Whiteline Positive Traction kit KTD922 ride height increase?

[Plumbus]

I got the ktd922 crossmember/subframe bushing kit and I'm just wondering if it will increase ride height of chassis in relation to the subframe/suspension/wheels? You would have to lower a bit more than normal to achieve the same wheel well gap I pressume? Not a huge deal I suppose, but I think you'd want to prevent lowering too much so as not to upset suspension geometry. I'm installing regardless but I'm just curious since I haven't seen anyone discuss this.

video to show bushings in action

[Capt Spaulding]

Many thanks for the video. I'm not sure who created it, but it is a great help for those of of us who were/are uneasy about the installation.

[ZDan]

Originally Posted by Plumbus

I got the ktd922 crossmember/subframe bushing kit and I'm just wondering if it will increase ride height of chassis in relation to the subframe/suspension/wheels? You would have to lower a bit more than normal to achieve the same wheel well gap I pressume? Not a huge deal I suppose, but I think you'd want to prevent lowering too much so as not to upset suspension geometry. I'm installing regardless but I'm just curious since I haven't seen anyone discuss this.

Ride height is controlled much more by the springs. If anything, since the subframe mount stiffeners *lower* the subframe and inner control arm mounts, they should *lower* ride height but only a smidge.

I just had these installed last week and didn't see any visibly noticeable change in ride height.

[Plumbus]

Originally Posted by ZDan

Ride height is controlled much more by the springs. If anything, since the subframe mount stiffeners *lower* the subframe and inner control arm mounts, they should *lower* ride height but only a smidge.

I just had these installed last week and didn't see any visibly noticeable change in ride height.

Just as a thought experiment, let's imagine you put a 1 or 2 inch thick bushing between the subframe and chassis. Would the subframe lower so it is basically scraping the pavement or would the chassis raise so it looks like a monster truck? That's what I'm trying to find out, being aware that the effect is probably negligible in the case of the whiteline bushings.

[ZDan]

Originally Posted by Plumbus

Just as a thought experiment, let's imagine you put a 1 or 2 inch thick bushing between the subframe and chassis. Would the subframe lower so it is basically scraping the pavement or would the chassis raise so it looks like a monster truck? That's what I'm trying to find out, being aware that the effect is probably negligible in the case of the whiteline bushings.

No. Lowering the subframe also lowers the inner pivots of the control and toe arms. This in turn will slightly lower the spring/damper, which will lower the car relative to the ground.

[Plumbus]

Originally Posted by ZDan

No. Lowering the subframe also lowers the inner pivots of the control and toe arms. This in turn will slightly lower the spring/damper, which will lower the car relative to the ground.

Ok, so the subframe would lower relative to the wheels, the control arms would follow and so would the struts, also lowering the car a bit in the process. The effect is similar to what happens when you lower the front of the car, making a roll center kit necessary.

Regarding lowering the car with coilovers, do you think the rear would benefit from using the upper hole in the RS-R rLCA to correct roll center just how the roll center kit corrects geometry up front?

https://www.rs-r.com/product/rs-r-re...-control-arms/

[ZDan]

Originally Posted by Plumbus

Ok, so the subframe would lower relative to the wheels, the control arms would follow and so would the struts, also lowering the car a bit in the process. The effect is similar to what happens when you lower the front of the car, making a roll center kit necessary.

Roll center kit isn't *necessary*. I'm not running one...

Regarding lowering the car with coilovers, do you think the rear would benefit from using the upper hole in the RS-R rLCA to correct roll center just how the roll center kit corrects geometry up front?

Using the lower hole won't change the suspension geometry, but it would slightly change ride height for a given coilover length. Might overcompensate, not sure. I'd just install bushings and change nothing else and see where you're at. Maybe I'll measure my rear ride height this evening and report back...