s4 na transmission power limits?
 

im making 250-260 rwhp, turbo 6 port. i stripped the a transmission gear(i think its called input gear) . i want to replace it with another s4 na trans, but is it going to last??

Btw trans that broke has 140,000 miles on it, and a damaged bearing.

will it last? how many licks to the center of a tootsie pop?

if you're worried, upgrade.

no one can answer this question with any integrity, the non turbo transmissions are hot garbage and usually break behind the non turbo engines with half that power. the turbo transmission? it is almost bulletproof to well above 350whp.

a transmission that is iffy to 200whp or a transmission that normally can handle 500whp with relative ease.. decisions decisions. if you look at the n/a transmission funny it falls over sideways, strips a gear or gets locked in reverse.

lol,, 100 licks. until she comes.


any alternatives besides t2 conversion? Cryo treat gears?, s5 na trans maybe stronger then s4 or the same?

RotaryEvolution is right, but it all depends on the mileage of the N/A trans and your driving style. if you want to keep the N/A, don't drag race.
AaronCake was pushing 400WHP through an N/A trans for a while, he blew two up and finally moved up to a TII trans.
Keeping the N/A trans is a Gamble, upgrading is not. All you have to do is get a TII flywheel, Trans, and a custom driveshaft to reatin the N/A rear end. Put down more power and you'll be risking that rear end too.

Also need the T2 starter and slave cylinder.

Yeah, sorry. :)

And a turbo model clutch hehe

not really, even if you can possibly overcome one issue there are others inherent with the transmission itself. if you cryo the gears it is only marginally more durable but the case will always be weak. the reverse detent mechanism has no 100% fix and the box itself is just lightweight, something where weight savings isn't in your best interest.

the miata boxes are a little stronger, and the gearing is way better. if you have a turbo, and thus torque, the NA trans is going to be fragile.

if you don't do any hard launches, and are nice to it, it should live a while (i'd have no problems), but put some animal in there, and it'll break.

yep, anything where you are snapping power through the drivetrain will break the weak link, in this case it is the transmission then the n/a half shafts.

if you roll on power without sidestepping the clutch then it will be much nicer to you in return. ie no hard drag launches, harsh quick shifts or clutch kicks to put you sideways otherwise the transmission will make you walk home.

just go with the TII

Thx for reply's . i found a turbo trans but have no time to pick it up due to work, if he still has it by next week i will get it, selling only for $150

Just a heads up. Make sure the TII trans has the crossmember with it because you cant use a n/a crossmember on a TII trans or visa versa.

I believe the reason for failed front gears is a failed bearing, The front lower bearing was completely destroyed. That caused the shafts to separate under load, and that not a good thing.

For now i repalced the old s4 trans with s5 non turbo trans with mobil1 synthetic fluid(to keep those bearings happy), will keep update on how it holds up.

PS. Not doing 1st gear launches and no drag strip.

I think i can as long its s4 to t2s4 and s5 to t2s5.

I just got a cross member for a na s5 trans, it came off a s5 t2 trans.

i am pretty sure the crossmember just has to match the series of the transmission

Opps yes you both are correct. Sorry for the misinformation. EK!

No. There is no mixing of crossmembers. There are 5 different FC ones:

S4 NA
S4 TII
S5 NA
S5 TII
Auto

Transmission

Yep

Horse power does not break drive line components, it's the torque that does that. If you are going to build a 6-port turbo out of an n/a car, then you have to upgrade EVERYTHING from the clutch back to the axles, not to mention needed upgrades to other systems. Depending on the car itself, it maybe easier just to buy a T2 car and swap engines.

I did the same thing with good bearings and half the WHP, N/A.

^
This.
Beyond the inherent strengths/weaknesses of a particular part (transmission in this case) is the driver's style.
Some people are just harder on equipment than others, at any given level of competence/speed.

I have a N/A with some work done, have driven standard transmission vehicles for many years and still grenaded a gear in my car once. they don't like to be spun past 10,000 going into second.

So far my NA trans holding up. at least 300hp. i dont boost in 4rth since its the gear that broke on previous trans.

4th is the only gear that is direct through the transmission. It's actually the least likly to break. :)

FYI for those swapping TII transmissions onto NA cars, you can use the NA mount if it's in good shape. Only difference seems to be the location of the mounting holes to the body. In fact if you look at the mount, Mazda jus welds on a plate over the slot to make the mount either TII or NA. The rest is the same.

I am so glad I found this thread. I am going tII in my vert, I was aming for 300 whp and keeping the s5 na trans and selling my tII trans and cluch, but I think I will dish out extra money for a flywheel and modified drive shaft for reliability.