If you have the ratios that I have on file, then it's a GREAT set of ratios for a 318. On file I have; ... 3.83-2.33-1.44-1.00-.79od
But;
IMO there are limitations;
After 55 years of driving manual transmission Mopars, I am finally happy with the ratios that I ended up at, which are;
3.09-1.92-1.40-1.00-.78od.
IMO, there is no better set for an A-body street machine.
the splits are .62-.73-.72-.78, which means that whatever you rev it to, on the shift, the Rpm will drop TO these percents. So, if you typically out-shift First at 3200, Second will come in at 3200 x .62= 1980; which means, your 318 has to have at least a little power at that 1980rpm.
Conversely, if your 318 doesn't wake up until 2400, then you will want to outshift First at 2400/.62=3870
So, IMO, the ratios that I have, with a hi-pressure 360 are perfect with a 3.55 rear gear. And I have run this gearset with a 318, for several winters, with lesser rear gears, even down to 2.76s, with good results. I am confident enough to say that if you had these ratios, you would never want for anything else.
Now then:
Back to the AX15
This gearset is NOT better than the Commando/GVod; But is a very close second choice.
The splits are .61-.62-.69-.79,
Which are pretty close to the Commando, except for Second gear. This means that for performance in a streeter, your engine is gonna need some grunt at the bottom of Second OR ...... OR, you would need to carry first gear out a we bit higher.
To get the Low-rpm Grunt, you need cylinder pressure.
Option 2, works just as good, you just can't show off quite as good.
Now we get into the heart of it;
To compare to the Commando ROAD-gears of
10.97-6.82-4.97-3.55-2.77
The AX wants the following rear gears
In First; .... 2.86
in Second; 2.93
in Third: ....3.45
in Fourth; . 3.55
in Fifth; .... 3.50
So, what do you do?
Well for me, Second gear rules, so I'm going with 2.94s.....
But for the 318, I'd go up to 3.23 for a bit more second gear punch. This will bring the rest of the gears down a bit, but for a streeter, that's no big deal, cuz top of third with 3.23s say 5000 rpm, would be 86mph.
In town, granny shifting will be just fine, but for excited driving, NOT WOT, you'll have to find a sweet spot just a bit further up the rpm band.
But look at the AX15 split from third gear on........ they are ideal for a modest powered 318.
To help you understand gearing, Here's what is happening;
every gear, multiplies your crankshaft torque by whatever the ratio is, which then gets multiplied by the rear gear.
So, in the case of the AX15 First gear of 3.83, and say you had 3.91s in the back, and say your 318 makes 250 ftlbs at 2000 rpm.
As far as the tires are concerned, at WOT, they're gonna see;
250 x 3.83 x 3.91= 3744 ftlbs, a very significant number.
Lets compare that to a 340 with the T/A box and 3.23s, Suppose the 340 make 300ftlbs at 2000rpm. The Tires, at WOT, are gonna see
300 x 2.47 x 3.23=2393 ftlbs.
Guess which combo is getting out first.
Ok I admit, not many guys use the 2.47 box, and not many use 3.23s, so lets pump it up a bit to
300 x 2.66 x 3.73= 2976, If you have the ratios that I have on file, then it's a GREAT set of ratios for a 318. On file I have; ... 3.83-2.33-1.44-1.00-.79od
But;
IMO there are limitations;
After 55 years of driving manual transmission Mopars, I am finally happy with the ratios that I ended up at, which are;
3.09-1.92-1.40-1.00-.78od.
IMO, there is no better set for an A-body street machine.
the splits are .62-.73-.72-.78, which means that whatever you rev it to, on the shift, the Rpm will drop TO these percents. So, if you typically out-shift First at 3200, Second will come in at 3200 x .62= 1980; which means, your 318 has to have at least a little power at that 1980rpm.
Conversely, if your 318 doesn't wake up until 2400, then you will want to outshift First at 2400/.62=3870
So, IMO, the ratios that I have, with a hi-pressure 360 are perfect with a 3.55 rear gear. And I have run this gearset with a 318, for several winters, with lesser rear gears, even down to 2.76s, with good results. I am confident enough to say that if you had these ratios, you would never want for anything else.
