Help...truggy doesn't go...
 

Good folks, I finally got my Mayham St up and functional but when I took it out, gave it a little throttle input, it really did not move. I put my foot in from of it and although the center diff was spinning, nothing was happening in the rear. Now just a few days ago I was cutting grass with it. Could I have killed the diffs in one run? I don't know the condition of them before I run a 1520 with 20 volts through them so what might my replacement options be for replacement?

You might try these:

http://cgi.ebay.com/SPORTWERKS-SWK91...item3f0421ba1d

http://cgi.ebay.com/SPORTWERKS-SWK90...item3f01c2dda3

http://cgi.ebay.com/LOSI-LOSB3528-HE...item3efbf2b500

They have held up in my 19lb buggy on 8s.

Brian,

Thanks for the advice, but upon further inspection, I noticed today the the center diff spins but does not engage the rear drive shaft. I can give it fill throttle like before but the rear shaft does not spin. Any suggestions? I dissembled the center diff, packed with heavy grease but just a lit of the same. Is there an option to ditch the center diff for a direct drive type center?

So something's wrong with the internals of the center diff if the rear outdrive doesn't spin - is the pin broken?

That is the thing...I opened it up...packed it with grease and put it all back together. With the wheels up and no resistance, I can get get pizza cutters from the rear, when I put it on the ground, it just does not go. What I can't understand though is after getting it together, the first run...it was beastly.

Take the diff completely apart! Pull all the gears out, there is probably a pin that is broken somewhere

After a complete disassemble of the front rear and center diffs I can surmise the following:

1. Carefully inspect and roller bought used and
2. Be prepared to spend a good amount of time rebuilding.

I thought the differentials on my truggy were belly up so I replaced the the front and rears with Titanium gears and cleaned and rebuilt the center unit. To my chagrin, the reason I was getting little to no drive is due to a lack of grease in the center and a broken CVD up front. I gutted each diff housing and cleaned the gears, packed marine grease into each and replaced the ring and pinion. Very stiff but manageable. I did this for both the front and rear differentials. I gave the center diff the same treatment so I hope that solves my no go issue. More to come...

Here is a tip, since you appear to have a vehicle with sealed diffs, spring for some 50k weight diff fluid and put that in the center diff. Much better than the best grease. Still use grease on the ring and pinion gears in the ft and rear diffs, and I like 30k diff fluid in the front and rear diffs. This is a great bashing setup for a truggy, and I used this with my heavy muggy.

Well....I can tell you this...the grease did not work. It did for a minute but after a while, no drive from the rear. No broken pins in the diff and initially the diff works but I want to see this thing run...I will JBWeld it this weekend.

So is the rear drive-line binding anywhere? It makes no sense that you cannot get power to the rear. Even without grease in the center diff, you should get power to both front and rear about equally -- unless one of them offers more resistance.


:neutral:

Got a video of this?
Is the diff full of fluid?
The back diff works fine?
Nothing slipping in rear wheels?

As far as I can see there are no binding points in the drive train to de seen. Like I said, I rebuilt all three diffs; new grease, new ring and pinions...no drive issues. Off the ground...it make pizza cutters on each corner but on the ground, under throttle the center diff spins but does not drive the rear and barely musters the fronts. I will get some video of it in action tomorrow.

Are you using thread lock on all of the set screws throughout the drive line? Motor pinion?

If all 3 diffs have been properly rebuilt, and all the CVDs are in good order, there should be no problem. I think you need to tear it down again. Even with no fluid in any of the diffs you would have plenty of power to the rear wheels if everything was mechanically correct.

You can see the CD spinning with the truggy on the ground just like off the ground? And no power to rear and little to the front with the CD spinning away?

Do the center front and rear cvd's spin with the CD or not? If you can see where you have movement and where you don't - you may be able to locate the problem point. If the CD is spinning and neither of the center cvd's are spinning with it - then your problem must be inside the CD.

If the center cvd's are spinning with the CD, then your proposed fix of locking the CD will not help.

If the problem is inside the CD, and the pins are in place, are the internal gears shimmed so they mesh properly?

I have another idea - a front wheel pin...

If a front wheel pin is broken then all the power is going to go to that axle...

A likely cause. Another might be a CVD grub screw that loosens up quickly, again somewhere in the front. Also make sure the grub screw is on the flat of the shaft or in the dimple, if there is one.

This truck is an enigma. The other night I can't get the friggin thing to move at full throttle, tonight, I am pushing concrete blocks across the garage floor. I am going to push it hard tomorrow to see what happens. I appreciate the suggestions. More to come.....

Almost sounds like your motor is slow to wind up.
Maybe you will work everything out of it.

Cool,

I don't think the motor is the issue. I shot two short videos of my truggy in action.

This one shows power getting to the rear. Big wheelie on the carpet.

http://www.youtube.com/watch?v=87Z_hB089bs

This video is a no load testing of the differentials. All the wheels spin and the wheels are partial pizza cutters. It is getting there.

http://www.youtube.com/watch?v=o-QKCun3ADQ

Looks fine to me - I suspect it is because of the grease in the CD - buy some 30k...

I am going to roll with the grease for a minute and then up to the 50K stuff. There is snow all over the place so no play outside. Focus is shifting to running 100+ with my GTP and HPI Super Nitro.

The grease is why the power is unloading to the front.

Thanks...I may have to make that change sooner than later...I did notice on the video that the fronts lite up faster than the rears.

It was a great day to get the Truggy out and it was great for about 10 minutes. The 1520 on 5s and a 15t pinion with stock gearing was a beast on the road and in the grass. It was fast as heck an the 1520 stops on a dime. The grease though, did not last. After tromping on it for a while, I lost forward motion. Next stop...locking the center. Once I get it running where I want it..6s and gearing up is next.

There is no need to lock the diff, just use the proper silicone oil as you've already been told

So what was the problem? What was moving and what wasn't?

Truggy doesn't go...No more!!!!
 

Truggy doesn't go is not the case anymore. I locked the center diff using hot glue and the truck is insane on 5s. Wheelies and front and reverse are as easy as throttle application. The 1520 is a beast of a motor and the Mayhem is a solid basher. Looking for wheels and tires for an onroad set up also.