rear axle ratio RPO

[70shorty]

Yo dudes, what's up,,,
I have a question about the numbers on the drive axle,,, what do they mean...WRD ? 343 2 the rest of it was to hard see,,,
Just replaced my old rear end with this one,
my old one was WRD C 258 1,,
I'm tring to find out the ratio on the new one,,,
old one is a rpo code GU-6 3.42's HELP,,,

[70shorty]

Ok here's one,,, Why the hell do I have to spin both tires to get the pinion to turn,,,? use to be all I needed to do was spin the right rear to check ratio,,,
Checking the ratio the old skool way,,,

[drperry]

If it's the 4 banger, you don't want 3.08. 3.23 would be the tallest I'd put in it...

If it's a single cab short box, you could maybe work with the 3.08... But 3.23 or 3.42 is what you'd want.

[70shorty]

Hey thanks for the come back,,,
Yeah it's the 98 4.3 ext. cab short box,,, I had the 3.42's in it had to swap it out for another rear end my old one cracked when the u joint on the rear of the shaft let loose at 80+ on the hiway,,, what a ride that was,,,felt like a paint shaker,,,,
So now I'm thinking I have 3.73' not sure yet,,, I need to pull the cover and check.
I like the new exceleration, so I'm thinking I have the 3.73's..
But I need also to reprogram the computer,, cruising the hiway at 3 grand, speedo's at 97mph and there's nothing left in the throttle,, sucks man,,up against the gov..

[drperry]

My bad, forgot to quote the post I was replying to and didn't check for a new page, lol.

Yeah, you probably have the 3.73s now...

[70shorty]

That's what I thought,,, now to find someone who can reprogram my ECU,,, Or swap out the gears,, hate to loose the 3.73's but what ever works the best.
I did think of buying the scanner for myself but, not sure I want to spend a couple of hundered for a one shot deal...

[Gator4x4]

my 96 4x4 4.3L has the 3.42 axle now i put 33x12.50 x15 on it with steel wheels and now my power is suffering a lil and it has to shit down on the highway to pull most hills now, should i change the gear ratio in the front and rearend, or just the rear and if so, what ratio should i go with i was thing 3.73 or 4.10 someone help me!

[Gator4x4]

my 96 4x4 4.3L has the 3.42 axle now i put 33x12.50 x15 on it with steel wheels and now my power is suffering a lil and it has to shit down on the highway to pull most hills now, should i change the front and rear axle or just the front and which gearing should i go with i was thinking 3.73 or 4.10, someone let me know!

[Hoover]

got a 96 S-10 4.3 auto with a 3.42 rear end and RPO G80

I have a silverado with the G80 locking diff and I know what it feels like when it is locked and my S-10 does not even come close. I've gotten stuck in wet grass and dug a hole with just 1 wheel. I'm the second owner, the first was an older gentleman that didn't change anything on the truck. Don't know if its just a mistake with adding the RPO code of if its just the locker itself worn out.

Any kind of help would be most appreciated.

[lowereds10extcab]

alright i am very confused. i have a 93 2.8L v6 with a 5spd. and i know i have 3.08 diff gears. but it rpms super high and has absolutly no power, (i have to downshift to at least 3rd gear and a million rpm to get up any incline) would it hurt or help to go to like a 3.73 gear. SOMEONE PLEASE HELP ME.

[personnaobscura21]

ok lemme cap what a locker open diff and a posi really are(and limited slip for those of u who think thers a difference between lim-slip and posi-trac)
lets start with the standard

"open differential" which is simply a standard rearend with a standard spider gear which by flaw of design directs all the power to the one wheel without traction.

A "differential locker" is a non street legal diff when locked that employs a lil device that locks the spider gear so that power is spread evenly across the axles at all times. downfall, one whell loses traction both lose traction.

finally my favorite the street legal "limited-slip differential" alsoo posi-trac(positrac is merely a brand name for limited-slip differential for those of you who think thers a difference) anyway the limited-slip diff allows for SOME variation in speed between the two sides of the axle, up to a preset limit so that if one spins too much faster the other will be forced to pick up slack in the traction and also this way if one wheel loses traction the other is allowed to stay hooked up and deliver power to the pavement.

with a lil practice this third "posi trac" can be manipulated thru feathering of the throttle/clutch to keep both wheels hooked up at all times seemlessly

[personnaobscura21]

