Why you need rear control arms

[SierraBronco]

Wasn’t me who created video. Just found it on my YouTube feed thought I would share. He breaks things down pretty easily for some of us cavemen to understand. Yeah you could probably argue arcs and all kinds of trig and calculus but most aren’t that smart or willing to do a video on it. Big props for him willing to take time to do a video and his video editing skills are quite good!

I agree with @5GENIDN 100%

But most people aren’t interested in doing a deep dive on how their suspension works. It’s so easy too! You just ask @87-Z28 and he gets you learned.

Homie that made the video needs to chill on the sound effects and portraying his dog as hateful. Doggo loves him. Cuz dog.

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[Brian_B]

Um, why does pinion angle matter as much? Our Broncos have CV (constant velocity) joints in the drive shaft, not U-joints. Speed in = speed out regardless of angle.

They still have an internal arrangement to adjust for angle - and the closer to neutral you can get them, the less heat and noise and wear they will produce.

 

[87-Z28]

They still have an internal arrangement to adjust for angle - and the closer to neutral you can get them, the less heat and noise and wear they will produce.

would be nice if the oem CVs could handle that angle.

 

[2023bronco]

Um, why does pinion angle matter as much? Our Broncos have CV (constant velocity) joints in the drive shaft, not U-joints. Speed in = speed out regardless of angle.

Yeah, cv joints allow for pretty aggressive angles. My lowered Chevelle needs a cv driveshaft (cv at the trans end, which allows for just 0.5-1 degree at the u-joint end). Before I was running it broke back and the angles were too severe and had a vibration. I don't know what the stock cv angles are in a Bronco, but I think you'd have to lift it pretty far to run into an issue.

 

[Brian_B]

but I think you'd have to lift it pretty far to run into an issue.

About 2.5" if you are using tophat spacers.

Everyday driving will be fine - the CVs will have some angle but be ok. But if you slide the entire coilover/CV assembly down with too many tophat spacers, the angle when at max droop can be excessive and pop the CV out. So most places will say somewhere between 2 and 2.5" is ok, but beyond that, you are taking a risk.

Stock m190 CVs I think are good up to 18°. I've heard m210's are better for angle, but I don't know what the official number is. Spicer Extreme/aftermarkets can hit 28° (I've heard Ford Performance ones - not the Extreme 32-splines, can handle more than 18 but I dunno what the max angle on them is or if it's any different from a stock M210 CV) - but it's that max droop condition you really need to look for.

As far as rear axle goes - I haven't seen a number on that one, but heard somewhere around 30°. Again, it would be full droop that would be the main concern, that's going to be the "omg you immediately broke it" figure, whereas just natural ride angle will contribute to long term wear and noise.

 

[87-Z28]

For front OEM LCA geometry the max shock extended length is 24.3”. After that you get some binding in stock CVs at full rebound. Most aftermarket struts do not exceed 24.3”. The stock struts have an extended length of 23.3” so it is not wise to add a spacer that is more than 1”. That gives about 1.6” lift at the wheel due to MR.

A lift of 2-3” at the wheel is best achieved with only 1” shock length extension and the remaining from the spring via a combination of rate, free length, and preload. Goal being to get static ride height near shock mid stroke. A 3.2” wheel lift only requires 1” from shock length and 1” from spring, due to motion ratio. Most of the aftermarket coilovers accomplish exactly this to get 2-3” of lift (ride, king, fox).

 

[dgorsett]

So, I didn't watch the video, but I'm betting maths is why.

Bank account balance > CA cost = yes

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