How close is safe between wheel/tire and fender lip?

[JT_67Tempest]

I think I know the answer to this question, but wanted to see what others think.

When tire/wheel has been mounted......

What is the minimum clearance you should have between the tire and fender lip or inner fender?

What is the minimum clearance you should have between the wheel lip and the fender lip or inner fender?

Can lateral movement of the body cause the wheel or tire to rub?

I have 20x10 with 285/30/20 tires on a 67 Pontiac Tempest (same as GTO) and I tried installing 2" lowering springs in the rear. Well the wheel/tire looked too close to the fender lip so I trimmed about 1/2" off the lip with air saw. Then I realized the inner fender well reached in from the outer fender side in just as far as the lip I just trimmed. So although the wheel/tire won't rub on the fender lip, they'll now rub on the inner fender and I proved my point like an idiot and took the car for a drive and sure enough the wheel lips rubbed on the inner fender well. Nice scratches all the way around!!

So like I said above I know the answer on what's considered too close, but I still wanted to hear from others.

thanks,
Johnny

[Nine Ball]

I try to maintain at least 1/4" side spacing. You also have to consider this on a car by car basis, as some cars have quarter panel shapes that quickly get narrower as the tire goes higher into the opening. So, if your car is slammed, you would want to account for the minimum spacing at the top edge of the tire, as the car is all the way slammed down and include any suspension travel upwards.

Suspension joints also flex during hard cornering. Cars with worn bushings on their leafs can cause the axle to move slightly. Cars with a fixed panhard rod and/or solid aluminum bushings help prevent side to side movement a little better.

[Boesch]

I always like to have a good 3/8 to 1/2 inch clearance at a minimum. The last thing you want to have happen is pushing a car hard around a corner and have your fender lip slice a sidewall open on you. The bushings in your suspension allow for things to flex quite a bit during a hard corner.

[JT_67Tempest]

Both of your comments are well taken and make a lot of sense. I don't have a sway bar in the rear, can that contribute to side to side movement of the body? Also, I think my body bushings are worn and cracked so they probably need to be replaced too.

But aside from this I'm wondering if it's okay to cut into the inner fender well?

This is a rendering of the driver's rear fender. The longer vertical line (a) is the outer fender or body quarter panel. The shorter vertical line (b) is the inner fender. The tire is (c).

You can see that the inner fender (b) is further in than (a) and so the tire/wheel will come into contact with the inner fender either by lowering the car or if the suspension compresses enough.

My question is whether I can cut into the inner fender (b) just at the points where the tire/wheel would make contact and somehow fabricate a new piece to replace what I cut out so that its contour allows for clearance of the wheel/tire?

Sorry my drawing is so bad, but hopefully you'll get the idea. The series of dots are just to show the clearance between the tire/wheel and the quarter panel fender lip.

BEFORE
(a)..(b)
|----|
|----| < --Cut into
|----|
|
|......|----------|
|......|----------| <-- (c) Tire
|......|----------|

AFTER
(a)..(b)
|--/
|-/ < --Fab a new piece like so
|-
|
|......|----------|
|......|----------| <-- (c) Tire
|......|----------|

[MrQuick]

god I hate trig....j/k

With the right backspace you should be fine. But since you already have the rims and tires rolling the rest of the lip should suffice. 67's have a lot of rom to fab with.

The upper inner well can be moved also. Just make a cut where the inner starts to curve the cut the section out where it starts to go back flat and add a section to that. This will allow the inner panel to mirror the shape of the inner side or the quarter.
edit* added pictures to help with my description.
What sizes for the fronts?

[MarkM66]

Is this what you're wanting to do?

http://www.classicperform.com/tech_articles/YellowNova/YellowNova3.htm

[ProdigyCustoms]

Triangle 4 bar rears like yours do a great job of maintaining side to side movement when everything is fresh and firm. Leafs have a tendency to "flex" side to side a bit more. So I plan for more clearance of leafs then 4 links. I would go down to 3/8 on a triangle 4 bar

[JT_67Tempest]

Mark and MrQuick your pictures are exactly what I'm needing to do. I have some other questions now. If I cut into the inner fender well and cut/remove enough metal that might be rub. Will that weaken the strucgtural integrity of the outside fender (quarter panel)?

I guess what I'd like to do as a temporary fix is to cut out as much of the inner fender well as needed and run the car like that for the rest of summer. I have a couple shows I'd like to attend and don't think I'll have enough time to weld in a new panel to fill what I cut out.

