nick1

the gsl-se im about to own has this setup, just wondering do the gears give me better low end, or top end?...(quicker pickup, or faster speed)...and the 88 tranny bolted to the 88TII n/a motor, good setup for the street? huge streetport, RB exhaust, weber ida 48 carb, etc...what do you guys think? im hoping for better pickup!!

Moonchopper

Quicker pickup. The gears are taller than stock, which allows more leverage; therefore, the engine turns the gears easier.

FD Racer

That is a sweet setup. I have 4.44 gears with a 12a trans and I am very happy with the increased acceleration I got from the gears. The 88' (NA right?) trans will have longer gears which won't make the 4.44's seem too short and the gears will be spaced closer (tighter ratio) which will make it a great setup for the street or the track. Your 5th gear will be good for cruising with that 88 trans over any other 1st gen tranny. I will b putting in a RWD 626 box in this weekend, which will be a similar setup....I can't wait!
check out this spreadsheet I made on mazda tranny ratios

REVHED

Short gears = quicker pickup. 4.44's are shorter than stock.

nick1

whoops, actually im not sure if the tranny is 88 sorry. im gunna find out now

2wankel

iTrader: (1)

Try this....download the rpmspeed excel sheet

https://www.rx7club.com/showthread.p...ighlight=excel

Hyper4mance2k

iTrader: (40)

now the general concensus is that the 626 tranny is shorter and therefore qiucker than the stock 12a tranny, then why does it have longer gears in 1st, 2nd, and 3rd gear??

RX729

4.44's will give you more low end...I have 4.88's in my stock 83 gs and DAMN!!! It Hauls ***!!! Thanks to Robert @ Rotary Shack for hookin it up!!!!

DriveFast7

iTrader: (1)

I have the 626 box behind my bridgeport. The gear ratios are closer in 2nd to 3rd, 3rd to 4th, 4th to 5th. 1st gear I'm not concerend with. Closer ratios mean less rpm drop inbetween gear shifts. Made a very noticeable increase in acceleration. The 3rd to 4th is especially good, and very very useful in road racing.

Very Satisfied.

Moonchopper

I was thinking in terms of the actual gears themselves. I suppose it's all a technicality, since they are physically taller, are they not?

DriveFast7

iTrader: (1)

Never measered if the gears are physically taller, or larger diameter as it were. The are physically thinner, mabye a millimeter thinner. So don't use them on turbo applications, the RWD 626 trans can't take that much torque. Or dragracing with wide sticky rubber.


But they can handle my bridge with 42mm chokes just fine. Know of a guy who put 44mm chokes in his IDA per GT2 rules of the time: trans internals were fine but the bellhousing cracked!

REVHED

Same size. Just a different number of teeth on the ring and pinion.

Moonchopper

That would make sense. I'll shut my mouth before I spew anymore false tech.

FD Racer

DriveFast7 pretty much answered it, but just to clarify....
-The RWD 626 has a taller 1st, 2nd, and 3rd...so top speed will be higher in each of those gears.
-4th is the same, and 5th is actually really short compared to all other mazda trannys, so fuel economy and top speed in 5th will take a hit.
-1st gear starts conciderably taller on the 626 trans than it does on any of the other trans, except the miata trans. So first gear will feel more like a 1.5 , get it?But that wont matter much on the race track or if you have 4.44's in the back.
-The advantage comes from how closely spaced the gears are. That means as you shift up, your RPM will be closer to where you shifted up from, allowing you to stay higher in the power band.
-take another look at the tranny chart I posted, and look at the bottom chart. The lower the numbers, the closer the gears are. The closest (and best) are in bold.

Hyper4mance2k

iTrader: (40)

nice. now i need to find one for my own!!

DriveFast7

iTrader: (1)

It's a good trans that is usually in pretty good shape. People didn't abuse those cars generally. Hard thing is that they're rare. That's why I scored 3 of them when I had the chance :-)

Hyper4mance2k

iTrader: (40)

what are the exact years that tranny was available in the 626?

DriveFast7

iTrader: (1)

79-82

If you do a search on the Race section on 626 you'll get all the info I have on the trans. Best of luck!!!!!!!!!!!!!!!!!!!

fatboy7

Usually its better to measure the difference between two gears by dividing the short gear by the tall gear. This gives you the percentage difference or the gear that would convert the tall gear to the short gear. It also allows you to better conpare the differences between shifts. Here's the numbers in this format
-------------------1to2---2to3----3to4---4to5
79-83 RX-7---1.6572 1.5482 1.4320 1.2121
626-------------1.7679 1.4028 1.2960 1.1655
84-85 12A-----1.6569 1.5405 1.4190 1.2392
84-85 13B-----1.6569 1.5405 1.4190 1.4065
87-91 NA------1.7358 1.4656 1.3660 1.4472
Miata-----------1.6610 1.4195 1.3300 1.2285
929,87-88 TII-1.7285 1.4486 1.3910 1.3123
89-95----------1.7285 1.4486 1.3910 1.3908

The winners are the same, but it gives you some further insight to how 'well' each is individually geared and how close the gearset is. Trucks with many gears will usually try to make these ratios be the same from gear-to-gear but cars with peakier power bands benifit more from a gradual decrease from gear to gear. The 626 set kicks butt on all but the 1to2 where it is the worst of all.

The 1.762 means that the rpm after the shift will be 1/1.762*shift_rpm or .5657 *shift_rpm. So shifting from 7000rpm you'll end up at 3960, which is below the torque peak, so the 1to2 shift on the 626 box really sucks. Compare with the miata box (best 1to2) which gives you 4214rpm after the shift. Compare these to guru's dogbox:

2.387 1.705 1.339 1.114 1.000

with distances

1.4000 1.2733 1.2020 1.1140

which shifts you down to 5000 rpm after the shift, now thats a nice short shift!

pillage6

The tranny in the turbo car is an 83 with a 5th gear from an 88. Seems to work well.

Siraniko

iTrader: (13)

FD Racer’s FB is nice. I was impressed with the F/I set up and gears. Except we couldn’t really go top end due to traffic and the nice bumpy LA freeway. Maybe next time.

And yes, thanks for the 626 tranny idea. Time for a junkyard run. take them apart and put them in my pockets

FB II

would the 626 tranny handle a turbo setup? or would taller gearing be better for boost, i've always been lost on that issue.

DriveFast7

iTrader: (1)

NO

FD Racer

Thanks bro.

I got an update on my 626 box install:
I've been driving around with the new 626 box....which has been a lot of fun. The 1st to 2nd switch seems great even though fatboy7 was saying it was wider apart than the stock trans. Can anyone validate what fatboy7 was saying about dividing the gear ratios instead of subtracting them for proper comparison? Someone did change the 5th on it though for sure, as it is nice and tall for Hwy cruising. I know the 5th gear is easy to change, anyone know if the other gears just as easy to change? I'm still working out some speedometer calibration issues but I am very happy with the 626 box overall.

DriveFast7

iTrader: (1)

Sweet! Glad you like it.

I don't divide to determine gear change drop but that is another way to look at it. I do the traditional subtraction method to determine the gear split.

I'd be impressed if someone took the time to change the 5th gear on an economy car. Don't know of any other gears that would swap into a 626 box. Mabye 323 or something?
Mabye u should just check the gear ratio to be sure.

Jack up rear. Put trans in 5th. Turn 19mm crank bolt by hand one full rotation. How many turns (or fraction of a turn in 5th gear instance) the driveshaft turns is your ratio.