Ok guys, I searched and searched and searched and I've finally found my super old comparison post about our 4.70:1 Gear Set compared to the A/A 5.0:1 set that I posted on the pirates bbs along time ago..
Here it is in all it's glory! Enjoy the reading!
Original Post:
http://www.pirate4x4.com/forum/showthread.php?t=164790&page=3&pp=25Regarding A/A 5.0:1 Gear Set
Date: 08-07-2003
Quote by Benny:
How do these compare to the 5:1 gears. I realize that the 5:1 is obviously lower, and that these gears are supposed to be stronger...
Quote by Ben Holloway:
good question, im wondering the same thing
Well, first lets look at some numbers. I think no one else knows this, but the 5:1 A/A Gear Set is in fact a 4.97:1. I know this because I counted the teeth when we got our first set and did the math. I've got a small write up for our webpage about this but never finished it. I believe that our webpage still says "Under Construction, Please Excuse the Mess" on our 4.70:1 page. Good work BigMike. Gee Thanks...... So the tech that I am about to present is supposed to be on our webpage.
Anyways, back to the numbers, 4.97:1 is only 5.4% lower then the 4.70:1 set. Using practical numbers, in a stock truck, it would be 76:1 (4.70:1 setup) compared to 80:1 (4.97:1 setup). And since we are on a practical note, the difference is unnoticeable. It would take two rigs 50 feet just to tell which one is slower than the other. And lastly on a picky note, its a lower ratio, so it is slower, and slower is sometimes better for more traction and increased torque. I'd like to have an option of being slower and so would you!
Here is the raw data:Marlin Crawler 4.70:1 Gear Set:
Input Gear: 20 teeth
Idler Gear: 35 and 16
Low Spd Gear: 43
A/A 5:1 Gear Set:
Input Gear: 20 teeth
Idler Gear:
37 and 16
Low Spd Gear: 43
Actual Ratios:Marlin Crawler 4.70:1 Gear Set: (35/20) x (43/16) =
4.703125:1A/A 5:1 Gear Set: (37/20) x (43/16) =
4.971875:1So now were clear that the 5:1 is really a 4.97:1. And you know what, its almost pointless to even worry about this. I mean what am I even am talking about? a 0.03 cover up by A/A? Why even bother, that's nil. Yes, it is nil, just like a 4.70:1 compared to a 4.97:1 on the trail, its nil. But hey its something right?
So maybe the ratios dont mean anything because they are so close?
Well here are some physical differences:
You can see that the 4.97:1's teeth are much more narrower than the 4.70:1's. This is because the idler has an added 2 teeth and the space has to be taken away from the input. These teeth are weaker, plus that input is the smallest gear so its the weakest point of the whole gear set. So the weakest point is a bit weaker now.... Also please note that the A/A gears do not have a 2° taper on the shift hub teeth. See my next post for more info on this...
Of course we've all heard about Marlin Crawler's Total-Spline input gear. This is probably the most important difference of the two sets. The Total-Spline design has ended the problems of stripped out couplers and broken input gears. Problem solved, period. And that I would say is very good technical information.
Now here's something new that is an improvement over even the stock 2.28:1 design. What Marlin has done to his gears is modified the oil feed/pump system of the low speed idler gear. What this does is as the gear is spinning, his system scoops oil from one side and throws it from the other. Its like a Supercharged oil movement system. It moves more oil at a faster rate which promotes cooling. You can see that the A/A 4.97:1 setup uses the same 4 cutouts that the stock 2.28:1 gears have. They are effective at moving oil around -- I've never heard of a 2.28:1 gear set burning up with the proper amount of oil in the case. So this is not a matter of something being weaker or not so good. It is already fine enough, but Marlin seems to never rest with
just fine enough. He always has to research and figure out how to make something better even when it is good enough as it already is. But I think its these little small things that Marlin does that makes his sets more unique.
So the 4.70:1 gear set has a better oil feed/pumping system then the 4.97:1 gear set.
There are a couple other advantages of the 4.70:1 (some teeth have been widened thanks to camo's "testing") but its not worth discussing at this time.
Quote by Benny:
Would it be wise to pass up the 5:1s in favor for these "stronger" 4.7s?
Well its ultimately up to you. Aside from the improvements that make the 4.7s stronger, think about ring'n'pinions. A 4.88:1 is stronger than a 5.29:1 because the teeth are wider and larger. Same goes for the transfercase gear ratios. A 2.28:1 is stronger than a 4.00:1 which is stronger than a 4.70:1 which is stronger than a 4.97:1. But these are just ratios. The weak link of the 2.28:1 is the actual size of the input dia at its smallest O.D. -- the point where the input will break.
The 2.28:1 input's skinniest spot is a
0.940" OD, the A/A 4.0:1, A/A 4.70:1, and A/A 4.97:1 all three have a skinniest spot of
0.995" OD (0.055" thicker than stock / 5.6% larger), and the Marlin Crawler 4.70:1 Total-Spline's skinniest spot is an impressive
1.080" OD (0.140" thicker than stock / 12.9% larger).
Hope this information has helped with your question.
Have a good night,
BigMike
Ok so there's your comparison of the 4.70:1 vs. 4.97:1 gear set.So I was wrong in my opening post on this thread about the teeth. A/A's gears have an added 2 teeth to only one gear and the rest have the same count as our 4.70:1.
Regards,
BigMike
