Knight Runner axle swap.

[smc-93]

I need the advise of somebody more knowledgeable than myself.

I've found/read on here that the stock gearing on the element trucks is 3.75:1, the RC4WD K44 axle is 2.67:1.

Does this mean the K44 will spin slower than the front for the same driveshaft input (2.67 rear axle rotations/one driveshaft rotation vs. 3.75 front axle rotations)? Or am I reading the ratio backwards?

I want to install a leaf sprung K44 rear on my new Knight Runner but I want to make sure my tires are spinning close to the same speed. A bit of front overdrive would be okay though.

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[Goro Majima]

You're reading it right.

[smc-93]

Originally Posted by Goro Majima

You're reading it right.

Okay.

I wanted to make sure I understood it correctly.

Thank you.

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[nismotuningrocks]

The 2.67:1 axle will spin much faster than the stock 3.75:1 ratio axle. Lower numerical ratio = faster speed.

[Goro Majima]

Originally Posted by nismotuningrocks

The 2.67:1 axle will spin much faster than the stock 3.75:1 ratio axle. Lower numerical ratio = faster speed.

Whoops I read his question wrong. My bad OP.

[Browneye]

AFAIK Element has overdrive built into/optioned in the transmission/gearbox.
Is there a reason to swap an axle out?

[smc-93]

Originally Posted by Browneye

AFAIK Element has overdrive built into/optioned in the transmission/gearbox.
Is there a reason to swap an axle out?

I know about the OD/UD transmission options, that's not what I'm after.

I want to swap to a K44 primary for looks and to easily make the rear leaf sprung. If I UD the rear axle in doing so? Not a big deal.

I just needed to make sure I was understanding the gear ratios correctly to ensure I wouldn't OD the rear axle.

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[smc-93]

Originally Posted by nismotuningrocks

The 2.67:1 axle will spin much faster than the stock 3.75:1 ratio axle. Lower numerical ratio = faster speed.

So the 2.67:1 K44 would OD my rear axle?

Do you happen to know the element OD ratio off hand (haven't had the chance to dig through the manual yet)? Is it close to the K44 ratio?

Edit: I did a bit of digging, what I can get away with at work anyway, and if I'm understanding this correctly, the 2.67:1 K44 would have less torque but a higher speed compared the 3.75:1 stock front end that would have a lower top speed but higher torque. Is that correct?
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[twade984]

Element ratio is 3.75:1 same as standard axial ar44 and ar45 ring and pinion.

I’m not super familiar with leaf spring stuff, but I would maybe look into the possibility of using an SSD pro44 rear axle and the jec leaf mounts

https://jecracing.com/products/ar-44...29642848895020

https://www.amainhobbies.com/ssd-rc-...zrqaeq6zqxactz

One thing you could do if you’re set on using a k44, is reverse the o/d in the trans to the front output (either by flipping the trans, or using the optional top shaft and flipping the gears internally) and if necessary use the 10% gear set to offset the ratio difference. This would also likely require running a smaller pinion to bring the final drive ratio back closer to stock.

Curious about the k44 though, it’s built to the same durability as the yota II axles as far as I know, and those are not particularly well regarded in that department. I would assume you’re going for a more scale accurate representation for a 1:1 Tacoma with leaf springs, but in that case, why not use the yota axle? 1:1 Tacoma’s use a rear axle very similar in design and appearance to the original 4x4 Toyota pickups.

[smc-93]

Originally Posted by twade984

Element ratio is 3.75:1 same as standard axial ar44 and ar45 ring and pinion.

I’m not super familiar with leaf spring stuff, but I would maybe look into the possibility of using an SSD pro44 rear axle and the jec leaf mounts

https://jecracing.com/products/ar-44...29642848895020

https://www.amainhobbies.com/ssd-rc-...zrqaeq6zqxactz

That's definitely an option as well, probably the more likely one honestly, I quite like the Pro44 and have a set leaf sprung under another WIP build.

I've like the look of the K44 but I've heard mixed reviews on their quality and longevity.

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[twade984]

Just running through the ratios (off the top of my head, so I may be slightly off)

Stock spur/pinion: 87/18=4.83
Standard trans gears: 52/20=2.6
11% o/d trans gears: 54/26=2.7
Stock r&p: 30/8= 3.75
K44 r&p: 2.67

Front final drive ratio:
4.83x2.6x3.75=47.09

Rear k44 final drive:
4.83x2.7x2.67=34.81

Total o/d percentage to the front: 30.402%


Using the team knk 25% o/d gears for the stealth x (56/20) yields a 25% difference front to rear.

Those numbers may be a little confusing because element calls it “overdrive” meaning the front wheels spin faster, but the standard trans gears are 2.6:1 and the “overdrive” gears are actually underdrive gears for the rear output, (2.65=5.5%, and 2.7=11%).

[smc-93]

Originally Posted by twade984

I would assume you’re going for a more scale accurate representation for a 1:1 Tacoma with leaf springs, but in that case, why not use the yota axle? 1:1 Tacoma’s use a rear axle very similar in design and appearance to the original 4x4 Toyota pickups.

That's the plan.

As far as Yota vs. K44? The Yota looks to slender to me. I realize the Yota/Yota2 are modeled after full size Toyota axles but they don't look right to me. The K44 is less scale accurate but I like the beefier look.

That being said, I like the look and build quality of the (not scale accurate either) Pro44. Which would also already have the correct R/P ratio to match the front.

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