Steering issue under braking !

[RedReplicant]

So, funny story...

I put Whiteline bumpsteer correction balljoints and tie rod ends into the car a couple of weeks ago so I also threw in SuperPro caster correction and flca rear bushings into the arms since they were out.

I lowered the car to roughly SuperMiata/949 recommended height but ended up putting the front way lower than I meant to because my pinch welds up front were smashed higher than I realized at the time.

Front:
Fender to ground: 24 3/4"
Pinch to ground: 5" / 127mm (this is clearly wrong based on fender to ground delta)

Rear:
Fender to ground: 25 7/16"
Pinch to ground: 5 3/16" / 132mm

I also had the car aligned to -3.75* / -2.75* and 0 toe all around.

For whatever reason the car did not cut EPS the entire weekend. I have no explanation.

Car would not put down power in 2nd gear exit corners and was super loose after going on throttle mid corner in 3rd/4th gear corners, but I attribute that to the way higher than intended rake and the turd-ass AR1s.

Either way, interesting. We will see if it holds through the bowl at Chuckwalla in two weeks.

[RedReplicant]

I talked to the guy that makes these today: https://www.nmstec.ca/product/psc/

He said the issue is power delivery and that he was able to replicate the cut out on his bench. Apparently, the unit demands a bunch of assist at first movement then drops down, which causes a big demand draw up front and leads to the cut out. He says that his unit doesn't create the initial demand spike, which prevents the issue from happening.

[Nmstec]

Originally Posted by RedReplicant

I talked to the guy that makes these today: https://www.nmstec.ca/product/psc/

He said the issue is power delivery and that he was able to replicate the cut out on his bench. Apparently, the unit demands a bunch of assist at first movement then drops down, which causes a big demand draw up front and leads to the cut out. He says that his unit doesn't create the initial demand spike, which prevents the issue from happening.

Ohi <3 I can show the simulation upon my return home, where I create a quick input against a decent load at 50% assist, and it would simply restart the EPS module. It uses a steering angle sensor(external) along with internal torque sensor to do a quick "boost" in assist. If the load is big enough, and voltage drops below 11v, the whole unit decides a restart is in order.

[gt5759]

Here is what we have been using on several builds, I figured all this stuff was a little more known but I guess not! https://www.brunosteering.com/produc...ller-kit-epas/
They also have fancier versions with gps speed control or you can operate it with a haltech or any other stand alone engine management.

[terboboost]

Originally Posted by gt5759

Here is what we have been using on several builds, I figured all this stuff was a little more known but I guess not! https://www.brunosteering.com/produc...ller-kit-epas/
They also have fancier versions with gps speed control or you can operate it with a haltech or any other stand alone engine management.

This unit solves the problem of the power steering cutting out momentarily with high grip tires?

[gt5759]

Originally Posted by terboboost

This unit solves the problem of the power steering cutting out momentarily with high grip tires?

Yes, they run Hoosier R7's. I have some theories as to what is happening, but I am no electrical/software engineer.

[eb66]

Glad to hear there is a cheaper option that works. Thanks for sharing.

[RedReplicant]

Update on my issue disappearing with the stock EPS / stock controller, it was there at Chuckwalla. Cut in a handful of corners every lap, the bowl was terrible.

[Nmstec]

Originally Posted by gt5759

Here is what we have been using on several builds, I figured all this stuff was a little more known but I guess not! https://www.brunosteering.com/produc...ller-kit-epas/
They also have fancier versions with gps speed control or you can operate it with a haltech or any other stand alone engine management.

Ehhh not quite. His unit does have analog input, but not meant for PWM control.

[gt5759]

Originally Posted by Nmstec

Ehhh not quite. His unit does have analog input, but not meant for PWM control.

Yeah, we use the Haltech via analog voltage for control and remove the switch he sends. For most the rotary switch he sends should be adequate, the other way is just fancier and don't have an external knob. All I know is it works great for a race car application as we don't have steering cut.

[Nmstec]

Hey while I'm here, may as well compare my **** size with brunos lol.

Here's demo UI for my controllers in case someone needs slightly more features:
psc-demo.nmstec.ca/

[amirnew]

Originally Posted by RedReplicant

Update on my issue disappearing with the stock EPS / stock controller, it was there at Chuckwalla. Cut in a handful of corners every lap, the bowl was terrible.

After the suspension changes?

[amirnew]

Originally Posted by Nmstec

Hey while I'm here, may as well compare my **** size with brunos lol.

Here's demo UI for my controllers in case someone needs slightly more features:
psc-demo.nmstec.ca/

Your unit can work with canbus and not cause any fault codes?
Is there an option\map that mimic the oem steering wheel ,without the peak current at initial turn?

[Nmstec]

Originally Posted by amirnew

Your unit can work with canbus and not cause any fault codes?
Is there an option\map that mimic the oem steering wheel ,without the peak current at initial turn?

The module itself simply allows the power steering system to operate under whatever conditions you like. If you want to integrate it back into the the same car (like the BRZ and redreplicant did), I allow that, and will supply you with custom firmware that gets rid of the EPS light.

Control can be done in whatever method you like, potentiometer, canbus control, canbus VSS map, anything you can think of.

The peak current is not done by my controller, it is done directly with the OEM steering system when you do a fast input (high torque, high assist). You can simply dial down the assist with my controller, that in turn will also produce a lower current peak during fast inputs.