SCX10 Wrangler G6 Rear Drive Problem

[Dwill]

Mods, one of the things I'm still not clear on about the forum is it organization.
Hence I'm not exactly sure if I should post this here or in the SCX10 forum.

So, if I've posted this in the wrong place please feel free to move it or let me know and I will edit it.

With that said here my question/issue....

My Wrangler G6 has developed a "shake" or a "wobble" in the rear.
While its not a obvious as it is when you see it in person, if you watch the attached video you'll see what I mean...

Whats happening is this. at partial throttle (the low end of of the throttle range) the rear wheels shake. It almost like they are skipping. As the throttle increases, from about mid-range on, the rear runs smooth.

The front end mean while is smooth throughout the entire throttle range.

This is a newly developed problem, I've got maybe 8 -10 hours on the G6 and this just started with the last pack I ran through it a week or so ago.

I've taken the pinion off and spun the drive train by hand, both front and rear are smooth at any speed I can spin it at by hand. The motor also runs smooth with or without the pinion attached. The transmission by itself is also smooth with not drive lines attached.

Here's the set up...

Batt: 3S
ESC: Tekin RSX
Motor: Tekin ROC 412 1800Kv
Trans: all metal gears (Robinson as I remember)
Spur: Robinson Racing metal spur and slipper assembly 48 pitch/88 tooth spur.
Pinion: Robinson 48P 16 tooth hardened steel
Drive Lines: MIP front and rear
Diffs: Axial OD front UD rear
Axels: Front Vanquish CVD's Rear: Axial HD stock
Ax Housings: SSD D60 front and rear

I've checked the sensor wire to make sure it hasn't come loose. Also there's not noise that usually occurs with cogging and would the front end would be affected as well if there was cogging.

I've checked the pinion bearings. While it's pretty obvious the pinion bearing won't last long due the angle and the amount of slop in the drive lines for now they are still smooth.

A side question why don't manufactures that make housing not use a bigger bearing, I think that would make the pinion bearing life longer.

Anyway, I've checked everything I know to check to diagnose the problem.

FWIW... it worse with a smaller pinion. I went down to a 14 tooth pinion to slow the G6 down and get a more torque. However, the rear bounce was mores pronounced and was through the entire throttle range as well.

Here's the video..

<iframe width="1280" height="720" src="https://www.youtube.com/embed/DFAmNqciCHE" frameborder="0" allowfullscreen></iframe>

I went through the throttle range up and down in the video.
You can see the front is smooth and the rear bounces at low throttle going up and down the range...

My only thought at this point is the difference in wheel speed due to the OD/UD diff gearing. But that really doesn't explain why it gets smooth in the upper range of the throttle, nor why it wasn't doing this from the start.

I'm hoping some of you guys might have some ideas what might be causing this..

Thanks for your help.

 

[Bmxreeves]

Only thing I I could think of is the drive shafts not being in time. Only thing I could think of.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

 

[Dwill]

Only thing I I could think of is the drive shafts not being in time. Only thing I could think of.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

That's possible I guess since I didn't know they had to be timed.

I know how to time the stock drive shafts, but how can check and time MIP drive lines?

 

[Bmxreeves]

Not sure about MIP's trying lining up the 2 drive shaft screws (at the transmission and axle) so the both are in a straight line.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

 

[srivera00]

That's possible I guess since I didn't know they had to be timed.

I know how to time the stock drive shafts, but how can check and time MIP drive lines?

If you look at the picture the pins (PN# 99023) are aligned you have to line then up on the transmission and axle both front and back drive shafts need to be same. If you put the shafts together and it's a little off pull apart and rotate one half turn they will line up... this may not be your shaft but the concept is the same. Good luck hope this helps "thumbsup"

 

[Dwill]

Not sure about MIP's trying lining up the 2 drive shaft screws (at the transmission and axle) so the both are in a straight line.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

We'll, your tip solved the problem. Right I replied to your first post I went in and pulled looked at the drives lines. The pins in the CVD joints were not lined up. In fact the CVD pins were nearly 90° off.

I pulled them and turned the shafts so the CVD pins are parallel. No more shaking. I checked the front and the CVD pins were off about 2 splines from parallel. I lined those pins up as well and now the entire drive line is pretty smooth.

The only going on now is now I hear something hitting in the drive line. I can hear a "click click" sound as the drive train rotates. It coming from somewhere in or near the trans.

Not sure what it is but I'll track it down.

I'd also like to clock my axels to reduce the driveline angles at the pinion. I can see I can do that by making the upper links longer. But if I do that it will change the caster and maybe even add camber because I'm running the Vanquish 8° knuckles and chubs.

I think I could click the chubs to fix that issue. Not Shure how I would do that other than drill new holes in the Axel housing. I've got no way of doing that accurately so that both sides are the same.

 

[hotwheels000]

Have you lubricated the dlines ?

If clocking them doesnt remedy the problem try raising your rear shock mounts up to the upper mounting locafion. It could be your dlines are at to steep of an angle.

 

[Bmxreeves]

That clicking probably the cvd running dry. I have the stage 1 kit and have no issues.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

 

[Dwill]

View attachment 339196

If you look at the picture the pins (PN# 99023) are aligned you have to line then up on the transmission and axle both front and back drive shafts need to be same. If you put the shafts together and it's a little off pull apart and rotate one half turn they will line up... this may not be your shaft but the concept is the same. Good luck hope this helps "thumbsup"

Thank you. I figured this out right before I saw this post. That the majority of the problem. I've got a couple other things I need to track down now (see my post) but at least the Axel bouncing issue is solved.

I had to think about about it but I remembered I pulled the rear drive lines apart when I changed out pinion. Can't remember why I did that, when I put them back on that's when I must have got them out of time.

When I originally assembled them I must have just gotten lucky, because I had no idea timing the drive lines was necessary.

Thank you again for your help.

 

[Dwill]

That clicking probably the cvd running dry. I have the stage 1 kit and have no issues.


__________________________
1.9 Ibex tuber - The Merica ibex.

R.I.P Dave Mirra

That might be. I use TriFlow Dry lube to try and keep dirt out. It works well, it leaves a waxy coating on the parts. But it has to be applied often and liberally to work well n CVD's.

 

[meatmonkey]

If your MIP's use the shorter output yoke that takes 4mm through pin then you likely have rubbing between the MIP shaft and the plastic spur cover. A little trimming with an exacto knife can take care of it. It can make a "clicking' noise if the pin in the MIP isn't perfectly centered and catches lightly on the cover every revolution.

Others just let it "self clearance" but I'm too OCD for that.

Dried out driveshaft joints can also click.