Julian

iTrader: (14)

The Gen 3 RX-7 was a perfect size, IMHO

Julian

iTrader: (14)

Dont think you could call those true double wishbones, upper lower control multilink control arms yes, but they did not have the camber control of true wishbones. The FD suspension geometry was world class at its time and still is today; plus spending twice on a P car didn't get you forged aluminium arms. Today my Lotus makes a big deal on its aluminium arms having moved from tubular rods, I am what the f***.

arghx

iTrader: (3)

One specific example I had in mind was the 2nd generation Mitsubishi Eclipse, which went to a multi-link suspension from the strut setup of the 1st generation:







We could all quibble over terminology though... some would call the Corvette suspension a type of doublewishbone due to the short-longarm arrangement.

j9fd3s

iTrader: (3)

i agree, double wishbone just means that there are two wishbones, whatever those are. nothing about that says there can't be a short and a long one....

i looked at the FC, and it actually looks like the mitsubishi graph, if you take it through its travel, there is almost no camber change until you get to the very top.

jkstill

iTrader: (11)

I have never gotten around to putting the FD race tires on the RX-8.

I'm afraid too - the RX-8 just might beat the FD in an autox...

JConn2299

In terms of handling I'd say the FD is superior to the RX-8 in most areas except one: steering feel. I've always thought the FD's power assist feels over-boosted for the kind of car it is.

In the 99+ FD's a restrictor valve was put into power assist hydraulics. I'm unlikely to get the chance, but I'd love to drive a 1999+ JDM FD and compare it back to back with an RX-8; preferably the model with the handling package offered in the last year or two of the series run.

(What was it called? I forget. R3? or something like that. Never drove one of those, only earlier RX-8's. Maybe I'd have to revise my opinion if I drove this enhanced handling RX-8. As I recall, stock for stock, the RX-8 didn't match the FD in lateral G's. It may have been behind in slalom speed as well...depending on if you're comparing R1/R2 or base. And modern tires can factor into the comparison as well.)

JConn2299

Late model FD improvements:

'99 FD3S

Improved Braking Performance
- The ABS control unit for all four wheels has been upgraded from the conventional 8 to 16 bits and equipped with an EBD (electrically controlled braking distribution) system. This results in shorter stopping distances when the brakes are applied suddenly and enhanced vehicle stability.
Enhanced Ride and Maneuverability

- The damping force of the suspension dampers has been changed (Type RB and Type RS) and a check value has been added to the power steering system for improved handling.

JConn2299

Whoa! Car and Driver found the RX-8 R3 coming up short in the lateral g department.

"Steering that answers to palm twitches remains the RX-8’s best selling point, the R3 cruising flat and neutral through the wiggles without tire squeal or shimmy. Call us surprised that our skidpad runs were lower, generating 0.87 g to our previous 0.92."

2009 Mazda RX-8 R3 - Short Take Road Test - Car Reviews - Car and Driver

And even that .92g figure is below that recorded for a base suspension FD back in the day. I think the RX-8 was a closer match for the FD in slalom speed, but I'd have to go look it up.

JConn2299

Trying to compare apples to apples, I chose Road & Track's slalom test which measures speed through a 700 foot course. Here are the results for the RX-8 R3 and the '93 RX-7 R1.

2009 Mazda RX-8 R3 - Road & Track

"That something is different with the new (RX-8) R3 is evident when first turning the steering wheel. Turn-in response feels crisper, and there's less body roll through corners. The overall handling stability has been improved, as evidenced by its 70.8-mph dash through the slalom (better than stock by more than 2 mph). Skidpad and acceleration figures remain basically unchanged, so in spirit, the RX-8 R3 is the same car as before, just with a little more stability and attitude through quick turns."


