i have just test drove a jap import wrx sti type ra!

when the car was being reversed there was a whine from the transmition!

before i asked about it i was told it was due to having straight cut gears in reverse does anybody know if this is true?

 

just about every car (off that age) has straight cut reverse gears.

 

Would that cause whining?

 

the straight cut gears will cause whining, which is one of the main reasons all the forward gears are not straight cut

 

just about every car i have ever driven has whined in reverse! Its perfectly normal.

 

perfectly normal....... mate had a mini with a complete straight cut gear set in it years ago,could hear him coming a mile away with the noise,straight cut gears are not so power sapping as conventional helical cut gears,race boxes tend to use straight cut for that reason,road cars have helical to reduce the noise levels

 

Thanks alot guys that is a relief!

comments much appreciated!

 

Noise isnt the only reason, If you think about it, reverse gear needs an Idler gear to actually reverse the gears rotation. This is usually a sliding gear, and it is much easier to slide a gear together if theyre both straight cut.

 

I don't think anyone has mentioned a reason why reverse is straight cut, just why forward cars are not straight cut.

 

okie doke, i'll have a nother crack at it:

Reverse Gears are normally straight cut because they are usually very low ratio (you can do about 10 mph in reverse?) and so that they transmit the torque more effectively, they are straight cut. im its also for the other reason I stated, but not sure.

Now, if you've got a CVT, then the fun really begins. Because they have a reverse gear BEFORE the actual Belt and pulleys,then you can go exactly the same speed in reverse as you can forwards Old Volvo's I think used this.

Hope that explains it better, but knowing me, i've probably just confused the whole situation!

Cheers,

James

 

Good response I thought. Cheery and polite too which is always appreciated