Gear Ratio ???

[chopped81step]

Does anyone know what the "standard gear ratio" is for an 81 2WD 6cyl 3SPD manual? The RPO Description for GQ1 says..... REAR AXLE - STANDARD. I don't want to pull the diff cover if I don't have to. Does anyone else have this combo & know what gear they have?? Any help would be great! Thanks.

[RandyP]

No other RPO codes that start with G on the label?

[chopped81step]

G50...HD rear springs. Thats the only other G code.

[allengator]

Why not just count??

Raise the rear, place in neutral, chock one tire (if non posi), rotate the free tire one full rotation while watching the driveshaft yoke. (mulitply this # by 2 if non posi)

With out making a degree wheel, there is a little guess work invovled in how far around the driveshaft turns, but this will get you close...

[LONGHAIR]

Why not just pull the cover off and be sure? Then you can confirm the condition of the other internals and change the fluid too. The rear end is one of the most abused/ignored parts of any vehicle. That could very-well be the factory lube in there.....it's 30 years old, give it a break.

[rayfinseats]

Just download the cheatcode.

[chopped81step]

I will end up pulling the diff. cover, I just wanted to see if anyone had this combo or knew what the standard gear was. One more thing.....
I've been searching the site & found i can run stock front shocks on the rear of my lowered truck? I have a flip kit on the rear with no "c" notch, I think it still has the stock legnth shocks on it & there bottomed out. I got this truck this past summer & liked it so much I drove the **** out of it all summer. Now I want to change a few things.

[bmchevy1979]

I believe it would be 2.73 by this

[N2TRUX]

Originally Posted by chopped81step

....I've been searching the site & found i can run stock front shocks on the rear of my lowered truck? I have a flip kit on the rear with no "c" notch, I think it still has the stock length shocks on it & there bottomed out...

I'm not sure if that correct or not, but I wouldn't do it. If it were me, I would run a set of shock extenders and put longer shocks on. You need as much travel from the rear shock as you can get to dampen the load.

Regarding the "standard" gear ratio, all this is "assuming" the stock rear axle is still in place. Pull the cover as LONGHAIR suggested, and know for sure what you have in there.

[ECU PIRATE]

I think I will end up doing the same since my 82' came with a 6 banger and a TH350 as std. from the plant. I have a feeling I will need to change the gears with my new drive train set up

[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.

[nbpro]

Originally Posted by N2TRUX

I'm not sure if that correct or not, but I wouldn't do it. If it were me, I would run a set of shock extenders and put longer shocks on. You need as much travel from the rear shock as you can get to dampen the load.

x2^^ If your vehicle's suspension is lowered, your stock shocks need to be replaced. Stock shocks allow only limited travel, and the lower you drop your vehicle the worse the problems get. Leaving stock shocks on your lowered vehicle results in poor handling, bone jarring ride, and limited shock life.

DJM Suspension Deluxe Flip Kit - 5" includes
Flip Brackets
Lower Shock Extenders
Bump Stops
Installation Hardware & Instructions

[chopped81step]

Thanks for the replies everyone. I would bet I've got 2.73's in the rear, it was a 6cyl 3spd... & now it's a 350 with a 4 spd. It gets pretty good gas mileage which I like but it only does a one wheel peel. I might put a locker in there since I don't drive it in the winter or on rainy days. It's just a summer ride.

QUOTE: Leaving stock shocks on your lowered vehicle results in poor handling, bone jarring ride, and limited shock life.

This I know all to well!!! The truck rides like a brick in the rear! I was thinking about fabbing up some shock extenders. Anyone know about how long the extenders are?

[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.

[Tx Firefighter]

I recently parted out a 6 cylinder 3 speed column shift truck. I could hardly believe it, but it did have 2.73 gears in it. I confirmed with the original owner (1 owner truck) that the rearend was unaltered.

Talk about a putrid combination. Six in a row, column shift and long leg rearend. I'm surprised anyone would buy one after a test drive.

[LONGHAIR]

Originally Posted by Tx Firefighter

Talk about a putrid combination. Six in a row, column shift and long leg rearend. I'm surprised anyone would buy one after a test drive.

Early 80s truck were just as bad...or worse. Imagine a 305 with a 700r4 and 2.56 gears. At least the lower 1st gear would get it going, but the OD was totally useless and the thing is a total dud. Now put that in a 4x4 with taller tires and it's worse yet...

[C-10 simplex]

Ok, all awake now--i work 3rd shift/night shift unfortunately hence the need to sleep during the day.

Also, i'm sorry---i rushed thru my notes and didn't list properly all the info:

In addition to the eng/trans combo you also need to know your GVWR rating which is printed on the certification label which should be on the drivers door jam.


So, 2nd try, In 81:

If you have a 6 cyl and your GVWR is 4900 lbs., AND you're 2WD your std axle ratio GQ1 is 2.73 regardless of which trans you got----3sp, 4sp, or auto.


If you have a 6 cyl and your GVWR is 5200 lbs. AND you're 2WD, your std axle ratio GQ1 is still 2.73 regardless of which trans you got---3sp, 4 sp, or auto.

Everything same as above and your GVWR is 5600 lbs. you still got 2.73

Now if the GVWR is 6100 lbs. (6100 lbs. in a 6 cyl truck wow) AND you got a 6 AND a 3spd then then std axle ratio GQ1 is 3.08 not 2.73

NOTE: i think it is because if this very reason is why GQ1 was never assigned a set number?

If the GVWR is 6100 lbs. and you got a 6cyl and you got a 4spd or auto, then the std axle ratio GQ1 is 2.73.


Now for 1/2 ton trucks with small block, not big block 8 cyls and 2WD:

If you have GVWR of 4900 AND a 3sp or 4sp, then GQ1=2.73
If you have GVWR of 4900 AND an automatic, then GQ1=2.56

If you have GVWR of 5200 AND a 3sp or 4sp, then GQ1=2.73
If you have GVWR of 5200 AND an automatic, then GQ1=2.56

5600lbs and 2bbl engine (check your vin#) and 3spd, then GQ1=3.08
5600lbs and 2bbl engine and automagic trans, then GQ1=2.73

5600 lbs and 4bbl engine and 3spd, then GQ1=3.08
5600 lbs and 4bbl engine and 4spd, then GQ1=2.73
5600 lbs and 4bbl engine and automagic, then GQ1=2.56


6100 lbs and 2bbl engine and 3sp, then GQ1=3.08
6100 lbs and 2bbl engine and automagic, then GQ1=2.73

6100 lbs and 4bbl engine and 3sp then GQ1=3.08
6100 lbs and 4bbl engine and 4sp then GQ1=2.73
6100 lbs and 4bbl engine and automagic, then GQ1=2.56

Whew!
Again, sorry---i rushed thru my notes and didn't see all the minute details.


Possible conclusions:
1) GQ1 was never assigned a set number because std axle ratio depends on alot of factors?

2) i think if one really wants to know what ratio they got is to bring the vin# to the dealer, they can type it in and tell you exactly which gear came with the truck and then to absolutely verify take the diff cover off and physically count the teeth on the ring and pinion; The oil probably could use a changing anyways.

[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?

[gregg72340]

Not to even remotly try to hijack this thread but where do the early 350 diesels play into this? Would the basic small block application apply here? I just picked up a free 12 bolt from a diesel but havent had the time to check the ratio yet and would definitly like to get rid of my 2.73's

[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
Posted via Mobile Device

[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.