I've been pondering this for a while, and when I had the car on a lift for a week while doing the cam chains, putting on headers, Ohlins DFVs, Figs solid bushings and upper control arms in the front, replacing the trunk struts, etc., etc...

So the front subframe was completely off the car to get access for the header install and I wanted to put it back on the car square with the centerline and concentric with the centerline. I found the four bolts holding the frame strap across the middle of the car, and saw there is a hole in the middle of this strap, AND the bolt locations are equidistant from the centerline. So my dad chucked up two of the bolts and hit them in the lathe with a center drill. We put them back in the front position, and measured in an X from the front machined surface of the subframe to the bolt locations. We also ran a chalk line up the middle of the car on the centerline. There was no weight on the subframe, and the only fasteners in place were the two large nuts on the front. We spun them down to lightly hold the subframe in place and took measurements. When we had both legs of the X equal, we knew the subframe was square with the centerline and centered on the centerline and tightened the nuts down to spec, then checked our numbers again.

I was hopeful this would work, but I didn't expect what I got. Camber was dead even on both sides at -1.2 degrees, and I mean dead even. We measured to millimeters, so we figured we were within about +/-0.020" and this is after installing Figs upper control arms with solid bushings all around.

I know a lot of folks have struggled with camber imbalances because their subframes were not properly aligned with the chassis. I now know exactly how to get it right. Next up is getting the rear subframe right. Camber in the rear is -1.6 on the left and -1.0 on the right. Definitely not what I want to see.

 

It never ceases to amaze me all of the work & new things you come across on this platform. Your wealth of knowledge is appreciated. Unfortunately, I don’t have the level of experience to pin point exactly where to tackle those measurements. When I purchased my car, I noticed the steering wheel wasn’t centered. It always settles around 11 o’clock position.

After a slight load, say 10-15mph. After multiple alignments, the steering wheel gets close to center but after several hundred miles it goes back. Inner tire wear is a huge issue im having as well. Just in the front tires, especially driver side. I also think I found hidden damage in the rear by the spare tire. I noticed the dimples you mentioned in another thread on the sunroof. This car has them on passenger side.

I’m definitely leaning towards this being a huge contribution to what I’m experiencing. I will definitely take note of this thread & try to get these measurements done. Alignment shops unfortunately are just looking for those green colors on the screen. I need to find one that knows a thing or two. I’m also looking into replacing bushings. I noticed during my recent transmission service. My driver side lower control arm bushing had a gouge.

 

I've learned a few things from this and other forums. Keeping your front wheels straight is really important.

If the front tires are wearing on the insides, you need to replace the front lower control arm bushings with Figs poly bushings. It was one of the first things I did when I bought my F ten years ago. No more inner tire wear. I also own two LS 430's. They require the same bushings, but first I'm going to use the new RC F/ GS F aluminum brackets and bushings because they are cheap.

These cars have front and rear sub frames. Lance is "right on" with getting them square. Makes a difference. A little pain, but a significant gain.

Notice he says "solid" front control arm bushings. For my type of driving that may be too much.

Loren

 

When I was doing chassis tuning on mini-sprints, step one was squaring the axles with the chassis centerline. You wouldn't typically center the axles on chassis center for a car that only turns left, but the axles "must be square with the centerline" according to every chassis tuning resource I could find. Having the IS F's subframe in a random position (where ever it happened to end up when putting it back on) always made me uneasy. When I replaced my starter, I knew for sure it was off because my camber balance was way off, but it was really hard to visualize what I needed to do lying on my back with the car on jack stands. My dad has a two post lift, so getting under the car and visualizing what needed to happen was a lot easier for me. I am sure I could do this on jack stands now just because I know what to look for and where to look for it.

This is so important, I'm seriously thinking of putting a video together for YouTube to show how easy it really is to get it right with just a tape measure and a helper. It's not something you can do quickly, but the results are so worth it.

 

please do this. Im still trying to get mine right and it seems like no one knows how to properly do it. Even more shocking that Lexus itself wont make subframe adjustments.

 

Please do! I'm a very visual learner. I'll even like and subscribe! (again)

 

I agree with comments above. Please make the video. I wish you made videos on every single subject you try and explain. Valve clearance, timing chain, starter replacement, sub frame alignment, and many more. I’m subscribed to your YouTube channel.

 

+1 on the video idea for front subframe alignment. I am not much of a video editor, but I know Powerpoint well and can help with diagrams if needed.

 

In the countless subframes I've had off the F cars. I've found that the subframe adjustment is incredibly minimal.
generally speaking your lucky to get no more than 0.1 - 0.2 degrees of camber or caster change.

 

Mine was off by 0.5 degrees after changing my starter. It was within 0.1 before. It's now even.

 

So after my latest alignment my current caster is off by 1 degree left to right. Is this likely the cause or should I be concerned that maybe something is bent up front? 8.1 Front Left and 7.1 Front Right.

 

Caster differences are because the subframe isn't square with the chassis centerline. Sometimes you can remedy this by loosening the bolts on the big bushing at the back and applying force to move the rear bushing (but only a little, one full degree isn't small) without loosening the subframe, but you really want the subframe to be square with the chassis centerline so you have the same wheelbase on both sides of the car. Some alignment racks will also measure wheelbase, and if you are using one of those you can at least get the front subframe square with the rear subframe.

 

FWIW, I need to drop my front subframe again to tighten my header bolts and (fingers crossed) remove the O2 sensor wiring extensions to (hopefully) eliminate the cat efficiency codes I am clearing every 2 out of 3 trips. I'll get my videographer this time and have him shoot a video so it will be clear what I am talking about.

 

Weird question on why are you having to tighten the header bolts again?
&
O2 wiring extensions elimination - any foresight on routing or tips to keep from using them? (I'm about to tackle this job this month)

 

You have to extend the wiring. The primary o2 sensor placement changes "downstream" about 12-16". Using wiring extensions makes changing out the primary o2 sensor a 10 minute job. That being said - cutting the wiring and extending it is a poor idea for future replacement.

I use the Michigan Motorsports extensions.

It's really common sense for routing: Keep them away from heat.
There's multiple spots where you can zip tie or tuck the wiring behind.