Adjusting front caster to correct pull/drift...

[Mikey V.]

My 08 IS F has a slight drift/pull to the right. After getting my alignment done, the front caster is slightly out of spec. Would this .2° cause a pull? I researched replacement LCA bushing, and I am thinking of replacing the right LCA bushing with P/N 48075-53020. The RH LCA bushing is a +20' /.33° adjustment. Would this LCA bushing take my RH Caster from 7.8° to 8.13°. I am trying to decide if balancing out the front Caster would fix my slight right pull/drift even though I would still be back at a .2° Caster difference.

Which bushing do you recommend to help improve my caster? Would it be wise to also replace the LH LCA bushing to bring it closer to 8.33°?

 

[zrxkawboy]

Have you tried swapping the front tires side to side?

 

[clinebarger]

That's quite a bit of Castor! The steer ahead is at zero because you have slightly more negative camber on the left that cancels out the slightly less caster on the right.

They're not taking account for road crown which will naturally make a car with zero steer ahead drift to the right. I'd likely try to decrease the camber on the left a little....-1.1° maybe & see what happens.

 

[Mikey V.]

Have you tried swapping the front tires side to side?

I plan on doing the swap before changing bushings to rule out radial pull.

 

[atikovi]

My 08 IS F has a slight drift/pull to the right. After getting my alignment done, the front caster is slightly out of spec.

Maybe I'm missing something, but if you paid for an alignment, why didn't they do it to spec?

 

[thescreensavers]

The Alignment you had appears to just be a Toe and go. They did not touch anything else.

According to this post, https://www.clublexus.com/forums/is-f-2008-2014/936267-perfecting-wheel-alignment.html#post10712818

You have adjustment on the bottom arm which can adjust both camber and caster.

Is this a national chain that did your alignment or a local shop?

 

[DuckRyder]

I would expect that car to go pretty straight.

Considering road crown its probably always going to go right eventually.

Depends on if it is a drift or a pull, if a drift i wouldn't mess with it, if a pull id start ruling out tires and other things.

I do agree if you want it to drift up the crown try to reduce camber on the left. Car has a lot of caster and i don't think its going to make a lot of difference. You might be able to shift the camber by moving the subframe slightly.

 

[DuckRyder]

According to Hunter an 08 IS-F does not have front cams. They don't even show an aftermarket kit, only the bushings.

 

[Mikey V.]

It was a local alignment specialist. The car tracks straight but has a slight drift after about five seconds. Not really a pull. I was told by the mechanic that the front caster was not adjustable unless he shifted the front subframe which he wouldn't do.

 

[atikovi]

A slight drift could be adjusted be tweeking the toe, but I would doubt they would do that for you if it was already set to spec.

 

[DuckRyder]

So to be clear you are letting go of the wheel and the car goes straight for 5 seconds like an actual 1-1000, 2-1000, 3-1000, 4-1000, 5-1000?

Absolutely nothing wrong with that IMO.

 

[mattd]

How hard does it drift? I would cross rotate tires first to see if the “drift” follows the tire.

 

[Mikey V.]

I have to correct the car at highway speeds to keep her tracking straight. The car wants to wander right.

 

[DuckRyder]

I'm trying to quantify the drift/lead/pull.

If you simply let go of the wheel (be ready to grab it back of course) does it immediately go right, or does it go straight for some period of time?

Because of the crown of roads cars go right unless the road is differently crowned or the car is tuned to lead up the crown, which obviously makes it lead left when the crown is level or revised.

When i was doing alignments we tried to set them up to lead very slightly up the crown, they were generally more adjustable then though. Also all of us could immediately discern the typical tire pull from an alignment pull on a test drive. Not to say there were not atypical tire pulls but probably 90% of them you'd drive it and instantly go "that's a tire".

I would try switching the tires around, i would caution however that although it's counterintuitive it's possible (but not common) for a rear tire to cause a lead. GM once had like a 12 page TSB on pulling/leading and half of it was moving tires around. I'm sure there are similar more contemporary ones.

Hunter does make a balancer that can calculate the amount of lead a tire is likely to generate, combine it with the alignment settings and generate a position for least propensity to lead. Finding someone able to and willing to use for a a reasonable expense may be difficult.

It may be helpful to move tires around and record the change or lack of change to be better armed for a shop.

Edit: I'm also confused the the tech did not want to move the cradle/subframe - is it extremely elaborate with many attachments? We used to do it literally daily, if not multiple times a day. It that were a w body GM id have had it perfect just by sliding the subframe ....

 

[Mikey V.]

The car tracks straight once I let off the wheel it continues to track straight. Only after a few seconds does the car eventually wander/drift right. I was told that the front camber and caster are not adjustable from the factory.

 

[DuckRyder]

That doesn't sound like a tire, it sounds like about what i would expect based on the readings.

Is there an interstate with a left crown in the left lanes nearby and can you try it out and see if it goes left there? Ive found this on some rural interstates...

According to Hunters manual, the bushings are the only adjustment, but that doesn't mean someone doesn't make camber plates or cams for it. I would try like cline said to lower the left camber a little, if you can raise the right at the same time great. Based on past experience (not lexus) that shouldn't bee too difficult between subframe and control arm mounts...

Also check the ride height and see if you can find the factory alignment specs, some of them specify a particular amount of weight in the car and no one ever follows that.

its a lot of effort for what sounds like a minor issue - However to be honest the

have to correct the car at highway speeds to keep her tracking straight. The car wants to wander right.

and

The car tracks straight once I let off the wheel it continues to track straight. Only after a few seconds does the car eventually wander/drift right.

Don't totally track for me, having to correct sounds much worse than straight until no hands on the wheel for a few seconds.

This car has hydraulic steering right? is the steering wheel straight?

 

[DuckRyder]

SPC makes adjustable ball joints

Meghan Racing makes adjustable control arms.

Neither is exactly cheap.

Im sitting here trying to work out the offset bushing it is difficult without actually seeing it, but it looks like to increase caster the bushing is going to have to put the lower ball joint forward, the side affect of this moving in an arc is also going to be to move it in, which is going to decrease camber (not what you want. but it may not be enough to be significant. I looks like that off set bushing will get you to 8.1 caster if you can eek that out without losing camber it might help.

After determining it isn't tires and you can't get it anywhere in shifting the subframe or other mounting points that's the cheapest option, you gonna be into the arms or ball joints for over $200+ and that's if you can put them in...

 

[DuckRyder]

Also it looks like FIGs has adjustable upper control arm bushings.

IS300 OE FRONT UPPER CONTROL ARM ADJUSTABLE AND STATIC POLY BUSHINGS

These bushings replace the staked rear inner rubber bushings on the upper control arm. Eccentric polyurethane lubricated bushings. Set includes 2 bushing sets to replace rear arms. .

shopfigs.com

BTW, how are the tires? evenly worn?

 

[Mikey V.]

Tires have 5K miles and show nice, even wear. I can install the LCA bushing on a weekend.

 

[Mikey V.]

I was incorrect in my assessment. On the highway the pull happens in about two seconds.