Transfer case re-gearing (1 Viewer)

[cruiseroutfit]

Don't be afraid of math..

I heart math

Tell where exactly I am wrong then.

At the tcase output shaft.

I don't think any body is debating the fact the "realized" Crawl Ratio (trans ratio x tcase ratio x axle ratio x tire size) is altered by tire size, I'm certainly not. Your math has nothing to do with your original comment.

What we (or at least I) and debating is your original comment the tire size has some relation to the throughput ratio of the t-case itself.

Allow me to explain...

I post a chart showing transfer case gearing options (just transfer case, zero other variables). As you can see on the chart, with UD/3.1 gearset low range you get (fact) an output of 3.31672. My math is clearly shown in the original chart but it's basically the low range output gear divided by the low range idler gear, that is then multiplied by the sum of the high range idler gear divided by the input gear.

iptmam replies...

Nice! So with both the UD high and low range low gears installed you get 3.3:1 low range gearing.

Then you call this a theory...

Only in theory, because it will depend on the tire size you run. The greater the diameter, the lower the final gear ratio will be.
Don't get me wrong, it won't drop to really sucky levels.

You would only get that 3.3:1 ratio with 31" tires.

Perhaps we are having two different discussions because none of your explanations and certainly none of your math show how the 3.3:1 has anything to do with tires.

 

[mct75]

What he's trying to say is, it's better to install 22" tires from a CRX to get that sick crawl ratio.

 

[-Spike-]

What he's trying to say is, it's better to install 22" tires from a CRX to get that sick crawl ratio.

Wrong lug pattern.

 

[mct75]

Wrong lug pattern.

 

[-Spike-]

That's awesome. Problem solved. Mods, please close this thread.

 

[Qball]

Tell where exactly I am wrong then.

The entire drivetrain has liner effect on final drive ratio and are independently changed. If you want to calculate everything and include even the tires then maybe we can come up with a formular that will translate to inch per RPM.

When we talk about gear ratio we are only calculating multiplication/divisional rate of the gears or tcase and diff. We can’t change transmission’s gearing and tires can easily be calculated separately.

What I use is a little simpler, I use original OEM final drive ratio as base or 1. I changed tires to 35s and my final inch per RPM now is 10-11% higher than before or I am 10% faster than before at same exact RPM. This includes both high and low range. At 60mph on speedometer I am going 66, validated by GPS.

When I installed my low gear which reduces gear ratio by 25% or slow down the drive shafts 25% at low range my equation became 1 x 1.1 x .75 = .825. This basically means now I am at 82.5 percenter speed of complete stock low range speed or a total reduction of 17.5% speed compared to full stock low range speed. At 10 mph on speedometer in low ranges I am actually going 8.25mph.

To add diff gear of 5.29 (5.29-4.11)/4.11=.287 or 28.7% reduction into equation———- 1 x 1.1 x 75 = .825 x .713 = .588 or 58.8%. This means my buddy’s 80 with low tcase gear, 5.29 and 35 tires will be at 5.88mph when the speedometer is showing 10mph.



Hope that makes sense

 

[Dragos80]

All I am saying is that you guys ignore the tire size, when you look at those ratios.
In order for you to be correct, you have to consider the same tire size when you calculate those ratios.

You cannot simply change tire sizes and keep the same ratio constant.
You cannot change one component of the equation and call it the same.
It stays constant, if all things stay constant, which in our case is the tire size.

Again, those who regear to 4.88 and running 35" tires are doing it so the car can get back, as close as possible, to a stock gearing ratio (which was lost with the change in tire sizes).
But when you consider the 35" tire, that 4.88 ratio will be more like (guesstimate here) the equivalent of 4.3 ratio with 31" tires.

You simply cannot say that a 3.1 ratio will be the same in this entire assembly of mechanical parts, no matter what tire size I use.

When specific ratios are designed for an application, everything needs to be included in the calculation of said ratio and that includes the tire size.

If your car would only be used on jack stands, the tire size won't matter at all and you will keep that drivetrain ratio constant.
But once you put it on pavement with different tire sizes than OEM, the end ratio will be different.

