Major bump steer with leaf spring sas, help

[Hagan]

Have you had an alignment after your SAS? After I did my SAS I had very bad handling. I had toe out on my truck. The front two tires were angled like this \ / going down the road. It was very unpredictable to drive. I'd hit bumps and it would throw my truck around the road. I fixed it by aligning it with toe in so my tires were like this / \ . It fixed that issue. It felt like bump steer which it wasn't.

 

[n_bannerman]

If I remember right, the caster is at about 6 degrees. Have not taken it for an alignment, just done the garage alignment on it. The weird thing about it, it caused all the bolts for my steering box to back out a couple threads after they had been loctited and I used lock washers when I put the new box on it.

 

[bobbywalter]

i have ripped the box right off the frame and busted a few sector shafts as well.


6 degrees is good.

make sure you set the toe 1/8 to 1/4 in at the front.

like mentioned above your issue sounds toe out or neutral.


if that dont do it, moving the drag link tie point on the tie rod might be a big help.

 

[n_bannerman]

When you measure the toe, do you usually go off the tires or the rotors? I used the rotors but maybe it made have to much toe?


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[bobbywalter]

measure up from the ground to the same height front and rear of the tire and measure that way. i have made tools for this....but a tape on trucks usually works good, but your pretty low.


the rear measurement for instance of 57 in and front of 56 and 7/8 would be close to 1/8 toe in....but toe in for sure.....not sure what you are but its just an example.


usually i look at the tire lugs and pick the matching spots in the center or off the rib.

 

[n_bannerman]

Okay I will have to try that. I did it off the front and back sides of the rotor when I was doing the swap, with it at 1/8 more on the front then the back.
Thanks for the help.

 

[koochman450r]

so at the rotors you were 1/8th in larger in front? Wow after you put tires on it, it will increase that to at least 1/2" Seeing as how the tires are far larger than the rotor. If you have a straight line that isn't parallel to another. Measure at 1' its off by .25" then at 8' it would be off 2". So definitely use the tires to measure toe. It gives you far more intricate measurements. And toe in or out would cause a darting drive down the road.

 

[Hagan]

Sorry to be off topic, but how have you guys measured caster?

 

[The Jester Race]

Take it to a Les Schwab on a slow weekday afternoon and ask them if they'll throw it on the alignment rack for you. They usually won't charge you anything just to see the numbers.

Or pull the knuckle off, knock out the ball joints, and put a rod through the ball joint holes in the C, then throw an angle finder on the rod. This won't give you the most accurate measurement since there wouldn't be any weight on the front end, but it would give you a ballpark measurement.

 

[n_bannerman]

I was told to use an angle finder in the top of the knuckle or on the flat spot on the diff when I was doing the swap.

 

[n_bannerman]

Fixed the toe on the front end and caster is good so I think it's time to make a track bar seems I will need one anyways when I link it, hopefully in the next few weeks I can get the parts and materials for it.


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[bobbywalter]

if the trac bar dont do it, the tie in point may be the solution.


having it inside the spring with as low and flat you are could make a significant difference ime.