Also, when I do weld in the new patch panel, can the heat from the welding ruin the paint on the quarter panel? I have a pretty nice coat of black on their now and don't want to mess that up.

thanks,
Johnny

[JT_67Tempest]

I'm still new to some of the suspension lingo since becoming a member. When you say triangle 4 bar rears, is that what my car has?

If so, I doubt the previous owner did any changing of bushings and whatever is under there is probably original.

Johnny


Triangle 4 bar rears like yours do a great job of maintaining side to side movement when everything is fresh and firm. Leafs have a tendency to "flex" side to side a bit more. So I plan for more clearance of leafs then 4 links. I would go down to 3/8 on a triangle 4 bar

[ProdigyCustoms]

Yes, your car is a triangle 4 bar rear. If you look under the car, you will see your upper arms are in the shape of a V, or a traingle. This suopprts the side to side movement in the rear.

Bushings are cheap to replace and fairly easy to R and R the arms. Just pull them and have the local auto parts store press the old bushings out and install new ones. They should charge less then $100 for the labor and the bushings will be less then that. A couple hundred should cover it all.

[MarkM66]

Mark and MrQuick your pictures are exactly what I'm needing to do. I have some other questions now. If I cut into the inner fender well and cut/remove enough metal that might be rub. Will that weaken the strucgtural integrity of the outside fender (quarter panel)?

I guess what I'd like to do as a temporary fix is to cut out as much of the inner fender well as needed and run the car like that for the rest of summer. I have a couple shows I'd like to attend and don't think I'll have enough time to weld in a new panel to fill what I cut out.

Also, when I do weld in the new patch panel, can the heat from the welding ruin the paint on the quarter panel? I have a pretty nice coat of black on their now and don't want to mess that up.

thanks,
Johnny

As for structure, I think you'll be fine. The quarter isn't going anywhere with a cut in the outer wheelhouse.

As for welding a patch in there and not hurting the paint. You could probably get in the trunk, and put a piece of metal between the wheelhouse and the quarter, for protection, before you attempt welding it.

[69LT1Nova]

Is this what you're wanting to do?

http://www.classicperform.com/tech_articles/YellowNova/YellowNova3.htm

Mark, you da man! Thanks for that link. It is now in my faves.

I got a set of cheap-o IROC 18's off Craigslist (don't ask... my budget got KILLED with grad school coming up :guilty:) They BARELY fit under there with my Hotchkis drop springs. I can just about fit a finger between the metal and the rubber. This will come in handy, fo-sho!

[MarkM66]

As for structure, I think you'll be fine. The quarter isn't going anywhere with a cut in the outer wheelhouse.

As for welding a patch in there and not hurting the paint. You could probably get in the trunk, and put a piece of metal between the wheelhouse and the quarter, for protection, before you attempt welding it.

Also, if you're worried about welding in that area, look into some of these panel adhesives. There's been discussion in the Paint and Body area.

[MrQuick]

Also, if you're worried about welding in that area, look into some of these panel adhesives. There's been discussion in the Paint and Body area. +++1 be sure to follow the instructions very carefully....

[JT_67Tempest]

As for structure, I think you'll be fine. The quarter isn't going anywhere with a cut in the outer wheelhouse.

As for welding a patch in there and not hurting the paint. You could probably get in the trunk, and put a piece of metal between the wheelhouse and the quarter, for protection, before you attempt welding it.

I took a look in the trunk and it didn't look there would be a way to slip anything down between wheelhouse and the quarter. And I should mention I have zero experience welding, which was the reason for my questions on possibly messing up the paint on the quarter panel. I do want to get into welding, just haven't gotten around to it yet.

But glad to know it's okay to get in there and cut a piece out that's causing the clearance issue.

Thanks again Mark!

Johnny

[JT_67Tempest]

Also, if you're worried about welding in that area, look into some of these panel adhesives. There's been discussion in the Paint and Body area.

I'll check into this too as I've never heard of this before.

thanks,
Johnny

[JT_67Tempest]

Yes, your car is a triangle 4 bar rear. If you look under the car, you will see your upper arms are in the shape of a V, or a traingle. This suopprts the side to side movement in the rear.

Bushings are cheap to replace and fairly easy to R and R the arms. Just pull them and have the local auto parts store press the old bushings out and install new ones. They should charge less then $100 for the labor and the bushings will be less then that. A couple hundred should cover it all.

Took a look under the car this afternoon and I see exactly what you're describing. Everything looks kinda old under there. So I definitely need to get in there and replace the bushings.

Johnny