Transmission excites Vehicle NVH

[Cars100]

I have a new final drive gear set for a Front wheel drive transmission. The gears tolerances are well within print tolerances. Unfortunately, the gear is exciting the vehicle axle. Are there any other solutions than hanging weights on the axles (axle dampers).

 

[GregLocock]

Hard to say without a lot more details. They aren't weights, they are tuned absorbers, usually. 5 kg weights can be very effective, but rarely get into production.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Tmoose]

The new gears howl? At certain speeds, or loads?

 

[Cars100]

The final drive sun gear is splined to the diff side gears. The diff side gear is splined to the axle shafts. Are any common methods of introducing compliance into the hard splined joint, that could damp-out the excitation.

The axle starts vibrating in third gear at about 30-35 mph, which "whines" during coasting.

 

[GregLocock]

Sounds like the new gearset wasn't installed properly. The side clearances and so on are critical.


No, generally automotive gearboxes do not use isolated splines. I'm tempted to say never, as the oil would attack most polymers.



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

There are oil resistant polymers, but I doubt they would withstand the load that would be necessary in the confined space.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Tmoose]

I've had a US RWD car or two that had some blue plastic-y coating on the drive shaft slipjoint

http://findarticles.com/p/articles/mi_m0FZX/is_2000_Sept/ai_65911584

"The slip mechanism uses a Nylon-coated involute spine that is designed for better wear resistance and decreased surface friction. John Crane, engineering manager, said while this is more common on larger drivelines, it is a standard feature for Rockford Powertrain on smaller drivelines."

Glidecote(TM) slip spline systems have a nylon coated yoke shaft and an integral tube sleeve to help prevent spline wear.

http://www.dana.com/offhighway_systems/products/3246f_spl.pdf

http://www.fusioncoatingsinc.com/spline.html