How can I adjust wheelbase?

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Hank Dodge

Hank Dodge

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We are in the process of upgrading the '69 Barracuda with new suspension and brakes all the way around. We installed the rear end components ( new 8.75" w/ Super Stock springs, shackles, big brakes, etc. ), all went in fine and centered nicely in the wheel wells. Got into the front end and replaced everything but the lower control arms ( new heavier torsion bars, upper control arms, all bushings, spindles, and a later model disk brake kit ). Also changed from stock 215/70R14 all the way around to 255/60R15 on 15x8 4.5" backspacing on the rear, and 225/60R15 on 15x7 4.25 backspacing on the front. Now, we have a problem with the right side wheelbase being longer than the left side by about an inch and a half? This is causing us to have contact between the tire and the forward lip of the front fender on that side. The left side looks fine and seems to have enough clearance ( about 2" ) in front of the tire. The exposed threads on the nose of the strut rods are equal side to side, and alignment cams and ride height are adjusted roughly where they should be. Where did we go wrong?
 
Are both strut rods the same length from where they mount to the LCA to the body?
 
Dana67Dart said:
Are both strut rods the same length from where they mount to the LCA to the body?
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Honestly, I should check that. They are the ones that were on the car before, but I must say that I never set them side by side to measure them against each other. I was just noting that the exposed threads on the forward side of the K-frame were about the same.
 
You could add a thick washer behind the strut rod bushing, that would move the LCA back to help the tire clear the fender, then readjust the alignment
 
Have you verified both front rims have the same backspacing?

Are the front fender braces (on my dart they connect to a bumper brace and the lower front part of the fender) in place and adjusted?

EDIT: Nevermind, I was thinking track width.....
 
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brian6pac said:
You could add a thick washer behind the strut rod bushing, that would move the LCA back to help the tire clear the fender, then readjust the alignment
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I was thinking about doing that. it seems like the thickness of a couple washers behind the rear strut rod bushing would not move much at the wheel? I've only got about a half inch between the tire and the edge of the fender on the right side, compared to almost 2" on the left side.....

Is there any "trick" to removing the strut rod without having to pull the torsion bar and LCA out?
 
You could always loosen the 4 K member bolts and try to move it where you want it and tighten it back up
 
brian6pac said:
You could add a thick washer behind the strut rod bushing, that would move the LCA back to help the tire clear the fender, then readjust the alignment
Click to expand...

1.5" thick? Yeah keep dreamin.

To the OP, something is WRONG somewhere and you need to find it. Whether it's been hit and has frame damage, different length strut rods as mentioned, something assembled incorrectly......SOMETHING SOMEWHERE is amiss. Shouldn't be that hard to find as big a difference as that is.
 
RustyRatRod said:
1.5" thick? Yeah keep dreamin.

To the OP, something is WRONG somewhere and you need to find it. Whether it's been hit and has frame damage, different length strut rods as mentioned, something assembled incorrectly......SOMETHING SOMEWHERE is amiss. Shouldn't be that hard to find as big a difference as that is.
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He doesn't have to go 1.5" on the lower' I was thinking maybe 3/8" then you have to move the upper control arm back to get the caster right.
 
brian6pac said:
He doesn't have to go 1.5" on the lower' I was thinking maybe 3/8" then you have to move the upper control arm back to get the caster right.
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I'm not sure there's enough adjustment there to get it that far out. And if he's still got factory strut rods, they are non adjustable. Plus, if he has adjustable rods, they are only supposed to be adjusted to square the arm up to the lower control arm pivot. That adjustment is not supposed to be used to adjust caster, OR adjust the wheel position in the wheelwell. IMO, to be that far out, something's wrong somewhere.
 
RustyRatRod said:
I'm not sure there's enough adjustment there to get it that far out. And if he's still got factory strut rods, they are non adjustable. Plus, if he has adjustable rods, they are only supposed to be adjusted to square the arm up to the lower control arm pivot. That adjustment is not supposed to be used to adjust caster, OR adjust the wheel position in the wheelwell. IMO, to be that far out, something's wrong somewhere.
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Sure there is enough adjustment, I could do it with no problems you just have to do what you have to do. offset upper bushings is one option, move the K member is another, washer behind the strut rod bushing, pull out the upper arm mounts with a frame machine. I can do all this at home and I don't have a frame rack but you can do a lot with a port a power and some metal for a frame to pull from. So many ways to fix the problem, I could go on and on.
 
have you checked your (caster) alignment specs?....or fender fitment?
 
