Diff drive cups

GST 7.7 , Nemesis 7.7 , GSR 5.0

Moderator: CEN Racing

Diff drive cups

Postby hagman911 on Thu Dec 12, 2013 9:30 pm

I have GST 7.7 and keep breaking the diff drive cups. What do I need to do?
hagman911
CEN Rookie
CEN Rookie
 
Posts: 1
Joined: Thu Dec 12, 2013 9:21 pm

Re: Diff drive cups

Postby Smaug on Wed Apr 08, 2015 2:07 am

Deleted
Last edited by Smaug on Wed Apr 29, 2015 9:39 pm, edited 1 time in total.
User avatar
Smaug
CEN Rookie
CEN Rookie
 
Posts: 9
Joined: Wed Apr 08, 2015 1:22 am

Re: Diff drive cups

Postby CEN Racing on Wed Apr 08, 2015 4:42 am

which drivecup? the front/rear diff or the center diff? Breaking during straight line or after landing a jump?
Image
CEN Racing
Factory Support
http://www.cenracing.com
User avatar
CEN Racing
Site Admin
Site Admin
 
Posts: 896
Joined: Sun Mar 30, 2008 12:38 am

Re: Diff drive cups

Postby Smaug on Tue Apr 28, 2015 8:01 am

My Colossus (GST-E, to those outside the US) has pretty significant diff outdrive cup wear at the cups where it exits the rear diff. I ran once with 6S and probably 10-15 packs with 4S. Nothing too extreme.

It seems like a tough problem, engineering-wise: too soft, and they deform like mine. (The dogbones are widening the grooves.) Too hard, and they break, like yours.

I'd be interested to hear if anyone has experience with aftermarket parts that work. I've read in the Colossus thread at ultimaterc that the older cups are much stronger. They're bigger, thicker, and harder. Since they're bigger AND harder, they don't break or wear as fast.
CEN Colossus w/Castle 1515 and Mamba Max
Tamiya Lunch Box
Traxxas Stampede 4x4 VXL
ParkZone Radian electric sailplane
User avatar
Smaug
CEN Rookie
CEN Rookie
 
Posts: 9
Joined: Wed Apr 08, 2015 1:22 am

Re: Diff drive cups

Postby Smaug on Wed Apr 29, 2015 9:38 pm

OK, I'm officially requesting some support on this issue. I have less than 20 runs on my new Colossus, and the diff cups (all of them) are worn out.

Seems like maybe someone forgot to harden them.

The stock shocks are also not oil tight. I bought a second set, thinking I maybe got faulty ones that wouldn't hold oil. But these leak too.

Here are some pictures and a video after today's run. I'm a pretty gentle driver. only very mild 1' high jumps, most of the time.

First, some diff cup (outdrive) pictures. Here are the ones coming out of the front and rear diffs:
Image

Image

Image

Image

Image

Image


...and here are the ones exiting the center diff:
Image

Image


Lastly, here are the leaking shocks. I put 22.5 wt. silicone shock oil in them, as I found the stock oil was much too thick for my driving style:
Image

Image


Here's a video showing the wobble, which I think is cause by the worn diff cups:
https://www.youtube.com/watch?v=kIPVOnSfs0U

To resolve this, would you please send me a full set of properly hardened diff cups?:
2 x MX301 outdrives for the center diffs, and
4 x GS029 outdrives for the front and rear diffs

Then, for the leaky shock issue, would you mind sending me a set of 8 shocks that don't leak? If you have 20 wt oil, please put that in, instead of the really thick stock stuff.
CEN Colossus w/Castle 1515 and Mamba Max
Tamiya Lunch Box
Traxxas Stampede 4x4 VXL
ParkZone Radian electric sailplane
User avatar
Smaug
CEN Rookie
CEN Rookie
 
Posts: 9
Joined: Wed Apr 08, 2015 1:22 am

Re: Diff drive cups

Postby cencanadian on Thu Apr 30, 2015 1:17 pm

i have a seven year old GST 7.7 nitro and have never seen drive cup wear like that. in some of your photos the cross pin in the shaft seems to have holes drilled in them what is that for? also may be an optical illusion but some of the cross pins dont seem to be centered in the shaft. One thing you can do to prevent the axle wobble is to shim the axle using 8mm shims to remove any play. Also you can put a rubber boot filled with grease over the joints to keep the dirt out and to help reduce wear.
cencanadian
CEN Manic
CEN Manic
 
Posts: 154
Joined: Mon Mar 31, 2008 4:09 pm
Location: Kamloops, British Columbia, Canada

Re: Diff drive cups

Postby CEN Racing on Thu Apr 30, 2015 10:39 pm

Hi Smaug

Thanks for choosing CEN Racing.

Please understand that the stock drivetrain is design to withstand the stock motor with up to 4S lipo. If you are using /Castle 1515 and Mamba Max along with 6S lipo, of course the drive cup will wear out faster than usual. There are also only one size of drivecup for the Colossus (either round or square , but they are the same size). You do have the option to upgrade to Nemesis outdrive which are a lot beefier but its definitely not needed and an overkill for stock setup as it just adds more weight.

Now, regarding your request, If the truck is brand new and showing signs of wear without little to no use, we will definitely warranty it , however, you had an aftermarket motor on the truck along with a lot of run time, its difficult to make the judgement. In fact, this is not the right place for such discussion either, please email customerservice@cenracing.com with your purchase receipt along with your inquiry and photos. They will be able to assist you from there.
Image
CEN Racing
Factory Support
http://www.cenracing.com
User avatar
CEN Racing
Site Admin
Site Admin
 
Posts: 896
Joined: Sun Mar 30, 2008 12:38 am

Re: Diff drive cups

Postby Smaug on Tue May 05, 2015 9:03 am

Thanks for the response.

Do you know what's interesting? The reason I bought the Colossus was that I was disappointed in the brushless E-Revo, even on 4S. That pesky diff kept leaking, as it depends on a tiny silicone gasket to remain oil-tight.

After reading up a bit, I found that the Colossus was reputed to have a very strong drivetrain; that it can handle 6S. What I wanted was to run 4S 90% of the time, and an occasional 6S run. After reading up a bit more, I saw that the stock speed control isn't good. Lots of reports of it crapping out. But everything else was good. So I found a brand new roller from a chop shop and put my Mamba system in it.

Again, driving mostly 4S with just two runs of 6S. Diff cups are totally worn out. Obviously not hardened properly. (even for 4S) Shocks are leaking, even stock.

So on one hand we have Traxxas' E-Revo, which is advertised to be good with 6S, even though it really isn't. On the other hand, we have the Colossus with its strong drivetrain, but with a couple small quality issues. (ESC, leaky shocks, soft diff cups)

I'll contact customer service, but from what you said above, I guess they'll tell me they can't help.
CEN Colossus w/Castle 1515 and Mamba Max
Tamiya Lunch Box
Traxxas Stampede 4x4 VXL
ParkZone Radian electric sailplane
User avatar
Smaug
CEN Rookie
CEN Rookie
 
Posts: 9
Joined: Wed Apr 08, 2015 1:22 am


Return to CEN 1/8 Monster Truck

Who is online

Users browsing this forum: No registered users and 0 guests

cron