Quote: Originally Posted by Gator4x4

my 96 4x4 4.3L has the 3.42 axle now i put 33x12.50 x15 on it with steel wheels and now my power is suffering a lil and it has to shit down on the highway to pull most hills now, should i change the front and rear axle or just the front and which gearing should i go with i was thinking 3.73 or 4.10, someone let me know!

thers really no need to blow the extra bill on axles the loss of power is because of the wheel size when u up the tire diameter any significant amount its the same as using a higher gear ratio

solution: install lower geared diffs fer example ur runnin 3.42 try 3.75s or 4.00s

matter of fact ill keep u posted on this cuz i kno in one of my off road mags somewher thers an equation u can use to calculate exactly what gears will bring u back to stock performance

[personnaobscura21]

Quote: Originally Posted by Gator4x4

my 96 4x4 4.3L has the 3.42 axle now i put 33x12.50 x15 on it with steel wheels and now my power is suffering a lil and it has to shit down on the highway to pull most hills now, should i change the front and rear axle or just the front and which gearing should i go with i was thinking 3.73 or 4.10, someone let me know!

sweetness check it out i found the equation i was talkin about i just need ur old tire size to calculate for u
so heretis

New tire diameter
old tire diameter x current axle ratio(:1)= new axle ratio(:1)

for those math illiterates say u had 18 inch tires stock u change em to 22 inch tires and ur stock gear ratio is 3.75 soo u take ur new tire 22 divided by old tire 18 times stock gear 3.75 gives u 4.58333
22/18x3.75=4.58333 round it up or down to the closest available gear set on the market and whala feels like u never did nethin cept now u got some sweet meats

[personnaobscura21]

this will also fix ur speedo calibration

[cruzerman350]

so i just checked and my 84 doesnt have a code in te glovebox and the codes dont match anyhting on the vin so how else can i find the gear ratio?

[drperry]

Put a mark on the tire and the ground, or fender, then put a mark on the drive shaft and axle housing... Count how many times the driveshaft goes around when you turn the tire in one rotation.

[ChopperCharles]

Quote: Originally Posted by DoubleDown

that is correct. they need to use the low gear ratio to multiply the little amount of torque the 4cyl puts out. damn near every s10 with the 4cyl and auto tranny has 4.10 rear ratio.

My 95 S10 regular cab 2.2L came with a 3.73. I HATE it, especially with 30" tires. SLOW. The 98 extended cab I used to own (that was bounced off a tree) had much, much more power due to those 4.10 gears.

Charles.

[DaRkCyDe]

hmm.. my truck is a 96 and i have no sticker.. its a 4.3 vortec extended cab.. what all does it have? lol

[RADSonoma04]

I Have been doing a lot of research on lifting my 2004 GMC Sonoma. I also know that I will be needing a gear swap. Whenever larger-than-stock tires are installed on a truck, it will have a direct effect on the truck's performance. Why? It has to do with the effective gear ratio. Your truck comes from the factory with the optimum axle gear ratio to work with the truck's engine, transmission, and stock tire combination as well as provide a good balance between acceleration and fuel economy. When taller tires are installed on a truck but the axle ratios stay the same; the effective gear ratio is reduced. This means the engine is forced to operate below its power band, and performance and fuel economy suffer as a result. In order to restore the effective gear ratio (and the truck's performance), you'll need to have the axle gears swapped to lower (numerically higher) ratios.

The chart is divided into three categories. The rpm highlighted in black are optimum for the tire size and ratio combination. These will most closely give you the best overall drivability. If you're looking for a ratio that will give better fuel economy for highway driving at the expense of some acceleration and overall performance, choose a ratio in the yellow shaded area. If you're looking for a ratio that will improve acceleration and towing power at the expense of some fuel economy, choose a ratio in the blue shaded area.

[philntx]

Where did you come up with this chart?

No modern OEM transmission has a final drive ratio of 1:1, which is what this chart is based upon.........

You should delete it and replace it with one that reflects overdrive transmissions. (or at least qualify your data better)

Your chart shows a 31" tire with 3.73 gears running at 2,628 rpms. However, you don't show the speed. My stock ZR2 would be running around 90 to 95 at those RPM's

[RADSonoma04]

Quote: Originally Posted by philntx

Where did you come up with this chart?

No modern OEM transmission has a final drive ratio of 1:1, which is what this chart is based upon.........

