Bilstein B8+RCE Yellows vs Tien Flex A's
 

Redline has the Flex A's for 899$ which I am not sure how they do but with tax its just under 1K. Already have stock dampers from 2017 non PP dampers and RCE yellows. One is leaking so I am trying to gauge how much better each setup would be over current setup? Or just to replace the current damper that's leaking and call it a day. Then add peddlers top mounts for extra camber.

Separate question. For the peddlers top mounts, would a good alignment shop be able to use the Peddlers + crash bolts to get an even negative camber of 2 to 2.5 degree's on both sides?

I had the RCE yellow + PP shocks and wasn't really happy with em. Thought they kinda rode like shit over bad roads. On decent roads they were ok i guess.

Havent tried pedders top mounts but my RCE SS1s came with nice top hats that are holding up well and haven't made any noise in the 15k i've had them installed. And with the crash bolts you can easily get 3+ degrees if you want it.

Decent coilovers are a good upgrade over lowering springs. Am i saying my car rides like an 80's cadillac over bad roads.. hell no but it doesn't feel like the damping can't keep up with the constant undulations in the road now.

Wow that’s a great deal. Hope to see more of that this month. I’d go with the Flex A’s. Heard a lot of good things about them. You’ve had lowering springs already so why not try some highly rated coilovers.

Why pedders? There are malady good top hat or camber bolt options.

I have whiteline camber bolts by themselves and have -2.5 in the front.

I have decided I rather just get a new OE damper which was under 150$ and save the rest of the money for other small suspension upgrades.

i'd usually replace dampers at least as pair though, at least if other one has already been through noticeable mileage.

Use Bilstein B6 with RCE Yellows FYI.

- Andrew

Did you have camber plates? PP struts have limited bump travel, with RAceseng plates and Swift Rspec springs (-1.25" lowering) I would bottom out the struts over the smallest bumps, BAM! My car rides infinitely better with Bilsteins vs. pp/Sachs dampers.

At that time i didn't. I didn't bottom them out at all.

Hell when the coilovers crap out i might try the bilstein b6/yellow combo, i have heard good things.

Why do you suggest using the B6 with RCE yellows? Is it because the drop is too mild?

Valving is the same between the 2, B8 has slightly less droop (extension) travel, presumably for short springs that otherwise would be loose. That's not needed with RCE Yellows or most springs for that matter.

RCE Yellows work well with either one, but droop travel is good to have.

- Andrew

Excuse my ignorance as I know very little of non-adjustable struts, but wouldn't B6 work well with short springs if you used helper springs with them?

In theory yes, but not really possible with an OEM shape or fitment spring...helper springs are only available in the smaller standardized coilover shapes/diameters.

- Andrew

What the man said ^^^

I got B8s to go with ~1.25" lowering springs (Swift R-Spec) to ensure they didn't unseat at droop, then found that others have used these springs with B6 without issue. No other differences between B6/B8 other than droop travel. Still it's nice to get tires off the ground with fewer pumps at the handle with the B8s! But unless lowered 1" or more I'd definitely go B6 for droop travel.

Using B6 or B8 will give different spring preload, right?

After having RCE Yellows with PP shocks, (NOT GOOD) and having tein Flex As now, it's a no brainer. Coilovers are the only way you're going to get a properly matched springs and damper valving. Otherwise you're just ballparking and settling for a solution for no apparent reason. Just go buy yourself some coilovers

Did you have camber plates too?
I find this a bit surprising as my only problem was with bump travel. To the small degree I was able to "fix" it (spring spacers brought front ride height up from around -1.5" to -1.25", factory bump stops cut down from 60mm to 25mm), I saw improvements. I would have guessed that with the increased bump travel available from springs that don't lower the car as much, combined with factory or Pedders offset top mounts (instead of camber plates with roller bearings that take away bump travel) that the ride should be fine, or at least close to stock (which the stock Sachs/PP dampers do have excessive high-speed compression damping).

You'd like to think so... In my experience, unless you have high-$$$ dampers with separately adjustable high- and low-speed compression and rebound damping, you might be better off with good non-adjustables.

Ferinstance, I like the high- and low-speed rebound and compression damping *better* with non-adjustable Bilstein B8s on my BRZ than I could manage with single-adjustable Ohlins Road-and-Track setup on my FD, which to me could have used a bit *more* compression damping for the level of low-speed rebound.

