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Old 05-19-2016, 09:18 PM   #1
driving smoother faster
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dp1 track suspension reinforcements (bushings, links, sways, arms)

Pay it forward...

This thread is not about coilovers/springs. It's about suspension reinforcements (bushings, links, sways, arms) that enhance driving experience at the track. If you (1) track your car, (2) often drive near the limit of traction, (3) use track alignment of at least -3f/-2r, (4) already replaced stock dampers, (5) run sticky tires with UTQG 200 or below (r-comps or slicks), (6) don't mind added Noise Vibration Harshness (NVH) in exchange for better feel/control, and (7) have already made upgrades to the stock bushings, links, sways, arms, etc., that made things better...please share your experiences

@Racecomp Engineering - "...bushings are often overlooked and I just have to shake my head when I see a dedicated track car with stiff springs and high levels of grip on stock bushings. It should be a fundamental change for every track car. With high grip comes noticeable bushing deflection and unwanted dynamic alignment changes. They're partially a "feel" mod since the car is more consistent/connected/solid but they will make the car faster too."
- "...bushing flex is real. The car actually rolls a little more with the stock bushings on sticky tires even if you're on fancy coilovers. It's nice to know exactly what the wheel is doing and taking bushing flex out of the equation is helpful."
- "...we replaced every bushing on our car...started with Group N STI parts (less NVH penalty, expensive, more difficult to install) and then Whiteline, and a few custom spherical bearing parts."
- "...we've not had problems with whiteline bushings squeaking when installed and properly lubed at the time of install."
- "...replace all bushings with pillowballs."
- "...the often overlooked rear upper control arm is very worthwhile [...bushing replacement]. Whiteline sells an adjustable (camber) and a non-adjustable poly bushing." also "The WL upper control arm bushing replaces a soft squishy OEM bushing in a key location. Adjustments here do not affect anything else either. Real pain in the ass to install and adjust though. I think the ideal way to go is to install the fixed WL bushing for the upper control arm and then get an adjustable lower control arm."
- "'ll feel some interesting things when you replace soft bushings with poly or solid bushings...enough that you may adjust your damping. Not "equivalent" to increasing damping but some of the things you thought were one thing actually were the bushings deflecting."
@CSG Mike - "...replacing all the bushings with sphericals/solids in the arms, and putting in collars for the trans mount, diff mount, and subframes. It makes EVERYTHING more direct. Also replace the engine mounts, although how stiff you go here is more subjective then the rest of the aforementioned."
@7thgear - "...bushings are the best mod you can do for your car if you're looking at improving feel and response, no doubt about it, the NVH increase is negligible and quite honestly greatly over exaggerated by the online community."
@yomni question "...If you had to recommend a group or set of bushings to a beginner for upgrading, what would you say was the best bang for the buck to eliminate some o that elastic feeling in corners when grippier tires have been added. Is this one of those subjects where you should replace them all or you could do the rear subframe bushings then front control arms...?" was answered by @Racecomp Engineering "...Front: Front control arm (front) bushing + Whiteline ALK + steering rack bushings; Rear: trailing arm front + crossmember inserts + diff bushings + rear upper control arm bushings (either the camber adjustable or the fixed). I bolded the ones I recommend most and are the better bang for the buck. The others are good too. Might as well do as many as you can stand at the same time since they're almost all kind of a pain to install."
@stockysnail - "...No issues with my car and all the bushings I have from Whiteline in my car (I have all of them) after two winters here. See my build thread for the list. No salt on the west side of 'murica however."

Rear subframe inserts
@gramicci101 - " Whiteline's subframe insert video and look at the two diff carrier bushings. They bounce around like they're on a trampoline. Replacing these bushings or getting inserts for the OEM bushings effectively removes any on/off throttle thump in the rear end."
@7thgear - "...if you're not doing autocross "stock class", then I would highly recommend rear subframe bushings... on ANY car, you will feel the improvement and the NVH is not important, you will be very happy that you've put these in."

