What kind of work is involved in this? Is it a direct rear end swap, or do you have to take yours apart and install the gear?

Anyone?

There's a writeup on this somewhere on the forum. It's fairly straightforward but like anything else it requires patience.

I have a 4.44 r&p ready to be installed, and I'm feeling pretty confident after porting my turbo wastegate.

--Edit--

Here we go: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fd-differential-remove-replace-writeup-897359/

Don;t forget about S2 4.777 gears as well as after market 5.125 gears.

Dale, I know you haven't posted in here in 6+ months but pulling the 5th gear off the shaft requires a puller with a long set of arms, not very common. If you can't get it off, give me a shout I can get it swapped around for you, I have had my 5th gear swaped before. I live in Fort Walton.

Thanks for the offer! I do have a gear puller I made with the long reach, I've done a few 5th gear synchros. It's not hard to make, just need some long metal strips and a gear puller.

Dale

I have some speedo issues as well. Through the years I have had 3 different boxes and 2 rear diffs , different size tyres etc

So my final box is a japanese spec which probably has a shorter 5th gear and my rear diff is either european or JDM

Using OEM tyres ( 255/40/17 rear on 17'' ) I saw 60mph in 5th with 3000rpm

Something is wrong

Could somebody give me a baseline in 4rth gear ( since in all boxes 4rth is the same ) @ 3000 and 4000 rpm ( in miles or kph ) to find out how far off my readings my be

Thanks alot

doing some quick calculations with a 25.03 inch diameter rear tyre the only way to get 62mph in 5th with 3000rpm is if I have a shorter 5th gear ( 0.806 ) and the JDM spec 4.3 final drive

So there are two possibilities. I either have a speedo that reads nonsence or I do have the shortest 5th gear and final drive available. I did notice that the car runs through the gears very quickly. Doing a quarter mile on a stretch of road I had 4rth gear in 250-270m and I was almost hitting 7500rpm in 4rth just after 0.4 of a mile

My calculation where wrong. In order to get 60mph in 5th with 3000rpm I need a shorter 5th (0.806 ) BUT I would need an RX8 4.44 final drive which I don't have... Worst case I have a 4.3 final drive so my speedo should be reading 64 mph which is not a massive difference but still...

You have to test your speedometer against a known good external reference. Different 5th gear ratios won't throw off the speedo but can change what RPM you're cruising at in 5th.

Get a GPS or a speed app for a smart phone, that's a dead accurate way to test. Failing that, have a friend in a newish car follow you on the road and communicate via cell phone.

Dale

Is there a source to buy the JDM .806 5th gear seperately?

I have a completely stock 1996 JDM FD and I'm getting around 14mpg on the highway cruising at 3500rpm. I really wish it was better, it makes taking the car out on any sort of long trip very expensive.

Just changing your gear ratios and rear end ratio and tire diameter will not automatically calibrate your speedo. Your speedometer will be off more and more as each of these mods will affect its accuracy in a different way.

Read my thread on calibrating your speedometer, I now have a dead-perfect GPS-calibrated speedo with the RX-8 4.44 gears and my 17" wheels. Search on my user name for the writeup.

Bigpanda, if your fuel economy is that bad, something is wrong with the car, it's not the gear or anything. With my 4.44's, US 5th gear, tons of mods, a trunk full of crap and a passenger I can get 22 MPG highway going to Deal's Gap. Fuel economy highway that low is something wrong - bad O2 sensor, car running too cold, something.

Changing the 5th gear won't make THAT huge of an impact on your fuel economy.

Dale

I was cruising to DGRR at aound 3400-3600 rpms with JDM short 5th , and 4:10

I got 23 mpgs on the trip up .

Bringing this back up, does anyone know the part number for the JDM 5th gear? RHDJapan has the syncro however I would like to source the gear itself.

R513-17-610B and R513-17-308.

the lower 5th gear was installed on every FD with 17" wheels, which was an option starting in 1996.

Thanks, any idea where to acquire them?

can't check availability on a sunday, but it wouldn't surprise me if these were used in something that came to the US, like the mpv or 929 or something

It's not clear if you are after the .806 pair or the .763?

Revolution in Japan did sell them a few years back. Probably cheaper to buy a second-hand import box though if their normal prices are indicative!

You might try Amayama Trading otherwise for something a bit less exorbitant.

I'm looking for the 0.806 gears. Thanks for the tip on Amayama Trading, they have them for $228.

For that price it seems just buying a jdm trans is a better deal however I am not sure if there is a way to verify which 5th gear is in the trans prior to purchase?

Counting output v input shaft rotation in 5th with 10 or 100 turns to see the .043 difference, maybe!

Lazy man's way - mine - if you remove the speedo sensor .806 should have a white gear for the 4.1 rear end/16" wheel.

The alternate ratio gear, although it fades a bit from the original vivid colouring with age, is purple.

Of course, if they've done a diff ratio change in Japan, and swapped that out, back to counting sheep. :lol:

interesting both parts are NLA in the US

So do all 99-02 jspec trans have the .806 5th gear?