You should delete it and replace it with one that reflects overdrive transmissions. (or at least qualify your data better)

Your chart shows a 31" tire with 3.73 gears running at 2,628 rpms. However, you don't show the speed. My stock ZR2 would be running around 90 to 95 at those RPM's

You are abosolutely correct. I forgot to add:
This chart is based on engine rpm at 65 mph with the transmission in a 1:1 gear ratio (Third with a three-speed manual, Fourth with a four-speed manual, or Third with an Automatic). Remember, the actual rpm indicated in the chart will be slightly higher (between 100 and 300 rpm) on vehicles equipped with an automatic transmission. This is due to the slip present in an auto transmission's torque converter.

I hope this helps

[RADSonoma04]

I don't know if this will be helpful or not. I Have asked around and I have a buddy who is a genius or a good Bull$hitter. It makes sense to me.

About Mile per Hour and Revolutions per Minute
First find the vehicle speed, MPH and the consequent engine RPM operating range:

Formula for MPH
MPH = TIRE RADIUS ÷ 168 x ENGINE RPM ÷ GEAR RATIO

Example: What MPH at 6500 RPM with a 4.9 rear axle and 14 inch radius
tire in 4th (1:1) gear?

MPH = 14 ÷ 168 x 6500 ÷ 4.90 ÷ 1 = 111 MPH

Example: in 3rd gear (1.34)?

MPH = 14 ÷ 168 x 6500 ÷ 4.90 ÷ 1.34 = 83 MPH

Note: Tire Radius is distance, in inches, from center of wheel to the top of the tire.

Note: Gear Ratio is Rear Axle ratio divided by Transmission Gear ratio.


Formula for RPM
RPM = 168 x GEAR RATIO x MPH ÷ TIRE RADIUS

Example: Using the first example, what will be the RPM after shift from 3rd to 4th gear at 83 MPH?

RPM = 168 x 4.90 x 83 ÷ 14 = 4880 RPM




Formula for Gear Ratio
GEAR RATIO = TIRE RADIUS x RPM ÷ 168 ÷ MPH

Example: Using the first example, what Gear Ratio is required for 120 MPH at 6500 RPM?

GR = 14 x 6500 ÷ 168 ÷ 120 = 4.51


Formula for Tire Radius
TIRE RADIUS = 168 x MPH x GEAR RATIO ÷ RPM

Example: Using the first example, what tire radius for 110 MPH but at 6000 RPM with a 4.11 gear?

168 x 110 x 4.11 ÷ 6000 = 12.7 inches

Note: Approximately a 25" diameter tire. Remember that the tire radius will be less during hard acceleration than when the vehicle is standing still. Also, radius will be greater at high speed due to tire expansion from centrifugal force.

[XmatttttthewX]

Quote: Originally Posted by MuddyS10

lmmfao, sorry guys, i just find that funny as shit.

hahah i want to see a v4

[palmerino]

Hey,
I have a 2.2L extended cab auto with a standard diff...
I want to put a posi rear end from the junkyard in it..
- I mainly drive Highway, from Baltimore to DC
- So I would like to increase my mpg, not to worried about accel.

My question is...What diff gear size should I go with?...As it will probably be hard to find a 4.1 posi at the junkyard...there are tons of v6 blazers there and almost no 4 cyl.

[Drag2Death91]

i have a 1995 ext cab, came stock with the 2.2 4 banger...from what ive read on here it has the 4.10 gears in it. the problem is, it doesnt have the 2.2L in it anymore...it has a built 355sbc w/350 turbo trans... but still has stock gears in it! my question is ... im considering getting 3.73's so i can go 60-65mph constantly down the highway to shows and what not without my motor screaming...it runs at about 3300rpms at what i think it 55-60mph(it dont have a speedo so i have no clue how fast im running) but i dont like it running that high for a long time main reason is gas MPG but im wondering if 3.73's would be a good choice? i dont want to race the truck its not built for it, its bagged and body dropped just a cool lookin show truck with a lot of balls...i dont want it to be a turd i still want it to get up n go when i need it to but i just want the best of both worlds....and i was thinkin 3.73?

[max1million]

In general lower engine rpm for same road speed give you better fuel mileage, but it depends on the tune of the engine. Go to far fuel consumption will start going back up, and mileage down.

To drop the engine rpm for same road speed, taller tires, and/or shallow differential gears (that's numerically lower gear ratio). It increase the max road speed if there is enough power to over come wind, gravity (uphill) and all other resistance (fatter softer tires add resistance along with better traction). It will also spread the shift point, shift up to next gear at higher road speed and more engine rpm drop when you do. You'd need to down shift more often to go uphill to get back in the power band, and it will feel more sluggish. Too much of a spread you drop out of power band when shifting. Of course doing any of them would throw of your speedometer/odometer reading if not re-calibrated. You end up going farther distance at higher road speed then is showing.

