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Problem with back wheels!

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Powerman6766

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The back wheels arnt turning on my Savage 25, so I am running front wheel drive. The same thing happened to my uncle's T-Maxx where the back wheels wouldn't turn. Come to find out that the gears were chewed up in the back of my truck. (Sorry but I forget what it is called, if you could name off some things pleasedo I might remember.)

Thanks,
Powerman6766
 
do the 4 gear spider mod and shim the middle sized gears in my savage 21 i just shimmed the diff and it works great now so much power from the rear and its the stock diff just shimmed!
 
No I don't have the 4-spider mod.But yeah this same thing happened to my uncle's T-Maxx and now it is happeneing to my Savage. What could have caused this?How do I got about doing the 4-spider mod, or whatevere else.Not sure about the spider mod, maybe if I get some parts numbers.

Thanks,
Powerman6766
 
I don't know, I received my roller with the diff mod already done.

Basically, there's just a lot of stuff to take off to get the diffs out.

Is any of it hard... probably not. This is a $400 toy, not rocket surgery... Just print out the parts explosions for the front and rear of the truck as well as the diffs so you have a map to follow to put it back together.

I've had my front and rear end off, but I never took the assembly apart. I had to mess with center drive shafts and do the MP steering upgrade. With a drill and a phillips bit, you can get the front and rear assembly off the truck in about 10-15 minutes. But each assembly has quite a few parts on it, so I'd suggested tearing each one down, rebuild the diff's, then put them back together. I'd do the rear assembly first from tear down to installing it back on the truck, then do the front one. Reason fot that is, you have to deal with the steering junk, so it may take a little longer and doing the rear drive first will get your feet wet so you understand at least what your doing before you have to deal whith the extra steering parts.
 
It is pretty easy to take the diff out and apart. I had to replace one of my 4-spider mod diff cups because the cross pins wore a groove in the plastic diff cup. The gears and pins were fine and the new cup made the diff as good as new. The whole diff repair took me less than 45 minutes start to finish. See my build page to see what a 4-spider mod looks like.
 
Anyone know how much it costs?I need to get some money before I do this. :) I know HPI diff gears cost $5.00, but I have no clue about the other need things.On the mod page for 4-spider mod it dosnt have any base prices.

Thanks,
Powerman6766
 
Well, here's what I've found when reading all the stuff I could find on the diff mod.

You can use these gears (1 set) per diff HB Steel Diff Gears Although, I've read that some suck and some work well. But I've read the same about HPI's stock diff gears.
These pins (a set of 4, 2 per diff) Kyosho Bevel Pins
and you probably need a couple stock diff cups since yours are more than likely notched HPI Diff Cups

If yours are fine, but you want to beef them up, it's cheaper. But if yours need work, you kind of should tear them down to see what's worn. Make sure the ring and pinion gears aren't worn. If they are, you will need to replace those as well. Also check the bearings and see if they are sloppy. If they are, they will cause the ring and pinion gears to wear quicker.

HPI Ring Gear HPI Pinion Gear
 
I am pretty sure the gears are bad.But I am going to tear it apart somtime this weekend to find out for sure.Same thing happened to my uncle's.
 

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