My friend has Ohline R&T on his FD and my Flex A's are better. I've never ridden in a car with shocks and springs that rode better than what I have now and had the versatility to stiffen up to a track-worthy setup.

As far as camber plates, no I didn't. The front shocks had too much bump for the twice-as-stiff as factory springs. I don't think it was a bump stop issue. The whole setup goes out of whack when you do mods like that. I'm sorry but you can't just throw random springs and shocks together and expect them to work properly. I've learned this the hard way and I stopped going that route. Even if Bilsteins are great shocks out of the box. My friend has Tein Flex Zs and I'd run those over a bilstein and random spring rate setup any day.

RCE Yellows are ~59% stiffer front, ~43% stiffer rear, not twice as stiff.

In my case, running Swift BRZ Sports which are only 34% stiffer in front, 43% stiffer rear, I did not feel like I had insufficient damping front or rear. At the track the setup was 85% OK, and surprisingly competitive. As stated my biggest issue was lack of front bump travel with 1.25" lower ride height and further ~3/4" loss of bump travel due to camber plates...

Worth noting that you only have to change damping by the *square root* of spring rate change to have exactly the same %age of critical damping. What this means is that a given set of dampers can work quite will for a surprisingly broad range of spring rates.

That said, I could see that with +59% stiffer front springs (RCE Yellow) you might feel closer to being "underdamped" with factory PP Sachs struts. I did not feel that way with the 34% stiffer front Swift BRZ Sport springs.

The Bilstein B8s honestly feel about perfect on road and track with the Swift Spec R springs I'm running now (+55% stiffer front springs, +68% stiffer rear vs. stock '17 BRZ).

My impressions, fwiw...

Welp, I highly disagree. You said you had to get camber plates and cut the bump stops, which I did not do. And most people won't.

My impressions were a pushy and crashy front end.

If you want enough camber to compete on track, you're gonna want camber plates for sure. Or at the very least offset upper mounts and maximum camber bolts. This car *needs* more than 3 degrees front camber at the track, preferably more like 3.5 degrees...

What was your front camber?

"Crashy" to me implies insufficient front bump travel and/or too much compression damping. Mine was *definitely* crashy upon initial installation, improved quite a bit by raising the front 0.25" and cutting down front bump stops from 60mm to 25mm. But I needed to be able to go further and didn't want to lose front camber, so went with the Bilsteins, which have significantly more usable front bump travel.

So we agree that RCE yellows and PP shocks give a crashy result. Unacceptable result for me. Definitely not acceptable to have to raise the car and cut the bump stops for most people. It's just not a good solution. By the time you buy camber plates and bilsteins, pay for labor 2 or 3 times, pay for alignments..just no. Lowering springs are not a good modification. And you're also going to be limited on what size wheels you can run. You don't have adjustability. And you're ballparking the damper and spring rate marriage. Tein Flex As are the correct answer here.

You'd have to be insane to hodge podge this solution when the price and quality of coilovers are where they are today.

My setup was first 1.5" lower up front, then I adjusted to be 1.25" lower than stock.

The Raceseng camber plates actually *lowered* the front of the car, I had to raise it with spacers .25" to compensate for that effect.

I.e., this is nothing to do with "RCE Yellows + PP/Sachs".

Cutting bump stops to run lower springs is perfectly normal and done all the time, and isn't necessarily "bad".

There are other things at play here... But suffice to say doing labor myself or with help of friends reduces cost a lot, and alignments happen semi-regularly anyway given track events and time trials.

Not true, lowering springs *can* be a great mod! And "coilovers" *can* be a BAD mod...

If you want to run 9" wheels, you have to choose offsets with care.
I'm running 17x9 +35 and also 17x9 +40 with 3mm spacers. It's no that big a deal. with 17x8 and 225/45-17s it's less of a deal...

"Adjustability" at the price range and setup-experience-level we're talking about is massively overrated.

I'm sure they're fine. They are *an* answer. There is no one "correct" answer. Bilsteins + RCE Yellows or Swift BRZ Sport or Spec R springs are another "correct" answer.

There's more than one way...

