gear selection help.

[Guest]

[angry5.0]

Hey guys
I have an 89 mustang. It has a 306 stage 1 cam and alot of motor mods...N/A motor and  an AOD trans with 3,000 stall. I do alot of city driving. Would 3.73's be better or maybe 3.55's or 4.10's... And how hard is it to do a gear swap? Im running stock tires..It has stock gears now.I want a gear that will really wake the car up.I don't drag race I do like to get on the car and punch the shit out of it and hammer down sometimes. LOL but seriously what would be suggested?

[James93]

My first engine(MAC headers, 2800 RPM stalled converter, 70 mm t.b., K&N filter...)absolutely woke up with a 4.30:1 ring and pinion. I drove on the interstate all of the time and used a 27" tall rear tire.

Not a hard installation if you have some experience working on mechanical things. A few tools can usually be rented at the local parts store, minus the press to remove the pinion bearing.

[69 Merc]

While doing gear swaps IIRC there are a few after-measurements that are very important.  Gear lash depth is a biggie.

If you don't mind losing some mpg a high stalling T/C woke my Merc up more so than anything that I ever did to the Merc in the past.  (The 408W monster that it has now would wake up the dead!)

[85_GT]

after-measurements

? 

[69 Merc]

after-measurements

? 

I guess not the best choice of words -- how about "mesh measurements"?  LOL.

[95GTspeeddemon]

i have 4.30's, 70mph / 25in tire / .64 OD im at 2500rpm.
more gear helps with city mpg from what i hear; less load to get going.

[69 Merc]

With more gear your engine is spinning higher which I've found equates to less mpg.

[69 Merc]

IOW your launch is easier on your engine true because better gears offer more of a torque advantage but when cruising your engine will be turning faster ...

[95GTspeeddemon]

With more gear your engine is spinning higher which I've found equates to less mpg.

its about load.
more to get going, but less rpm = best highway
less to get going, but more rpm= better city
55mph is only 2k for me, thats not much at all. 3.27's were like 1500rpm or so.

[juiced coupe]

more gear helps with city mpg from what i hear; less load to get going.

Thats been my experience with trucks. Never paid much attention with cars, because I wasn't worried about mileage.

[85_GT]

With more gear your engine is spinning higher which I've found equates to less mpg.

its about load.
more to get going, but less rpm = best highway
less to get going, but more rpm= better city
55mph is only 2k for me, thats not much at all. 3.27's were like 1500rpm or so.

^^ +1
That's the same case for us in the heavy cars in the caprice/impala world.  Not the light weights like Roberts

[69 Merc]

I guess that after switching from 3.00 to 4.56 with a 3 speed you might see it my way -- driving in the city and heaven forbid if you flew down the highway as far as which eats gas more ...

Overkill?     

[85_GT]

It's that inefficient 5000 TC doing it to you...

[69 Merc]

With more gear your engine is spinning higher which I've found equates to less mpg.

its about load.
more to get going, but less rpm = best highway
less to get going, but more rpm= better city
55mph is only 2k for me, thats not much at all. 3.27's were like 1500rpm or so.

I guess it depends on how far you cruise when you are doing your city driving?

I was just saying that 500rpm more so than before will eat gas faster, right?

[69 Merc]

So you are saying that the city red lights launch hurts the mpg that badly compared to a higher cruise rpm mpg killer?