cups v. coilovers? Now weight & 4spd. vs. 5 spd.

[jdbubb@ix.netcom.com (Dan Bubb)]

> > One other thought, (since you must have available any f/d you care to
> > pick from) is why use a 3.89? The 3.89 gear set has 93 teeth vs. 84 >
>  teeth for the 3.94 or 3.67 gear sets. Bigger teeth are stronger!
>
> Interestingly, the 2H I just built for Tobias (via Eric S) had a 3.94:1
> made of a 63R + 16P = 79 total.  The choice of which ~3.9 R&P combo
> would be an issue if rings and pinions tended to fail, but IMO they're
> pretty robust.  But to dive in anyway, are few big teeth really
> stronger? or more small ones (less polar moment on each tooth, less
> time engaged, although less material supporting it)?  Since my
> knowledge of mechanics and gears is waaaay old, I'll defer to one of
> the ME's on the list...(is that you?).
>
> Practical observation: why didn't VW continue the use of the 63/16 2H
> 3.94 combination above if it was stronger?  Fewer teeth = less gear
> grinding therefore cheaper to make.

Well, I have to agree I haven't heard of alot of  busted ring and pinions.
Really I was just stirring the pot.
As far as the 2H r/p I guess I'd have to agree with Larry that the finer
pitch is smoother and quieter, so maybe the 63/16 was too much and the 74/19
of the 3.89 was not enough! Kinda the same deal with the 9A 5th vs. th 4K
5th. Almost the same ratio, but the 9A gear pitch is courser and alittle
stronger. Unless you're running a turbo and drag racing tranny reliability
doesn't seem to be an issue.

Dan