Road & Track test of a 93 RX-7 R1:

Road & Track: Track Test: The Best-Handling Sports Cars in America (March 1992)

Slalom speed: 66.4 mph.*
Lateral acceleration: .95g*


RX-8 R3:

Slalom speed: 70.8 mph
Lateral acceleration: .87g


*Not to put too fine a point on it, or to seem to favor the FD, but there is 10 years worth of tire development between the two tests. It's a fair question to ask. Would a stock '93 RX-7 R1 post higher numbers with 21st century street tires mounted on the original 16 inch stock wheels? To be fair, you'd have to put both cars on the same set
of tires. The only Bridestone Potenza RE050 tires available in the FD's original size are maximum performance summer tires, but they're run flats. Is that close enough?
Maybe.

(Road & Track tested a standard RX-8 in 2004. Lateral acceleration was .88g and the slalom speed was 65.4 mph. http://www.roadandtrack.com/special-...s/mazda-rx-8-1 )

$lacker

iTrader: (9)

It seems counterintuitive that a car would have a significantly higher lateral acceleration AND a significantly lower slalom speed.
Would that mean that the RX8 would be better in transition (ex autocross) whereas the RX7 would be better with longer, more sweeping curves (ex road course)?

dabigesii

iTrader: (4)

Very interesting information in here, I've never driven an rx8 at any serious speed...this thread has gotten me curious to see what it could do.

ptrhahn

iTrader: (9)

Yup, modern rubber, and modern SIZED rubber.... 225/50/16 is really humorous by modern standards. It's like a space saver spare. Even the latter model's 17" 235/255's would help. Shock tuning continues to improve as well.

It is interesting that the cornering force is so much better for a slower slalom speed though.

JConn2299

Road & Track has pretty good standardized testing procedures. I was trying to compare apples to apples and keep the variables to a minimum in order to compare the designed-in handling capabilities of each car. Once you start allowing one car or the other to experiment with various modifications then you lose that standarized comparison and people can say one car or the other has an unfair advantage.

I was trying to post reliable and comparable data while acknowledging that at least one modern variable, the tires, could make a significant difference.

Anyone know test results for a post 2000 RX-7 for lateral acceleration and the 700 ft. slalom? I'm not sure what tires those late FD's were running on, but they probably didn't have the same rubber we were getting in the USA in 93-94-95. (I don't want to open up a can of worms here because tire engineering is a complicated art & science in and of itself. And bigger isn't always better.)

JConn2299

Lateral acceleration is pretty much a steady state condition, whereas the slalom test tries to measure the transition between right and left turns, so to some extent you're measuring two different things.

So, theoretically, you could have very sticky tires (or maybe thick anti-roll bars?) that allow you to get a high lateral acceleration G number, while at the same time those same tires (or your suspension) are sluggish at shifting your car from the left to the right and vice versa.

I think you're right that the RX-8 is good in making those transitions. But that's a bit puzzling to me. Although my car has the standard suspension, I drove a stock R2 when they were new. I have rarely driven a car that was as sharp in its steering and as precise in its handling as an R2. It was far better than the RX-8's I drove. But handling has a large subjective element. It may be that the R2 and my standard FD just "felt" better than an RX-8 while at the same time the numbers each car was putting up were close, or even that an RX-8 could go through a slalom course faster.

JConn2299

Let me try to clear up some possible confusion. The details make a difference and things can get complicated.

In the beginning I was trying to compare the best handling stock RX-7, the R2, against the best handling RX-8, the R3.

The RX-7 results came from Road & Track. The only RX-8 R3 results I found came from Car and Drver.
Road & Track uses a 200 ft. skidpad to measure lateral acceleration.
Car and Driver uses a 300 ft. skidpad.

Those test results were:

RX-7 R2 (Road & Track)
Slalom speed: 66.4 mph.
Lateral acceleration: .95g


RX-8 R3: (Car and Driver)
Slalom speed: 70.8 mph
Lateral acceleration: .87g

Previously Car and Driver tested a standard suspension RX-8 and came up with a lateral acceleration reading of .92g

Road & Track published test results for a standard RX-8 in 2004 which were:
Slalom speed: 65.4 mph
Lateral accelerationL .88g.

