Neg toe in the rear

[SHunter]

Before replacing my subframe bushings my car had pretty funky alignment specs in the rear, uneven tire wear, and a vague feeling out back. So I bought OEM TABs, AKG poly subframe bushings, and IE posi-lock alignment adjusters.

When I pulled the subframe it was obvious what the biggest culprit was. One of my subframe bushings was torn through. My TABs were in decent shape but I changed em out anyway and welded in the adjusters looking forward to crisper handling and improved tire wear. I followed IE's directions by welding the toe adjusters with their adjustment toward the back of the car and double checked my work with the picture they sent in the package.

After the work was finished I threw on new tires and headed to the alignment shop. Voila! my alignment is nice and even. Camber is a nice -1.8 per side but whats this?! The toe is -0.53 evenly L to R and the adjusters only allow to further decrease toe or push the front of my tires out. What gives? I would have welded a bit of adjustment in the other direction had I thought there was any chance a lowered E30 would need more positive toe correction.

My car isn't super low but it has H&R sports with no spring pads. My understanding of the semi-trailing arm rear is that the more you lower it the more toe-in you're gonna get. Could something else be at work here? Bent parts seems pretty unlikely considering the L is dead even with the R and thrust angle is 0.

What do you guys think?

-Shunter

[Madhatter]

You dont want more toe in on the rear. If you go lower and don't change the camber, it results in more toe in, so you want adjustment back in the opposite direction (ie toe out). So I don't really see what your problem is here. Be an issue if you were already toed out and couldn't bring it in, but as it stands it seems you have what you need.

FYI, we usually set the majority of cars with about half a mm toe in each side in the rear.

[SHunter]

Read again. Toe "out" is the problem and I don't have room to make it toe in. Granted 0.5 degrees of toe out is not a lot but spending $200 on adjusters and the time to do it makes it feel like a lot.

-Shunter

[jlevie]

If the outboard plates were installed with some forward adjustment past the stock position, there should be no problem in obtaining toe-in on the rear wheels.

[SHunter]

"I followed IE's directions by welding the toe adjusters with their adjustment toward the back of the car and double checked my work with the picture they sent in the package."

I don't think a lowered car should need any adjustment to have more toe in. That's what is confusing me. Normally a lowered car would have too much toe in naturally and would need correction in the other direction i.e. moving the front of the rear tires out rather than in. Currently the front of my rear tires point out like a duck when they should point just slightly in like a pigeon. Usually when a car is lowered it naturally becomes more like a pigeon.

-SH

[SHunter]

.....Unless -0.5* toe actually means that it is toed in!? That wouldn't make sense to me but maybe my brain is backward. Also, the guy that did my alignment said that the opposite is true. Negative toe sounds like the front of the tires point out to me. Have I lost it?

[jlevie]

Should be a silly question, but you do have the inboard camber adjusters vertical and outboard toe adjusters horizontal, right?

[SHunter]

Should be a silly question, but you do have the inboard camber adjusters vertical and outboard toe adjusters horizontal, right?

Yup.

[jlevie]

The picture makes me think that the toe adjusters are as far to the rear as possible. Which is wrong and is why you can't get toe in. At least 1/3, or a bit more, of the slot shout be forward of the original RTAB bolt hole. I install them centered so as to have adjustment in both directions (trailing arms are easy to bend).

[brent5631]

Yeah centered is better. You will never need the whole adjustment range to the rear. So you have the arms all the way forward and still get a lot of toe out?
You shouldn't have very much if any in the stock position.

[SHunter]

I measured the toe with a tape measure today. Not super precise but gave me an idea of how much room I'm gonna need when I weld up a new subframe. The front of my rear tires are 3/4" further apart than the rear. Quite a bit I think.

My science brain is still having trouble wrapping my head around this. Clearly welding the adjusters with all of their in adjustment rearward was "wrong" for this application but it was right according to the theory that these cars will always gain toe-in as they are lowered. It was also right according to the directions from the manufacturer of the adjusters. I'm sure I'm not the first person to put these on their car.

Anybody wanna put a theory out there as to why my car has substantial toe-out despite being lowered about 1.5"? I'll have trouble swallowing that the trailing arms are bent considering the toe is equal side-to-side to within .01 degrees.

[jlevie]

The rear suspension does gain toe-in as the wheels move up with respect to the subframe, but the gain isn't all that much. The data I've seen suggests a gain in total toe of 1/64" for 1.5", 2/64 for 2", and 3/64 for 2.5". Camber changes faster.

If your toe measurements are correct, something is really wrong to have that much toe out. When checking toe the car needs to be on a level surface and you need to use toe plates, or better yet, strings. It the rear of the car has just been in the air the car needs to be rolled back and forth over several feet to allow the wheels to settle.

[Madhatter]

Read again. Toe "out" is the problem and I don't have room to make it toe in. Granted 0.5 degrees of toe out is not a lot but spending $200 on adjusters and the time to do it makes it feel like a lot.

-Shunter

your specs say negative? that is usually toe in and positive is toe out. What does your actual alignment sheet say? toe in (mm) : xx.xx? or something different?

I don't think a lowered car should need any adjustment to have more toe in. That's what is confusing me. Normally a lowered car would have too much toe in naturally and would need correction in the other direction i.e. moving the front of the rear tires out rather than in. Currently the front of my rear tires point out like a duck when they should point just slightly in like a pigeon. Usually when a car is lowered it naturally becomes more like a pigeon.

-SH

This was my point exactly. You dont need to toe the car in further if it is already toed in.

If you are checking with a tape measure you need to check the wheel at the same spot. So place the car on the ground, mark the front of the tyres with a spot of chalk on both wheels. Take a tape measure out and measure the height from the ground to the chalk mark on the tyres (obviously want enough space to put the tape measure across both tyres, so roll the car backwards or forwards to get the mark in the right place). Once you have this height measurement, measure the distance between chalk marks, then roll the car backwards so the chalk marks are facing in the opposite direction. You need to measure the height again from the ground to the mark on the tyres so it is the same as the height you measured at the front. So roll the car forwards or backwards to get this measurement the same. With the chalk marks at the same height you can then measure the distance between these two marks again.

Reason for doing this is you need the measure the tyre in the same spot on both wheels because things like strut angles, camber, etc will alter toe readings quite substancially. If you measure from the exact same spot front and rear in relation to height, you'll get a pretty accurate measurement.

If the distance between the two marks is larger at the back, the wheels are toed in by the difference between the front and rear measurements.

If the distance between the two measurements is less at the back, the wheels are toed out by the distance between the front and rear measurements.

Make sense? The height is an important factor though, make sure you get the chalk marks at the same height every time you take a measurement.