FirstYrLS1Z

iTrader: (4)

The 3.42s' will be fine, you'll like them.

440_Stroker

My Z28 had 2.73 and went to 3.73. I would average within 2 MPG's of having the 2.73's. going on a few 300+ round trips the car got about 23 MPG's on the highway doing around 70 mph.

FirstYrLS1Z

iTrader: (4)

^^^ thanks for the 3.73 23mpg post.
5 posts back I estimated that 3.73s' would have been spec'd at 24mpg had they built them.
There isn't much mpg variance among all the possible ratios from 2.73, 3.23, 3.42, 3.73. 4.10, 4.56 ( I know I omitted 3.08, 3.90, 4.30). The computer controlled air/fuel ratio does a good job handling it, much better than if you just calculated mpg change based on mechanical ratio change.
As ratio changes to a higher numerical ratio, the powertrain then has a better mechanical advantage over the vehicle weight and wind resistance. A better mechanical advantage equates to less power required which in turn the computer can start demanding less fuel while still maintaining the OEM range of acceptable A/F ratios.

440_Stroker

My only concern is with the 10 bolt. The greater the mechanical advantage the rear has the less tooth contact (# of overlap) and size the pinion gear seems to have with the ring gear. Maybe I'm fearful of nothing?

440_Stroker

One correction of one of my post. The 23 mpg average was for the entire trip with the highway portion being about 50% averaging about 70 mph. Of course there was in town driving which I am unsure if mileage really suffers as it takes less effort to get moving. Be that as it may, I did have some fun driving on the trip with some spirited driving. lol So I'm thinking the MPG's would be better without that aspect.

FirstYrLS1Z

iTrader: (4)

I live close (1 hour drive) to Summit in Tallmadge Ohio. They used to hold at the retail store 'Super Summit' (now held at Summit Motorsports Park) where the manufacturers would set up their displays in the large tented midways and display and answer questions. With my interest in rear ends for our f-bods I always spent time at the Richmond and Motive booths. Same info/answers from both, there can never be two teeth fully engaged at the same time, a 'lockup' would occur. The only time 2 teeth are being used at the same time is when it's sliding off of one and sliding onto another,
Per both of them, the smaller pinion (like a 4.10) is not any weaker than a 3.42. Per them. when we change ratio for performance we have a tendency to abuse them more.
I've been running 4.56s' for 14 years now, a used Richmond set I picked up at the Canfield swap meet for $25. I set the pattern up for maximum contact irregardless of noise, It's difficult to set up a used set anyway. The 4.56s' have the smallest pinion gear size. 14 years now with dragstrip runs and much abuse in 'street fun', they're fine.

440_Stroker

Good post. I've been to that Summit. Agreed that only one tooth can be fully seated but with multiple others partially I would think, I'm probably wrong, it would be stronger.

I've used both Motive and Richmond with no issues in automatic and stick cars.

FirstYrLS1Z

iTrader: (4)

Where you located, I'm up by the lake, Cleveland area.

440_Stroker

Was PA but long since moved south, it was a trip three of us took. A friend lived out near where Mike Tyson trained I think.