I hope that makes things clearer and easier to compare.

j9fd3s

iTrader: (3)

at least the FD was on a premium tire, at least the R1, it got S01's, the Rx8 was on RE040's or something like that, they stuck ok for about a lap, and then get really greasy!

pd_day

iTrader: (6)

I think the answer to this puzzle is the size wall.

Stack a set of stock FD rim/tire (225/50R16) and a set of Stock RX8 R3 rim/tire (225/40R19) next to each other and the FD stack will be taller (both sets of rims are 8 inches wide).

Tem120

iTrader: (5)

WHERE???? LOL , I'm about to go look at a 99 spec long block for a swap onto my car ,I'm still going to use my old harness / rats nest .

BUT I WOULD BE VERY happy if it came with the said check valve do you know where its located ? wether if its in the rack ? or somewhere in the pump?

Tem120

iTrader: (5)

premium tire from 20 years ago . isnt exactly concidered awesome even by a decade ago's standards

ptrhahn

iTrader: (9)

Yeah, the SOTA aftermarket tire around that time was the Bridgestone RE-71. That's what the McLaren F1 came with (17" sizes, no less). We're several generations beyond even those.

JConn2299

I don't know.

I'm guessing that it might be some simple sort of restrictor valve in the hydraulic line that reduces the amount of power assist. But that's a complete guess.

I've always been surprised that the aftermarket never offered this part, whatever it is. Also, I've never seen it offfered for sale someplace as a JDM part.

Yet, there must be some demand. I know there have been some Forum members who have disconnected their power steering altogether ---- an unsatisfactory solution as I hear the car becomes a real bitch to drive at slow speed or trying to park.

I would think something that would reduce the amount of power assist on the FD by, say, 15% to 20% would be a significant improvement. The FD steering feels over-boosted.
I owned a 3 series BMW when I bought my FD and the steering feel of the BMW was always better even though the overall handling of the RX-7 is sharper, more precise, and has higher limits.

stevensimon

iTrader: (11)

i own both rx8 and fd
rx8 is 2005 sport
fd is 1993 r1

back to back. rx8 feels like a 20 year improvement in every aspect over the rx7 and they can be had in running condition for under 10k all day long. plan is to buy a blown one and swap the 3rotor into it.

BLUE TII

iTrader: (9)

Quote:
Originally Posted by Tem120 View Post
WHERE???? LOL , I'm about to go look at a 99 spec long block for a swap onto my car ,I'm still going to use my old harness / rats nest .

BUT I WOULD BE VERY happy if it came with the said check valve do you know where its located ? wether if its in the rack ? or somewhere in the pump?
I don't know.

I'm guessing that it might be some simple sort of restrictor valve in the hydraulic line that reduces the amount of power assist. But that's a complete guess.

Racers sometimes drill out the restrictors on a PS pumps outlet to lower the pressure and therefore assist. Some PS pumps are fancy and have variable restrictors stock, others you can add them.

j9fd3s

iTrader: (3)

little bit of trivia but the DTSS system in the FC was developed with the RE-71, which was the OE tire in 1986, so its toe control curve is optimal for those tires.

i just looked, that's not a typo either, RE-71 is from 1985!

JConn2299

To the best of my knowledge McLaren didn't mess around with RE-71 tires for the McLaren F1 road car (love that car). They used "bespoke" (as the British would say) tires developed specially by Goodyear and Michelin. Every inch of that car was given fanatical attention.

" The McLaren F1 uses 235/45ZR17 front tyres and 315/45ZR17 rear tyres.[8] These are specially designed and developed solely for the McLaren F1 by Goodyear and Michelin. The tyres are mounted on 17-by-9-inch (430 mm × 230 mm) and 17-by-11.5-inch (430 mm × 290 mm) cast magnesium wheels, protected by a tough protective paint."

http://en.wikipedia.org/wiki/McLaren_F1

Tyres front Goodyear F1 235/45 ZR 17
Tyres rear Goodyear F1 315/45 ZR 17
1992 McLaren F1 car technical specifications