Gear Ratio ???

[1LowToy]

My 79, 6 cyl automatic has 3:42s. A little low for my liking but I'm thinking of going to a 700r4. I have another rear end, i'm thinking 3:08s as it was from an 84 v8 model. time will tell what changes will take place.

[C-10 simplex]

For 81, The 6 cylinders got 2.73 as std axle ratio. GQ1


The 8's got 2.56 GQ1


Unless it's a california truck; In that case 6 cylinders got 3.08 as the std axle ratio code GQ1 and 8's got 2.73.

i went thru this dilema yrs ago when i first got my truck.

Also, if you bring your vin# to any decent gm dealer they can type it in and tell you exactly what gear ratio came with the truck originally.

[ECU PIRATE]

Originally Posted by C-10 simplex

For 81, The 6 cylinders got 2.73 as std axle ratio. GQ1


The 8's got 2.56 GQ1


Unless it's a california truck; In that case 6 cylinders got 3.08 as the std axle ratio code GQ1 and 8's got 2.73.

i went thru this dilema yrs ago when i first got my truck.

Also, if you bring your vin# to any decent gm dealer they can type it in and tell you exactly what gear ratio came with the truck originally.

Good to know. I guess for an 82' model year, the rear end ratio would be the same? What would be your recommendations for a lowered 82' (4/6 drop) with a 350 and a Muncie M20 4 spd. tranny?

[C-10 simplex]

Oh S

i screwed up i think? Std gear ratio is ALSO dependent on the GVWR of your truck. Will report back in detail after i wake up. Sorry.

[C-10 simplex]

Originally Posted by ECU PIRATE

Good to know. I guess for an 82' model year, the rear end ratio would be the same? What would be your recommendations for a lowered 82' (4/6 drop) with a 350 and a Muncie M20 4 spd. tranny?

1) Yes, 82 appears to be identical to 81 gear wise.


NOTE: i'm not really that good with drivetrain combos so.....

2) As far as recommendations i'm struggling with that myself because i want to tow about no more than 5000lbs but only occasionally so this right there means i don't want to go too low because i'll spend most of the time commuting not towing. But i can't go too high because trying to tow 5000lbs with 2.56 would put too much strain on the engine if i use a "smaller" engine i'm thinking.

On top of that to confuse the issue further i'm not sure if i want to use a 383/400 really good for towing not so good on gas. Or a 6.2 diesel or 305 better on mpg, but less power.

What are you planning on using your truck for? The other thing, i'm thinking is 4th gear on a muncieM20 1:1? And what ratios are the first 3 gears?

[ECU PIRATE]

Originally Posted by C-10 simplex

1) Yes, 82 appears to be identical to 81 gear wise.


NOTE: i'm not really that good with drivetrain combos so.....

2) As far as recommendations i'm struggling with that myself because i want to tow about no more than 5000lbs but only occasionally so this right there means i don't want to go too low because i'll spend most of the time commuting not towing. But i can't go too high because trying to tow 5000lbs with 2.56 would put too much strain on the engine if i use a "smaller" engine i'm thinking.

On top of that to confuse the issue further i'm not sure if i want to use a 383/400 really good for towing not so good on gas. Or a 6.2 diesel or 305 better on mpg, but less power.

What are you planning on using your truck for? The other thing, i'm thinking is 4th gear on a muncieM20 1:1? And what ratios are the first 3 gears?

I here you..........the choices are endless. My truck is only going to be for play!!!!!!!! Muncie M20 gearing
1st - 2.52
2nd- 1.88
3rd - 1.46
4th - 1.00

I figure I may need to move up to 3.08 or 3.73 to see any real improvement
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[C-10 simplex]

i'll get back to the both of yous later in more detail; i'm actually dizzy from all the numbers (and from working nightshift).

But yes, the diesel mirrors the smallblock gear selections, although not identical in all cases---the diesel usually gets the next step up (next lower gear).

i'm thinking maybe 3.42 would be "fun" yet still get decent mpg with the 350/M20 combo?

[chopped81step]

C-10 simplex.....great info. thanks! I'm not sure what the GVWR is, the door sticker's long gone but I'm thinking it's got a 2.73. The diff. cover looks like it's never been off. I've got two projects going right now that need to be finished before I can really tear into the truck & then I'm gonna change the gear to a 3.73 & some type of locker. I'm running a saginaw 4spd I believe the gears are 1st - 3.11, 2nd - 2.20, 3rd - 1.47, 4th - 1.00. This is my summer DD but I still want to have fun with it.

[LONGHAIR]

Originally Posted by C-10 simplex

i'm thinking maybe 3.42 would be "fun" yet still get decent mpg with the 350/M20 combo?

I doubt that you will get much "fun" out of a 2.50 first gear with a heavy pick-up truck? You really need a lower rear end gear to make it more drivable, but that creates highway RPM issues.
These "performance car" transmisions just don't have a wide enough gear spread for trucks as an "all around" daily driver. The generally taller tires of a truck make it worse.