Diff inserts
@dp1 - "...good next step after the subframe inserts. Can add to the whiny/buzzy ride on highway, especially around maintenance throttle with my OS Giken 1.5 LSD but not very loud and well worth it for track. Not sure if any other of my reinforcements affect this sound."
@DarkSunrise - "...I'm not sure if I got lucky or what, but there's barely any increased NVH [with Whiteline KDT925]. My wife couldn't even tell. I don't have any other inserts or bushings though."
- "...they (WL diff inserts) basically fill the voids in the OEM bushings with polyurethane to minimize flex. Whiteline also makes replacement bushings (KDT924), but those are more expensive and would require you to drop the diff cradle and press them in."
@was385 question "...I keep going back and forth on the diff bushings. Half the people seem to say that the added NVH isn't bad, half say it's awful. Do you have any experience with the whiteline or a similar kit with regards to NVH?" was answered by @Racecomp Engineering "Yes and IMO it's fine. My tolerance for transmission NVH is that I don't mind gear whine that much but can't stand clunks or too much vibration. Others may be different..."
- Whiteline differential insert bushings review
- KDT 925 installed

Transmission inserts
@Who8myrice - "...I have whiteline transmission insert. Inside the cabin got louder but my gear feels great."

Steering rack inserts
@Who8myrice - "...also have Cusco steer rack bushing. Difference is very little but my steerwheel feels tighter, I think I felt more from Trd door stabilizer then this."

Engine mounts
@dp1 - "...limit engine movement and reduce wear on certain parts. Can increase NVH quite a bit depending on solution. Some could melt from proximity to exhaust pipes."

Adjustable endlinks
@dp1 - " fine tune swaybars, especially when trying different mounting locations in aftermarket rear LCAs (i.e., SPL LCA has three link mounting holes to choose from). Two of my four Whiteline endlinks weakened recently and were replaced before failure. After seeing several videos with endlinks failing in turns, I am looking to replace them before the next season with surdier heim joint options."

Adjustable toelinks
@dp1 - "...allow fine adjustment of toe."

Front control arm
@Racecomp Engineering - "...bushings or full replacement control arms with heim joints are excellent."
- thread commenting on fitment of RacerX front control arm

Rear Lower Control Arm (LCA)
@dp1 - "...very useful for dialing in negative camber in the rear and for sway bar adjustments. Strong aftermarket LCAs can aid in bending of a subframe in an accident."
@Sleepless - "...(SPL LCA)...the effective spring stiffness is altered by choosing one of the three shock mounting holes. In other applications this is usually expressed as a percentage relative to stock which I presume is the center hole...Got the answer from SPL. +/- 6% stiffness. Pretty useful LCA"

@CSG Mike - "...sways are used to tune the under/oversteer balance of the car to your preference. In an autox environment, you'll probably want a beefy front sway, since you'll likely value quick transitional speed over sustained cornering speed."
@Racecomp Engineering - "...I don't like running a larger rear bar without a larger front on this car. But maybe try it and see what you think. I suspect you'll like it more with a bigger front bar."
- "...we generally like a 22mm front or a 25mm hollow. Our own RCE bars are 25mm and 19mm (hollow so about 22 front and 16mm solid equivalent). That works well for most set-ups but if you're going very stiff on springs you may want to go smaller. Adjustable bars are recommended"
@ultra - "...On the topic of swaybars I'd be careful what you choose. I'm running the Hotchkis bars, which are very stiff compared to stock (over 200% stiffer at the softest settings). They're good match for full R compound rubber and even more aggressive alignment settings on a track but not so good on the street, with street tires and a less aggressive alignment. They do keep the car extremely flat but I get a lot of crosstalk on bumpy surfaces and the breakaway characteristics are very abrupt. I'll be swapping back to a much milder swaybar combo soon. I'd actually recommend swaybars as an absolute last step in the 'mod chain' but that's just me. If you're super keen offense dialing in your car I'd speak to a pro and get them to recommend something tailored to the other parts already on your car and your own specific use cases."
- Sway bar option list

Rear Strut Tower Bar
@Calum - "...A rear strut tower brace on this car is a complete waste of money. On the front they're still open for debate."