If just switching from nonoverdrive to overdrive tranny, say a 4 to a 5, assuming first 4 are same gearing the shift point doesn't change you just have an extra gear which give you a lower rpm at on highway, but 5th will feel more sluggish then 4th. Your speedometer/odometer may need to be re-calibrated.

Shorter tires or steeper differential gears (high numerically) basically the opposite. Some reasons to change to steeper gears generally include, to make up for tall tires (often fat stickies), higher revving engine, narrow power band (needing closer shift points), you want a crawler/hauler (slow speed/heavy load), it give a better performance by keeping engine in rpm range with most power. You upshift earlier, loose max road speed (for same max rpm), usually loose highway fuel economy, and add more wear/stress on engine because of higher rpm. Your speedometer/odometer reads high if not recalibrated to match. Not much reason to use tranny with fewer gears, except durabilty if you don't have or can't find one strong enough that fit, or less shifting.

This reminds me of a person I knew wanted to change to steeper differential gears on his truck. I asked him why and he said because it did have enough power/rpm to climb a hill 45mph in top gear. Asked him if he had problems getting it going from stop. He said no, the only problem he had with it was the need to keep down shifting out of top gear on the back roads. Asked him what it had for a tranny and he said it was an overdrive (I don't remember how many speed/gears). I suggest just not using overdrive (to use the next gear down) on the back roads instead to get same effect of steeper differential gear. He didn't like that idea, I guess feeling that if the gear was there and wasn't in the city that it had to be used. I also pointed out that the last gear before overdrive is same as running a non-overdrive tranny in last gear. It is 1:1(tranny) not wearing any gears in the tranny. Overdrive would still be there for highway use (also ran highway alot), and better highway fuel mileage. He still didn't really like the idea or was unsure of it, which didn't make sense to me. Keep in mind he had no problem with the gearing and shifting of any other gear just not being able to leave it in overdrive on the backroads.

My old car (it's gone now) had a decent 289ci, with old home rebuilt 4barrel Ford carb, Edlebrock dual plain intake, Crane HMV-260-2 cam and lifters, home ported stock heads and dual 2 inch exhaust, on/in otherwise stock (cleaned, ridge reamed, honed, new rings and bearings) 9.0:1 compression engine. With overdrive 4speed auto trans, 2.73:1 (if I remember correctly) gear ratio differential rear axle, and 205x75(or 70?)x14 tires, I was quite happy with 2000 (to 2600 w/converter slip wot) rpm at 80mph. Give it a kick at lower speed and drop into 3rd to go (or 2nd etc. depending on speed). Keep in mind power was generally between 2000 and 4500 rpm, and valves would float by 5500 rpm (stock springs), it was meant to be a low rpm street engine. But sometimes I'd run it in 3rd (or 2nd) on backroads (especially when slick) so it wouldn't constantly shift.

Yeh long post, well maybe something of use there. Happy hauling or haulin.

[max1million]

Oh and currently 92 S10, 2.5liter, 5speed manual trans, stocker turning 3000rpm at 70mph (if all reading correct). Seems high but runs ok, about 25mpg highway. Haven't checked diff ratio.

[D DEEZY]

So I guess I have 3.08 with a posi. Is this good or am I going to experience any problems. Single cab 4.3 with 5 speed is what it's in.

[Mr. Front Cup]

are u still needing the RPO codes for the 4.10 gears and the limited slip differential??? i am currently searching for a 4.10 rear end and have those codes.

[lowhardbodynissan]

Quote: Originally Posted by Nate8727

Ok here is a rundown of the different cabs and engine combos for differentials. I found this out just by building an s-10 on chevy.com

2.2 4cyl- regular cab LS - manual tranny/3.73
auto tranny/4.10

extended cab LS- manual tranny/4.10
auto tranny/4.10

regular cab xtreme- manual tranny/3.73
auto tranny/4.10

extended cab xtreme- manual tranny/4.10
auto tranny/4.10


4.3 6cyl- regular cab LS- manual tranny/3.08
auto tranny/3.42

extended cab LS- manual tranny/3.08
auto tranny/3.42

regular cab xtreme- manual tranny/3.08
auto tranny/3.42

extended cab xtreme- manual tranny/3.08
auto tranny/3.42

Positraction is not available on the 4cyl engines

Positraction is available on either the 6cyl manual or automatic transmissions. I didnt get it in mine, darn it I should of ordered one. Ah crap... oh well, better luck some other time. arrrrrr

