IS250 steering overhaul - Part I: retrofit to ISF sway bar and bushings

AFlex · August 28, 2022

Hey guys

I'm really trying to get in the habit of posting my DIYs online more often to try and help others who might be thinking of doing similar.

I've got a mainly stock manual transmission 2007 IS250 and I'm gradually refurbishing and upgrading it. My logic is it's an absolutely solid car and they don't make manual transmissions any longer so I might as well hold onto this one for a bit.

Anyway, I hate long intros so let's get straight to it.

My steering has been feeling quite loose lately. So I've planned the following upgrades:

Front lower ball joints - a relatively easy job which I completed a while back. Thoroughly recommended for older cars - makes the steering feel much more accurate, albeit did little to remove free play.
Upgrade to ISF front sway bar, bushings and links (today's topic)
Upgrade to stiffer rear sway bar, bushings and links (currently sitting in my 'parts bin' )
Inner tie rods (currently on their way from Japan) - hope this will remove the remaining free play
Steering rack bushings (struggling to find these parts currently - i don't want poly bushings)
Upgrade to Bilstein B6 suspension (TBC)

Parts required:

48811-53070 - ISF front sway bar x1
48815-53060 - ISF front sway bar bushing x2
48824-30130 - ISF front bush bracket x2
90119-10965 - ISF front bush bracket bolt x4

48820-53010 - sway bar link RH
48810-53010 - sway bar link LH
94151-21241 - sway bar link nut x4

Now strictly the 4x bolts and 4x nuts were optional but, since mostly everything steel is rusted on my 15 year old car, I decided to replace. (There was also the chance i might damage them taking them off)

I ordered a new metal bracket because, firstly, the old one was very rusted, but secondly, I was LED to believe that the ISF sway bar is thicker (hence reduces the body roll more than stock sway bar.) Therefore a larger bracket was needed to accommodate it.

Having taken the old sway bar off the vehicle, I'm not sure how true this was - they look the same size/diameter to me. But bear in mind I have a Sport model which could potentially have a thicker sway bar than non-sport models.

Procedure:

Pretty simple in theory. I decided to detach the sway bar links first. In practice this was an absolute ball ache of a job due to 15 years of rust and corrosion.

First off, I recommend driving the car up on ramps. (I use rhino ramps which are also really handy for quick oil changes). Then remove all the plastic under-tray which starts at the front bumper. Remove the two pieces of plastic which hang down from the wheel arches connecting to the plastic under-tray.

Next, remove the sway bar links since this is the hardest part. A lot of PB blaster was used, torque wrench helped loosen a couple of the nuts. Once all the nuts were off, one of the sway bar links wouldn't come out of the lower control arm (LCA). A combination of hammering the bolt from one side, and blowtorch to heat up the LCA, and eventually it came out. If you attempt this job on an old car, make sure you're pre-prepared to try multiple methods to get your rusted bolts and nuts off!

Once sway bar links are off, you need to check whether you have an AFS ride height sensor for your headlights. It's connected to the passenger side of the sway bar and attaches to the wheel arch. Unbolt this and you're ready to remove the entire sway bar assembly. Simply remove the two bolts on each bracket holding it in place and the whole bar should drop down.

You can see the difference in the condition of the bar and bushings in the photo above. Yes - that is decomposed parts of the bar laying as dust on the ground.

Now as I said previously, other forums suggest that ISF bars have larger bushings and brackets than stock. But mine appeared to be the same size - see below. Your mileage may vary.

I recommend assembling the bushing and bracket onto the bar before assembly. Also helps you to get it in the same orientation since you can directly compare the positioning to the old bar that you just took off.

Bolt in the new bar and everything else is the reverse of what you did to take it off. You may find the sway bar links won't go into the LCA because of the height of the suspension on the ramps. I jacked up the suspension from under the LCA to get the sway bar level so that the links could bolt in through the holes. Alternatively you could probably temporarily loosen the bolts on the sway bar so that it has some free play up and down.

That's about it folks, other than to report that the steering feel is completely transformed by this 'mod'. Some of it will be down to the rusted old bar and sunk bushings. However, it definitely feels stiffer and tighter in corners than i ever remember it being, so the ISF bar is probably thicker than my stock bar was. Downside, is I notice a little unsteadiness if the road is uneven on only one side - since the suspension is now a little less independent from left to right - but given the improvement in cornering this is only a minor compromise.

Really recommend this, especially if you have an older IS250 and are looking to keep it a few more years!

H3XME · September 1, 2022

On 8/28/2022 at 1:55 AM, AFlex said:

Having taken the old sway bar off the vehicle, I'm not sure how true this was - they look the same size/diameter to me. But bear in mind I have a Sport model which could potentially have a thicker sway bar than non-sport models.

I'm 99% sure anti-roll bars are the same across the range. 250/350/ISF.. It's probably the new bushes that made a difference. Cusco do thicker ones - 30mm vs stock 27mm I think and 19mm rear compared to 17mm rear.

Front 30mm Sway bar part no. - 199 311 A30

Rear 19mm Sway bar part no. - 983 311 B19

There is a few companies in the UK that get Cusco from Japan.. They are the same thickness are TRD ones but those are considerably harder to get - Cusco ones are still available new.

Sway bars would definitely make a very noticeable difference because despite improving the body roll by being on coilovers it could still do with less of it.

I have been eyeing up Hardrace lower control arm bushes (linked) for quite some time now.. I might actually get them before I get camber adjustable top arms.