nad
1/2 ton status
Anyone else have any luck?
CK5
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Gear ratio question
- Thread starter nad
- Start date
nad
1/2 ton status
Okay guys, I'm a complete idiot, it's cold and dark outside. it's GU6, not G06. Sorry. I'm still not having much luck finding it. I found one that said it's 3.42 gear ratio. Not sure if that's accurate or not.
nad
1/2 ton status
Which leads to my next question, why does my RPO codes have both GU6, for 3.42 ratio, and G80, for Posi-Trac? Is that my front and rear? Or wtf?
Someone please explain this to me.
Someone please explain this to me.
nad
1/2 ton status
But doesn't a gov-lock look like a locker? Maybe when the PO had the rear end rebuilt, he had the gov-lock taken out? Because I looked last time I changed the diff fluid, and it's definitely an open diff.
I didn't know they put gov-locks in just any standard issue Blazer or Jimmy?
I didn't know they put gov-locks in just any standard issue Blazer or Jimmy?
Gov loc was an option, just like anything else in your truck.
There is a good chance your diff(s) have been switched out in the last 20 years, you'd be best to take a cover off and start counting teeth on the ring and pinion, or counting the driveshaft revolutions
There is a good chance your diff(s) have been switched out in the last 20 years, you'd be best to take a cover off and start counting teeth on the ring and pinion, or counting the driveshaft revolutions
Slapperbar
Retired Navy NDT Examiner
If it truly is open, it's because the G80 lived up to its nik-name. Gov-Bomb.
An open diff and Gov-lock look a lot different, pretty hard to confuse a Gov-lock for an open diff if you have any knowledge at all about them. But as already mentioned, it's quite common for old trucks to have either had the axle rebuilt or replaced.
Also as mentioned, the Gov-lock was an option that was available on just about any truck.
nad
1/2 ton status
Yeah, I guess come spring time I'll have to take change my diff fluid again, and this time I'll count the teeth.
I know they're much different looking, but I just can't remember what mine looked like
Didn't really pay much attention, just cleaned it up, put the cover back on, and filled it with fluid.
I know they're much different looking, but I just can't remember what mine looked like
Didn't really pay much attention, just cleaned it up, put the cover back on, and filled it with fluid.1-8-4-3-6-5-7-2
Registered Member
There is an easy and accurate way to determine your gear ratio without removing the differential cover... it's accurate enough that it's easy to tell the difference between a 3.50 ratio and a 3.55 ratio.
First block one of your tires to keep your truck from rolling away. Jack up only one rear tire (if you have an open differential). Rotate the tire until the valve stem is at the top. Crawl under the truck and put a mark on the driveshaft, u-joint, etc... (I usually use a paint marker on the driveshaft near the yoke where it goes into the t-case).
Now get a friend and have them rotate the tire 20 times and stop the valve stem at the top where it started at. You need to count the driveshaft turns as your friend turns the tire. Divide the number of driveshaft turns by 10 to get your gear ratio.
For example...
35 driveshaft turns would be a 3.50 to 1 ratio
35 1/2 driveshaft turns would be a 3.55 to 1 ratio
So even though a 3.50 and 3.55 gear ratio are very close, it's easy to tell them apart by the extra 1/2 turn of the driveshaft.
(It's highly unlikely that you have either a 3.50 or 3.55 gear ratio, I just used them as an example to show the accuracy of this method.)
.
First block one of your tires to keep your truck from rolling away. Jack up only one rear tire (if you have an open differential). Rotate the tire until the valve stem is at the top. Crawl under the truck and put a mark on the driveshaft, u-joint, etc... (I usually use a paint marker on the driveshaft near the yoke where it goes into the t-case).
Now get a friend and have them rotate the tire 20 times and stop the valve stem at the top where it started at. You need to count the driveshaft turns as your friend turns the tire. Divide the number of driveshaft turns by 10 to get your gear ratio.
For example...
35 driveshaft turns would be a 3.50 to 1 ratio
35 1/2 driveshaft turns would be a 3.55 to 1 ratio
So even though a 3.50 and 3.55 gear ratio are very close, it's easy to tell them apart by the extra 1/2 turn of the driveshaft.
(It's highly unlikely that you have either a 3.50 or 3.55 gear ratio, I just used them as an example to show the accuracy of this method.)
.
blazin_blazer
1/2 ton status
the dealership can tell u your ratio with the vin...i called my friend at work(a gm dealership)who is a gm tech and gave him the vin of a burb i was lookin at..he typed it in the computer...he told me the gear ratio, that it had a gov-bomb, that it was a k2500 sub...and all the options the truck came with
What year burb? The VIN # doesn't give that info in the 70-80's trucks. Maybe for the 90's and up though.
YZEATER
1/2 ton status
who says it wasn't swapped out??? just do the turn the wheel and count the pinion revolutions. you can also just rotate the tire 2 times and count the pinion rotations and WAAALAA there is your ratio. very simple. just have one wheel in the air.
blazin_blazer
1/2 ton status
it was a 91 burb....he knew the color and everything....2hrs away from home, he didn't know the truck!
