suggestions for high-angle driveshafts?

[dreadshawn]

Finishing up my J2-TT comp crawler, and just put a DNA dig on the new Axial trans and got it all mounted up! Crawler WB is about 12.5" fully stretched out, and I have a pretty good droop setup going (maxx shocks, Losi gold springs, 40wt oil)...

My shorter driveshaft is hurting a bit on the drive angle, I am looking at about 55 degrees from the dig unit to the shaft itself, and the longer driveshaft is rubbing up on my 87t spur. I am going to go down a few teeth on the spur (got a HH revolver coming!), but otherwise, does anyone have any suggestions for a functional high-angle driveshaft for me? Overall I am torn between these options:

-rebuilding using steel Pede yokes
-RC4WD Punisher shafts
-Junfac CVD driveshafts (though I would have to cut and file one shaft to be shorter)

Any suggestions here? My shaft lengths are 3.450-4.025in (front) and 2.520-3.650in (rear), if this helps to clarify.

 

[rhett314]

The Pede yokes are a great upgrade and may help some.

Another thing to consider is setting up a forward bias. 45/55 or 40/60. This will help make the rear shaft longer and decrease the angle of the rear shaft, and put more weight up front.

How much belly height do you have? Running droop, i wouldn't think you would be too tall. Droop should keep the ride height low, and less of an angle on the drive lines.

 

[gottorque]

Would it be possible for me to see your pinion angles front and rear as well as the rig from the side with wheels off. That will give me an idea as to weather the problem is something other than short drive shafts, such as link length

 

[dreadshawn]

Sure thing, I can post up some pics in the morning, I have to begin winding down for the evening, sorry. With the pics I'll include measurements, rulers, link lengths, etc.. I'll be sure to include pics at rest, compressed, and full droop on both ends.

moving the trans further forward is a pretty good idea, I neglected to notice how much the dig would shorten the shaft, lol!

 

[dreadshawn]

Alrighty, first things first: I am using Traxxas lower links, at 125mm per link, and my upper links are custom, at 90mm all around. As for the pics, I haven't adjusted anything yet, since I haven't gotten it running, so all the various positioning of the components, it hasn't been finalized.

First is the over-the-top-center-shot, to show trans placement. The camera was angled to be directly over the center of the belly pan, so you can see how the trans and dig are positioned relative to the belly pan:

The next three shots are of the setup at full droop, at rest (approx.), and at full compression. The respective belly pan clearances are 4.25in at full droop, 3.35in at rest, and 2.25in at full compression:

With the wheels off, I did the best I could to get the front and rear shots depicting both the input and output yokes and how they relate to each other at maximum droop.

The front:

The rear:

Hopefully these pics will help in deciding the best course of action. I just called my LHS and they have a couple packs of steel yokes (four individual yokes total) in stock, so I may be making a trip out there before I go to work this evening.

 

[constantmotion]

The next three shots are of the setup at full droop, at rest (approx.), and at full compression. The respective belly pan clearances are 4.25in at full droop, 3.35in at rest, and 2.25in at full compression:

The first pic is actually fully extended. Full droop is when the shock is fully compressed at rest (ride height).

 

[JeremyH]

I have built a few short WB scalers over the past few years that run TLT axles and have found that the stampede shafts provide for the most angle at the u-joint with the MIPs slightly behind and the Junfac shafts WAY behind...

 

[dreadshawn]

I figured this may be worth mentioning for posterity, and in case anyone else researches this thread:

I have found my optimal setup, and it also involved putting rubber spacers inside my shock shafts to lessen the droop action. In all I have about 50 degrees of articulation on a 12.5" WB, using the following setup:

-0.400 inch rubber tubing spacers placed inside the shock below the piston
-80wt oil
-1.4lb Losi gold spings
-Jato halfshafts (one pack) (TRX 5550)
-Steel Pede/Slash Yokes (two packs) (TRX 4628X)

On the axles themselves, I had already drilled a hole in the pinion input for my Maxx shaft setscrews, so I grinded down the axle-side yokes to fit another crosspin setscrew (or in my case a 1/2in steel screw) through there. Likely is a person wants to avoid using a crosspin and drilling their pinion, all they have to do is grind down the smaller flange. It is all direct-fit and assembly otherwise, and I am exceedingly happy with my setup!