DanielB

I have a MY00 lowered ~1" with Ohlins and 11kg front and rear from Sakebomb Garage. It tamed the rear end but I still notice some bumpsteer at the track. I've held off going with aftermarket bumbsteer kits as there has been some debate if those parts are really durable enough for regular use - I did 13 track days this year, but still drive the car a lot for fun on the street, and often my wife is with me so reliability is even more important.

I have a chance to pick up an AP2 rear subframe complete (except for diff) including control arms, hubs, brakes for about the price of a bumpsteer kit and wanted to check a few things:
1. From my searching it appears that it just bolts in with no mods, but nobody has explicitly said that. Can anyone confirm?
2. How much is bumpsteer reduced with the AP2? Is it equivalent to adding a bumpsteer kit to AP1 and properly dialing it in? And to be clear, I'm asking for a car lowered 1", not at stock ride height.
3. Can anyone point me to graphs comparing toe curves between AP1 and AP2? I thought I had seen a thread here that covered this but can't find it now.
4. What about long term reliability of aftermarket bumpsteer kits? Does anyone have experience with them over years of daily driving and several 10ks of miles?

I usually prefer to go with OEM parts for suspension etc that's going to take a pounding (e.g. occasionally going over curbs at the track). Obviously there's more work involved to swap to the AP2 subframe, but that's not a big deal to me as the winter is coming and I'll have the time. I'm more concerned with which approach does a better job addressing rear bumpsteer and doing it with the most reliable components.

B serious

I swapped subframes for the same reason. Wanted to avoid aftermarket chassis links for reliability and simplcity reasons.

I have a MY00. I swapped in a subframe from an 07. It bolted right in. I only had to kinda massage the mounting for the charcoal canister. I think on a 04-05 subframe, the charcoal canister bolts in the same as an AP1...no welding or custom bracketing required.

It tames the bumpsteer and oversteer noticeably (I am also using the AP2 rear bar). I cannot say how much numerically. My car is quite a bit more stable now, and I can run consistently fast laps in a more relaxed mode.

I knew I wanted to do this mod after driving my wife's stock AP2 on a track for a few laps for fun.

I have OTS Ohlins with pass-thru rear mounts.

I removed the complete AP1 subframe and reinstalled a complete AP2 subframe. I did this myself in a garage. It took me...idk? 2 or 3hrs with a floor jack and power/air tools.

Car Analogy

People have reported running into frozen subframe bolts. My advice, well before the time you'll set aside for the swap, remove each rear subframe bolt to make sure its not seized. Remove it all, or at least most of the way. People have reported situations in which it broke free, but once down into the exposed threads it wouod bind up. It quickly becomes a real mess if you force the captive nut inside the frame to break free of its weld.

I would apply a little antiseize to the threads, then reinstall. Then you'll know the job will go smoothly when its time.

I would remove one bolt at a time, so nothing shifts (so you can still drive tje car until swap day).

If a bolt starts to seize up, I am sure that if you very, very carefully, and very, very patiently, work it back up to clear the threads, then back it down cautiously until too much pressure is encountered, then back up to clear the threads, never generating too much torque to snap bolt or break welds, you can slowly, eventually, clear the bolt out fully.

Patience is key. Just think how much effort it would be to cut open frame to reweld the nut, then repair frame and rust proof the repair. That should be all the incentive needed to be gentle with any seized bolts.

DanielB

Good to hear, this one is from a 2004 so shouldn't have the small canister issue you described.

DanielB

Good point, I may give this a try this weekend. I changed the clutch earlier this summer and so had to drop the front subframe. The bolts came down with no issue (dropped about 3" IIRC) and the underside is rust free. I think this car didn't see much action during the winters before me.

mojo_jojo77777

When you did this, did you reuse any AP1 components? Such as rear hubs/knuckles, lower control arm, toe arm? Because the only part I am aware that is totally different is the rear upper control arms which would have to be switched out when doing AP2 rear subframe conversion.

B serious

I bought a bare AP2 subframe.

Bought AP2 UCA's.

Bought Low low mile AP2 spindles.

Bought an AP2 rear sway bar.

Cost and availability wise (including shipping), it was the best way to go.

Everything else swapped in from my existing AP1 subframe.

mojo_jojo77777

Is there a difference with AP2 spindles? I couldnt find any concrete evidence in past that would state otherwise. I dont know if it changes suspension geometry or not

DanielB

From the craigslist picture, it looks like I'll be getting a complete AP2 subframe with upper and lower control arms, spindles, rotors, calipers etc. If they are in good condition, I plan to install all but the brakes and anti roll bar. MY00 has a stiffer bar than 2004, which I prefer.

B serious

They are different part numbers. Visibly, also different. IIRC, the mounting points for all the 3 arms are in different spots.