Front tire help 70 Duster

[Freighttrain]

I have a problem with the front tires and need some help. My front tires rub in the rear and hit the fenders when I turn the wheel.

The car has disc brake conversion from 73 and up car that came off a dart. Has anyone had this problem before? On the ground the car has about 3/4” behind the tire and 2.5” in front. Tires are a 215/70/15.

We used the urathane bushing on the lower control arms and it appears to be really thick. On the passenger side it doesn’t look like it’s seated forward as much as it should be. Is it possible the strut rods are to long? They came with the car so not sure why they would be but it almost seems like it. The tortion bars seem like they are seated ok, might be able to move forward a little if I cut them down? Is it possible the ball joints are to long, maybe the knuckles are flipped drivers to passenger side?What’s everyone’s thoughts.

 

[Oldmanmopar]

Using the fine thread strut rods will move the lower control arm back if you use the 73 two piece bushings. We just did a conversion on a Barracuda. The large bolt disc from a 73 moves the rotor face out 3/8 to 1/2 inch. Also the 6 inch wheel and offset for the big bolt pattern is greater then the 5 1/2 inch wheel.

I use 67-72 small bolt disc brakes and 68 ford mustang rotors to change to big bolt pattern. Keeps the rotor face at the narrow position. We ended up using 195 65 15 tires on the front of the Barracuda with 6 inch wheels to prevent them from hitting the front of the fenders. Good luck

 

[Freighttrain]

Using the fine thread strut rods will move the lower control arm back if you use the 73 two piece bushings. We just did a conversion on a Barracuda. The large bolt disc from a 73 moves the rotor face out 3/8 to 1/2 inch. Also the 6 inch wheel and offset for the big bolt pattern is greater then the 5 1/2 inch wheel.

I use 67-72 small bolt disc brakes and 68 ford mustang rotors to change to big bolt pattern. Keeps the rotor face at the narrow position. We ended up using 195 65 15 tires on the front of the Barracuda with 6 inch wheels to prevent them from hitting the front of the fenders. Good luck

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When you say it prevents it from hitting the front of the fender are you talking in front of the tire or behind it?

I’m not hitting in front of the tire. It’s hitting in the rear, I’d need to move the tire forward.

 

[Demonracer]

Adjustable strut bars will help a lot.

 

[dvw]

Using the fine thread strut rods will move the lower control arm back if you use the 73 two piece bushings. We just did a conversion on a Barracuda. The large bolt disc from a 73 moves the rotor face out 3/8 to 1/2 inch. Also the 6 inch wheel and offset for the big bolt pattern is greater then the 5 1/2 inch wheel.

I use 67-72 small bolt disc brakes and 68 ford mustang rotors to change to big bolt pattern. Keeps the rotor face at the narrow position. We ended up using 195 65 15 tires on the front of the Barracuda with 6 inch wheels to prevent them from hitting the front of the fenders. Good luck

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Thanks for the response. This exactly the issue. I'll cut these up and shorten them with chrome moly tubing. By my estimatoon it'll take about 3/8"- 1/2" shorter.
Doug

 

[Mtrhead]

Send us a pic when you get it done

 

[72bluNblu]

This has been discussed before with the poly strut rod bushings. The poly bushings are only one size and can push the LCA back depending on the strut rod type used. Because there’s no adjustment in the stock strut rods the bushing has to be the right size, otherwise the LCA won’t sit in the right location.

You can look at @autoxcuda ‘s post in this thread about cutting the poly bushings down to fit properly

Cutting strut rod bushings for correct geometry?

The amount may vary a bit, and it will affect your alignment. The amount of caster will change if the lower control arm moves forward. What you want is for the LCA to be perpendicular to the frame rail, with the LCA snug against the shoulder of the LCA bushing and the nose of the bushing snug against the K frame. Just like you don’t want the strut rod pushing the LCA backwards, you also don’t want the strut rod pulling the LCA forward.

In your pictures it looks like the shoulder of the LCA bushing has a gap to the LCA, which would indicate the LCA is being pushed backwards. It should look like this…

 

[dvw]

Shifts are cut down 5/8". If they're to short I'll shim them at the front.
Doug

 

[autoxcuda]

So the tire rub in the back and the front ?

