Dan_s_young

iTrader: (1)

Hey there. Im wondering if anyone out there has fooled around with 4.444 gearing and a lightweight flywheel... Oh ya and this is on a 12a, Im wondering how good the combination would be for street use and if it was really quick off the line. Seems like some faster accellerating gears and a lightweight flywheel allowing the engine to rev up quicker would be a mean combination. Im wondering if these mods would help alot to keep up with other cars.

Thanks

hornbm

im putting in 4.44s real soon along with a torsen. once i put the supercharged motor on it, it will have a lightened flywheel on it too. I'll let you know how the combo turns out

MPM

Yes it will be quicker. Its a simple gearing advantage. The higher the rear gear ratio the more torque(<----not sure if thats the correct word) present at the rear tires. But, your gas milage will suffer some.

Dan_s_young

iTrader: (1)

Ok thanks keep me informed... Im sure it will be alot quicker I can't wait to hear the results.

Bukwild

yeah I formaly used to mess with alot of my Dads muscle cars and the first thing they did when they modded out a car was change the gearing. Here in the import world we almost never do this. My t2/vert has 4.10 I will change those to 4.30 maybe this year. I am a huge fan of gearing but gears that short will force me to run wider rims and tires on the back. But yes I agree with you totally.

TrentO

Depending on the year of your 12A the flywheel could vary from 19 lbs up to over 23. A lightweight flywheel / pressure plate setup will alow the engine to accelerate/decelerate quicker. This additional acceleration will be noticeable in the lower gears, but will not be noticeable in higher gears. The car will also drop RPM's much harder when you engage the clutch due to less inertia. For a drag car people typically stay with a heavier flywheel as the launch benefits typically outweight the faster acceleration.
If you plan on road racing the car I'd do the flywheel and the gears, for drag I'd just do the gears. On the street the light flywheel will require more throttle to start from a stop, which will make everyday driveability a little worse.


-Trent

Dan_s_young

iTrader: (1)

hey trentO where about are you in edmonton? Do you have a TII ive probley seen you around... You a member of the edmonton Club? Ive heard from some other Edmontonians that Conroy ports engines... Im gonna keep this in mind for if i drop a 13b in my 85 one of these times... How much does he charge do you know? Is he on this forum maybe i can PM him. Im probly gonna come to some of the club get togethers this summer... Im just working on my car all this winter fixing some rust and getting some aftermarket stuff installed.

13BMiata

IMO, just my .02, etc:
The Supercharged 13B/alum Flywheel/4.44 Torsen is neat, but not really workable unless the car itself is VERY heavy, or the car is running HUGE blingin' wheels, if 0- 50 acceleration is important to you. Way too much wheelspin......

I just had that exact combination in my Miata, the gearing was (still is) way too short. The blower gets the power and torque up really good, the alum. flywheel doesnt dampen it (as it shouldnt), and the short gears mean constant low speed wheelspin. Cant get out of the hole no matter what. The combination of that level of power and gearing is whipass above 50mph, but below that wheelspin is a problem.

To answer the thread question tho-
the 4.44 and light flywheel would be awesome in an NA 13B 1st gen

4SPresident

Im gonna have to agree with ^ that the 13b and 4.44 gears combo is probably WAY too much for a street setup on an FI 13b or 12a, but on an NA application would make a great setup. You are gonna love the way that aluminum flywheel revs.

Dan_s_young

iTrader: (1)

I was thinking more of the lightweight steel flywheel because i have heard of some of the problems associated with the Aluminum one. I heard it is just plain unpractical for street driving...

hornbm

For the track, if wheel spin becomes a big enough problem I WILL run slicks. I think if I launch the car at a low enough RPM, i should be able to minimize wheel spin, and the added acceleration from the lightened steel flywheel should make up for the lower RPM launch

We'll see what happens in april

1234rotor

iTrader: (1)

Supercharged engines with lightened flywheels and all that should be better off with a stock or longer gear ratio. The low-end torque will pull the long gears just fine. Otherwise, you will be losing too much time shifting.

DriveFast7

iTrader: (1)

Yes Dan, that is a good street combination. Motor will rev much better.

My 74 repu has the RB Aluminum flywheel and factory 4.625 gears. It really revs up quick and is much more responsive and more fun to drive than by buddy's 74 repu with stock flywheel and 3.90 gears which is sluggish in comparison.