Now then:
Back to the AX15
This gearset is NOT better than the Commando/GVod; But is a very close second choice.
The splits are .61-.62-.69-.79,
Which are pretty close to the Commando, except for Second gear. This means that for performance in a streeter, your engine is gonna need some grunt at the bottom of Second OR ...... OR, you would need to carry first gear out a we bit higher.
To get the Low-rpm Grunt, you need cylinder pressure.
Option 2, works just as good, you just can't show off quite as good.
Now we get into the heart of it;
To compare to the Commando ROAD-gears of
10.97-6.82-4.97-3.55-2.77
The AX wants the following rear gears
In First; .... 2.86
in Second; 2.93
in Third: ....3.45
in Fourth; . 3.55
in Fifth; .... 3.50
So, what do you do?
Well for me, Second gear rules, so I'm going with 2.94s.....
But for the 318, I'd go up to 3.23 for a bit more second gear punch. This will bring the rest of the gears down a bit, but for a streeter, that's no big deal, cuz top of third with 3.23s say 5000 rpm, would be 86mph.
In town, granny shifting will be just fine, but for excited driving, NOT WOT, you'll have to find a sweet spot just a bit further up the rpm band.
But look at the AX15 split from third gear on........ they are ideal for a modest powered 318.
To help you understand gearing, Here's what is happening;
every gear, multiplies your crankshaft torque by whatever the ratio is, which then gets multiplied by the rear gear.
So, in the case of the AX15 First gear of 3.83, and say you had 3.91s in the back, and say your 318 makes 250 ftlbs at 2000 rpm.
As far as the tires are concerned, at WOT, they're gonna see;
250 x 3.83 x 3.91= 3744 ftlbs, a very significant number.
Lets compare that to a 340 with the T/A box and 3.23s, Suppose the 340 make 300ftlbs at 2000rpm. The Tires, at WOT, are gonna see
300 x 2.47 x 3.23=2393 ftlbs.
Guess which combo is getting out first.
Ok I admit, not many guys use the 2.47 box, and not many use 3.23s, so lets pump it up a bit to
300 x 2.66 x 3.73= 2976, Guess whos moving out faster.
Ok so maybe your 318 cannot muster 250 ftlbs.
To equal the 2976 of the 340, your 318 would need to have
2976/(3.83 x 3.73)= 208ftlbs which IMO would be pretty sick.
But suppose I guessed the 340 wrong. To equal 3744, it would need to be making ; 3744/(2.66 x 3.73)= 377ftlbs at 2000rpm. In a streeter, I can't see that at 2000rpm.
Furthermore, your first gear of say 3.83 x 3.23=12.37 is pretty deep, and to run that with a Mopar 2.66 would require a rear-gear of 4.65 which would be highly unusual for anybody to run. Therefore, of all the Mopar 4-speeders that you are ever likely to meet, not even one of them can compare to your first gear. Well, maybe one.
As for second with the AX15, 2.33x3.23= 7.52,
and with the Mopar is 1.92 x 3.55 =6.82 what most guys will run so you are 10% greater , so your engine can be 10% less powerful, and you guys might run neck and neck.
By third gear, your AX15, 1.44gear is about the same as the Mopar 1.40 but the 340 car is running 3.55s to your 3.23s , so, sooner or later, the 340 car is gonna leave you behind.
So that's how that works.
Finally, the combination of overdrive and 3.23s makes for a very low cruise ratio of 2.55, and 65=2060, which is about as low as you can go with a 318, and still feed it optimal ignition timing, with the factory systems. Any slower rpm, and yur gonna need a computer, to better your fuel-economy. So that means, a little more rpm will not affect your economy much. in fact, 2400 is about when it begins to drop off, which is why I run 2240. To run 2240 with the AX15 would require a rear gear of 3.55s, so, IMO, you wouldn't run any more than that, cuz of what happens in First gear If you already have these installed, I would leave them in there with the AX15. But if you have anything bigger, I would swap them out for not more than 3.23s unless you already had nothing but the 3.55s under the bench.