215/70/15 is a very large diameter tire.

What are your front rim specs: width and backspace?

 

[dvw]

So the tire rub in the back and the front ?

215/70/15 is a very large diameter tire.

What are your front rim specs: width and backspace?

They only hit in the rear, barely. They actually 215/65×15 we had aprox 3/4" gap at the rear, 2 1/2" gap at the front. Can move the front a rad. We'll see how it looks when it's back together this weekend.
Doug

 

[72bluNblu]

Shifts are cut down 5/8". If they're to short I'll shim them at the front.
Doug

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Well, I can't say that's how I would have done that. Hopefully that doesn't pull the LCA too far forward and you can still get enough positive caster.

 

[dvw]

Shortening the shaft adds positive caster. The only reason they would be too short is front wheel lip clearance. I understand geometry. This question was posted because the only issue that appearedthat would cause the problem were that the strut rods were too long. I mistakenly assumed that all A body strut rods were the same. Didn't want to go chopping something up if I missed the real issue. Built plenty of racecar suspensions from scratch. Probably performed 5000+ alignments In my career.
Doug

 

[Sterling]

I am installing new poly bushings and shafts in a 71 Demon. I noticed that the bushings are not flush with the cup like the original. I don’t think that it will be an issue with the manual steering street car, but I thought that it would lose positive caster when reassembled. When it is back together I will check the alignment myself, then have it checked at my local shop.

 

[72bluNblu]

Shortening the shaft adds positive caster. The only reason they would be too short is front wheel lip clearance. I understand geometry. This question was posted because the only issue that appearedthat would cause the problem were that the strut rods were too long. I mistakenly assumed that all A body strut rods were the same. Didn't want to go chopping something up if I missed the real issue. Built plenty of racecar suspensions from scratch. Probably performed 5000+ alignments In my career.
Doug

The front lip clearance isn’t the most important issue. If the strut rods are too short and pull the LCA past perpendicular to the frame you will cause binding within the range of suspension travel. As a drag car that could mean a slower response from the suspension on hard acceleration, so, the opposite of what you want.

I’ve run adjustable strut rods on all of my Mopars, and the change in length to take the LCA from no binding at all to binding at the ends of the range of travel isn’t very much at all. With the tuning process to get the ideal length you basically end up in a window that’s only like a 1/4” wide at the most. The strut rods aren’t there to add caster, they’re only to keep the LCA located properly when it’s under braking or acceleration loads. And if you pull or push the LCA too much with them, the LCA will bind up as it cycles up and down.

Maybe in your case the front tires are tall enough that the fender clearance will be an issue before LCA binding from too short a strut rod is, but the LCA placement is more important.

 

[dvw]

5/8" was the magic number. Fits perfect. Frot and rear lip clearance with the wheels turned. As far as bind goes. Never been an issue. My 64 Belvedere drag car has the stock rods shortened for increased caster. Only used the factory ends cut down. Then used moly tube for the entire body of the rod. Strut rods can be manipulated to move the lower ball joint. Bind with poly bushings and short rods? It's been 1.239/5.639/8.967@150 . Front suspention is basically stock. 11 years, 1000 passes leaving like this. As for those aluminum adjustable ones. I watch one break in half on a mid 9 second E body. Fortunately it was in the burnout box.
Doug

 

[Inertia]

Nice work, good job .
I used to grind the stop off, run a die down as nec, then just run 2 nuts and a tube spacer inside the rubbers/washers..
Totally adjustable for free.
Way back

 

[Oldmanmopar]

Go get the correct bushings for your strut rods. Sounds like you have 73 -76 bushings with 67- 72 strut rods. Don't cut your bushings like mentioned. You'll just create more problems .

You will need one piece rubber style with the fine thread strut rods pictured .

first picture coarse thread strut rod use the two piece rubber with a steel sleeve and a shear sleeve molded into the rubber bushing to prevent the K-member from shearing the bushing nipple off. Second picture shows the sleeve molded into the bushing. This prevents the k member from shearing this off. After market poly type bushings do not have this and usually shear and then get side movement

Last picture is the fine thread strut rod one piece bushing