Centering wheels in wheelwells

[coreyjhen]

I was contemplating our trucks recently (kind of like navel contemplation for the middle-aged), and it occurred to me that the front wheels are aft of center in the front wheel arches, and the rear wheels are forward of center in theirs. It almost looks like the body was designed for a chassis that was a couple of inches longer. Will doing the infamous caster mod move the front wheels forward, and lowering move the rear wheels rearward, appreciably?

[darrellyates]

Well, you will likely get a lot of opinion here. I first built a '68 about 8 years ago. I kept lowering it, as I liked it better the lower it came. I started with drop spindles and springs, and noticed the front wheels seem to move rearward as I lowered it, and the rear wheels seemed to move forward. The more I lowered it, (in stages), the worse it appeared to be. To me, it was more noticeable in the rear than the front, although both were visible.

It would be easy to correct the rear, by making the trailing arms longer. The front, I'm not so sure about. This is the reason that now, on my second build, I went with an aftermarket frame that corrects this issue. Several bolt or weld on front ends, and rear end modifications will also correct this. However, my "building" skills are very limited, and I opted with an aftermarket frame. I would have to check specifications, but I think it's 2 1/2 inches longer wheelbase than the stock short bed frame.

Anyway, good luck. I am not familiar with the "caster modification" you reference.

I am sure there are less expensive ways to correct this than the route I've taken.

[coreyjhen]

The caster modification is detailed in several threads; basically, you move the lower control arms forward ¾" to get more positive caster on the alignment. It seems like that should move the wheels forward at least a little.

The rear confuses me, though. It seems that lowering the frame relative to the axle on a fixed-length trailing arm should tend to move the wheels back relative to the frame and, hence, the body. How is that not so?

[darrellyates]

Well, I can't give you the math or physics, all I know that the clearance at the front of the tire/wheel was about 1/2 of an inch, and the back had more space. It might be that it's a visual thing because of the curve of the back of the wheel opening in the bedside. Maybe it's different in a step side? I just know that when I lowered my truck with 5 inch drop springs, a c-notch, and another 2 inches of lowering blocks that the tire nearly hit the front of the fender opening on the rear wheels. I haven't been able to successfully upload a photograph (I'm new here, and something doesn't seem to be enabled to allow me to do it, I've tried thru the control panel, and thru simply posting... It says my photo's upload but they are not coming thru)... And, I don't have the bed on my new frame yet, so I really can't verify. However, look at lowered trucks and the rear wheels seems forward on nearly all of them as well. I only replied as I've observed the same thing you have, and am trying to eliminate that on my new build as well.

I hope you have better luck than I have had. My new frame has a 4 bar rear, and is supposed to be able to adjust this out on the rear. I am confident my front is correct, as I've had that end together already.

Hey... I got a picture to post!!!! Not really very obvious in this photo, as it's a 2.5/4 drop here. Bring it down another inch in the front, and 2 in the rear, and it gets tighter though. Glad I got a pix to post!!

[coreyjhen]

I gave the rear wheels a little thought, and here it is: The trailing arms will locate the wheels as far from the pivot as possible when the arm is horizontal. Moving the arm off horizontal in either direction will pull the wheels forward relative to the pivot point. Therefore, I will strive to have my trailing arms as close to horizontal as possible in order to get the wheels positioned better, even if it means flipping the mounts. Thanks for spurring the thought process!

[67 chevelle]

Compared to the advance design trucks [47-55]

67-72 are perfect

[darrellyates]

coreyjhen:
At least you are thinking!! That's better than me. Sounds like the correct explanation to me. Like I said, you will figure it out better than me. I can't remember what I did on the blue truck, think it started with drop springs. Then went to 5" drop, and a C notch. The reinforcing of the C notch moved the rear end back up a little bit, so I added the spacers for the extra 2" of drop. I am sure there is a better way, and will center your wheels correctly, like I said, lots of guys on here smarter and more creative than I.

Thanks for the explanation!