autopaul

hey i was just wondering... i have a 12a race motor thats gonna be turbo, and i know tis gonna blow apart a 12a tranny,,,

yea, i know your all gonna say go for a t2 tranny swap, i know its the tried and tested method. but it seems like allot of work with different counterwieghts clutch, driveshaft etc....

besides im not one to follow the crowd...

so as i am going to school to be a millwright/machinist. i got to thinking. why not run the motor untill the tranny goes... then when something goes boom,, take it out and apart find out what went wrong. and then when you find the chipped teeth shattered gears or w/e then go to another spare tranny and get the in tact part.. and replicate it ( with chromoly ) cut it to spec, but leave extra material that looks like it would strengthen the gear as a whole...

i know its not just that easy, but think about it, if you had the knowledge and tools neccisary would you go and buy race gears, or swap in an expensive t2 tranny or would you try somehting new and be unique...

i just wondered what other complications there would be... it would be trial and error, but i think in the end you could have a really bullet proof tranny and if you were good later on you could even cut different gears and have whatever ratio you wanted...

wish me luck

Max7

I belive the T2's ribbed tranny is much stronger than the NA case. Not sure how you would beef up the NA case.
And do you feeling like dropping the tranny every weekend, and spending the next week making a new gear only to brake something else?
If you have tons of spare time, I'd like to see it, should last forever on a normal car.

autopaul

dropping the tranny on a fb isnt hard, ive done it in a couple hours... but i wonder if the case would hold up with better gears in it? well it wont be a normal car... iit will be raced fairly regularily.. as for beefing up the na case, i wonder how that could be done...

does anyone have pics of tranys that have blown on them? just for research cause if it was the case then i guess nothing can be done...

Zyrano

it sounds like a lot of work and down time, and it's not something that's worth being unique about, since a tried and true method already exist. if you have that kind of time and resources, I'd consider things like suspension pieces. A tranny / gears seems like a waste of time in my opinion...

Alvin

jgrewe

iTrader: (1)

I'm not one to follow the crowd either which is why I sometimes end up lost in the woods by myself. What about the mazda comp gears? Or, would you time be better spent adapting a stronger non- mazda tranny? Maybe a Borg Warner T-5, they have internal shift linkage like the mazda and are fairly small, they also survive behind a V8 engine. Mustangs, Camaros and S10 series pick-ups use them so they are real cheap.

Terrh

iTrader: (7)

Adapt a TII tranny. It's the easiest cheapest way. The 12A trannies are junk. So is every other M type mazda tranny. Go with the TII/Mustang R type tranny.
Transmissions need to be built to survive revs as well as torque too, don't forget.

ErnieT

iTrader: (2)

Call Ari at RP. We worked out a deal with a company that is making a straight cut gear tranny swap for the stock casing.

Kim

If you are able to make your own gears, do it right. $$$$$
A guy in my raceclass made his own gearbox from ground up, from casting the housing cutting the gears to the roller thingie for sequential shifting. Its a drysump gearbox, which means its pressure-lubed from inside the shafts and spray-lubed on the gearfaces

Supposedly it saves you a few ponies lost in the regular sloosh-type gearbox.

R.P.M.

iTrader: (3)

Straight cut gears for what stock casing? The N/A casing ?

ArmyOfOne

iTrader: (12)

I would be interesten din some straight cut gears. As far as the TII swap goes all you need is a good N/A chutch with a TII center, driveshaft and a tranny mount. No counterweights or flywheels. I thought it was too expensive and refused to go along with my tuners suggestions. I paid with 4 N/A transmissions. If I add all the downtime and cost. I could have paid for it all right off the bat.

I think that to improve the N/A transmission the only upgrade it needs is to go with a better synchro setup and a better (closer tolerance) shift linkage. The shift fork ends have too large a gap between them and the shift lever slips between them and locks up the transmission.

Maybe even a dog type gear would be beautiful.

speedturn

iTrader: (1)

There are a lot more failure points in a transmission than just teeth on gears. Things like small shafts and worn bearings and light weight housings can deflect and that prevents the teeth from meshing perfectly, and that too can lead to busted gears. I predict you will quickly get tired of patching a problem transmission.

I finally installed a purpose made racing transmission. Look at the difference in the Mazda input shaft vs the racing transmission input shaft. I doubt you can put bigger diameter shafts and bigger bearings into stock cases, and I know you cannot put bigger gears in because then you would have to change the shaft center to center distance between the main shaft and the counter shaft.

Do you have enough metalurgy experience to know that your steel material choice and heat treating processes and surface hardengin processes will produce a tooth that has enough surface hardness for wear resistance and yet a tough core that will not fracture under shock loads and that your choice of material is better than the original Mazda choice? Gears are normally not made from 41xx or 43xx series chrome moly steel alloys.

immanuel__7

iTrader: (8)

ok i have an 85 n/a 5 speed i took out the trany this summer and when i took it apart the intire casing was craked from so much stress i only realy took that car to the rack 2 full week ends, and 1 other time and did many street races and did a trip from london ont to 100km past montreal in 5.30H. thats a stock 12A with 230000miles tho. keep in mind when i lunch at the track i lunch at 6k so that might cause some stress on the trany but ya man if your going to build a trany build the second gen one. might be more work but it will take the abuse. where are you from i have a friend that hase a 87 n/a that might just sell you the whole car for 600$ obo (just needs new apex seal for engine to run with out the cluking hehe)
http://www.cardomain.com/ride/833695 link to his car just pm me for more details bro

old_skool

i'd do the tII swap. im a machinist in the air force, and found out that unless you have a waterjet system, cutting gears is a B*TCH! but if you really want to do it, i'll try to help you out.

-first you'll need to find out the gear tooth pitch, depth, and teeth per degree.(total teeth on gear/360)
- the chunk of metal is $$$. and if you are off by more than .001" overall, the gear will basically disintigrate at speed.
- you'll want the metal to be about 50-56 on the rockwell C scale.
- using an indexing head (for a vertical mill), or a rotary table (for a horizontal mill), find out your head spacing. (usually 40 revs of the handle equals 1 complete turn...360 degrees...of the head)
- you'll need to grind a bit for a fly cutter the shape and pitch of the teeth- THIS MUST BE PERFECT!!!
- next, touch off, set your depth, and cut. index to the next spot. repeat. and repeat. and repeat...etc.

hope that helped. feel free to correct or e-mail me with any questions!

-PS- get a machinists handbook. it will help you out with just about any metalworking. like the bible for machinists!