Today was the first day that I drove behind someone else driving my 73 scamp. On the freeway there is a small but noticeable crabbing going on. The front is stock. The rear end was narrowed (so perches moved). 8-3/4. New ss springs. The shock plates needed a sleeve to match the hole size and pin on the leaf spring. It is not snug, maybe 1/16 inch slop. I also needed to place 4 degrees shims to correct the pinion angle. Where do I look to make changes to the alignment of the rear? When going down the road the front left is more left than it should be
Crabbing
- Thread starter Kent mosby
- Start date
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LJ67barracuda340
Well-Known Member
shim in the front spring mount???
Rear leaf springs
LJ67barracuda340
Well-Known Member
guess I should have said "put a shim in the front leaf spring mount to align the rear"
Take it to an alignment shop and have your observations verified.
There are dimensions in the FSM that might help
There are dimensions in the FSM that might help
This needs remedied as it will not hold the axle in position, 1/16 each side could be an 1/8 of movement total. Then you can start measuring. When I set up the rear of my Demon, with the springs relocated to frame, I leveled the car with the rear axle on jack stands no wheels. I dropped a plumb bob off the torsion bar anchors at the cross member. Marked the location on tape on the floor. Then did the same at the axle flange for each side. Measured from the marks at the torsion bar points to the points for the axles, on each side, then I crossed right front to left rear and left front to right rear. I did have to move the axle housing on the spring perches some to get the dimensions square. After measuring pinion angle and setting it I tacked the perches to housing. Pulled housing back out to finish welding the perches. When I had car aligned shop said it was square. Guess my point is you could follow the plumb bob stuff to see how true the axle is off the torsion bar crossmember. May take some time but might show you what is off.
Think its called “dog tracking”
See it with lots of vehicles on highway.
See it with lots of vehicles on highway.
It could be offset too. They weren't that great from the get go. Like Dana76Dart said. Have an alignment shop verify the rear thrust angle. There is some tolerance here. If the steering wheel is straight and is in the center of the steering box while driving, the thrust angle has to be pretty close.
Thanks for the tip. I will do the measurements and see where I am. I may have to machine some sleeves to perfect the fit of the pin to the shock mount plate. From there I will see how far off I am. When I have the measurements, I will post where I am to ascertain the corrective measures.
This weekend is the Car d'lane car show so I will not get to it this week. By next Friday I should have numbers
Kent they don’t have to be a perfect fit as long as they aren’t sloppy sloppy. When you welded the perches to your housing I don’t know how you measured so was throwing out what I did. As stated earlier shims at the front leaf hangers between the bracket and frame may do what’s needed. My thought process is the torsion anchors are pretty constant and if you find the dimensions off by a bunch that it might lead you to the issue.
Liberty MW
Well-Known Member
If you see the left side, that is the side you need to shim. A quick measurement of your wheelbase on each side will tell you a lot. Measure from center of ball joint to the center of the axle.
The first thing to do is make sure the car's frame rails are square according to an X measurement. If that's good, then I would measure from each leaf spring center pin to the front leaf spring mount. You'll find it somewhere.
famous bob
mopar misfit
Or , u could just tape measure from the trans. crossmember to the rear axle shaft, compare both sides , no need to make it harder than nessesary .
It is harder than that. Technically, we should be taking into consideration the height measurement too. Though, the height would have to be off a significant amount to effect the tape measurement. The so called cross measurement isn't always the tell all answer. Like I said before. Something could be offset but still be parallel to the centerline of the car. Not to mention the individual toe of the rotational plane's. It takes 3 dimensions to ultimately measure something. Length width and height
Inertia
Well-Known Member
"String it"
Many track side alignments don't have time for plumb bobs.
Here's a quick easy way to align "tracking" - done it many times .
How To Do A Wheel Alignment With String
Many track side alignments don't have time for plumb bobs.
Here's a quick easy way to align "tracking" - done it many times .
How To Do A Wheel Alignment With String
67Dart273
Well-Known Member
you can NOT tell a car is crabbing by following--unless it is really really REALLY bad and you would likely notice driving it. IT MIGHT BE an optical illusion
In my 20's when in the Navy, San Diego, a friend had a brand new Chev K20, raised 8, big tires, and ran spacers on the front for the tie rod ends. The front and rear track were different width, and you would SWEAR that it "crabbed" while following. But it didn't. It was straight as an arrow
YOU MUST measure the whole thing "for square" (by several means) to determine
In my 20's when in the Navy, San Diego, a friend had a brand new Chev K20, raised 8, big tires, and ran spacers on the front for the tie rod ends. The front and rear track were different width, and you would SWEAR that it "crabbed" while following. But it didn't. It was straight as an arrow
YOU MUST measure the whole thing "for square" (by several means) to determine
512Stroker
We are all here because we are not all there.
Adding 4 degrees of pinion angle is a bunch.
Start out with a 2* shim and sneak up on it if you need to.
Added shims makes a bigger difference on the pinion angle than u may think.
Gordie340
Member
Has car ever been in accident. Have seen cases where car body work gets fixed, but accident caused frame issue.
no, very straight body
famous bob
mopar misfit
if both ends are measured and square off the crossmember , more than likely it`ll be good to go , it is supposed to be the one centralized /most accurate point on a mopar , according to ols chrysler info .
I measured the trans cross member to the front of rear axle. Passenger side 73.75 inches, Driver's side 73.375 inches. Then I measured the leaf spring mount to leaf spring center. Both sides are 22.250. Finally, measured from axle pin locators across the body to opposite side and it was off by .250 inches with passenger side axle being longer. Next step will be to make and install a .250 shim on the driver's side and install on the leaf spring mount.. Loosening up all the rear mounts to eliminate binding when doing so. That might be a couple weeks while I address cooling issues.
Yes, you can, but that eliminates the frame rails, doesn't it? DOing it that way and you don't know "where" the discrepancy might be. .....but, doing it both ways will tell you for sure. Because since the rear axle bolts in, there could be some differences there apart from the frame.
Where is your measuring point at the front of the rear axle?
512Stroker
We are all here because we are not all there.
What does it measure from the center of the front spindle to the center of the rear axle? Both sides
another check was to look at the tire clearance . the passenger side has 3/8 inch more clearance in the front of wheel well. Not a reliable measurement but it is obvious that the right side axle is further back than the left
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