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S

Stafor

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I just bought a savage 21 about 2 weeks ago, off of craigslist. It has the axial .28 and he said 3spd transmission, but as far as I can tell, it only shifts once. Just something I've noticed is that it acts a lot more like fwd than 4wd, although all 4 wheels do drive, when I punch the gas, the front wheels peel out and the rear just roll, if I hold it off the ground or hold the front off, and apply gas, then the rear wheels still spin, but is there a way to evenly distribute power? or set it to apply more to the rear? thanks
 
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Sounds like you could be missing a drive pin, or possibly have a damaged diff. Hold your front two tires off of the ground (while holding the front two tires) and try to roll the truck.

You shouldn't be able to roll the truck, as the driveline between front and rear diffs' is pretty much a solid setup (no differential action).


The key place to check if you can roll it, is each of the center drive cups on the rear; there is an allen-key set screw holding each cup on (at the end of the center drive shaft). If that is missing, it could explain your symptoms.

Now, if your center driveline setscrews are there, the next thing to check is if you are missing a drive pin. Remove the rear tires (8MM socket is needed), and check the hexes in the rim. If they look rounded (possible), you'll have to replace the rims.

If the hexes aren't rounded, remove the hex adapter from the axle, and make sure there's a pin there. If there is, check the other side.

If you have pins in the axles, and good rim hexes, the only thing it could be is a damaged diff. For that, you will have to crack open the diff casing. Depending if you have the X or the .25 savage, this can be easy (X) or time consuming (25).

If you need further help, please don't hesitate to post back on the thread, and someone will help you out asap.
 
that right there is solid advice!

if you have more power to the front or to the rear follow heartbreaks check list 9/10 it's something that gave on the drive line agin 9/10 it's usually the pin holding the cup for the diff I've busted wayyy too many to count now I keep a few on hand for spares.

as for the three speed once you get the drivline problem sorted out check again for it shifting, as it is it could be shifting so fast it only seems like it's shifting once.
 
Happened to me last summer(missing cup screw and only had front traction) Had fun for a bit but i fix it back up. Just guessing!!
 
It looks like all the pins are in, I'm not exactly sure what I'm looking for, but where the driveshaft ends, theres a pin holding it into the adapter or whatever that has a pin through it

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like that, on both the front and rear, and by the transmission on front, and can't tell on the rear because of the brakes. also took off the wheels and theyre good.

Any good websites or info on tearing apart the differential to check it out and/or repair it? Thanks for the info
 
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Actually, taking the rear end apart isn't all that hard. Remembering how to put it back together (the first time) can be a tricky thing, but don't let it intimidate you.

First, remove the fuel tank, exhaust pipe, and roll cage (if you have the X style rollbar). Also, remove the rear tires, and the upper ends of the inner-rear shocks. This should give you a good clear shot at all of the screws that you'll need to loosen.

Next, remove the four screws (two on each side) that are at the rear end of the TVP plates. Next, loosen the screws that screw through the tvp's and into the cross braces under the engine.

From there, GENTLY spread the TVP; the whole rear end should come loose. At this point, if you want to change out your rotostart/pullstart assembly, now's the time.

Now, remove the skid plate/bumper brace assembly, and pull ONE sides' hingepins for the arm. Unscrew the shock tower, and the bulkheads should split right apart.

You should now have the diff in view.

Here is the manual for the Savage 25 (Same thing, just a few very minor changes, but the process is the same): http://www.rcdocuments.com/file_info/download.php?file=HPI_Savage_25_Manual.pdf

Also, if you have the original 2 gear diffs (very likely), now is a perfect time to upgrade your truck to the revised 4 gear assembly:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJLH6&P=ML

You'll need two; one for the front and one for the rear.
 
Great info, ill tear it apart in the morning, thanks :)
what exactly am I looking for in the differential? stripped gears or what?
 
Most likely. that or a stripped center hub, but chunks of gear teeth are likely.
That's one of those things that even if you don't know, you probably will as soon as you open it up. If nothing is obviously wrong, check back with us.
 
Rolex pretty much nailed it. If you have a damaged gear, you'll literally see teeth missing. While you have the diff apart, make sure to clean out all of the fragments before re-assembling. The 4 gear diff upgrade makes the diffs much stronger, so you won't have to worry about them.

I'm going to guess that your truck has the stock 2 gear assembly, which is known for stripping out when landing on-throttle.
 

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