So, at the output shaft things don't matter at all what they are. It matters on the pavement where all that power and multiplication of gears actually does the work.

To illustrate differently, if you have a pair of pants and they are riding low on your hips, you might want to pull them up a little. This action will have a direct impact on covering your ankles. The length of the pants stays constant, therefore the ankles will be exposed.
You can't say if I cover my hips more, the ankles will also be covered. In order to have the ankles covered too you need a longer pair pf pants, but that will imply you just changed the equation since the pants are no longer of a constant length.

Think about this analogy of the pants and the tires in out case here.

 

[mct75]

 

[-Spike-]

All I am saying is that you guys ignore the tire size, when you look at those ratios. Blah blah blah blah blah.

Nobody has ever suggested that tires don't affect the force applied to the ground. Ever. The discussion was gear ratios. The key word there is gear. GEAR. Get over yourself already.

 

[JohnnyOshow22]

Another thread that gets lost because one person wont shut up... No one is disputing tire size vs gear ratio in this thread. This thread is about Transfer Case Regearing period. It might even say it in the title...

 

[Dragos80]

A better title would be "Variable transfer case re-gearing... depending on the tire size".

It is misleading. Nobody will get the advertised effective gear ratio while running larger diameter tires than OEM.

 

[mct75]

So the size of your tires changes the number of teeth on a gear?

 

[-Spike-]

Original post-

Has anyone heard of or seen a kit to regear the transfer case HIGH RANGE of the 80 series permanent 4wd transfer case? It is available for lots of other types of trucks like Nissan, LandRover, Suzuki etc, but I cannot find such gears for the 80 series. I do find low range gearing kits, but I want modified high range gearing, as it would seem easier and cheaper to do compared to changing R&P wich is very expensive.

A better title would be "Variable transfer case re-gearing... depending on the tire size".

It is misleading. Nobody will get the advertised effective gear ratio while running larger diameter tires than OEM.

Are you serious? You are suggesting the OP titled his thread incorrectly? Do you think he cared a whit about tire diameter affecting final drive ratios? You have a freaking huge ego, brother. He asked if there was a kit to reGEAR the TRANSFER CASE. I'm pretty sure he had an idea why he might want to get such a kit. STFU already.

 

[Dragos80]

So the size of your tires changes the number of teeth on a gear?

The effective crawl ratio.

The reason you want to regear, after going up in tire size is that your effective crawl ratio has changed in spite of maintaining the same number of teeth on all gears in play.

 

[Dragos80]

Original post-



Are you serious? You are suggesting the OP titled his thread incorrectly? Do you think he cared a whit about tire diameter affecting final drive ratios? You have a freaking huge ego, brother. He asked if there was a kit to reGEAR the TRANSFER CASE. I'm pretty sure he had an idea why he might want to get such a kit. STFU already.

I don't expect you or most of the people who argued against me to understand the following. I am really not surprised if you don't.


I can out crawl you with my 33" tires vs your 37" given the same setup for the transfer case and axle gear.

 

[JohnnyOshow22]

I don't expect you or most of the people who argued against me to understand the following. I am really not surprised if you don't.


I can out crawl you with my 33" tires vs your 37" given the same setup for the transfer case and axle gear.

Everyone gets that... You are beating a dead horse

 

[-Spike-]

I don't expect you or most of the people who argued against me to understand the following. I am really not surprised if you don't.


I can out crawl you with my 33" tires vs your 37" given the same setup for the transfer case and axle gear.

Be as condescending as you like. I and everyone else fully grasps the concepts you are spouting. They are simple, and very basic to the hobby. What you don't get (and I am very surprised that you don't) is that this conversation is not about tire size, beyond the obvious in that people want to find gearing solutions to improve crawl performance. You are insisting that we can't understand a concept that is in fact intrinsic to the conversation, so much that it isn't necessary to discuss it. It's a given. You don't need to educate anyone that tire size affects perceived and realized power. We know.

 

[Heckraiser]

 

[nukegoat]

head gasket

 

[orangefj45]

Ok people.......

Can we stick to the topic at hand "transfer case re-gearing" and stop diluting this thread with off-topic responses?!

Thank you.