC replacements. One other thing that was brought to my attention was the possible need for an adjustable panhard bar. Sorry for the long post, but any input would be greatly appreciated.

-Matt

[MTL_4runner]

One other thing that was brought to my attention was the possible need for an adjustable panhard bar.

Matt, that was the first thing that came to my mind.

Then I looked at what you were running:

Suspension
Fabtech front coilovers
LC rear coils
Fabtech rear shocks

If this is what you do have on there right now, but have not done anything to correct the panhard bar geometry, then I am pretty sure that is why your truck is tracking so poorly. I assume you had done a front end alignment done when you installed the coilovers. If you have not, you absolutely should get that done as well.

[Lee]

yup, panhard could be the culprit. you may also benefit from stiffer shocks.

[slosurfer]

Stiffer shocks will help with symptoms 2-5 especially the skipping over bumps. It may be that the fabtech shocks in the rear just aren't a good match for the LC coils.

[MTL_4runner]

I should have prefaced what I said above. The tracking issue is probably the panhard bar. The bouncy / floaty rear end is probably your spring / shock combo as the others above have mentioned.

[MATT0404]

Thanks for everyone's advice!

I was also thinking that the fabtech shocks wouldn't compliment the LC springs very well. This suspension setup was on the truck when I purchased it about six months ago. Should I replace the fabtech shocks with LC shocks or something else(OME)?

I've been aligned twice now in the last 4 months. Once after the tie-rod replacement and then after the 285's. Looks like I will be needing the adjustable panhard bar. Thanks again for everyone's help.

-Matt

[garrett]

saw your thread on yotatech, but i'm no longer allowed to post over there.

though this is redundant, i also think it's your shocks.

[MATT0404]

I just went out to have another look at the truck. The panhard bar is practically slack. I can shake it with my hand. Also, what color code do the LC springs have? Mine both have (bear with me, I'm colorblind) a yellow/green dot on the first visible coil from the bottom and the next coil up has a red dot. That's it.

[BruceTS]

check all the links, make sure the bolts are tight, there should be no play. If you can move the panhard bar then there's a problem....

[MTL_4runner]

check all the links, make sure the bolts are tight, there should be no play. If you can move the panhard bar then there's a problem....


Ditto, if you can move it by hand, I'd bet money you've found your issue.

[MATT0404]

Thanks a lot, guys. It looks like the bolt/nut at the top of the panhard is stripped and immobile. The nut is actually only on the end 5 threads or so of the bolt. I have no idea what the PO's were trying to accomplish back there, but all they did was screw things up. Looks like I'll be ordering the Sonoran adjustable panhard bar and cutting the old one out.

I'm still going to replace the rear shocks. OEM LC's or OME's?

[Lee]

OME's.

[MTL_4runner]

I'm still going to replace the rear shocks. OEM LC's or OME's?



LC's will be softer, OME's a bit stiffer.....it's all preference.
I'm obviously partial to the OME's myself, but either should work fine.

I'd suggest you fix the panhard bar issue first and then see how bad the shocks really are.

[MATT0404]

You guys are great! Thanks for everyone's help. I just got finished dremeling out the old bolt on the panhard and replacing it with new hardware. Went out for a drive on the highway and it's a remarkable improvement! This is just a temporary solution since I just ordered the Sonoran adjustable panhard.

On another note, I was talking to Steve on the phone about my rear suspension setup and the coil color codes. I told him that mine had a yellow and red dot only and he told me that they were, in fact, stock 99 coils with spacers. So, looks like I have been completely misinformed about the suspension setup. Oh well, I'm going to replace both springs and shocks with LC replacements. You guys have any info or links on what washers and/or hardware will be needed to make the LC shocks work? Time to start searching. Thanks again!

[Lee]

just a quick bump to say installed my ome n86's at last (only had them kicking around for one year :hillbill:) and they are A VAST improvement over my stock length bilsteins.

somewhat better flex but a much more controlled ride, no bounce.

wheeled em today too...

http://kidmoe.com/4runner/omeshocks.jpg

[Lee]

flex pic on my friends wall :hillbill: :tongueout:

http://www.kidmoe.com/omeflex.jpg

[MATT0404]

Looks good!

[Lee]

thanks man :)

not to take over the thread but this is relevant...

i got really great flex out of these things on the trail too.. the kid at the back was gonna grab on in case i almost went over, but never had to.

http://kidmoe.com/erv715.jpg

for comparison here are a taco and fj on the same obstacle

http://inlinethumb55.webshots.com/5174/2649029200074624248S425x425Q85.jpg

http://inlinethumb56.webshots.com/4407/2260477510074624248S500x500Q85.jpg