When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I need to apologize right out of the gate. I have some observations about my current FD and I know what I want to accomplish. That being said, I'm probably **** at describing things and I don't know what I don't know. Thus, I turn to the fold for help. I'll give as much context as I can at the risk of rambling on like an idiot.
I bought my most recent FD in January and spent the first half of the year prepping the car for a complete rebuild and overhaul. First up was the suspension which was replaced with brand new Ohlins coil overs. I replaced every single bushing in the entire car (including diff bushings and steering rack) with the Super Pro kit. I also replaced the pillow ball mounts with new OEM units from Juan at J-Auto (great dude to deal with). I put a lot of time into other pieces of the car to get it ready to handle the power it would eventually make. Rotary Performance is wrapping up my rebuild and EFR7670 build and I should have the car back soon. Shooting for an extremely meaty 400-420whp on water/meth injection.
At this point, I haven't really dialed in the suspension due to not having driven the car much since I finished the suspension. It's a much nicer ride that's for sure but I'm wanting to dial in the car to feel confident. To be specific, I was driving my father's fairly new Porsche 911 and it just feels so planted and confident. The vehicle isn't "upset" by undulations in the road and even with wide tires, the handling is extremely direct. To explain it another way, I don't always feel like the 911 is trying to kill me while doing 30mph in a straight line. The Porsche is a car I've only driven 3 times but I'd be totally comfortable driving it 150+ and wouldn't remotely have a heart attack. Don't get me wrong, I don't want to lose the excitement of driving the FD, but I don't always want to be "on edge". I'm also noticing what I feel like is a latency between when I turn the wheel and when the car starts to react. It's something I don't recall from owning my last FD. I've owned a 2017 Golf R between my old FD and this one so I'm not certain if it's just a change in my own standards as a result of the Golf.
I setup my Ohlins to recommended spec (2mm of preload, 10 clicks of adjustment from total firm) and I'm hoping to get some guidance on further getting them right. I'm sure that's a big piece of this but I like to have a vision in mind before I run off and buy a bunch of parts or do a bunch of work. Additionally, what types of things should I try and do sway bars need to be addressed? So I guess what I'm asking is, what types of other things should I be looking to address to help with that goal?
The elephant sitting in the room is - did you get it aligned after replacing all those bushings and installing the coilovers? If so, what specs?
How old are the tires and what are the f/r sizes?
The elephant sitting in the room is - did you get it aligned after replacing all those bushings and installing the coilovers? If so, what specs?
How old are the tires and what are the f/r sizes?
Great question. I did get it aligned at a Firestone nearby. I have a print out of the specs but I don't have them in hand (although I can get them soon and will post them).
Not sure on the age of the tires but they are Bridgestone Potenza RE-11 225/50 R16. They are from the previous owner and are on the stock wheels.
My first thought for symtoms was alignment as well.
Then also noticed you are on stock 50 series tire sidewall.
For sure check the tire pressure first, but...
50 series sidewall should help the ride quality over rough pavement, but compared to a newer car on lower profile tires there will be a mushyness in your inputs.
For your EFR 7670 high boost build and all that torque I would get 18x11 +45 wheels like I have on my FD and some nice 285/30-18 RE71R or 295/30-18 AO52 or some other tire that works great with little to no heat.
Im currently running 305/30-18 Rolex GT touring car rain tires at the moment and they actually hook 1st on sequentials at 15psi becaise they work cold. Never had a tire hold 1st on a modded turbo rotary before (not even MT drag radials).
On my FC with EFR 7670 and 225/50-16 Hankook RS3 it would spin 4th gear on a freeway roll-on.
took those off and ran 17x9.5 and 255/40-17 Maxxis RC1 slicks which put power down well because they work 20deg F lower than NT01, R888 etc.
If you have eliminated the stock passive toe bushings in front lower control arm and rear upper control arm I will recommend some alignment settings to make the FD feel alive.
If you still have the stock sliding bushings in those locations swap them out before going to really wide wheels and tires or it gets weird fast.
Near zero toe up front and just a hair in the rear. Max front camber and minimum rear camber. Front caster is fine as high as you can get for some good return to center on the steering wheel.
You will definitely want to ditch the stock Torsen rear and get a high quality clutch type- I went with the gold standard OS Giken Superlock.
I had an FD Torsen in my FC with the EFR 7670. The bias ratio wasnt enough for the engine torque so it could spin up one tire and send the car veering sharply to one side or another- which was scary on the freeway at 70mph.
Unknown alignment, and crappy, small tires. Should work out great!
The car should be on 100 treadwear tires (200 at the bare minimum) with a good alignment, corner balanced and the entire suspension should be gone through to make sure nothing is binding, loose, or out of adjustment.
That is the difference between throwing parts on a car and actually tuning the suspension. The car is never going to drive like a new Porsche. It is going to feel raw, communicative, and yea if you don’t respect it, it will kill you.
Last edited by LargeOrangeFont; 12-23-19 at 09:26 AM.
50 series sidewall should help the ride quality over rough pavement, but compared to a newer car on lower profile tires there will be a mushyness in your inputs.