ANYWAY ENJOY, IM SURE ALMOST EVERYONE IN HERE WILL

how about the first gen s10's with the 2.5 5speed or 4 speed no rpo codes in my glove. the dash looks like it was taken out of a parts truck maybe blazer since i have the bucketts and console

[Tiiimay]

hey sorry if this is a stupid question but i have a 03 extended cab 4cyl 2wd, still at school so i cant check the gearing. but does anyone know what that would be? and i wantt o switch to a limited slip, so G80 right? but how would the gearing change effect me? i know nothing about gear ratios.

edit: just saw quote above. so i have 4.10 gears then. is G80 4.10? id like to get my rpm's down on the highway idk which gearing would do that.

[Mr. Front Cup]

jw....has anyone ever seen or found an s10 with the 4.56 rear gears?? i myself didnt even know they made them and was curious to just how rare they are or if there is a certain give away as far as drivetrain package or year or trim package that would identify that it might have the 4.56 rear gear???

[drperry]

Quote: Originally Posted by Mr. Front Cup

jw....has anyone ever seen or found an s10 with the 4.56 rear gears?? i myself didnt even know they made them and was curious to just how rare they are or if there is a certain give away as far as drivetrain package or year or trim package that would identify that it might have the 4.56 rear gear???

Doing 60 MPH @ like 4500 RPM cruising speed?


Gotta look for the glove box code, be able to roll the truck, or open the diff and look at the gear... It should be stamped on it.

[SlamThiz]

ok well i got an 01 2.2l 5 speed.. i need a rear end.. what years will fit it? also will the sunfire or cavi rear ends fit? and will my swirlies fit the rear end??? i want top end speed and good gas mileage too haha

[towb3]

I am in the process of trying to order parts for my small block swap. Needing to find the gearing for intake and cam application. I know what pairing the G80 with other codes gets you. But, my sticker in the glove box gives me the GQ1 and GU4 code both. GQ1 is the first code. Any ideas on that? Thanks.

[lowhardbodynissan]

Quote: Originally Posted by SlamThiz

ok well i got an 01 2.2l 5 speed.. i need a rear end.. what years will fit it? also will the sunfire or cavi rear ends fit? and will my swirlies fit the rear end??? i want top end speed and good gas mileage too haha

do a search on the rearend swap you should get a answer,that's some funny shit on the cavi and sufire rearend they are fwd and bolt pattern is smaller, so unless you want to ride like fred and barney it won't work

[max1million]

GQ1 standard rear axle ratio
GU4 3.08

[aberkenpas]

Quote: Originally Posted by meangreen9c1

Don't all 2.2s come with the 4.10s?

nope sorry man my 98 2.2 has 3.73

[unperfected]

dzE

[mccoy900]

wow 4.10 seems high at 60 miles an/h id think you would be at 3500 rpm

[max1million]

with no other changes, 4.10 about 200-300 rpm more then 3.73 on highway, if not mistaken

[drperry]

If I remember right, in 5th gear, my 3.42s are running about 2200 RPM @ 110km/h

[max1million]

195*75r14 tire, .86 fifth gear, 3.73 diff, 70.99mph(mile/hour) at 3000rpm (looks about right for mine)
4.10 diff drops to 64.59mph
3.42 diff up to 77.43mph
http://www.kabamus.com/garage/gears.html
1 mile about 1.6 kilometer

[drperry]

235/75R15
.73 5th gear
2000 RPM = 68.82MPH

Which is about right for my Blazer, with it's 3.42's

[Blktalon456]

I have the GU4 non locker. Damn. But mine spins posi say the previous owner. I don't do that kind of stuff.

[drperry]

If both tires have no traction, they're going to spin... A lot of people mistake that for having posi/locker.

Easiest way to check, since winter is coming, put one tire on clean pavement, and the other on ice... it should take a bit to get moving


When the locker is working, you can feel it in the whole truck... Especially if you've got a manual transmission...

But the truck will feel like it's bucking

[sdimewisher]

so then why does my 1985 4X4 blazer with a 2.8/5 speed say HO4 which is 4:11's???

rare? I thought they only came with 4:10's???

[So_vayne]

I have a 1994 Chevy Blazer VIN W 4dr 4wd. The previous owner spray painted my codes.. whats the quickest easiest way to figure out whats in my rear? Does anyone have an educated guess? I'm not too worried about gearing but wouldn't it be g80 since its 4wd and all?