Trying to calculate my gear ratio

Good deal when you finally find out for sure post here i'm interested to know. Always willing to learn more .

 

Try this put the truck on the ground, mark your tire and Shaft, get someone to drive very slowly and you count the revolutions. That will eliminate any slack. I can't for the life of me see how you have 5.29 gears and are 20mph faster. That right there indicates a higher (numerically lower) gear ratio. I'll explain, my truck has 3.73 gears I installed larger tires, that reduced my gear ratio to about 3.5? and now I am faster by 2.7mph. Therefore taller gears increase your speed. Not only that but your RPM's would be insane with 5.29 gears.

If anyone can explain to me where I am wrong please do, i'm willing to learn but can't see the error in my train of thought if any.

 

His speedometer is reading faster than he's actually going. If GPS says 70mph, speedo says 90mph.

That's what happens when you go to lower (numerically higher) gears.

 

My appologies I have been reading this wrong. I was understanding that his speedo was reading 70mph and he was actually doing 90mph.
Well since I am lacking in the reading department, i'm gone read back through the post.

 

Guys if iv got 5.29's than shouldn't I have serious low end power? But I really don't. I mean I can climb a hill pretty good but It just doesn't feel like I have tons of torque. I still feel bogged down at low speeds

 

yes with 5.29s you should have some pretty gnarly low end power, you should also be topping out at like 70 with 31s

 

Nah I'm getting to 80 and than my governor kicks in. I could go faster
And I really don't have alot of low end torque but than again I don't have anything to compare it with.
My scion tc had more torque but it was a manual.

 

I still don't think you have 5.29 gears. I was only reading some things incorrectly.
With such gears you would launch like crazy, and not be able to go very fast without exploding and or much trouble.
Your truck may have other issues combined with high gears.

Go with my last reccomendation on rolling and counting your revolutions, that will eliminate the slack theory. When rolling it is what it is.

 

Lots is relative. It's still not a big powerful engine.

But with your transmission controller messing with your shift points, it's awfully hard to get a read on how much power you actually have.

Additionally, something else could be going wrong with the engine, causing it to have less than full power.

5.29 is lower than typical, but some of the replies in this thread treat it as if it's like having the transfer case stuck in low range or something. Some of the diff gear calculators on the web seem to omit the fact that modern transmissions all have top-gear overdrive - and use 1.0 as the top-gear transmission ratio. That was true back in the 60s and 70s when all we had 3 speed automatics. Not any longer.

Look at http://www.richmondgear.com/101032.html

With the .8 overdrive and pushing 31" stock diameter tires, even with a 5.29 rear end you'd only be turning 3670 RPM at 80mph (no typo), and still WELL below redline at 4690 RPM if you were to decide to go 100mph and the engine were not regulated and had enough power to do so.

 

Ok I'll do that later today when I can get my gf to drive while I watch

What I'm thinking is like this...I'm imagining a bike...in a higher gear you pedal like crazy and go nowhere and a lower gear let's you pedal less and go faster from a start...so isn't may ratio considered high? Because the drive shaft is rotating more to cover the same ground as say a 4:10??
Also remember I'm rolling on 31's when the gearing were thinking I have is ment for a larger tire that would cover more ground at 1 revolution. So I'm not covering the same amount of ground as I should. Could that be where the weirdness of how it feels be coming from?

 

The engine is like your feet, the Lower the gear the less you pedal, yet you go faster. However with vehicles a lower gear ratio is a numerically higher number, and a High gear ratio is a numberically lower number.
BJmoose is right about the new OD's versus the 1 to 1 of a 3 speed and the older .68 OD's, But I still think that with such a low gear (5.29) you would feel it at take off, unless your engine is having some issues and is way under powered itself.

 

It still doesn't make sense to me how can more rotations per tire rotation be low?example- 5.29 revolutions vs 4.10? That's like more pedaling on a bike hence a higher gear? But your saying it's actually lower?

 

When speaking vehicle a larger number 5.29 is known as a lower gear ratio than 3.73.
The higher the number the lower the ratio.

Your tires are turning 1 round for every 5 turns of your driveshaft. When done right it puts/keeps your truck in its power band. I can't find any words to simplify this for you, I do understand what you are saying but I'm falling short.
And after looking so do these guys, lol
http://www.classicoldsmobile.com/tech/69.shtml

 

You guys have "low" and "high" on bike gears reversed.

In both car and bike, with a low gear ratio the engine (or your legs) spins fast but the vehicle goes slow. This is the only way you have leverage to climb a steep hill.

Conversely, with a high gear ratio, the vehicle moves further with each turn of the crank or crankshaft. This is the only way the engine (or your legs) can keep spinning the driveline when the vehicle is moving at high speed.

 

^I'm glad you are picking up my slack here, I hadn't realized I wrote it that way. Jason, my apologies for that mix up. I'm trying to make this easier to understand and that in turn is having the adverse affect.

 

It will not feel like you have MORE power, you will just get throw your power band faster with much less speed. Just like if you go from four high to four low. The truck is a little more jumpy and it goes through the gears faster, but less speed per gear. But you should have no problem putting it on the floor from a stop and spinning tires. Everything I have read tells me you have gone up in gears.

Does anyone know the stock gears in a '06 5 speed Auto?

 

Sounds like you have 5.29's and your automatic transmission is confused with it's shift points, making it feel like you have no power.

 

Gears have no affect on shift points. Shifts points are affected more by other things. Now if you go with lower gears you could hit your rev limiter because you are going through the rpm's much quicker, but in no way will your shift point change because of rear end gearing. Running many times down the track with two different late model Trans Am, I know this to be the case.

 

I may have mis understood what you are saying, the shift points could be set to shift at certain speeds in normal driving therefore you could be shifting early causing you to be in lower rpms seeming like you don't have power. That could be the case.

Although this would not be the case under WOT conditions. This was my first thought because I used to always be in WOT conditions!

 

3.73's really? I thought this truck had more gear than that, but I guess it could be the tranny gears help make it seem lower.