rx8thunder

Has anyone installed an 09 4.77 differential in their 04 8? Does it fit, does anyone know for sure? Thx

bse50

i have intalled fujita engineering's one and it works :p
You could also source one from a 2000 or so Kia sportage's front differential.

rx8thunder

I have access to one from a local dealer but didn't want to purchase unless I knew for sure that it would fit. Not sure whether the 09 version is teh same as the fujita.

How do you like the mod? Noticeably quicker off the line?

bse50

It's not something that you notice on long straights but it helped my laptimes on the very twisty tracks we have here

G3tR3DDY2GR3DDY

iTrader: (8)

problem is that its impossible to get one almost. If you have access to one and you feel like spending the money, go for it. You will notice some difference

staticlag

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/feed-4-77-review-6mt-126949/

rx8thunder

Yeah, read your thread. It is the reason I am so interested in this mod.

Hoping someone has done this mod using Mazda's 09 diff so I know it's safe to proceed...

dipatrx8

my 4.7 sounds a little bit but my 8 accelerating better than 4.4

rx8thunder

Well it seems if I go forward with this, I will be the first to use the 4.77 gearing from an 09 RX8. I have a rotary specialty shop confirming as to whether it will fit and should have an answer early next week

rotarygod

4.77

rx8thunder

^ Please elaborate on your thoughts... Thx

tiltmode43

iTrader: (15)

For reference:

https://www.rx8club.com/mazmart-88/transmission-153887/

Also, onlinemazdaparts.com offers a complete kit, including the 09 ring + pinion.
http://www.trademotion.com/partlocat...catalogid=4010

I planned on it but ended up picking up the FEED unit instead...

tiltmode43

iTrader: (15)

Only thing I can think of is a technicality, 4.777*

rx8thunder

^ Yeah, i hadn't heard anything negative other than increasing RPM's on the highway and cost

paulmasoner

iTrader: (1)

pretty sure thats not his intended thought on the subject. but rather that the reduction of the gear is not the proper solution to the challenge Mazda came up with.

staticlag

The argument is which one will give more total power(area under the curve)? I forgot my calculus. So if anyone wants to think up a sample problem for us they can go right ahead.



vs

staticlag

Uh huh, I just figured it out. Lol. Ok the total power is the same, each set will put down exactly the same amount of total power to the ground 1/2 of the box.

staticlag

but really there is no point in arguing. Cause if you play forza motorsports you know that higher ratio gears will out accelerate lower ratio gears any day of the week.

paulmasoner

iTrader: (1)

assigning arbitrary values of 3, 4, 5 to the smaller triangles yields an area of 6 square units each - total of 12 square units.

assuming proportions in the drawing that would give the larger triangle values of 6, 4, 7.21 which yields the same 12 square units of total area.

lol at static

Razz1

But I like the torque curve in the second graph, besides the cup is half empty...

tiltmode43

iTrader: (15)

Makes sense...



As a language arts major, I will submit that my curve shall look like this:



I understand the blunt power curves/power output argument but really, is anyone offering this as a solution? Seems more of an alternate viewpoint on the subject. I fail to see the issue here, higher horsepower was unspoken of... ?? Yeesh, I feel as though I'm missing something here, touting my ignorance...

rotarygod

I actually have many times. 4.77 is an absolute joke. A complete waste of time on a street car. A race car may be a different story depending on the track, it's rpm range, and gearing. I thought the original 4.44 was too high. That car already has to shift too many times. Why shift more often and go slower? The '09's are slower to 60 as a result. I can't understand the logic. More is not always better. Sometimes less is. The car needs what the RX-7's all had and that's a 4.10 rear end. That's plenty and it's not any slower on the street.

rx8thunder

^ Correct me if I'm wrong, but the 09's changed gear ratios when they went with the new 4.77 diff, nullifying its effect.

Anyways, going to call the shop tomorrow about feasibility and cost. If the numbers don't look too bad, pretty sure I'm going to go for it. Love shifting my 8 with the AFE short shifter so shifting more isn't a problem for me

rotarygod

They did change gear ratios. However you still have to shift more and your rpms are still higher for any given speed. I wouldn't say that nullified it's effect but rather partially countered what it did.

tiltmode43

iTrader: (15)

RG - your argument only makes sense to a certain point. Our gears are not so short that excessive shifts come into play too much. Really? You'd like a 4.1 ratio?

I respect your opinion through experience but I can't imagine the car with that gearing