Body to Rear Tire Alignment Question

[Gumball]

UPDATED - 5/27/16 Here's another TTT on an old how-to that will be helpful to anyone with a three-link rear end.

Original post follows.....

I was going to put this into my bodywork thread, but thought that I may get more feedback having it as a separate topic, as well as the fact that it'll be searchable as a stand-alone question.

I've been working on final body fitment before moving to the real work of gapping moveable panels and the rest of the actual bodywork (i.e., filler, feather fill, block sanding, etc...). I've had very good results so far and I'm quite happy with just about everything, which is a surprise given the compromises fitting these bodies can present.

But... I'm not completely thrilled with how the rear quarters are situated over the rear tires. Viewed from the ahead of the car, the leading edge of the rear quarters seem very uniform and an equal amount of the rear tires are visible. However, viewed from behind, the passenger side tire is slightly more visible. When looking down from directly overhead, the trailing edge of the driver's quarter seems to be shaped a bit differently from the passenger side - so this is most likely causing the issue.

I've tried quite a few things to move the body over, but although those things help make the rear view appear a bit more symmetrical, each results in unfavorable changes elsewhere on the body. The rear end is well centered in the chassis, so I'm not concerned there - this is really just an appearance issue. Short of overcoming this issue by creating a couple more, the only solution I can think of to correct this is to put a 1/8" spacer behind the driver's side wheel. Not a good alternative from a mechanical standpoint, though, so I'm inclined to leave it where it is.

What say you?

[SCFFR]

Chris,
I went through the same process when fitting the body on my MkIV. I came to the conclusion that I would get the body centered on the chassis and tires and leave it at that. I really don't like the wide open space in the front of the rear tires and had considered modifying to a more street version. Also consider the impact of paint on the body as opposed to the gel coat on it now. Some of the "flaws" seemed to disappear on mine once the body had been painted.

Keep up the great work!

Ron

[wbulk]

Not bad at all for a Cobra. Most cobra bodies are not the same from side to side except for Kirkhams. I have seen a lot, lot worse. Not many would catch that. The question is can you live with it? If you can't, another option is to go to a three link or adjustable four links. But it really is not bad at all.

[skullandbones]

Not bad at all for a Cobra. Most cobra bodies are not the same from side to side except for Kirkhams. I have seen a lot, lot worse. Not many would catch that. The question is can you live with it? If you can't, another option is to go to a three link or adjustable four links. But it really is not bad at all.

X2 on that. I know you don't like it but if at least it is in the rear where there is an overlap of the fender. If it were in the front, it would be easy to see with the tire edge being lined up with the fender edge. Have you considered the settling in of the suspension? I have heard from others that you have to re-adjust some with the breakin of the suspension. Mine has changed a little with only 100+ miles on it. Ride height is most likely to change but you might luck out a little because it is a little number (maybe 1/4 inch). Worse case is that you have to shell out for some adjustable control arms and then re-align the front end after "centering" the diff. Since you would be compromising the measurement on the diff to fix the cosmetic issue with the wheels. Still it's a small number. I'd wait til I got it on the road to do anything. IMO, WEK.

[Mike N]

I think you can tweak it by how you fit the elephant ears. You don't need to move it much and the body is quite flexible in that area.
315s.JPG

[Gumball]

Well, as a couple people here and at ffcars suggested, I double checked my rear end to chassis alignment today and... wouldn't you know it... the measurements were 1/4" greater on the passenger side. Using the adjustment on the panhard bar (with wheels up, just loosen the jamb nuts and rotate the bar) I was able to easily move the axle back 1/8" to the driver's side.

I was sure that the axle was located properly and, since I've been doing body work for the last few weeks, was convinced it was an issue with the body. All mounts were in place, as were the splash panels; i.e., elephant ears. To that end, I never re-checked my axle orientation and instead was looking for the solution through all sorts of movements with the body. Classic example of not seeing the forest for all the trees!

I took measurements from four points, including across to opposite sides of the chassis, both before and after making the adjustment. I'm now convinced that the axle is in the proper location and, more importantly, I'm happy with how the body is sitting.

On to real bodywork!!!

[Mike N]

Is the rear centered to the chassis? From what I remember the lateral location of the rear of the body is largely set by the roll bar and a small amount of material removed from the roll bar holes in the body would allow for some lateral movement of the body. If it were me I would set the rear centered to the chassis so that the control arms are aligned correctly to the thrust axis that way you won't get any strange handling characteristics.

[Gumball]

Is the rear centered to the chassis? From what I remember the lateral location of the rear of the body is largely set by the roll bar and a small amount of material removed from the roll bar holes in the body would allow for some lateral movement of the body. If it were me I would set the rear centered to the chassis so that the control arms are aligned correctly to the thrust axis that way you won't get any strange handling characteristics.

It is now... it's a three link and is now definitely centered in the chassis. The problem was that although I thought it was before, it wasn't... see my update and pics above. Even without the grommets around the roll hoop, the splash guards (elephant ears) and the brackets I have inside the trunk (replacing those that were hooked to the exterior hinges on the Mk1-3) hold things in place very well... no side-to-side movement. With the rear centered (and confirmed by lots of measurements), the body to wheel orientation looks great.

Thanks to all for the input!!!

[Gumball]

Here's today's TTT - for those of you who are trying to align the three-link side-to-side.

[cnutting]

Perfect timing, thank you very much!
Chris