For your EFR 7670 high boost build and all that torque I would get 18x11 +45 wheels like I have on my FD and some nice 285/30-18 RE71R or 295/30-18 AO52 or some other tire that works great with little to no heat.
Im currently running 305/30-18 Rolex GT touring car rain tires at the moment and they actually hook 1st on sequentials at 15psi becaise they work cold. Never had a tire hold 1st on a modded turbo rotary before (not even MT drag radials).
On my FC with EFR 7670 and 225/50-16 Hankook RS3 it would spin 4th gear on a freeway roll-on.
took those off and ran 17x9.5 and 255/40-17 Maxxis RC1 slicks which put power down well because they work 20deg F lower than NT01, R888 etc.
Tires are on my list for sure. The Golf R had Continental Sport Contact tires and they were the best tire I've ever driven on. Like you said, newer car on newer tire tech was likely a good combination. Sadly, it's looking like they don't make that tire in a very wide variety that I'd be able to fit under the FD. I may end up on some variation of a Pilot Sport depending on what is offered. It's been years since I've shopped for sport tires as the only car I've had long enough to need tires is my Toyota Tacoma (10 years now) and the shopping criteria differs juuuuust a little bit.
Question @BLUE TII how do you know if a tire works with less heat? I don't think that's a spec I'm familiar with but it totally makes sense why it's important. Ultimately, I'm going to get new tires but if I do that, I'm going to get new wheels at the same time so I can get the contact patch I need and so I'm not stuck on 16s for another 15-20k miles. My only hold up here is I hate the look of pretty much all aftermarket wheels.
Originally Posted by BLUE TII
If you have eliminated the stock passive toe bushings in front lower control arm and rear upper control arm I will recommend some alignment settings to make the FD feel alive.
If you still have the stock sliding bushings in those locations swap them out before going to really wide wheels and tires or it gets weird fast.
I might need a slightly more detailed explanation on this one. I believe I replaced every single bushing in the entire suspension by hand but I'm not keen on the names of each. At this point, I removed everything that was 25 years old and replaced it with fresh units.
Originally Posted by BLUE TII
You will definitely want to ditch the stock Torsen rear and get a high quality clutch type- I went with the gold standard OS Giken Superlock.
I had an FD Torsen in my FC with the EFR 7670. The bias ratio wasnt enough for the engine torque so it could spin up one tire and send the car veering sharply to one side or another- which was scary on the freeway at 70mph.
That's sage advice. I don't suspect that will be something done initially but I can see that as a potential later down the road once I get some miles on the car and feel it out. Like I said before, I pulled the entire car apart, put it all back together with fresh suspension bits, and got it aligned so I could drive it to Rotary Performance. Now I'm just looking to put together a good plan of attack to dial her in.
Originally Posted by LargeOrangeFont
The car is never going to drive like a new Porsche. It is going to feel raw, communicative, and yea if you don’t respect it, it will kill you.
I'm aware it will never feel exactly like the Porsche entirely. I thought I made it clear that was being used as a baseline for an explanation. Also relevant, this is my 3rd FD...so I'm more than aware at this point.
Originally Posted by TomU
Poly is going to be harsh even with alignment. You may want to try Mazda comps, esp at the control arms
The Super Pro bushings are a bit softer than the Power Flex bushings I used on my previous R1. So although they aren't as soft as the Mazda comps I think it's a nice midpoint.
Race tire manufacturers publish what temps they work best at so you can dial in alignment and tire pressures to achieve that temp across the tread with a tire temp probe- this includes most of the DOT-R tires.
This manufacturer data is how I found the Maxxis RC-1 work 20 deg F lower temp than R888/NT01/RA1.
Max performance street tires are trickier to find out which tire works better cold.
you have to read the user reviews. The ones that can hold up to track lapping like RS3/4 like lots of heat and are sketchy cold- others like RE71R, AD08R work better cold and will overheat and chunk or get greasy with multiple laps on the track- those are the ones you want for the street (especially when you go wide tire on a light car).
Basic street tires like the michelins you mention will all work best cold, but wont have near the performance of the max performance street tires (200utqg made for autox racing).
Looks good.
If you start attacking lowspeed cornering limit where you have bodyroll and notice some understeer you will want to bump the front camber up to fix that.
front camber will make the front a bit more sensitive to turn in as well, but at the expense of a bit more hunting on uneven pavement from camber thrust
First step will be getting the car back with the final tune on it next week (I hope). Following that, I'll check tire pressures and then see what I can do about corner balancing. I'm betting I can find someone in the Dallas area with a corner balance setup.
Also, @BLUE TII which sliding and passive bushings were you referencing earlier? The front lower control arms only have two bushings that I'm aware of (one front, one rear per arm) and I'm not sure which one you're referencing in the upper rear control arm. Just wanting to confirm I didn't miss some extras.
The toe bushings on the FD that are multi-piece so they can slide back and forth are the two bushings in the front lower control arm where it mounts to the subframe and the rear upper arm bushings where they mount to the chassis.
Replacing them with poly bushings or Mazdaspeed bushings will greatly reduce the toe changes Mazda built into the FD to make it "easier to drive" for general public.
You can read about them in the Yamaguchi FD book if you have that.
