HPI WR8 HD Center Drive Shafts.

[MikeGozz]

I just got a set in for my WR8. Who's excited for me?!?

I'm excited because I've had all kinds of issues with the center drive cups.

First the stock center drive cups wore out in a matter of 3 months. HPI replaced them but I still think they should last a bit longer.

This is what the stockers looked like (Front):


Rear:


The pins on the dogbones even work down to practically nothing. Check out the sliver of drive pin left on that thing!:


So I did some research online and decided to harden my replacement cups myself. For the most part it worked but during the process I failed to notice that the slot that holds the pin widened just a bit (think of packman) which cause all kinds of slop and backlash in the drivetrain. Eventually all this slop started causing problems with the motor. Bearings, broken shafts etc..

The hardened cup did hold up though... but they did more harm than good.


So I ordered the HD cups. The part numbers I ordered are 109920, 109924, and 109925. Unfortunately they don't make HD axles for the WR8 but it you run the 9mm wide alloy hexes you just order the 40mm axles for the Bullet (part number 109921)

The slots on my new HD drive cups will be nice and tight and hopefully they will last a good long time.

Check these bad larries out!




I also ordered a set of HD diff outdrives (part number 109926). They should be here soon. I'll post up some pictures of them installed!

[going2fast]

love the work you put in to these wr8's..very cool

[MikeGozz]

Originally Posted by going2fast

love the work you put in to these wr8's..very cool

Thanks man! Everything is finally installed. I took a few days to build the diffs with spair and new parts and tonight I finally got down to business and swapped everything out.

Here is the center diff ready to go:


And the front and rear:

I used 10k for both, I'm not sure if I'll notice a difference or not as I was running 10k front and 7k rear previously. We will see.

Here is the diff tucked into the case with the HD input shaft (front I think):


Rear same deal:


And here is the car buttoned up and ready to go-
The back end:


The center (you can just see the shiny bit):


And the front:


The only issues I ran into were with the orange cast aluminum toe brackets... Make sure you check those out if you are digging into the car. I noticed my a-arms had a little bit of forward/backward movement along the pin so I was expecting there to be something out of alignment.

This is what I found- The rear toe bracket:

On the left there you can see it is bent up a bit. It should be flat on the table. I had an extra set of brackets so I just replaced them.

Here is the front:


Now it is supposed to rain the rest of the week. Kind of my luck I guess.