Final Drive Design
Final Drive Design
(OP)
Hello,
I have been charged with the design of a new final drive for a gearbox, this is for a FWD car that has a flat final drive and needs to be modified for use in mountains. I have two big questions you guyus can help me with:
1.) I have knowledge of design and manugfacturing of ISO gears, from what I see in the donor car a different type of automotive gear is used, anyone has a link to data on these gear profiles? What books references do you have?
2.) The other question is material, I have thought about using 8620 nitrided steel with cryogenic microstructure stabilization, but this can be quite an expensive solution. Anyone can suggest alternative materials and processes, the application is OEM and the car is a 1600cc engine withj modest hp and torque ratings.
Any help would be greatly appreciated
I have been charged with the design of a new final drive for a gearbox, this is for a FWD car that has a flat final drive and needs to be modified for use in mountains. I have two big questions you guyus can help me with:
1.) I have knowledge of design and manugfacturing of ISO gears, from what I see in the donor car a different type of automotive gear is used, anyone has a link to data on these gear profiles? What books references do you have?
2.) The other question is material, I have thought about using 8620 nitrided steel with cryogenic microstructure stabilization, but this can be quite an expensive solution. Anyone can suggest alternative materials and processes, the application is OEM and the car is a 1600cc engine withj modest hp and torque ratings.
Any help would be greatly appreciated





RE: Final Drive Design
And, given that this is part of a transversely-mounted transaxle, that pinion gear is probably one-piece with the output shaft of the transmission. Have you thought about this?
I've never heard of anyone aftermarket who actually makes non-stock ratios for transmissions like this. Usually one just finds another transmission of the same series but meant for a different vehicle model, which has different internal ratios (but is of the same general design), and swaps parts.
If you are working for the OEM who builds this gearbox, you ought to have plenty of co-workers who can help! What's your usual manufacturing process? Go out in the plant and have a look!
Can't comment on the material choice.
RE: Final Drive Design
One problem with nitriding gears is the limited case thickness. Doesn't provide much allowance for finish grinding. If your budget permits, you might consider using a vacuum melt quality raw material like 9310, rough the blank, shape the teeth, stress relieve/carburize/quench/temper, and then finish grind.
If you prefer to avoid the cost of finish grinding of your gear required with carbrizing, you can use a vacuum melt quality raw material like Nitralloy N, rough the blank, stress relieve/quench/temper, shape/shave the teeth, nitride, and then finish hone the tooth flanks after nitriding. For nitriding, Nitralloy N is a better choice than 8620.
RE: Final Drive Design