Roll Center/Bump Steer Correction Kit
@troek - "...i just put on the whiteline roll center kit, with my rsr super down springs, its a very noticeable difference in steering response, and the front end doesn't dip down under sharp cornering like it did before. very worth it in my opinion. i didn't think i would notice anything but i did."
@Racecomp Engineering - "...the bumpsteer kit is not very useful at stock ride height. Front control arm bushings including the ALK would be much more effective. Not sure on which costs more points for you but the bushings are the better choice."
- "...The WL RCK kit will not hurt your handling at stock ride height. There won't be much if any benefit either. I say go for it if you realistically plan on lowering the car later."
- "...The Whiteline roll center kit is NOT primarily for bumpsteer. It is a roll center adjustment kit that includes tie rod extenders. With just the roll center adjustment part of the kit (the ball joints), you induce some bumpsteer by moving the tie rods out of plane. The tie rod extenders minimize that change. Anyway, yes there is a small benefit to the WL kit. It is not very dramatic, but it helps."
@Tor question "...How much lowering before the Whiteline roll center and bump steer correction kit becomes a worthwhile upgrade? How little of a drop before it becomes contra productive?" was answered by @Racecomp Engineering "...It becomes noticeable at 25mm of drop. Even more so at 35mm. I would use it with a 20mm drop, but not any less than that."

Please buy from vendors who support us and who help us make optimal choices (i.e., RacecompEngineering and CounterSpaceGarage). Examples of parts they carry or can source: SPLParts, Cusco, Whiteline, Perrin Performance, Racer X Fabrication, etc.

Additional resources on the topic:
Discussion: Upgraded Bushings & Mounts

My suspension reinforcement upgrades (others are on my build page, see sig link):
Cusco 956 464 AV - Front lower control arm front spherical bearing.
Cusco 692 464 BV - Front lower control arm rear bushing.
Cusco 965 464 LV - Rear upper control arm front bushing.
Cusco 965 464 IV - Rear upper control arm rear bushing.
Cusco 965 928 A - Differential mount collar.
Cusco 965 927 A - Rear subframe collars.
Perrin engine mounts.
Perrin transmission support.
SPL Adjustable Rear Toe Arm.
SPL Bumpsteer Adjustable Front Tie Rod Ends.
SPL TITANIUM - Rear Traction Arm.
SPL Titanium Rear Lower Camber Arms (LCA).
Whiteline KLC179 front/KLC182 rear adjustable endlinks.
Whiteline W23448 rear sway bar - mount bushing 14mm.
Whiteline W23447 front sway bar - mount bushing 18mm.
Whiteline KBR38 rear brace - sway bar mount support.

Grouped in Stages...

Stage 0 (stock)
Limited camber adjustments, body lean, some rubber bushing slop, potentially limited lifespan of stock dampers.

Stage 1 (fix few key areas)
- $2k+ damper upgrade.
- Camber plates in front (if dampers don't have them) and rear LCAs to get optimal track/ax camber/toe.
- Transmission/subframe/diff/ inserts or collars and engine mount to remove slop, if NVH is not a concern.

Stage 2 (complete suspension refresh)
- $4k+ damper upgrade
- Everything in Stage 1
- Everything else noted above
- Potentially upgraded sways (i.e., for AX)

What suspension reinforcement upgrades worked best for you or your customers?
track it, mod it, track some more

Last edited by dp1; 10-02-2016 at 01:47 PM.
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The Following 14 Users Say Thank You to dp1 For This Useful Post:
7thgear (05-27-2016), Bonburner (11-06-2017), Calum (05-23-2016), cbryant514 (07-20-2017), CSG Mike (05-23-2016), Deep Six (07-08-2016), Hostile_Kittens (05-24-2016), Jonsey (05-27-2016), kch (05-24-2016), Pekingduck (07-10-2016), Racecomp Engineering (05-24-2016), Sleepless (05-24-2016), smg1138 (05-16-2017), troek (05-24-2016)