FEED 4.777 final drive installed!
 

I'm not good at mechanics, so I put up some descriptions and pictures for references

The attachment from left to right are factory final drive, FEED kits, 2 angle view of FEED final drive installed

According to my mechanist's words, The installation of it was quiet tough. The rear end of differential gear
should be removed completely. 3 bearings (The largest one in the center and the other two small ones) should be replaced. The ring in the picture is for thinner FEED gear (there are two ring in factory final drive already). FEED gear is quiet fit, I did not notice any grinding sound in it during drving.

I just take few minutes test drive tonight. The first impression is quiker response at lower end as its advertisement. The rpm during low speed driving (God damn city traffic jam!) is only a little higher than it is before

Did you change the LSD at the same time?

No

Nice. Video of driving would be appreciated.

coooll beans !

Awsome!

Report back on gas mileage. I'm expecting it won't be as bad as some think.

wow, really nice. I would also like to see a LONG video please! :D: I would prefer watching a 10+sec. video versus a 2 sec video for enjoyment purposes :p:

Man I want this. It'll be a while though.

-Cody

Awsome.. one day I'll do the same but oi the money for it all haha.. please report back any and all details about the way the car feels will ya ;) you should know most of us here in the forum we can't get enough details haha..

based on my recent experience with a Kaaz LSD, I would highly recommend doing an aftermarket LSD at the same time. The labor cost should be the same.

The Kaaz is that big of an improvement? How so?

Yes please post updates regarding gas mileage. From another member there mileage does not seem to have changed much either.

Thanks!
Edgardo

Anything new on this?

Hey man, good stuff. Can you list some of cruising RPM levels?

Say 55 MPH & 80 MPH.

Thanks

Sorry to put on my observation late because of heavy rain in these weeks here (Taiwan) and a business trip.
My car is a 2004 AT with GT package. current mileage is 32000km
The power mod including Odula ram air intake, Rmagic drop in filter, A-RF TREC, hand built catless midpipe and catback. No addtional oil cooler but Plot ATF cooler. The sus mod includes Ohlins coilovers, Racing beat front/rear swar bar, Autoexe tower braces and member brace. wheels are OZ ultraleggera with Yokohama AD07tires (225/45/18)

I notice the rpm at every speed raised about 500-750rpm. For examples, At 60km/hr, It is 6700rpm/1st gear, 3750rpm/2nd, 2450rpm/3rd and <2000rpm/4th. The top speed lowered at every gear about 10-20km (I did not have a good record becasue most of the time I drove alone and most aggressive driving was around the hills).
The gas mileage decreased, but almost not noticeable (about 0.5km/litter). In urban driving, 4.8-5.1km/litter. For highway driving, it's about 8km/litter

Hope these info help.

fixed

Thanks!!!:smoker:
:us4allswi

does this upgrade affect the top end in any way

Top end? as in high-end power? or Top Speed. As stated, this Mod would reduce the car's top speed as far as gearing goes. But, as 6sp'd are GEARED to go about 185mph, I doubt most any RX8 would notice their real (Hp-Limited) Top speed reduced.

We are building one of these right now and it's not looking good. The machined spacer is not equal thickness around and the sleeve on the pinion also hasn't been machined true. We may opt to return these parts to their owner and have it done elsewhere rather than ruin our reputation.

Our builder has been doing diffs for 35 years. Needless to say, I'm a little disappointed with Feed.

Paul.

Any of you that have had this done have any thoughts or advice for Paul? I'm guessing he's talking about mine. Crapping my pants as I'm sure I won't be getting my money back from JonDemand based on recent discussions...

Maybe I jinxed myself with my sig, going to take it out of there for now...

lol

All is well. The unit is built. It's just a shame to not get more precision from Feed. This required a fair amount of machine work and multiple assemblies.

We're looking good.

Paul.

AWESOME!!!

Paul, you and Mr Engman are the... well, I was going to say THE MAN, but there are two of you. :)

Although you did give me a bit of a heart attack :)

But it is very comforting knowing it was done right!

how much does this bad boy cost and i'm sure labor will vary a bit, but can u share with us what your costs were?

