Bilstein B6 + TRD Rally springs + Pedders top mounts
 

People keep asking for my thoughts on these so I'll start a thread.
I've had these on since early December, kind of as an experiment and as something to hold me over for the winter.

https://live.staticflickr.com/65535/...01140612_c.jpg

Bilstein B6 notes
Super solid, feel good, not cushy but confidence inspiring and controlled.

Pedders top mounts notes
Also good stuff, have run these briefly in the past, no issues.

TRD Rally springs
+10mm height
259 lbs/in front (4.6 kg/mm)
294 lbs/in rear (5.25 kg/mm)

Those rates are no joke! These are stiffer than you'd expect for a "rally" set up but I think the idea is to make the most of the limited amount of travel of an OEM style fixed perch strut.

Height
Seems like +10mm to me. Subtle but kinda cool.

Road handling:
Unfortunately I've only been on my winter tires with this set up so far, which are 195/65/15 size on 15x6.5 wheels. It's a lot of fun and the car certainly seems more "active" but obviously there's not a lot of grip. It does require a little attention with these tires...you're not divebombing highway on-ramp apexes the same way...you still can but with a little more finesse. I will put my summer Michelin Pilot Sport 4s on the car at some point soon. Winter's over man.

Dirt/snow handling:
Nothing yet really. This winter sucks!
I'm planning on an April rallyx event and I think it will do well.

Ride:
It's firm. The little bit of extra ride height helps but they're still stiff springs. Overall it's less comfortable than the OEM 2022 BRZ suspension I was running right before this set up.

I think combined with the long OEM bumpstops in rear and Bilstein internal bumpstops in front it's just too much overall rate (remember the bumpstop spring rate is in parallel to the main springs, so you add them together). Even with the slight lift you're still not that far from the bumpstops.

There are 2 things I want to try with this set up before moving on and I'll update the thread when I do. First is the MCA traction mod, and the next is different (shorter) bumpstops.

https://live.staticflickr.com/65535/...b0bfba75_c.jpg
My car is very dirty and I'm not good at taking pictures.


- Andrew

update in post #19

How about lowering gas pressure a little?

That would proably improve the ride but there are enough advantages to the gas pressure that I don't want to do that.

The ride isn't "bad" but just isn't as good as it could or should be. I think the new bumpstops will make a nice difference.

Also, the roads I drive on are truly awful.

- Andrew

Thanks. This is really interesting. What about softer, longer springs preloaded to get your desired ride height?

On the Pedders hat front have you experimented with caster adjustment? I’m familiar with rake and trail changes from my MC days but my thought experiments on cars have flopped. My guess is that increasing caster would slow turn and increase straight line stability, but I haven’t seen anything testing that hypothesis.

Thanks again.

For sure but it’s easy and you could find a compromise between a better ride quality and still soaking up the bigger potholes. Aren’t Oem bumpstops fairly progressive though?

Wow those spring rates are anything but rally. :)



I've been contemplating having a set of B6 dampers re-valved for a more true rally setup on stock springs, but wanting to try out more travel in the rear. This would be more of a "recce car" setup and not a full fledged competition spec.

RCE has been working on their own lift springs. The project is stalled for the moment, but I think things in the background are in the works. In the mean time, Chuhatsu Plus Multiroad lift springs also exist.

Andrew,

The MCA traction mod is good. 10/10 would buy again. Rear end takes a nice set and provides what I perceive to be additional grip both on and off throttle. I'd be curious to hear what you think with your suspension setup and knowledge.

B

The top hats are fixed, so no adjustment...though I guess you can rotate them. With the increase in negative camber and positive caster, it's all good things (though not a huge change). The easiest way to think about the caster is you keep more of your negative camber as you use more steering. It's a nice thing for rally and rallyx for sure.

- Andrew

Yeah I'm looking forward to getting it on. Will be testing with this higher ride height where it should make a big difference and then again at a lower ride height when I switch to my 3 ways for summer. :)

- Andrew

Agreed!

Yeah these definitely make me feel better about the spring rates I had in mind for our springs which are somewhere between these TRD springs and the Chuhatsu springs (mega-soft but I think use longer bumpstops).

Either way, good information gathering exercise!

And I do think the springs will be great on back roads and stuff, just maybe not the best for rougher roads. I do think different bumpstops will help though.

- Andrew

I'm also glad about the rear overload you have planned as i tend to occasionally tow a trailer. I might pick up the traction mod in the future too. I'm about to have my shop install my lift kit next week with bilstein b6, 1" spacers and the Chuhatsu springs.

Is an alignemnt required after installing the mca traction mod, or does it bolt up in a way that nothing changes?

I am watching this with interest. Your goals are different to mine but I currently have the TRD Rallye springs with stock '13 shocks and the MCA traction mod. I have been wondering if the B6 shocks would be a good match as I am looking for more of a rough tarmac setup with occasional gravel. With my setup I found it a bit too tail happy. I have removed the rear sway bar for now which has fixed that but in future i'll look at a softer than stock Cusco or Mann Engineering as a better solution than none at all.

The TRD Rallye shocks are a softer version of the stock shocks it seams. I had them dyno'd and posted the results in another thread.

That is very high, when I had the TRD springs with 1" spacers i didn't like the handling at all. I suspect it messes up the roll centers.

They claim no alignment needed but i found it affected my toe a little so probably worth the alignment anyway.