Kill No Cone

iTrader: (6)

Hey, is it true that the Seires 5 engines come with hardened stationary gears from the factory?

Aviator 902S

I'm not sure if they did or not. But you only need them if you intend to mod your engine to exceed say, 9000 rpm.

Latin270

I read somewhere one could just heat up a stock stationary gear to a certain degree to harden the metal....never tried it though.

perfect_circle

i think you would get better responces if you posted thisin the 2nd gen forum

perfect_circle

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s5-stationary-gears-better-than-s4-225420/

it was at the link at the botom with similar topics

Aviator 902S

They would have to be heated to a specific (ie: red hot) temperature and then held at that temp for a specified time period, which would depend on the alloy. After that they would be quenched in oil so as to cool quickly, but not so quickly as to become brittle. Unless you know these temps and time periods it's not recommended you try this. Besides, I don't believe hardened gears are all that expensive.

Jeff20B

iTrader: (13)

You're right. They're not much more expensive than stock ones. I always tell myself if I ever need to get new stationary gears, I'll get the hardened ones.

builder7

if you guys can get me the time and temp i can probably heat treat them at work. btw i work in a foundry.

Aviator 902S

A machine shop may be able to provide the correct time and temp, but they may need to know the alloy as well. I don't know what it is other than that it would have to be a very strong steel alloy. Molebdenum, cobalt, tungsten maybe?

smnc

Right... but it would usually be heated a second time to a lower temp and quenched in oil, then possibly a third time to a much lower temp and either quenched in water or left to air cool to reduce brittleness...
The exact process depends on the metal and desired hardness/brittleness...

Not somthing to experiment with on your engine internals

Aviator 902S

Agreed. Go buy a hardened set and avoid the hassle.

Supper

The hardest part is getting the correct hardness in the end product. A few degrees too much on one side of the part compaired to the other and you get serious embrittlement issues and would most likely wind up shearing something off inside the engine. Not to mention work hardening of metal that hasn't been properly heat treated. If you were really wanting to try and do them yourself, I would suggest talking to either a heater-treater or stress relief company (they do most of their work in the oil/gass industry around here on pressure vessels) they might let you know about propper heating techniques, cooling processes, etc.

Kill No Cone

iTrader: (6)

Man, you guys are working too hard!
The whole reason to buy the seires 5 gears is so that you don't have to deal with the time and the tempatures.

You just bolt them in...