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Regarding the FD RX-7 and the FE RX-8 suspension designs-
FD is all 100% analog stability control as outlined above using the sliding bushings.
FE is about 95% digital stability control with the other 5% analog stabillity control being just alignment settings, spring rates, swaybar rates and inherent design (long wheelbase, superior chassis rigidity, etc.)
FE suspension design/phiplosophy s also published Mazda materials if you want to dig, not *just* my opinions.
Mazda kindly made completely disabling the FE digital stability control possible so the FE drives with just the 5% analog stability control.
After a performance alignment and coillovers to change f/r spring rate bias the FE is ~99% free of any stability control and the brilliance of the chassis as a "race car driver's" car really shines.
I still prefer my FD to my FE because FD looks so good and its easy to make power.
Well replanting an FD engine into the FE solves that issue. While externally an FD3 will always be the Queen of Jezebels, your wifely FE is true and faithful forever, even ever an ever more ...
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).
there was a running change to the front upper bushings, they clunked when they slid, and so any replacement bushing does not slide.
But are you sure the newer bushings are also not sliding bushings? The bulletin only states that the modified bushing is designed to eliminate the clunking noise, thats it.
So can anyone confirm:
- whether or not the newer "modified' OEM bushings are in fact sliding bushings (in those respective locations)?
and
- are the Mazdaspeed 40% stiffer bushings also sliding bushings (in those respective locations)?
I'm very curious about this, as to me it seems unlikely that Mazda would invest so much effort into developing their toe-changing suspension geometry using their sliding bushings just to eliminate them in 1993 because there was no other solution to solve the clunking noise issue?
Lots of sage advice and good conversation going on in this thread. I like it.
As mentioned above, I'm curious if the change outlined in the service bulletin resulted in the elimination of the sliding bushings all together.
Also, it looks like I've gained access to a corner balancing system and will be pursuing that quite soon to get the suspension dialed in. If y'all have any "DIY Corner Balancing" write ups or videos I'd love to see them so I can get prepared in advance.
Tire sidewalls can be drastically different as far as stiffness from mfgr to mfgr. I really liked the falken azenis on my stock wheels. Going from azenis to current 18's I didn't notice that much change in stiffness. The conti's on my 5 might as well be open cell foam even at 38 psi.
I would be just a little scared to drive my car flat out on 225 200tw tires with my cranked up twins. Must be quite an experience with the EFR single!
On the ohlins what I did was stiffen up the front to induce a bit more understeer since the car felt like it wanted to rotate more than I liked if I shifted weight off the rear during a turn. I think I'm 7 front, rear 9 for street. It improved the feeling of confidence for me.
Definitely recommend front camber as well as lower tire pressures.
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-
Rear trailing arm front bushing. (7)
So, after processing your post and this graphic would you say it's acceptable to use super pro poly bushings in the locations you have not called out as unacceptable? I have a super pro kit to install into my car and want to know how much I shouldn't use although this thread is making me think I shouldn't use any of it except for the rack and anti-roll bar bushings.
I would be just a little scared to drive my car flat out on 225 200tw tires with my cranked up twins. Must be quite an experience with the EFR single!
On the ohlins what I did was stiffen up the front to induce a bit more understeer since the car felt like it wanted to rotate more than I liked if I shifted weight off the rear during a turn. I think I'm 7 front, rear 9 for street. It improved the feeling of confidence for me.
Definitely recommend front camber as well as lower tire pressures.
Let me be clear, those 225s came on the car. They were not purchased. Going to deal with them for the time being, as scary as that might be, till they die (which will be quickly).
By "stiffen up" I assume you mean you dialed in a bit more preload? Any idea how much? And I'll give your damper settings a shot.
PS: I just got confirmation that I should have the car back next week. Fun will start then.
Yes, just the ones I listed in the post with the corresponding graphic will introduce binding into the suspension movement.
The diff mount bushings I found created more thump noises over small bumps/road reflectors.
The other locations work fine. As poly bushings do, they will start to squeek after a few years when the applied grease is worn off. Grease fittings would keep you from having to disassemble suspension to maintain them.
The diff mount bushings I found created more thump noises over small bumps/road reflectors.
That's an interesting observation. I wouldn't have thought diff bushings would have affected ride quality over road imperfections. Thinking about how the suspension is designed, the only forces that should be hitting the diff are torsional forces from the drive shaft and axles (and similar forces from the PPF). The load of the vehicle (as it relates to weight) should be supported by the suspension itself.
I had the diff bushings in my first FD (an R1) replaced with derlin units. When I did, I noticed the car had a different feel under engine load. Way less sloppy and felt like the energy from the engine was making it to the tires instead of just flexing the car. Overall, I thought it was a hugely positive change. That being said, I was going from crappy old bushings to derlin. No idea what new OEM or Mazdaspeed would feel like.
Last edited by ItalynStylion; 01-03-20 at 08:07 AM.