Those bushings, the swaybar bushings, front upper arm bushings and the rear lower shock mount are the only bushings you can replace with poly/delrin/etc and not introduce binding as the rest of the rear suspension points are pillowballs, cushioned pillowballs or multi axis compliant bushings.
Unfortunately, aftermarket bushing suppliers sell bushings for the FD that compromise performance/safety.
The toe bushings .... the swaybar bushings, front upper arm bushings and the rear lower shock mount..
The list i have gotten from either long time members here or in the Howard Coleman thread regarding suitable places for poly was:
- Diff mounts
- Engine mounts
- Trailing arms
- Sway bars
- Steering rack.
Everywhere else use stock rubber or if not, Mazda competition (i guess Mazdaspeed).
The problem i think many are facing here is that a full suspension job with OEM Mazda parts + Powerflex in the above mentiones places, would come in at $1950. ($550 front $1400 rear).
For competition its quite a lot more.
So my "suspension plan" is the spreadsheet under here + Öhlins. Does it sounds reasonable or have i been sold on the snakeoil?
The front trailing arm poly bushing will introduce a ti y tiny bit more stiction than stock, mazdaspeed or a spherical rod end because the trailing arm does move in an arc.
Still, I did put poly bushing there myself.
At a later date I did the poly rear diff mounts and... regret.
Bumps shake the diff and make a clunk from the rear tjat wasnt there. Like, even changing lanes over the bots dots.
If you can, go mazdaspeed on the diff mounts to keep the fluid.
Thats all good!
The front trailing arm poly bushing will introduce a ti y tiny bit more stiction than stock, mazdaspeed or a spherical rod end because the trailing arm does move in an arc..
Awesome! One solution for stiction with poly is to add a bronze bearing to the sleeve. I think some of the Miata guys does this when they go with poly for budget track driving.
A thin brass sleeve over the steel sleeve that is shorter so it doesnt get pinched like the steel sleeve sounds like a great idea to reduce friction in the poly bushings.
The binding/stiction I mean in the rear trailing arm with poly is from the trailing arm being pulled inward as it moves up from the arc of the lower arm it is attached to.
Multi-axis movement.
I'm really enjoying this thread, as I completely forgot how much effort Mazda's engineers put into developing their Dynamic Geometry Control System (DGCS) suspension for the FD. One could only wonder if other manufacturers at that time have also put as much effort and attention to such details as Mazda did. I went ahead a dug up my own copy of Yamaguchi's book and scanned pages 92 through 103, where it goes into detail about what Blue TII is talking about.
I would like to hear more on how the FD's DGCS suspension philosophy of the early 90's compares to the more modern RX-8 platform as I have absolutely no experience with the RX-8 but I always hear from others how it has better chassis dynamics compared to the FD? What did Mazda do differently in the RX-8 in terms of suspension dynamics and can we FD owners learn anything from that?
Originally Posted by BLUE TII
The toe bushings on the FD that are multi-piece so they can slide back and forth are the two bushings in the front lower control arm where it mounts to the subframe and the rear upper arm bushings where they mount to the chassis.
Replacing them with poly bushings or Mazdaspeed bushings will greatly reduce the toe changes Mazda built into the FD to make it "easier to drive" for general public.
@BLUE TII Are the Mazdaspeed bushings for those locations also sliding bushings like the OEM, just 40% stiffer, thus still allowing some toe change but not as much as OEM? Or are they just stiffer regular non-sliding bushings? My assumption is that they are also sliding bushings ( in those respective locations) just stiffer.
You also mentioned:
Originally Posted by BLUE TII
If you still have the stock sliding bushings in those locations swap them out before going to really wide wheels and tires or it gets weird fast.
I understand why things would get weird fast when using much wider tires and wheels while on the stock sliding bushings, but how would the Mazdaspeed bushings hold up in this case of using much wider wheels/tires?
Thanks!
Anyone who is interested in this subject should really read the excerpt below.
Very interesting thread and read, thanks @Spalato and everyone else!
Few questions.
1. Are the Mazdaspeed the same correct sliding or fluid filled as the OEM ones are? I never knew the front lower rears were fluid filled!
2. @BLUE TII & @Narfle which exact bushings from Powerflex or SuproPro are actually dangerous and what makes them dangerous? Are you referring to the sliding upper bushings? The ball-joint rear toe links? Obviously no one is replacing the rear pillow ***** with bushings?
Yes, the poly bushing manufacturers actually sell poly bushings to replace factory rubber isolated ball joints- and they should not be used as they cause binding.
These are-
rear toe link inner and outer " bushings" (18, 19)
rear lower arm inner "bushing" (8)
Another factory high compliance bushing that may cause minor binding when replaced with poly is-
I havent purchased the Mazdaspeed replacement bushings for the FD, but for the FC they were all 100% same as stock but made out of 40% higher durometer rubber for the rubber portions of the bushings.
I expect the FD bushings are the same.
If you do use stock or Mazdaspeed bushings, always follow the factory service manual installation proceedure (using alignment marks on bushings and final tightening done with correct load on bushing if indicated).
12-22-19, 04:11 PM
