Gear ratio?

[DD98chevy]

I was wondering if this is correct. Having 4.10 gears G80 locker and 265/75/16 tires. At 66 mph im turning 2200 rpms. Is this correct for 4.10 gears or am i off? Picture of it.


Also at low speeds when the rear tire slips on snow or ice i hear a clunk sometimes. Is that the G80 or should i be worried

[outalne94z71]

it should be about 1900 at that speed, you probably have the wrong pulley on the alternator

[TheDrip]

With 4.10s and 235/85r16s, that looks a lot like my highway drive to work. 70 is about 2500. Speed reads 1-2mph low on my truck vs gps, but pretty close.

[57diesel]

Seems like we just had another thread and that was deemed normal for 4.10's with stockish diameter tires.

[dixiepc]

Maybe this will help. We don't know what your transmission is.

http://www.grimmjeeper.com/gears.html

[DD98chevy]

Originally Posted by outalne94z71

it should be about 1900 at that speed, you probably have the wrong pulley on the alternator

I dont know. I ordered the alternator with the correct specs and got it brand new. I hope its not the wrong pulley.

Originally Posted by TheDrip

With 4.10s and 235/85r16s, that looks a lot like my highway drive to work. 70 is about 2500. Speed reads 1-2mph low on my truck vs gps, but pretty close.

Ok im glad someone is around my readings. I read a few threads where people were getting less. And it started to make me worry a little.

Originally Posted by dixiepc

Maybe this will help. We don't know what your transmission is.

http://www.grimmjeeper.com/gears.html

According to the RPO codes i have the 4l80e transmission. I dont know what the ratios are in it.

[JorgeNY]

That's sounds about right, I have 4.10s with 265 tires. Runs the same RPM as you posted. The clunk in the rear is most likely the stock locker locking in. The g80 isn't the greatest from what I've heard and I've blown the one in my truck. I had an open diff carrier installed so I can eventually ad a real heavy duty locker.

[dixiepc]

Running the numbers on the calculator you should be turning around 2122 at 65mph. You don't have to know what your transmission ratios are, there is a drop down menu where you can select your transmission and the calculator puts in the right numbers.

A G80 is an OK diff, you just have to treat them right. They wind up to lock so they if you have traction on one wheel and not the other and then romp on it they wind up to fast and explode. When you need it just let it wind up slowly then you can get on it all you want in that direction.

[DD98chevy]

Originally Posted by JorgeNY

That's sounds about right, I have 4.10s with 265 tires. Runs the same RPM as you posted. The clunk in the rear is most likely the stock locker locking in. The g80 isn't the greatest from what I've heard and I've blown the one in my truck. I had an open diff carrier installed so I can eventually ad a real heavy duty locker.

Ok perfect i was beginning to worry a little about something being off lol Like the alt pulley or something. Yeah i have seen some G80 vids on youtube and being that my truck has one it has worked ok so far except that clunking noise it makes when it locks up. Or from a stop and its slick it locks and then i turn and grab traction and its starts barking the balding tires a little. And hops for a bit. Around here they use gravel on the roads for traction......

Originally Posted by dixiepc

Running the numbers on the calculator you should be turning around 2122 at 65mph. You don't have to know what your transmission ratios are, there is a drop down menu where you can select your transmission and the calculator puts in the right numbers.

A G80 is an OK diff, you just have to treat them right. They wind up to lock so they if you have traction on one wheel and not the other and then romp on it they wind up to fast and explode. When you need it just let it wind up slowly then you can get on it all you want in that direction.

Ok so im within specs thats good to know. Thats a good website to look at thats for posting it. Thats good to know about the G80 there has been a few times i have stood on it playing around in an open grass field. Glad ya told me that to let it wind up slow first and let it lock and then get on it. I appreciate it man. It locks in both forward and reverse right?

[dixiepc]

Yes, it locks in forward and reverse, but you have to change direction and let it unwind and then wind up. So it's not good for rocking your truck back and forth like when going from forward to reverse and back again to get out of a hole or something.