yaw under acceleration

canjeep · **Posted:** Tue Feb 24, 2009 12:36 pm

Hi,
I have a 2006 jeep liberty limited KJ with a OME lift all round. I am running 245/70 R17 Revos. I really like this set up and I think it makes the liberty look like it should have come from the factory. However, just recently it has started to yaw under acceleration and braking. i.e. when I accelerate (esp up hill or under hard load) the steering needs to be corrected to the left. Then if I suddenly let of the gas, it rapidly pulls back to center. Its only a minor adjustment on the steering wheel but at speed and in snow etc it can be enough that the jeep gives quite the wiggle and can be unnerving. Being the daily driver the minister of finance would like this issue fixed before any other mods are allowed on the jeep. You can see my desperation to resolve this issue. I don’t want the minister of finance also being promoted to the minister of fun!!!
I have also noticed that the front tires have started to wear slightly more than the rears. This may be due to the constant correction being applied to the steering wheel. There is always slight pull even under normal driving conditions. Just not as unnerving as hard acceleration.
Does anyone have any idea as to what might be causing this?
The alignment was just done b/c I thought that might be the problem, but now I am leaning towards a control arm issue, as the alignment did not fix the issue. Under coasting or braking the steering wheel is in the center position with no pull to either side.
Thanks in advance.

tjkj2002 · **Posted:** Tue Feb 24, 2009 2:09 pm

It's called torque steer,more common in FWD cars but can happen in 4wd's,normal.Do you have the select trac t-case with the full time option? If you do are you running in full time 4wd when this happens? If so it's totally normal.ESP is the devil :twisted:

!

canjeep · **Posted:** Tue Feb 24, 2009 2:20 pm

I do have the full time option, but when driving in full time 4WD the yaw is less than when driving in RWD.

tjkj2002 · **Posted:** Tue Feb 24, 2009 2:33 pm

canjeep wrote:

I do have the full time option, but when driving in full time 4WD the yaw is less than when driving in RWD.

Still normal.

canjeep · **Posted:** Tue Feb 24, 2009 4:12 pm

This has only just started to happen over the last two months. I have had the car since new in the beginning of 2006. If this was normal I would have thought I would have noticed it. Is it a result of the lift and new tires? Do other people with lifts and larger tires all experience this? As I mentioned before it happens all the time in the jeep. Under hard acceleration it is more pronounced but it is there even under constant throttle.
Thanks

tjkj2002 · **Posted:** Tue Feb 24, 2009 8:23 pm

canjeep wrote:

This has only just started to happen over the last two months. I have had the car since new in the beginning of 2006. If this was normal I would have thought I would have noticed it. Is it a result of the lift and new tires? Do other people with lifts and larger tires all experience this? As I mentioned before it happens all the time in the jeep. Under hard acceleration it is more pronounced but it is there even under constant throttle.
Thanks

The lift and tires raised your center of gravity so it is more noticeable now.

Guest · **Posted:** Tue Feb 24, 2009 10:27 pm

Tell the minister of finance to send some of that money this way and then we can talk. :lol:

e_poirier2004 · **Posted:** Wed Feb 25, 2009 1:52 am

I just had the same problem on my 2006 CRD. When I was driving 65mph and I was accelerating, it was pulling to the left. When I released the accelerator, the jeep was pulling to the right. I inspected my bushings and I discovered that the rubber bushing on the lower control arm of the rear left suspension on the diff side was badly worn. Result being that under acceleration, the diff would shift slightly forward, having the jeep to pull on that side. Those bushings are not like the other years. They have two holes in it for dampening the vibrations and I think that's what's causing premature wear. The rubber is stretched so hard due to those holes that it gets detached from the center part of the bushing. I think the previous years Liberty don't have those holes in the bushing. I changed the bushings on both sides and now the jeep runs straight no matter how hard I accelerate. I also fill the holes with rtv.

canjeep · **Posted:** Wed Feb 25, 2009 7:10 am

Thanks everyone,

e_poirier2004, I`ll check out the bushings.

Straight6Jeff · **Posted:** Wed Feb 25, 2009 1:25 pm

my left lower control arm at the diff housing was loose. The bolt was stripped at the factory, so it did have the required torque at the nut, but the control arm was not tight in the pocket. I ended up having to break the bolt off and replace it. There is absolutely no yaw now.

