rear axle input angle...

[celt]

Gents,

Any after-market upper/lower links that correct the rear axle input angle?

Bomber kit build puts it at about -20 degrees, that can't be right.

[wcdfmt510]

Mine is the same way. Thinking about trying my incsion ss yeti rear upper links. They are $12

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[Jboucher]

Try jato rod ends to make your upper links longer

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[celt]

Originally Posted by Jboucher

Try jato rod ends to make your upper links longer

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Ah...those look to be about perfect...thanks.

[Jboucher]

Is that angle really an issue?
I read plenty of build threads before buying my Bomber and never heard of people having to "fix" this...

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[wcdfmt510]

Originally Posted by Jboucher

Is that angle really an issue?
I read plenty of build threads before buying my Bomber and never heard of people having to "fix" this...

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I don't think its a issue. I think its more that people think its wrong. Here's a pic showing the axle angle.here you can see how the axle is slightly pinion down. At full suspension compresion the drive shaft is damn near level
.

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[celt]

Originally Posted by wcdfmt510

I don't think its a issue. I think its more that people think its wrong. Here's a pic showing the axle angle.here you can see how the axle is slightly pinion down. At full suspension compresion the drive shaft is damn near level

It is wrong, or at the very least not optimal.

Ideally the output of the gearbox and the input of the axle pinion would be in alignment no? This reduces drive line angle and therefore drive line wear. Also, that joint as it sits statically (running ride height), is nearly at the same dimension from the running surface as the lowest part of the axle ring gear housing (pumpkin) - meaning, it's the first thing a rock is going to bash into. That joint is also one of the most fragile assemblies of the entire chassis, is it not?

Doesn't matter if the drive line is level at full compression, the chassis spends little time under full compression.

If one can rotate the axle up, you get all of the benefits that I described above with what negative impact?

[angrchair]

Yeah I noticed this too, even after swapping to Vanquish Currie F9's.

[MAC FAB]

Radical angle also requires more power. Upper link mount locations and lengths of the links would have to be changed. Theoretically, it could always be at whatever your desired angle may be, as it cycles, just may have to be a scratch build chassis to do it. Autocad savvy folks could mock it up in 2d, run it thru the paces in 3d. I have a class 5 unlimited bug as another iron in the fab fire, a bit of an engineering nightmare to get a tiny VW style long travel beam front end to work, keeping consistent caster as it cycles about 3-1/2", so the same concept should apply here. No engineer here, but in my head, longer links and moving the pumpkin mounts up and back would change the radius points and swing of the upper arc, allowing the input angle to be more consistent. Then once the input end is up, you automatically get a lift kit because the axle rotates down at the training arms. Does that make for another can of worms?

[Jboucher]

Supershafty / jec racing trailing arms are shorter by 3mm to help with the pinion angle.

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[wcdfmt510]

Originally Posted by Jboucher

Supershafty / jec racing trailing arms are shorter by 3mm to help with the pinion angle.

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So $45 for a set of arms or $12 for longer incsion upper links

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[Jboucher]

You get the benefits of stainless arms which are stronger than the axial plastic aluminium sandwich arms

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[FlatLander72]

This is what I used. A lot cheaper that anything else mentioned.
http://www.ssd-rc.com/m4-rod-end-spacers.html

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[Jboucher]

It works but after 2.or 3 you will need a longer set screw as well

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[calcagno45]

Why do you think the angle is incorrect? Once completely assembled, all is fine.

[angrchair]

really long read
Driveline 101

but TLR the faster your driveshaft spins the less pinion angle you want, but at the same time you want the output shaft and pinion angles to be the same so they are close to parallel, which is what we have in the rear of the Bomber.




SHAFT RPM OPERATING ANGLE
5000 3.25°
4500 3.67°
4000 4.25°
3500 5.00°
3000 5.83°
2500 7.00°
2000 8.67°
1500 11.5°

[celt]

It could be that "wrong" is a little excessive. I'd just like to get the input on the rear axle to, at the very least, not angle down.


Plenty of suggestions here to help me do that, thanks guys.

[FlatLander72]

Originally Posted by Jboucher

It works but after 2.or 3 you will need a longer set screw as well

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It only took two shims to put the pinion angle in the acceptable range.


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[PileDriver]

I just used long traxxas rod ends as mentioned earlier in the post. Works perfect!

[jstein87]

I wouldn't worry about it to much unless your breaking parts as a result. Driveline angles are more specific on 1:1 stuff because it can cause stresses and vibrations that lead to premature failure and uncomfort while riding (vibes). RC's dont spend most of their life at highway speeds like what 1:1s are designed to do so as long as it isn't binding during the suspension travel your probably not going to see any issues with it.