Street Beasts Owners: Differential "binding" Problems??

[52chevyred]

All: I am finally in the process of building my Street Beasts Cobra. I have already ran into a pretty good problem with the differential, being in a bind.

I found out the "ears" on the frame for the upper control arms were welded wrong by Street Beasts (surprise). I contacted SB support and got them to measure another frame and that's where the problem began. My "ears" are 9/16" off, shifted towards the passenger side.

I have since cut one of the upper control arm brackets lose, but still have the binding problem, which seem to be "inherited" in a Mustang style set up. And we know Street Beasts didn't build the Mustang, thank goodness!

With the frame on jack stands, diff. jacked up, and the upper control arms installed, the differential "shifts" about a half inch or more, towards the driver side. With the upper control arms off, it drops straight as an arrow.

Here are my questions: Have any Street Beasts builders had this problem and how did you solve it?

Would there be any difference in the length of the upper control arm for a 9" over an 8.8?

I am considering replacing the "stock" upper & lower control arms with after market ones, but there is no guarantee that will solve the problem.

I know StreetSnake had a similar problem (or worse) and went with coil-over's on the rear, which I'm game for that too.

I have seen where Ford "compensated" for the binding problem by using "softer" bushings, which "over time" would "self adjust". I want it "right" from the get go.

Any and all suggestions will be greatly appreciated!

Sincerely,

[Woodz428]

Although I have NO first hand SB experience, it sounds like a general geometry issue that could have occurred on any chassis. From what you have described, it sounds as if the upper pivots are located incorrectly creating the sideways shift. That would cause the bind you've described, as the upper links want to move sideways it creates a conflict with the travel path of the lower arms.

[relaxinrob]

pinion angle is off. get adjustable uppers

[52chevyred]

I'm trying to borrow a set of adjustable upper control arms now. I have bee thinking of that for a few days.

Thanks for the advice.

[relaxinrob]

My dad's CMC had the same problem. When you get the adjustable arms, set the pinion angle down about two degrees, so when it is under torque, it will be straight.

[Woodz428]

Originally Posted by relaxinrob

pinion angle is off. get adjustable uppers

If the driveshaft isn't installed, he didn't mention that it was, how does the pinion angle affect the travel of the axle housing? I understand how it could with the driveshaft acting as yet another pivot, but without it I don't.

[52chevyred]

Originally Posted by Woodz428

If the driveshaft isn't installed, he didn't mention that it was, how does the pinion angle affect the travel of the axle housing? I understand how it could with the driveshaft acting as yet another pivot, but without it I don't.

He was talking about after it was installed, however, if the arms are wrong or have other problems, that will affect that too, before it's installed.

I now have a set of fully adjustable "after market" upper and lower control arms. I am confident my problem is solved now.

I also discovered the driver side lower control arm (from Street Beasts) is bent outward, adding to the other problem. It will go in a junk pile now.

The build continues......

[Woodz428]

It sounds like the arms are basically to correct deficiencies in the construction of the chassis/parts.

[52chevyred]

Yep, you got it right and it's all supposed to be "jig welded".