Suspension overhaul: what "needs" doing?
 

Hello all, quick background on all potentially relevant details:

• 2015 FR-S @ 85,000 miles
  • Currently DD
  • Preparing for dedicated track build
• JRSC C30
• Tein Flex As @ 1" lower all-around, stock preload/camber/toe/damping
• Whiteline Bushings:
  • Rear lower control arms
  • Differential
  • Transmission mount

I'm looking for some advice on a few suspension topics to back up the research I've done so far.:

1. Considerations w/ lowered vehicle
   I've read a lot of anecdotal information that a lot of odd things can start happing with a suspension after lowering, especially in the noise and wear departments. I've seen some coilover kits offer to come with "special" replacements for other suspension components specifically for those intending to lower their vehicles. So, question: if I'm lowered an inch, what components of the front/rear suspension (besides the ball joints, I'm already familiar with 'em) *should* be replaced with appropriate parts in order to better support the new geometry of the suspension?
2. General bushings replacement
   With the vehicle being @ the 85K mile mark, a lot of the bushings are starting to look rough. And if I'm going to take the time to replace some, I'm replacing them all. And if I'm replacing them all, I'd like to go the OEM+ route. With that in mind, I've ID'd the Energy Suspension Master Kit as a good looking route to go. Is this a reasonable option for the price point, or should I be looking higher/lower for the best bang-to-buck?
3. CV axle rebuild/replacement
   Both CV axle boots are starting to leak, one very badly. I am planning on additional horsepower down the road, so am vaguely interested in upgraded axles entirely (eventually). However, for now, I'd be content replacing the boots and grease. Is this a reasonable course of action? Should I just replace the entire axles with OEM in the meantime? I'm not particularly interested in dropping large $s on upgrades at this point. Is the cost-to-effort ratio there for just replacing boot + grease?

Thanks for any help!

I do my best to avoid poly in locations that move/pivot, only real exception being swaybar bushings. I prefer OEM, hardened rubber, and spherical bearings.

So, dedicated track build. What kind of tires and what size are you running? Are you planning on competing anywhere and do you need to worry about classing?

- Andrew

Interesting, have gathered a generally positive opinion at large on the durability of poly bushings. Particularly as I'm interested in the highest stiffness/lowest energy loss setup.

Currently running stock-sized Firestone Firehawk Indy 500s (17x7.5) mounted on 5x100 35s. They're on their last year of use likely, and I'm open to suggestions on best choices for track uses.

I'm most interested in competing in the power:weight class after probably a solid 6 months of self-pacing to get comfortable with the ultimate setup. Planning on doing a full non-essential strip and roll-cage install; everything from AC delete to full interior trim removal and glass-->polycarbonate (Lexan). Very, very up in the air at this point on deciding between an LS swap (yes, very original), or gong full send on the FA20 and going forged short block + internals running E85. Could consider upgrading from the super to a turbo, however I settled on the super route originally because I wanted to preserve the fundamental FA20 characteristic. If I'm sticking w/ an FA20 build, I'm staying committed to that intent.

Your in Vegas right? Would you car to see how my car drives with spherical bushings?

I would be interested! Have you ran poly vs. spherical in your build? Or only spherical?

I have the whole SPL Parts catalog on the car. I have SuperPro steering rack and diff outrigger bushes. I am waiting to install the diff mounts and subframe bushes.

I have not experienced poly bushes in the suspension arms.

If this is your first year extensively tracking your car, I would focus on the basics: reliability and safety.

So, it's unlikely that you'll be able to do a complete motor revamp and/or swap and still get decent and consistent track time in (and then troubleshoot motor issues at the track when you should be focusing on driving). Make sure what you have now is working well and stick with that while you get comfortable. Just my opinion.

For suspension, yes going through your bushings on your 85k mile car is a great thing to do.

If you want to maximize on track time and driver improvement, the easy solution is replace everything with fresh OEM.

If you want an improvement over OEM, I'd replace most with OEM and strategically replace a few key bushings by replacing the full suspension arm. Rear toe arm, rear trailing arm, rear LCA. You can go farther after that...but that's a big chunk of the potential improvement in bushing replacement and adjustability. Worry about the rest later.

Get a good performance alignment from a good shop.

Good track brake pads and track fluid. Probably worth getting some fresh OEM brake lines or stainless if you really want to.

Lots of options for tires. If you're sticking with 17x8 wheels then 225/45/17 Falken RT660s are one good way to go.

Remember...more complexity, more parts, more things to worry about, potentially less time on track driving.

- Andrew