Siraniko

iTrader: (13)

. deserves an A+++++++++++

Dan_s_young

iTrader: (1)

I wish someone knew a 0-60 mile time with the 4.444 gears and the light flywheel so i could compare it with the factory time. I still want to see the actually proof of a large accelleration difference.

Chemical

I'm putting a 4.44 with miata torsen into my GSL-SE in two weeks..

Should be fun

Dan_s_young

iTrader: (1)

keep me informed with the results and how hard they are to install... thanks

Chemical

Okay so its in, I ended up using a Mazda comp race LSD with 4.44's instead of the miata torsen with 4.44's but the net result would've been the same; it makes quite the improvement in acceleration. I tested it in the wet, unfortunately, and I didn't have traction through first, second and third. First doesn't last that long either

BTW this is a GSL-SE with RB header and presilencer into an N1 style muffler, no other engine mods yet.

When it is dry I will gtech it and get you a time.

rkcarguy

I had a stock 12A + header and ported carb/intake in my 83 with 4.88 rear end gears and they made a huge difference, It really let the motor rev up freely. I put a couple 5.0s to waste with it. Even in 5th it was better, with the stock 3.90's the car would pull 128 MPH around 7000RPM, with the 4.88's it was pulling 132MPH at almost 7800. This wasn't strip or anything just a empty piece of highway. 4.44's would be perfect but I thought they stopped making that ratio?

slvr7

iTrader: (1)

I can't speak directly to your proposed change, but I can offer my experiences with a similar situation.
I have a 12A tranny and the RB alum flywheel on my '86 streetported NA.
The 12A tranny ratios are equivalent to a 4:30 diff ratio when in first, and a 4:50 in second.
The car accelerates to redline much more quickly, and is much livelier to drive! I easily light up the tires when pulling away from a stop if I feed in about 3500 rpm. I wouldn't say there are any street drivability hardships with the lighter flywheel, other than occasional stall when coming to a stop (and I'm not sure I should blame that on the flywheel). Due to the ratio change, I hit my 7500 rpm shiftpoint at 61 mph in second, as opposed to 67 mph with the stock tranny. I got a couple quick G-tech runs in the day I put the car away for the winter. On street tires, on damp ground, it went 15.3 with a 2.6sec 60 ft time. Some launch refinement could have it running 14's I think.
Anyway, for NA cars, I think the lightweight flywheel is a great thing.

SPiN Racing

On my old RX-3.. with a 3:90.. and a street port primary, Bridge secondary.. ITA RX3... So it was lighter etc..
A friend had a 84 12A RX-7. He installed exactly that.. a light steel flywheel and a 4.44.
It was a DEAD HEAT. He was a scootch ahead in like 1st.. but as I came up in the revs I would pull next to him.. then it was just pounding through the gears till I walked away when he ran out of revs in the 120+ world (After my change to 5th gear at 125ish)

Soo yeah.. change to a 4.44 and that alone will make a HUGE difference in performance.

louved_gen1

im planning on putting either a 4.88 or 4.44 in my 84 BP. Im kinda leaning towards the 4.88 because i want the most bang for the buck and rpm difference doesnt bother me.

KillaKitiie

how would i go about putting shorter gears in my 87 gxl it was an auto but now has an 5-sp the rear is a 3.9,any help would be appreciated.

SPiN Racing

Check with Mazdatrix.. or Racing beat for the gear you want for the car.. buy it.. then take the new ring and pinion to a local Gear vendor, and or Rearend shop.. and have them install it in the center chunk.

You dont want to try setting the lash on the rearend if you are a novice at it. Most of the shops I know of do not do them themselves.. they simply pay someone with the time and setup to do it for them. It is much easier and less time consuming. ALSO... if you mess up... your new gear can be gone in under a week... even if it feels "right" and you are off by a little on the lash... it will quickly trash your gear.

Chemical

Funny, that reminds me; we installed an lsd differential into my friend's fc and when it was all apart we discovered that there were no dial indicators or micrometers in the shop so we eyeballed it back together..

Well, it turns out we can eyeball backlash to within 0.01" and set the proper preload as well, because the diff is still doing fine..

..creepy eh?

(ps. i promise not to do that ever again)