Petah78

I know the best way to correct this is to get an OE AP2 rear subframe but they are so hard to come by around here. Couple questions:

https://speedfreaksusa.com/i-2379057...000-ap1-2.html

1. I wanted to know if this product from J's is the correct part to correct bump steer on a mildly lowered AP1?
2. Any worries about the fakes in the market?

TIA

B serious

Yes, a height and length adjustment to the RTA is a way to adjust bump steer. You need to measure a bunch if different combinations to determine where your bumpsteer ends up.

Guess...measure...guess again...measure again....and so forth.

AP2 subframes are available on eBay, if you want a surefire solution with zero measuring. You would also need the AP2 spindles and UCA's to go along with it.

To answer about fakes...Speedfreaks is a reputable seller, so I'm sure they'll sell you genuine parts.

I am using Megan racing RTA's and they work fantastic. Do the J's have additional features?

Also, why are you trying to delete the bump steer?

Petah78

Thanks for the reply, i thought this was going to be a bolt in and be done kind of thing. If there is such a process involved, i will likely skip this route.

I just want to make the car more predictable at the limit but having said that, this can be mitigated by smoother inputs. And no, i am not sure if the J's offer anything additional to the Megan offering. I will take a closer look at the AP2 option.

SheDrivesIt

Stopwith all the TLAs please, if you can. It makes it a whole lot easier to read. Guessing RTA is rear trailing arm
TIA

B serious

What is a TLA? Mybad...is something I'm doing making it tough to read the post?

engifineer

lol Three Letter Acronym ... which ironically was posted as ... a three letter acronym requesting that you dont use three letter acronyms

engifineer

Honestly when I first got my AP1, I thought it was twitchy as hell. I love the way it drives now. Having autocrossed it and spent a lot of time on track with it, I never even think about bumpsteer correction any more. In some ways you can use it to your advantage, especially on an autox course. But I know it makes things feel pretty sketchy in some applications. But smoother inputs and getting comfortable with controlling weight transfer helps a ton.

I never did it originally because there is no bump steer correction method that was SCCA compliant for autocross in STR, so then I just got used to it and use that knowledge in how I drive the car. Lift/brake a bit to initiate mild rotation, add throttle to transfer weight to the rear and plant it and go. So now even for track driving I just like it the way it is. The same mistakes (lifting when you should not be) punish you in any car but they are just amplified a bit on the AP1 setup

B serious

Ha! Ironic indeed.


Bruv, are you FR ILR RN? I have to call UCA's by their Christian name?

RTA is Rear Toe Arm.

AP2 is referring to my friend Albert Persimmons the 2nd.

Yeah, funny thing is that when I used to track my AP1, I never did any kind of bump steer mitigation.

I didn't really know any better, so I just drove it in its twitchy form, with the stock MY00 sway bars.

I knew that the difference between going a little faster vs spinning out was razor thin, but I just never really thought about it. A few track people talked about swaybar changes to settle it down, but I just shrugged it off.

After I drove an AP2 on the track for the 1st time, I was blown away by how stable it was. It was inherently faster, but that was just because of the additional torque and power. The big thing was how consistent the laps could be because it was so stable.

That lead me down the path of trying to figure out where the stability was coming from. I learned it was the changes in bump steer and instant centers, as well as less UCA deflection.

I didn't get around to AP2 subframe swapping my AP1 for years. I think I tracked it once or twice. Didn't go any faster, BUT ran the fast laps very consistently.

Then I bought an AP2 track car because it fell into my lap.

My AP1 is now 100% street car since its been repainted. I never push the limits of the car too far on the street, so its all a bit useless.

Anyway, that's my cool story, bro.