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RWD not working

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G

Gwen

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I have a HPI Savage 25 and the RWD is not working. The FWD is working fine. I have a Robinson Racing Metal Spur Gear. When I have the truck raised up, the rear wheels still spin when I turn the front wheels as normal. I am on vacation right now and I do not have the tools with me to take it apart, so I am hoping someone can let me know what is in store for me.

Thanks in advance.
 
Check first to make sure the screw pin in the rear center drive shaft did not fall out and that the cup is just spinning on the pinion gear. If it has not fallen out then most likely you have stripped the rear diff, it happened to me twice when I first got my Savage SS.
 
If it is the rear diff, you can get one on ebay for around $20. I think you can also use the rear diff from the XL, that is what I heard.
 
Thanks for the responses. Is there any quick test I can do to determine if it is a stripped rear diff?
 
lift the truck off the tires, hold one rear tire in one hand and try to spin the other rear tire. if it doesn't try to spin the tire in your hand (opposite direction of other tire) the diff is shot.
 
Hold three tires stationary and turn the remaining tire. Watch the center drive shafts as you turn the wheel.
 
HeartBreak said:
Hold three tires stationary and turn the remaining tire. Watch the center drive shafts as you turn the wheel.
Click to expand...

Ok, I tried this, and with three tires stationary, one rear tire spins the drive shaft and the other does not.
 
Gwen said:
Ok, I tried this, and with three tires stationary, one rear tire spins the drive shaft and the other does not.
Click to expand...

i just tried this method on one of my savages and no wheels would spin?

its in perfect running order.
 
Sounds like you have a roasted diff. Did you feel any clicking (like something trying to grab), or was it a smooth rotation?

You could be missing a grub screw in the outdrives.
 
HeartBreak said:
Sounds like you have a roasted diff. Did you feel any clicking (like something trying to grab), or was it a smooth rotation?

You could be missing a grub screw in the outdrives.
Click to expand...

It's weird. One rear tire has a smooth rotation, but the other does not as it spins the driveshafts.
 
Sounds almost like you could be missing a drive pin. Take that one tire off, and remove the hex. See if you have an axle pin there.
 
Wow...I took the free wheel off to check the drive pin, and the drive pin is there, however the inside of the wheel/rim is stripped, the part that is supposed to be hexagonal is now round. LOL. I put the wheel back on and super tightened it and now the drive shaft turns with the 3 wheel stationary trick on both back tires. It just looks like I need new wheels. Sweet I think I am going to get larger than stock rims and tires this time. Much better news than a stripped out diff!!
 
That was another common problem with hpi Savage rims. You may also want to replace the hexes with better hexes at the same time to help prevent the new rims from stripping as well, if the old hexes have rounded corners they will cause the new rims to strip out too..
 
OK just for an update on this thread. I ordered new wheels and tires, except I upgraded to 17mm hubs, and got Warlock wheels & tires. The tires are slightly smaller than stock, maybe 1/3 of an inch. All I have to say is OMG! My truck seems 25% faster and rides so much smoother at top speed.
 

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