RLCA bearing question

Bluemustang · Jan 19, 2018

Hey suspension gurus,

I have the RLCA bearing installed on my car and my understanding is that in addition to reducing the deflection in the control arm, this bearing also increases the effective spring rate in the rear suspension. I assume from the elimination of the bind/artificial spring rate of the OEM bushing?

Is this true? If so, an increase in effective spring rate results in increased wheel rates yes?

BmacIL · Jan 19, 2018

Bluemustang said:
Hey suspension gurus,

I have the RLCA bearing installed on my car and my understanding is that in addition to reducing the deflection in the control arm, this bearing also increases the effective spring rate in the rear suspension. I assume from the elimination of the bind/artificial spring rate of the OEM bushing?

Is this true? If so, an increase in effective spring rate results in increased wheel rates yes?

No, actually the opposite. It is often perceived that way, because the elimination of the rubber there removes some damping of road inputs, increasing the rate of change of load into the vehicle. It actually lets the spring and damper work better in isolation. Pairing the RLCA bearing with a slightly lighter spring can be a good option for improving ride while retaining the responsiveness and precision gained from adding the bearing.

Bluemustang · Jan 19, 2018

BmacIL said:
No, actually the opposite. It is often perceived that way, because the elimination of the rubber there removes some damping of road inputs, increasing the rate of change of load into the vehicle. It actually lets the spring and damper work better in isolation. Pairing the RLCA bearing with a slightly lighter spring can be a good option for improving ride while retaining the responsiveness and precision gained from adding the bearing.

Ok I am kind of more confused now lol

Let's say my rear springs have a maximum rate of 1,040. Would that increase? Is there more force to dampen by the shocks?

BMR Tech · Jan 19, 2018

Bluemustang said:
Ok I am kind of more confused now lol

Let's say my rear springs have a maximum rate of 1,040. Would that increase? Is there more force to dampen by the shocks?

Nope.

Keep in mind that, the centerline of the rear spring is aft of the centerlines of the front and rear pivot points - and laterally, the centerline of the spring is actually in line with the factory rear pivot that has a mono-ball ("bearing") already installed. :thumbsup:

BMR Tech · Jan 19, 2018

Now, even if this rear was a rubber bushing, keep in mind the forces at play would absorb that deflection and during compression to achieve your desired wheel rate - bushings would exhaust their deflection before the rate at the wheel would show any significant changes. If you really break it down, we would see variations - but nothing outside of say, a 2% spring rate variance in production I suppose.

Bluemustang · Jan 19, 2018

Thanks [MENTION=10281]BmacIL[/MENTION] and [MENTION=9985]BMR Tech[/MENTION]

So basically no change in wheel rates. I'm just getting increased chassis responsiveness and vehicle reaction time?

I think that's been my complaint- that with my stiff suspension setup, the addition of the RLCA bearing has added some additional harshness because the rear suspension will react so quickly to inputs and road irregularities.

I noticed it right away after doing the bearing and the Steeda diff bushing lockout - on the highway the rear suspension reacts quickly to every undulation in the road. I noticed also a much different feel on/off the throttle as well. And perhaps the differential lockout is contributing to this.

BMR Tech · Jan 19, 2018

The primary benefit to the RLCA bearing is reduced deflection, specifically fore/after and outboard knuckle movement. Said deflection increases suspension movement, bind and erratic geometry change when being pushed hard.

Bluemustang · Jan 19, 2018

Thanks guys. I am just trying to understand the theory to see if it made sense for me to remove the RLCA bearing, go to a lighter spring, or go to a shock with greater rebound damping. Naturally Ford did not design the track suspension components with a RLCA bearing in the equation.

Ultimately I think the handling benefit may be worth it even if it makes the ride a little too responsive sometimes.

Rebellion · Jan 19, 2018

Bluemustang said:
Thanks [MENTION=10281]BmacIL[/MENTION] and [MENTION=9985]BMR Tech[/MENTION]

So basically no change in wheel rates. I'm just getting increased chassis responsiveness and vehicle reaction time?

I think that's been my complaint- that with my stiff suspension setup, the addition of the RLCA bearing has added some additional harshness because the rear suspension will react so quickly to inputs and road irregularities.

I noticed it right away after doing the bearing and the Steeda diff bushing lockout - on the highway the rear suspension reacts quickly to every undulation in the road. I noticed also a much different feel on/off the throttle as well. And perhaps the differential lockout is contributing to this.

I'm not near as adept on the theory and stuff, but one thing...have you changed the shock mounts?

In my case, it did get rid of a lot of, let's say "weirdness", on the IRS behavior...seems smoother and more predictable. It feels as if the shocks are dampening better.

Bluemustang · Jan 19, 2018

Yes I have the Steeda shock mounts. It got rid of a lot of oscillations but I still feel like it reacts too much to road undulations and irregularities. I have a lot of theories as to why but no amount of certainty about any of it.

BmacIL · Jan 19, 2018

Bluemustang said:
Yes I have the Steeda shock mounts. It got rid of a lot of oscillations but I still feel like it reacts too much to road undulations and irregularities. I have a lot of theories as to why but no amount of certainty about any of it.

I still stick with my theory.

keltymd · Jan 20, 2018

check your alignment. I have notices a slight difference in toe makes a HUGE difference it feel on the rear end

Bluemustang · Jan 20, 2018

BmacIL said:
I still stick with my theory.

That being a lighter spring?

Bluemustang · Jan 20, 2018

keltymd said:
check your alignment. I have notices a slight difference in toe makes a HUGE difference it feel on the rear end

My rear toe is off .05 from side to side, I don't know if that matters?

BmacIL · Jan 20, 2018

Bluemustang said:
My rear toe is off .05 from side to side, I don't know if that matters?

That's quite a bit actually. I'd try to get that to 0.02 difference or less.

RLCA bearing question

Bluemustang

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