dibesh638

Hello all,

I am starting to have some steering issues with my 2008 IS250 AWD with about 109,000 miles. When I'm driving my steering wheel seems to turn left or right when I hit bumps or ditches (left or right depends on the bumps and if it pulls car to the left or right). I've also noticed that the car will drift left or right when going highway speeds (60+mph) depending on the roads (maybe road surface unevenness?) . I've changed the tie rods, and also got a wheel alignment, but the problem is still there.

After researching some online, some have mentioned that this may be bump steering. I was wondering if anyone had similar experience and if so, how did you fix the issue.

Thanks all!

jr4div2

Your lower control arm bushings are shot. What you are experiencing is call bump steer and is common with factory LCA bushings and especially if they need replacing. Even if they are not trashed which yours obviously are, the car tends to follow bumps and troughs as you drive. I recommend replacing the bushings with the RR-Racing or FIGS poly bushings. They are much stiffer and eliminate the bump steer and more importantly the inner tire wear on the front. Take a look at the inside of your front tires. I'll bet you have no tread there and maybe even exposed belts.

RRRacing

iTrader: (1)

The previous reply is a great start. Below is a video of how a good set of lower control arms behave during driving conditions. You can imagine a highly worn set. This is directly related to your steering.
-Justin
RR Sales

https://www.rr-racing.com/Lexus-Lowe...isfxlca001.htm

2013FSport

iTrader: (2)

Definitely start with new LCAB's. You can go aftermarket or OEM from the RC-F which are noticeably firmer than stuck but do not induce NVH. Do a search for RC-F LCA and you'll find the PN's.

A key ingredient when replacing vulcanized rubber bushings like the LCA is that the car is sitting on its own weight when the large pinch nut is tightened or the new bushing will be ruined from over rotation. Poly is not impacted like the OEM bonded components.

Also, increase the front tire pressure to say 38/40 PSI.

Protholl

I searched the IS forum for RC-F LCA and didn't get any hits (except this post). Since I didn't find it are you talking about full replacement arms or just the bushings? After reading a few threads this one matched my issue with my 125K mile is250.

Thank you,
Jeffrey

2013FSport

iTrader: (2)

.

Here ya go....

GS F/ RC F Parts
48075 - BRACKET SUB-ASSY, LWR ARM, NO,1 - Right
48075-24010, RIGHT, OFFSET:0
48075-24080, RIGHT, OFFSET:+20
48075-24090, RIGHT, OFFSET:-20

48076 - BRACKET SUB-ASSY, LWR ARM, NO.2 - Left
48076-24010, LEFT, OFFSET:0
48076-24050, LEFT, OFFSET:+20
48076-24060, LEFT, OFFSET:-20


You don't need the offset parts unless you can ID your existing parts by the paint dots on them. So just get the offset:0 parts left and right..

Do NOT tighten the pinch nut until the vehicle is at ride height.

Edit, adding tag. #2IS Suspension RC-F

primavera

https://www.clublexus.com/forums/is-...l#post10338780

dibesh638

Thank you all very much! I am planning to get the RC-F bushings. I do not have ramps, so I may end up taking it to a shop to install the bushings.

2013FSport

iTrader: (2)

Ramps are not much help until you need to tighten the nut. You need both wheels hanging freely so a jack and stands. It's a pretty quick job.

Because the LCAB bolts do have some freedom, I'd suggest measuring from the center of both shafts to a fixed point on the chassis, remove the old, install the new, move new to old location and secure the bolts. Tighten the nuts when the car is sitting on its tires.

dibesh638

Thank you this diagram is very helpful!

2013FSport

iTrader: (2)

Np....

Gl

MrCross

Hello everyone, new to the forum, but I had the same experience over the last few months with my 2007 Is250 SE-L so I believe I can shed some light.
If you want a direct answer go to second paragraph, otherwise here is the full story:

My experience with driving lots of cars is that I am used to having a clearly defined centre point on the wheel where you can let go and the car would go straight, as long as everything is working as intended. It was very difficult to keep the car straight even when holding the wheel with strength, especially on motorways, it would wander left or right when it wants, or due to the smallest inclination in the road or bumps. This is very stressful on long drives. I changed the inner tie rods and track rod ends followed by an alignment. this gave a slight improvement, but the problem persisted. I then changed the ball joints followed by another alignment. It improved it more but I think it was because the car has 57000 miles and all original parts. It still wasn't 100% but massive improvement. Those mentioning about the lower control arm bushing, this was going to be my next move but I've had my mechanic check mine out and said it was tight with no play.

I scoured the internet and came across "zero point calibration" using an OBD tech stream tool by accessing the VSC settings and re-calibrating the suspension and steering. Basically this should be done after you change any suspension parts and do an alignment, at least with Honda, Lexus and maybe a couple of other makes, not sure. I've never owned a car that needed this, this is my first. This should be done after the alignment. It tells the car where the new middle or 'zero' is so when you move the wheel from left to right there is a clear centre point so the wheel is not floating across or vaguely passing the centre, which is what I felt with mine. Believe me this worked magic and fixed my problem. I can now drive at 60+ MPH one handed with ease. Just make sure when you do an alignment that they are all in the green and similar ranges, or you might want to get specific advice on the alignment, I'm not a mechanic...

I would at least try this first before changing parts, especially if you've already changed parts and had an alignment.
Lastly, some mechanics don't know about the zero point calibration, even some alignment centres, so find one that has a good OBD tool, my mechanic has one that cost him £800 apparently. You just need to plug in the OBD, choose your car model and year, then it tells you the steps and what to do on the screen. the wheel will vibrate slightly and you're done, just make sure you're on level ground and the wheel is perfectly straight. The instrucitons will tell you anyway.

Apologies for the long write up. Hope this helps

MikeFig82

iTrader: (13)

Are you sure you didn't do a steering angle sensor reset? I had it don't on my car some time back.

I've also done the zero point calibracalibration, and don't recall the steering wheel vibrating. Though I did the OBD port shorting out method, and not using tech stream.

MrCross

Hi guys its been some time but I'd like to give another update.
After changing the drop links, track rod ends and the ball joints followed by alignment and zero point calibration (or steering angle whichever it is), I still wasn't sure it fixed the problem as there was still some wandering.

I switched the front wheels left to right, which made a difference in handling so I bought two brand new Michelin primacy 4 tires in the front, now there is 100% no wandering, car will drive straight all the time even on high speeds and on bumps or uneven roads.
The tires were coning I believe and that was making the wheels wander and me constantly fighting against them.

I must say the primacy 4 is more comfortable and quieter than the previous Pirelli Cinturato P7 and gives more MPG. I was shocked.

My final issue now is if I very slightly turn the steering wheel to either left or right while driving, lets say just a few degrees, it just stays there and doesn't turn back to the center, is this normal? If I take a turn while driving the wheel will come back but not fully recenter, I have to guide it. It feels kind of loose, so I'm assuming that this is what the lower control arm bushing would help with?

Has anyone actually changed the lower control arm bushings and did it work to fix the problem?

MrCross

MikeFig82, I think the steering angle and zero point calibration is the same thing. And yes if you use the OBD tool the wheel briefly vibrates to let you know that its done.