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Old 03-23-2011, 08:53 PM
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YerDugliness YerDugliness is offline
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Join Date: Sep 2006
Location: No city...only 118 residents in Manter, KS
Cobra Make, Engine: Cobra Auto Works body, Ron Godell Racecars chassis, 1989 Mustang GT 5.0 HO (converted to carb), W/C T-5, 3.73's in a Ford 9" Traction-Loc.
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Default Need advice on adjusting a parallel 4-bar rear suspension

I just crawled out from under the Cobra, having replaced all the 15 year old plastic bushings with graphite impregnated urethane. In the process I had to remove the bars and when I put it back together I went to great lengths to ensure that the longer lower bars were both the same length and the shorter upper bars were both the same length. When I put it back together I found that I had to lengthen one of the shorter upper bars in order for the bolts to fit through the brackets on the rear housing.

Is this going to be a problem? I worry that the differential housing might be in some kind of a bind, or that perhaps the wheelbase on the driver's side might be slightly greater than that of the passenger's side, or that the pinion angle might well have changed enough to put the U-joints into a bind.

These are nice pieces.....one merely needs to loosen the jam nut on each end of the bar, and then the length of the bar is quite easily adjusted, much like the way a tie rod adjusts.

So, here are a few questions:

1. Will a decent front end shop be able to make sure that the wheelbase is the same on both sides?

2. I do have an inclinometer, and I also have plans on lowering the engine (Mustang convertible motor mounts will lower the engine by 3/4", I'm told), so at some point the pinion angle will need to be adjusted to match that of the transmission yoke. Is it better to use the lower bars to adjust the pinion angle, the upper bars, or does it need to be some combination of the two?

3. How much of a problem is the manner in which the upper bars had to be different lengths? Logic tells me that as long as I had one side tightened up (the passenger's side), adjusting the bar on the other side so that the bolt slips through the bracket and the sleev smoothly didn't harm anything, and in fact might have eliminated any bind I might have induced had I attempted to move the rear housing around so that the bolt would fit without the bar needing adjustment....but a little knowlege is a dangerous thing in matters such as these !

I would also be grateful if you'd let me know if there were any "How To Adjust Your 4-Bar Suspension for Dummies" books out there. Magazine articles would also be welcomed....any "how to DIY" type info on getting these suspensions right.

Thanks!

*Note to moderators: I looked all over the place for an area where suspension issues would be placed, this seemed the best. If I missed something (a distinct possibility at my age), please feel free to move this thread to the appropriate location. TIA!!

Cheers from Dugly
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