Lowering question-lower rear control arm angle?

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James OBrien

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Hey there.

I've been working on lowering my 2018 Ram RCSB 4x4 truck (hemi) and had a question when it comes to the best angle/geometry for the rear control arms. I lowered my rear by about 2" this weekend using a lowering spring, IHC adjustable control arms and added a Hellwig sway bar with belltech shocks.

What is the ideal angle for power and handling? I'm running like 1-2 degrees up, from mount to axle on the lower control arm, I'm wondering if I need relocation brackets? I'm putting out about 500 WHP.

Initial drive test was really good, got up to about 70 on the back roads with no problems, can't believe how much of a difference there is in handling and rear end bounce! Really big difference.
 

razor1

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if your not getting any vibrations, don't mess with the angles. It quickly becomes a can of worms after you start down that road.
 

Tim Garceau

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What about the track bar? Drop bracket and/or adjustable panhard? I just picked up a Belltech 4992 and am curious if I’ll notice anything bringing the bar closer to parallel.
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James OBrien

James OBrien

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Appreciate the feedback and illustration! I don't seem to have any issues so I'll leave it alone. My control arms are pretty much still at the stock alignment angle other than the lower arm being slightly angled up, they're mostly parallel
 

StickyLifter

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What you are looking for is a concept called "Instant Center" and it matters when you are trying to launch with maximum grip from a stand still, like at the drag strip. I'm wondering this myself because that is my next stop after I get all of the other things done that I'm working on. Your factory suspension is called a "four link" and it's the best suspension out there for a solid rear axle. A panhard bar is used to laterally locate the rear housing. Here are some links:




 

StickyLifter

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Appreciate the feedback and illustration! I don't seem to have any issues so I'll leave it alone. My control arms are pretty much still at the stock alignment angle other than the lower arm being slightly angled up, they're mostly parallel
See above. Couldn't get it to delete the post and add your quote. Let me know how things are going with your 2" drop.
 
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James OBrien

James OBrien

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Going great! I would say it's almost ideal for my setup at least, no wheelhop and the rear is really firmly planted. Also went with a truetrac rear diff which I'm really happy with as well. Going to put my truck up on the lift in the next few days to track down a rattle and will check things out to make sure everything is solid. Also upgraded the rear sway to a helwig. I really like these bars too, most folks go with the Core 4x4 arms, but these have worked out well for me so far. Just looked on IHCs site, doesn't appear they have the control arms any more on their own.
 
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