Let me be clear, those 225s came on the car. They were not purchased. Going to deal with them for the time being, as scary as that might be, till they die (which will be quickly).
By "stiffen up" I assume you mean you dialed in a bit more preload? Any idea how much? And I'll give your damper settings a shot.
PS: I just got confirmation that I should have the car back next week. Fun will start then.
I wouldn't mess with preload. I've also never corner weighted my car. By stiffen up I just meant try a different damping adjustment.
When you say you aren't confident in the car I assumed you meant you are experiencing oversteer. I combatted oversteer with my Ohlins by loosening the rear up via the damping adjustment *****. I am 7 front, 9 rear on street tires. They recommend 7 all around.
It took me quite a bit of seat time to trust the Ohlins due to the high rate and equal front and rear spring rate. I think it makes the car rotate more easily from throttle inputs, which is fun for short course work. I really had to change my throttle/braking habits coming from the squishy Eibachs. These coilovers are not nearly as forgiving, but they make the car feel like a 350hp go kart and I love them.
Several things I would check/change if my car had delayed/uncontrolled steering response:
The alignment could be wrong. I've gotten bad alignments where the sheet said toe was perfect, but it was out a couple degrees. The $75 firestone alignment only pays for an hour of work max and they probably aren't giving you extra time on the rack for free.
I just spent $240 on another custom alignment yesterday. It took the tech 3 hours and he does custom alignments on the regular.
Steering rack rubber bushings could be loose or shot.
One other area to inspect is the double jointed steering column. The locating pin wears in the knuckle joint, allowing steering wheel play and a delayed steering wheel response. I noticed this immediately when I purchased my FD and my car at the time had only 55000km from new. Awesome car but a white knuckled ride!
I fixed it by adding some JB Weld material around the pin and 5 years later my FD still steers as sharply as my Porsche 996TT.
One other area to inspect is the double jointed steering column. The locating pin wears in the knuckle joint, allowing steering wheel play and a delayed steering wheel response. I noticed this immediately when I purchased my FD and my car at the time had only 55000km from new. Awesome car but a white knuckled ride!
I fixed it by adding some JB Weld material around the pin and 5 years later my FD still steers as sharply as my Porsche 996TT.
Hope this helps.
@RogerRX7 Can you post some pictures or diagrams of that part? Is this on the interior or is this on the engine bay side? I'd like to look into this when I get my car back this week. What your describing sounds a lot like what I'm experiencing.
here are a couple of tips i've picked up over the years, although i don't claim to be an expert
1. Tire pressure is important. the tire acts like a spring, and tire pressure changes a lot with temperature. for a Mazda, street car, the tire pressure on the door jamb is a good starting place for what the pressure should be COLD. for a race car, its a good target for hot pressures.
2. basically for a race car, you need to try all of the adjustments, too see what they do. this takes forever, but once you have done this, you know what adjustment does what (and how much). for the street its a little simpler, as you need a ride height that clears bumps, etc
2A. try the shock full stiff, and then full soft, and then half way. this calibrates the seat of the pants.
2b. if you have adjustable sway bars try all the adjustments
@RogerRX7 Can you post some pictures or diagrams of that part? Is this on the interior or is this on the engine bay side? I'd like to look into this when I get my car back this week. What your describing sounds a lot like what I'm experiencing.
There was a thread on it recently. I think it's called the u-joint pin and it is on the engine bay side. Seems like it goes on some cars and not on others. Checked mine after reading and at 160k it's toyt loyke a toyger.
Apparently the steering rack rubbers can have a similar effect if they are loose or dead.
My car was apparently blessed by the steering gods when it left the factory. That or it's the having been garage kept it's entire life.
So yeah, I finally have the car back and since the entire country is basically on lock down....I have time on my hands.
Chris at Rotary Performance is letting me borrow their corner balancing system. I slacked on doing this for a while because I knew tires were in my future. Wider tires unfortunately meant I needed a wider wheel....this is what took me so long. I landed on the RZ Sakebomb wheels and I really like them. Now that I'm on my final set of wheels and tires for the foreseeable future, it's time to balance the car. I'll start by getting the ride height proper and closing that fender gap a little bit. I'll likely increase the dampers AFTER I balance the car because I want to see how the new settings change the car. Alignment to follow. Here goes nothing...
obviously there are a couple of hardware differences in the miata, but the process and end product are the same. well i guess in a street car you'd run less camber...
I'm seeing conflicting info on sway bars....disconnect them during the corner balance process or leave them connected? The miata PDF posted above says to disconnect but Rob Robinette's guide says to leave them connected. Curious what logic to go with.
I'm seeing conflicting info on sway bars....disconnect them during the corner balance process or leave them connected? The miata PDF posted above says to disconnect but Rob Robinette's guide says to leave them connected. Curious what logic to go with.
12-29-19, 04:11 PM