Strongly disagree with everything you are doing, but I'm sure we enjoy our cars equally, so :cheers:

Damrite!
:cheers:

Wow what happened with this threads [emoji14]

There is one or more way to skin a cat. Also you don't need camber plates. I like the current dampers with yellow springs. (17 non pp) going to add peedlers top hats to get some camber without loosing any height or droop travel. Combine this with camber bolts I can get -3 degrees of camber if I wanted.

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FWIW, the Spec R spring rates are extremely close to the springs rates at ride height on the B14 kit, which has identical valving to the B6/8. The Spec R is 4.4f/5.3r vs the B14's 4.2f/5.5r. The damping should be well matched.

I think B14/B16 springs are progressive and start out with much softer rates than Spec R. Main reason I went with Swift Spec R/B8. Also no height adjustability saves me 42 lb. for car classification for time trials!
https://www.ftspeed.com/part/47-2283...a#.X73BQMhKhPY
https://www.ftspeed.com/part/48-2282...t#.X73B9MhKhPY
Front: 2.5-4.5kg progressive
Rear: 3.0-7.0kg progressive

Yes, they start very soft but that's at full droop. With the car's weight, the effective rate is stiffer. Here is a spring dyno by Vorshlag. Take the sprung weights at each corner, and then calculate the corresponding displacement and rate at that displacement. You should get pretty close to the 4.2f/5.5r I quoted. Quoting the 2.5/3.0 rates is a bit like quoting helper rates on other coilovers.

Attachment 195139

not exactly what you’re asking, OP but my personal experience on this car was:

trd springs + blistein b6 -> bilstein b14 -> ohlins r&t

and i honestly felt like each progression made the car feel better all around. from cruising around town, to canyon runs, to autocross.

Next season I will get new coils and try and get some ride alongs at the track. Was not ready to drop that much coin on coils and I really want to skip the ground so hence just getting a new damper+peddler top hats

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PP shocks are fairly firm on compression damping, meaning they work well on softer (stock) springs and with stiffer lowering springs they do perform really well but you do feel some more harshness.

17+ non-PP shocks are the most comfortable of the OEM shocks.

Previous OEM shocks have a lot of rebound (and also plenty of compression) which affects the ride.

Plenty of rebound headroom on all of the above for a stiffer than stock spring, but obviously that's not the only thing to think about!

Coilovers can definitely perform and ride better if done right. More money than just springs. And of course the wheel size issue.

The valving on Bilstein B6 and their B14/16 coilovers is just far superior to OEM. It's not about the spring rate they can support, it's the overall design of the valving. They're very good.

If adding up springs + camber plates + Bilsteins, it's definitely worth thinking about a coilover, especially if you're hitting the track (and rules allow). But it's still very good.

Different strokes, budgets, rules, and priorities for different folks. Bilstein + good springs is easy and simple and very good. Good quality coilovers can be awesome especially on track with a little more set up and usually more cost. Using just good springs on OEM shocks might be the way to go if you only have ~350 bucks to spend and want to improve performance.

- Andrew

Great info! Yeah, looks exactly like the soft initial rate is just a built-in "helper". I had some bad info on these, someone reported negatively on the "soft initial rate"!
My math says there's ~825 lb. on front springs and ~855 lb. on the rears (2850 lb. car+driver, 55F/45R, 0.95 front 0.75 rear motion ratios). That's out of the range measured for the fronts, going by the last half inch of travel measured I get 232 lb/in or 4.14 kg/mm, close enough to 4.2! For rears in the range of static load I get 404 lb/in or 7.3 kg/mm.

Anyway, glad to confirm the *actual* real-world stiffness for these! Still glad I went with the Swift RSpec, these rates seem very rear-stiffness biased...

Ahhh good catch with the motion ratios! I think when I measured the springs myself I got a slightly higher rate in the front than Vorshlag, so I managed to get the same answer there with the wrong methodology.

Don't those weights include unsprung mass? I had used ~685 lbs front/~560 lbs rear for just the sprung mass. Corresponding force on the springs would be (685/.95) and (560/.75) or ~720 lbs and ~745 lbs, leading to ~4.1-4.2 kg/mm front and ~6.4 kg/mm rear. About halfway between our two numbers :lol:

Oh yeah, good catch yerself!

I def would have given these more consideration if I'd had a better idea what the *real* spring rates are. But I saves 42 lb. with no ride-height adjustability, and not gonna lie, I like the idea of competing against "serious" coilover setups with "just lowering springs and struts/shocks" :P