Well, i bought the gear 6 months ago from JonDemand, so the prices are probably a bit out of date. I got the gear with shipping to Paul for 675 USD. Paul is charging me 450 for the build plus a 500 deposit until I send him my old diff as a core swap. It was originally going to be 300 for the build, but the FEED gear had some problems so he had to do some additional machining on it. Not sure what shipping will be for the new diff or shipping the old diff back. Not sure what installation costs will be yet. A family member of a good friend is a good mechanic with his own business, so I'm guessing my install costs won't be too bad. I'm guessing my total outlay will be somewhere in the 1500 ballpark, maybe a bit more.

Keep in mind these were "group buy" prices from 6 months ago, so I'm guessing it might be a bit more now.

mdw1K, what kind of difference, in terms of tenths of a second, do you expect this new gear ratio to do in the 1/4? Half a second, or more? Your car sounds lightly modded, otherwise. I would think a car with a full exhaust, some sort of intake and a pulley would see maybe a full second of improvement.

btw, I'm totally throwing out random numbers. I'm just trying to match the improved acceleration you're defintely going to feel, with the increased shifting you'll have to do. Shifting at the line in a 1/4 can kill a time, when a car is actually fast. Know what I mean? Anyway, just wondering.

hmmm half a second...? if this final drive did that much of a difference for 1500 dollars... i think everyone woulda gotten it. i got all the bolt ons and it shaved .5 secs lol.

i mean if it did make that big of a difference, that'd be great, but from what i read, people said they felt only a slight more pull earlier in the rpm and reading that, i dont think it'll do much for shaving more than .3 (if that) on the 1/4 mile

Well, I haven't seen any hard numbers from anyone. I vaguely remember Paul at Mazmart speculating that it might take a quarter or third of a second off the 0 to 60 time for the 4AT. But that discussion was about 6 months ago, so my numbers could be way off. And he was just speculating off the cuff, no hard calculations.

But keep in mind I have an automatic, so my shifts are either automatic or with paddles - usually with paddles to keep the revs up :)

As far as intakes, exhaust, etc, I have the mazdaspeed dual exhaust. From everything I've read on here intakes and exhaust add sound more than power with this car. My MS exhaust definitely improved the sound. As far as power goes, I thought I felt a slight difference, but that could have been me just infatuated with the sound.

Every review of it I've read on here seems to be good, especially for the 4ATs. Our gearing is so tall that it has to help some. If nothing else i figure it will help get to the upper revs faster where the power is.

In stock form, you end up in 4th gear before crossing the line, and a 4.777 is not enough of a ratio change to cause you to top out 4th and need fifth. It can only help.

Got my diff in the mail yesterday from Mazmart! Will be dropping it off thursday for the install, so hopefully I'll have a review sometime early next week.

Just in time for this weekend's track day at AutoBahn :)

i wonder how close my track wheels and tires are to this diff. I am running a 17" wheel with a 235/40 Toyo ra 1.
olddragger

Miata.net calculator.....
 

According to the tire size calculator, your tires give a 6% difference, for an equivalent to a 4.70 ratio......

S

pretty dang close!

thanks
od

how does acceleration feel?

you can't use a tire size calculator :spank:, you have to use the actual measured loaded radius and even then it changes some due to the tire ballooning out due to centrifugal force relative to speed

one of the better ways to derive the info is from the speed vs engine rpm vs trans gear from a dyno

Hi everybody, when can I buy a 4.77 final drive? I have read some posts about Mazsport. Will Mazsport supply a 4.77 final drive?

Thanks

I'm guessing the quickest way to get one is Mazdaparts.com. I got mine from JonDemand for a bit cheaper, but it took several months.

with the 17's on i can tell you that acceleration is MUCH better. It was a secondary gain as my original intent was better gearing for the tracks I run and tires are much less expensive.
olddragger

First impressions are pretty much the same as others have said. Revs faster, rpms are higher at a given speed and gear, acceleration is improved. Acceleration hasn't made a great leap or anything, but is definitely better. Time will tell if I decide it was worth the money.

My total outlay for purchasing, shipping, building, installing, etc is going to be right around 1600 USD.

My mechanic did say the diff swap was more time consuming than he thought it would be.

Many thanks to Sam at JOD and Paul and Rick at Mazmart for making this happen!

^ glad everything came out nicely! keep us posted on how it is in the longer run!

After driving it a bit more, I'm definitely noticing more of a difference around town. Haven't taken it on the highway yet.

Any problem of you guys during fitting?

Mazmart had to do some machining on mine...

Really really really love you to elaborate more mdw1000

So much money on an automatic? Why?

lol. i know someone who has spent well over 10g's on his automatic... i won't say who though

the answer: cuz he can.