First get an actual wheelbase measurement (Center hub to center hub, left vs right). If it's really off by 1.5"... it's not on one side! It's most likely the difference is split between the two sides (one 3/4" forward, one 3/4" back).
 
brian6pac said:
Sure there is enough adjustment, I could do it with no problems you just have to do what you have to do. offset upper bushings is one option, move the K member is another, washer behind the strut rod bushing, pull out the upper arm mounts with a frame machine. I can do all this at home and I don't have a frame rack but you can do a lot with a port a power and some metal for a frame to pull from. So many ways to fix the problem, I could go on and on.
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I guess.
 
Thanks for the replies. The strut rods are the same length side to side, my kid did compare them when things were apart. I'll need to get the exact numbers side to side for the wheelbase / hub-to-hub measurement, but the right side is definitely a greater distance apart than the left. Maybe you are right and the K member is out of alignment? I did have it loose at one point to weld some cracking on the right side frame. It had busted out the captured nut at the rear K member mount on that side. I located it in the original position and welded it back in place, but I did have things kicked loose in the process. It sure didn't look like there was room for it to move much, but that makes sense to try moving the K member around a bit.

Again.....Is there any trick to pulling the strut rods without pulling the whole torsion bar and lower control arm loose again?

Thanks
 
Other than cutting it into two pieces, not that I'm aware of.
 
Historically, owners/members here have OEM rear springs, etc... They find oversized tire runs closer to rubs at one side of rear. Then others try to explain why, the engineering involved.
Even though that built in difference wasn't a full 1.5 inches, I'll assume your aftermarket super stock springs change it for drag racing and straight line launch. So what I'm saying is all that 1.5 inches isn't a fault in the right front suspension. You may need to alter both left and right sides to get it equal. I don't know how drag racers set up their wheelbase. Good luck with it.
 
RedFish said:
Historically, owners/members here have OEM rear springs, etc... They find oversized tire runs closer to rubs at one side of rear. Then others try to explain why, the engineering involved.
Even though that built in difference wasn't a full 1.5 inches, I'll assume your aftermarket super stock springs change it for drag racing and straight line launch. So what I'm saying is all that 1.5 inches isn't a fault in the right front suspension. You may need to alter both left and right sides to get it equal. I don't know how drag racers set up their wheelbase. Good luck with it.
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Has it had a fender changed? I have experienced a diff. between fender yrs., even tho they are supposed to be the same , and interchangeable , even tho they look alike .
 
I got most all of the suspension stuff from Doctor Diff. He sent us what look like stock upper control arms. The brakes are his early '70s disk kit ( knuckles, spindles, disks, calipers, etc.). I guess that makes the track width a bit wider up front? The lower control arms had new bushings pressed in. Strut rod bushings and washers are new as well.

The rear end is all good to go. The new 8 3/4" centered nicely on the new springs, and everything went together very well.

I think the project for the weekend will be to see if we can move that K-frame any in the chassis. Try rotating it a bit back on that right side and see what happens. Can't even begin to try getting it onto an alignment rack until we generate a bit more clearance by getting the wheelbase measurements closer side to side.
 
Hank Dodge said:
I got most all of the suspension stuff from Doctor Diff. He sent us what look like stock upper control arms. The brakes are his early '70s disk kit ( knuckles, spindles, disks, calipers, etc.). I guess that makes the track width a bit wider up front? The lower control arms had new bushings pressed in. Strut rod bushings and washers are new as well.

The rear end is all good to go. The new 8 3/4" centered nicely on the new springs, and everything went together very well.

I think the project for the weekend will be to see if we can move that K-frame any in the chassis. Try rotating it a bit back on that right side and see what happens. Can't even begin to try getting it onto an alignment rack until we generate a bit more clearance by getting the wheelbase measurements closer side to side.
Click to expand...

I don't see how a k frame could be off that much , unless the car has been wrecked , or u didn't install something right !
 
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