My factory bolt was worn down to 3/8". The bolt should be 9/16" shank size (but metric equiv). I figue in another 5k miles, the bolt would have sheared off. Oh Yeah, the vehicle only has 40k on the clock, and is completley stock.

canjeep · **Posted:** Wed Feb 25, 2009 2:28 pm

straight6jeff,
was the bolt loose? was there any play in the lower control arm? If I pull on it will there be play? Do I need to jack it up or can it be done while on the ground?
I would like to get under the jeep and have a look, so any more info on what I can look for to help diagnose would be appreciated.
Thanks

Straight6Jeff · **Posted:** Wed Feb 25, 2009 7:20 pm

I had been chasing this issue for a while. I had had the vehicle on the ramps many times. I had the suspension hanging to compressed, and everywhere in between. Each time I checked the control arms, all seemed tight...BUT the last time I had it on ramps, the control arm had about 1/32" horizontal play. At that time I took a ratchet to check the bolt for tighness...the bot spun. Not freely, but it spun. When it spun, I could see the control arm moving an an arc, and the rear end moved also. After I spun the bolt, the control arm did not have any move free-play, but the bolt still spun. I then took my IR2131 impact gun to the nut(with a wrench holding the bolt) to tighten it....it would not budge. I dug out my 3/4 drive impact gun (1000lb/ft tq)...it would not tighten. I then took my ratchet and was able to still spin the bolt, with the resultant control arm movement in an arc. When I cut the bolt out, I was glad to see that the bolt had worn, no the control arm sleeve, or the rear end mount pocket.

phxtoad · **Posted:** Thu Feb 26, 2009 11:45 am

Simple solution: To counteract adverse yaw, just apply more right rudder.

itsajeepthing · **Posted:** Thu Feb 26, 2009 11:59 am

alignment problems can cause this too. Mine did exactly what you describe after I had the driver side outter tie rod end replaced. An alignment took care of it.

e_poirier2004 · **Posted:** Fri Feb 27, 2009 8:54 pm

New story, I just jumped a curb with my jeep yesterday and it restarted making the yaw. I disassembled the control arms today. I had put rtv in the bushing holes and on one side, it tore. I removed all the rtv and I'm filling the holes with windshield urethane. This time, I will do it in 2 shots just to let the urethane dry. From what I saw, the rtv wasn't dry enough and it just squirted out. It was holding with a layer of about 3/16" on the surface and it held until I jumped that curb. The trick is to make layers of about 1/8" and let it dry for 24h before putting another layer otherwise it doesn't hardened and just squirt out as soon as you accelerate. Those holes are really making my life complicated. Most people think it is torque induced yaw but believe me, with the holes filed with rtv, it wasn't wiggling at all. Urethane should be better than rtv since it sticks better to rubber and is more resistant.

e_poirier2004 · **Posted:** Sun Mar 01, 2009 7:23 pm

Latest update: I just finished reinstalling my suspension and everything seems a lot more solid. No more yaw. I cleaned the rubber bushings with thinner to remove any contaminant. I filled the holes to half with urethane and let it hardened for 24 hrs. I filled the holes and cover the bushing with urethane, making sure the tube still sticks higher than the bushing and let it hardened for another 24 hrs. After, I put both control arms in the oven at 150 with a bowl of water (urethane hardened with humidity) for 3 hours. After I made sure everything seemed alright and reinstall the whole outfit. After driving on the highway and accelerating and releasing the pedal several times, it seems that all yaw is gone. Good luck.

canjeep · **Posted:** Fri Mar 06, 2009 8:16 am

e_poirier2004,
Did you replace the original torn bushing or only repair it with the urethane?
Would you suggest if replacing it to replace it with one from another year model without the holes, or will they not fit?
Could you replace them with a polyurethane bushing from a manufacturer?
Thanks

e_poirier2004 · **Posted:** Fri Mar 06, 2009 10:45 am

I purchased new bushings from Morris 4x4 center (cheaper than the stealership) but it restarted doing yaw after a short while. I would check the bushings first, if they're not too stretched or show no tears, I would not change them. The most important thing is to use 2 parts windshield urethane (catalyzed so you can do the job in one shot) or to do it in step with one part windshield urethane to make sure it hardened all the way in the middle(if it remains soft, it will just squirt out). Leave 24hr between layers to dry and after the last layer, just put it in the oven at 150 for 4 hours. Also make sure you have no bubbles. Another important thing is to clean your bushings before applying the urethane with thinner or acetone or mek to make sure urethane will stick properly. So far, It's been about 500km and no more wiggling. As for replacing the bushing with pre-2005 bushing, I don't know if it would fit. If somebody knows the answer please post it, it would save a lot of trouble to everybody. When I changed mine, I used a hydraulic press and it took more than 5000lbs. Let me know if I can be of any help.
Good luck!

yaw under acceleration

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