Dumb question about rear wheel thrust angle

[GTP]

Help me confirm my thinking.

Say your front end alignment is perfect, but your rear toe has a thrust angle pointing to the right. (For example, consider zero total rear toe, but each rear wheel is angled slightly to the right.)

Wouldn't you have to compensate by steering slightly to the right to keep the car straight on the road? In other words, the car would have a leftward yaw (car angled counterclockwise), requiring you to steer back to the right. Like this:

The car "crabs" to the left, the steering wheel is to the right, but the car goes straight.

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[NightmareMoon]

Sounds right

 

[NightmareMoon]

Help me confirm my thinking.

Say your front end alignment is perfect, but your rear toe has a thrust angle pointing to the right. (For example, consider zero total rear toe, but each rear wheel is angled slightly to the right.)

Wouldn't you have to compensate by steering slightly to the right to keep the car straight on the road? In other words, the car would have a leftward yaw (car angled counterclockwise), requiring you to steer back to the right. Like this:

The car "crabs" to the left, the steering wheel is to the right, but the car goes straight.

Although usually the front is usually considered 'perfect' when it allows the wheel to be centered when driving straight regardless if the rear wheel thrust angle is a little off. You can have a straight wheel but still crab down the road with the rear toe askew and probably never know it.

 

[xl_cheese]

I came across this guy's post the other day. I did some upgrades to my suspension recently and need to get it alignment dialed in. I'm going to do this to get the thrust angle set.

https://www.mustang6g.com/forums/threads/home-alignment-thrust-angle.184982/post-3723368

I also bought this tool to diy in my garage.
https://www.vevor.com/toe-plate-c_1...uge-toe-plates-measuring-tapes-p_010857275524

 

[GTP]

Hi Wes, thanks for your post. (Love your avatar, btw.)

I use Longacre plates for toe. They are more basic than the Vevor product you posted.

I tried the laser line to the front hubs method. That method relies on the laser tool being very accurately made so that the line truly points straight out of the device, that is, it does not deviate in angle. Also the laser tends to spread enough to make it hard to determine where it really intersects the ruler. A quality and accurate laser is expensive.

As for the camber angle gauge method, it relies on zeroing the gauge to a line that you know is parallel to the floor, such as with the 6' level I use.

I wrote up some alignment tips and methods, found in the DIY section, under GTP.

--

Anyway, the true purpose for this thread is that I stood up the left rear wheel camber a little, which changed the toe, and so I adjusted the LR toe. Next I am discerning if the car goes straight and the steering wheel is centered. I'm kinda trying to avoid doing another full string alignment, because that is a hassle.

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