Suspension options 67 Dart convertible

[autoxcuda]

With everyone's help I think most of the suspension elements have been figured out.
73+ K frame
F-Body spindles and brakes (or aftermarket brakes)
Aftermarket upper and lower control arms + taller UBJ
After market adjustable strut rods.
Bigger sway bar and torsion bars
275 35 R18 tires and min 9" wide wheels
Lower front ride height about 2"
6 leaf HD rear springs
1/2 off set hangers or mini tubs and spring relocate
Rear sway bar

For 275 in the rear you will have roll fender lips, move leaf springs in, maybe cutout and fab a section of the outer wheel wheel or mini tub it. Like was talked about above.

Note 1967 A-body gas tanks mount cross-wise of the chassis and can interfere with full out the back exhaust routing.

 

[jjack]

I believe Wade used the older version of the GT500 wheels. Not sure how they compare: Build thread- 73 duster, forged 5.7 w/ PS and AC, 5 spd, big brakes and floater rear

I think those are Mustang wheels. Thanks for the link, I look forward to reading about his build.
I have struggled to find wheel choices. I have not found many with the right backspace and lug pattern.
Since the Ford lug pattern is the same, I was taking the lazy way out by looking for Mustang wheels.

 

[DionR]

That’s what I look for too. Mustang heels will be your best bet.

If you run a stock brake, those +30mm wheels will probably work. If you run an aftermarket brake package like from Dr. Diff with a rotor that fits over the bub, you probably need a +35mm wheel. I generally use American Muscle for my searches and bought four 18x9 +35mm Forgestar F14 wheels for my car.

An 18x9 works for a 275/35 but a 9.5 would be better. I just haven’t found many that have the right offset.

 

[jjack]

For 275 in the rear you will have roll fender lips, move leaf springs in, maybe cutout and fab a section of the outer wheel wheel or mini tub it. Like was talked about above.

Note 1967 A-body gas tanks mount cross-wise of the chassis and can interfere with full out the back exhaust routing.

72Blu and Dion have done a lot of research into what works. I do know that I must still take my own measurements mostly because of build tolerances. Offset shackles are the minimum needed, but if it needs a mini tub then I will do it. I did see a post that someone has successfully tubbed a convertible, so it should be OK. I expected the wheel/tire limitation to be up front, but actually it's the back end.

Do you know of anyone running 275 35 18 rear tires on a Dart? What was done to make it work? I don't want to mess with the wheel lips because I want to install wheel opening trim.

The passenger side quarter panel has some rust around the wheel opening, I suspect the same for the outer wheelhouse. The driver side door and quarter panel were damaged and replaced. It was a very bad repair. They didn't replace or bump out the striker pillar, they just welded on the qtr and made a door gap out of Bondo. That qtr is junk, it was left in primer and rusted out. I assume that the outer wheelhouse was damaged, not repaired, and probably rusty. Fabing up new wheelhouses that provide more clearance won't be problem for this build.

I don't like the 1967 fuel tank arraignment with just one strap. If I use an A-Body tank, it will be the two strap design.
I want the same size wheel and tire so I can carry one spare. If I end up with a tire the same OD as factory, it might fit in the spare tire well, but it will stick out of the opening. I am thinking about eliminating the spare well. I doubt that an A-Body tank would be secure under a flat floor. There is a Charger tank that fills from the side like the Dart. I'm considering the 1970 Barracuda tank. it fills from behind the license plate. Never been a fan of how the fuel opening looks on an A-Body.

I am still confused about the relationship between backspace and offset. My brain thinks every 9" wheel with a 6" backspace will have the same offset? I am not seeing a certain aftermarket wheel 18X 9 with options for different backspacing. If they offer that size, there is only one backspace available.

Thanks for your insight. I appreciate all the help I can get.

 

[jjack]

That’s what I look for too. Mustang heels will be your best bet.

If you run a stock brake, those +30mm wheels will probably work. If you run an aftermarket brake package like from Dr. Diff with a rotor that fits over the bub, you probably need a +35mm wheel. I generally use American Muscle for my searches and bought four 18x9 +35mm Forgestar F14 wheels for my car.

