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65scout80

Farmall Cub
ive heard that the 20 was stronger than the 300 and from "reading" ive come to belive that they are. so whats the advantage of a 300?? is it just the crawl ratio? how would you go about "twin stickin" a dana 20 twinstick? as in allowing front h/l rear h/l and 4wheel h/l???
 

troutbum

Farmall Cub
hmmm...the design is very similiar..I would be surprised if there was a significant stength difference. The d20 is cheaper. IIRC you need to remove the front output shaft to twin stick a d20. Concept is the same you need to remove the interlock. .64 does not seem like a big deal but it takes me from 47:1 to 62:1 (pre TC)
 

Joe D.

High Wheeler
The big deal with the d300 is the lower gears from the factory, and the option of a 4:1 kit. The d20 only goes down to 3.15:1.

The rear output shaft is a big weakness on both of them, with the d300's shaft being a fair amount weaker. Burly replacement shafts are available for both cases.

D20's are more common, so an alternative to new output shafts are spare assembly's. Just find a used d20, I believe any application will do, unbolt the whole assembly on the back, and take it along with you wheeling.
 

troutbum

Farmall Cub
Originally posted by Joe D.
The rear output shaft is a big weakness on both of them, with the d300's shaft being a fair amount weaker.

They are both 26 spline, not sure of shaft diameter??? just curious to what leads you to believe the d300 shaft is weaker?
 

Scott Sinner

High Wheeler
All D-20s...

Joe,

You arn't saying all D-20s are alike are you, and you can interchange easily?

Lots of different Bull Gears on the input side...

Scott
 

Joe D.

High Wheeler
They are both 26 spline, not sure of shaft diameter??? just curious to what leads you to believe the d300 shaft is weaker?

Spline count isn't everything. My local machinist assures me that the d300 mostly used a lesser alloy in it's output shaft. It tends to survive stock just fine, but when you start swapping in granny low trannys or 4:1 kits, it becomes the weak link. Replacement versions can be the same size but with a better alloy. I've noticed over the years that quite a few stories in fourwheeler mention new 4:1 kits and broken output shafts. All told, I'm a believer


You arn't saying all D-20s are alike are you, and you can interchange easily?

I'm trusting my jeep friends on this one. Their experience is that the OUTPUT assembly is fairly universal. One guy I know well is running a scout output on the back of his jeep d20 after busting his in the back country. He now carries an entire spare assembly.


Lots of different Bull Gears on the input side...

I thought there was only two different tooth varieties on the bull gear. Many different spline counts, but as long as the replacement d20 is for the same teeth, it doesn't matter what the splines are, just re-use your stock bull gear. But I'm not actually talking about replacing the whole case, just the output assembly, that is housing, bearings, and output shaft.

New shafts are better than the old shafts, mostly because they don't have years and years of use on them. New, extremely burly shafts are available, but it all costs money.
 

troutbum

Farmall Cub
Originally posted by Joe D.


Spline count isn't everything. My local machinist assures me that the d300 mostly used a lesser alloy in it's output shaft. It tends to survive stock just fine, but when you start swapping in granny low trannys or 4:1 kits, it becomes the weak link. Replacement versions can be the same size but with a better alloy. I've noticed over the years that quite a few stories in fourwheeler mention new 4:1 kits and broken output shafts. All told, I'm a believer

Hmmm...I would love to see an analysis to back this up?? 4:1 is tough on the stock output ( you should try 5.3:1 ;)) but it is not apples to apples until you get a d20 to 4:1. The fact that more d300 shafts are broken does not mean that the alloy used in the shaft is inferior.

Was your machinist trying to sell you something?? :p
 

Joe D.

High Wheeler
Well, neither him nor I are a metallurgist, he's basing his opinion on his experience and that of his customers. Perhaps I should pick his brain on how he backs up his claim.

Specifically, he told me that the output shaft is similar in size to the pinion shaft on the dana 44's that are typically behind them, yet it's always the d300 shaft that breaks first.

So, in the absence of scientific training, I'm going by anecdotal experience of people who've been there and done that.

And no, he doesn't try to sell me anything. He builds very custom rigs, really cool stuff, and I can barely afford to buy the parts to build the rig myself. I call him my machinist, but perhaps wheeling buddy would be a better term. I've seen the work he does, and it comes out really nice. I use his work as a benchmark against which to judge my work.
 
Last edited:

Wheeled Scout

Binder Driver
Originally posted by Joe D.
Well, neither him nor I are a metallurgist, he's basing his opinion on his experience and that of his customers. Perhaps I should pick his brain on how he backs up his claim.

Specifically, he told me that the output shaft is similar in size to the pinion shaft on the dana 44's that are typically behind them, yet it's always the d300 shaft that breaks first.

So, in the absence of scientific training, I'm going by anecdotal experience of people who've been there and done that.

And no, he doesn't try to sell me anything. He builds very custom rigs, really cool stuff, and I can barely afford to buy the parts to build the rig myself. I call him my machinist, but perhaps wheeling buddy would be a better term. I've seen the work he does, and it comes out really nice. I use his work as a benchmark against which to judge my work.

As far as I know, the yokes on a D20, D300, and D44's all interchange. That is assuming you are not trying to swap a course with fine spline yokes. And the fact that I used a D44 pinion on my 300. And I use the same 1 1/8" socket to remove the yokes on all of them.

I don't buy the alloy line, might have a different treating process between the two. I would say the D20 and D300 running the same gear ratio have the same strength.
 
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