An 18x9 works for a 275/35 but a 9.5 would be better. I just haven’t found many that have the right offset.

I'm done with drum brakes. I know there is no huge advantage to disc brakes on the back, but I think discs perform more predictably. My plan is for a stock A body rear end, disc brakes, and 5 x 4.5 axle swap. 72Blu thought that set up might also need a small spacer if I want the same wheel as the front end.

I hope I can find the combination that uses one wheel, and the wheel opening gap is about the same front to back.

Won't the offset affect the backspace? I'm confused about offset. Some list it as 30MM some list it as +30MM? Which way are we moving the mounting face? If we move the mounting face toward the outside of the wheel that should increase the offset and increase the backspace, right?

Every 9" wheel with a 6" backspace should have the same offset, right?

 

[autoxcuda]

72Blu and Dion have done a lot of research into what works. I do know that I must still take my own measurements mostly because of build tolerances. Offset shackles are the minimum needed, but if it needs a mini tub then I will do it. I did see a post that someone has successfully tubbed a convertible, so it should be OK. I expected the wheel/tire limitation to be up front, but actually it's the back end.

Do you know of anyone running 275 35 18 rear tires on a Dart? What was done to make it work? I don't want to mess with the wheel lips because I want to install wheel opening trim.

The passenger side quarter panel has some rust around the wheel opening, I suspect the same for the outer wheelhouse. The driver side door and quarter panel were damaged and replaced. It was a very bad repair. They didn't replace or bump out the striker pillar, they just welded on the qtr and made a door gap out of Bondo. That qtr is junk, it was left in primer and rusted out. I assume that the outer wheelhouse was damaged, not repaired, and probably rusty. Fabing up new wheelhouses that provide more clearance won't be problem for this build.

I don't like the 1967 fuel tank arraignment with just one strap. If I use an A-Body tank, it will be the two strap design.
I want the same size wheel and tire so I can carry one spare. If I end up with a tire the same OD as factory, it might fit in the spare tire well, but it will stick out of the opening. I am thinking about eliminating the spare well. I doubt that an A-Body tank would be secure under a flat floor. There is a Charger tank that fills from the side like the Dart. I'm considering the 1970 Barracuda tank. it fills from behind the license plate. Never been a fan of how the fuel opening looks on an A-Body.

I am still confused about the relationship between backspace and offset. My brain thinks every 9" wheel with a 6" backspace will have the same offset? I am not seeing a certain aftermarket wheel 18X 9 with options for different backspacing. If they offer that size, there is only one backspace available.

Thanks for your insight. I appreciate all the help I can get.

I have a 1968 Dart convertible.
I have 245/60/15 with 15x7 rims and 4.25" backspacing on the rear
small bolt pattern axles.
stock leaf springs
Car is low in back.
Rubs slightly on outside and inside.

 

[jjack]

I have a 1968 Dart convertible.
I have 245/60/15 with 15x7 rims and 4.25" backspacing on the rear
small bolt pattern axles.
stock leaf springs
Car is low in back.
Rubs slightly on outside and inside.

Nice car. I love dart convertibles. I like rally wheels on A-Bodies. Your car does look a little low in the back. Have you compared your ride height to specs? Perhaps raising the ride height would stop the rubbing. If it's not low, then perhaps stiffer springs and shocks will help if you don't want to increase rear ride height. Is the wheel opening clearance the same front to back with those wheels?

Looking at Tire Rack, they offer 3-246 60 15 tires. They have an overall width between 9.5" and 10", with tread widths between 7.5" and 8.3", and 26.6" diameters. The tires I'm considering are 10.9" wide, 9.5" tread, and 25.6" diameter. I need to measure body clearances and my final ride height. I thought the rear wheelhouses are wide enough; it's just a matter of centering the wheel in the opening.

I need at least a 9" tread with engine choice I have made. This is based on my 6.4 300. That car had 8" wide tires, and they would spin on hard take off before the traction control kicked in. I installed 9" wide tires and no wheel spin. I have not tried it with TC off, perhaps the tires would spin easily. The Dart is about 1,000 LB lighter so the issue will be greater. I might find that a 9" tread is not enough traction.