Savage diff screws backing out?!

[Boxxer]

So Ive been running my Savage for about a week(around 20 tanks through) and lost my RWD. I heard about the stock diffs being weak so I expected to have a stripped bevel gear.... I take the rear end apart and pull the gear diff assembly out. I found all 4 diff screws backed out about 2-3 turns. Once I open the gear diff i found one of the bevel gears missing a tooth. Im going to call HPI to see if they will warranty it and Ill post what happens.

Also, same day, about 10 minutes after my savage is out of order. My friends savage which is newer(about 10 tanks) the drive train locks up and wont move. I take that truck apart and find the input bevel gear for the rear diff is missing 2 teeth and binding on the diff bevel gear. After I saw the missing teeth I decided to check the gear diff screws while I had the gear box out. I pulled the diff assembly to check the 4 bolts to see if they were loose like mine. Again, all 4 bolts were loose at least 3-4 full turns, but the diff was still ok(no internal damage). So I tightened the bolts(after applying some thread lock) and threw it in my truck to get one of them running. Again, Im going to call HPI and see what happens.

One more thing. On my friends Savage 25. I decided to take a wrench to check a few of the bolts. Found all 4 engine mounting bolts loose about 3/4 or a full turn loose.

I know this sounds like Im not happy with the Savage, but the reverse is true. I think its well engineered and its a blast to drive.

Any of you Savage owners have similar problems? Im going to do the 4 gear diff mods to the front and rear of both trucks no matter what happens with HPI.

[Walter]

Both my front rear diff screws backed and cleaned out the internal and ring and pinion gears.I am going to call HPI today and see whats up . I need two complete diff assemblies, ring and pinion include.

[-=ADA$=-]

i think that all owners should check all screws, and add thread lock!!

[kitty]

If you're talking about the four screws that hold the ring gear to the case, using loc-tite is not a good idea. CA glue would work better, though I'd recommend different screws with a machine thread over the self-tapping ones. A little bit (not much!) of CA can help for now, as it sorta melts a little bit of the plastic, thus helping to bond the screw to the plastic better. While you're at it, I highly recommend doing the spider gear mod (4 gears instead of the stock two) with silicone fluid (anywhere from 3000-10,000wt) inside instead of grease.

And for about the fourth time today, I agree with ADA$ - check all of the screws often. Nitro vehicles rattle a lot more than electrics and screws need to be checked more often, especially the ones around the engine.

Did you use loc-tite on the engine screws? If not, then for darned sure use some. I'm pretty sure the manual suggests it as well.
kitty

[Boxxer]

Yea, I used TL on the engine mounts.

So the update from HPI. They are sending parts to repair both trucks(no charge, no questions asked and I dont have to send the broken parts back) but said they had never heard of the 4 screws for the diff bevel gear backing out even though both trucks had the same problem leading(I think) to different failures. As far as the input bevel gear for the rear diff losing 2 teeth on my friends truck, I cant really figure out if it was some abusive driving(likely full, or close to full throttle landings) or actually a defective part or caused by the diff bevel gear being loose. I told the guy from HPI what I saw and how the trucks were used/abused and he seemed to think the 4 philips diff screws werent torqued to spec from the factory.

Thanks for the info on the CA Kitty, Ill use that when I do the diff mods on the trucks this week(spent about 240 on parts today that I "need":D )

By friday mine will be running with 3,ooo weight up front, 1000 out back with the 4 gear diff mods. An internal antenna(since i seem to like doing throttle assisted wheelies to back flip to grind on my lid and break antenna move alot.) Adjustable upper arms. Throttle servo mod, HD TVPs, alloy steering hubs and a few other odds and ends... :D

She already has a new pipe, hump pack, servos, receiver, airfilter, fuel filter and body. Its been a good 2 weeks...

Shes also going to get the full thread lock treatment when shes apart on my work bench(kitchen table) when the parts arrive.

Coolest move Ive pulled with it(besides a 20 foot gap hip jump) is jumping(a step up gap) from a very slow speed up a BMX launch ramp to a loading dock, landing on the rear tires only and wheelieing across about 20 feet off the other side and landing clean to the ground again. There is a step down jump i built in the woods about a year ago(BMX) thats about a 30 foot gap and about a 10 foot step down to a good transition. Ill have picks up soon.... :cool:

[kitty]

Originally posted by Boxxer
Thanks for the info on the CA Kitty, Ill use that when I do the diff mods on the trucks this week(spent about 240 on parts today that I "need":D )
I can relate to that "need." Before starting putting my SS together, I bought a full set of HB CVAs (all around), MP servo saver, linkage kits for the linkage mod, tank guard, fuel filter... the list goes on. One thing, though, when you put the diffs together, if you're using new diff cases, just use machine-thread screws. Only do the CA thing if you'll be using the old cases. Speaking of, I placed an order on Tower last night and they had some diff cases in stock. It said "limited supply" but they definitely had a few.

By friday mine will be running with 3,ooo weight up front, 1000 out back with the 4 gear diff mods. An internal antenna(since i seem to like doing throttle assisted wheelies to back flip to grind on my lid and break antenna move alot.)
I recommend 5000 out back if you'll be using 3000 up front. Some guys are using 10k out back for a limited slip type setup. Personally I'm not big on the internal antenna idea. I did that once with my E-Pede and lost a lot of range. But if you have the HPI radio setup, it seems to work okay for most guys who've done that. I have a FM radio system (shorter antenna wire than the HPI stocker). I bought a GS Racing aluminum antenna holder and use the "clear" (semi-transparent) generic antenna tubes that I get at my LHS. I buy the stuff in like 4' lengths and just cut a new one and change it when the installed one gets too scuffed up. The tubes I buy are a little thicker than the stock HPI or Trinity replacements, but they fit pretty tight in the aluminum antenna holder very well and rarely pull out. Have fun with the new parts!

Oh yeah, which TVPs did you buy? I'm thinking I'll switch to the 5mm CNCd (down to 3mm with "fins") when my current set get too worn or bend on me. I forget who makes them but I've heard they work great and don't weigh much more than the stockers.
kitty

[Boxxer]

Cool, ill check into tower for the diff cases.

I have the GPM TVPs on the way. They are the ones that are ribbed(insert joke here). It comes with screws which is cool. I bent my OEM TVPs on the 4th tank. I used my fine adjustment tool( a crab hammer) to get them back to reasonably straight, but theyve been stretched and compressed in some areas and are still pretty tweaked.

I suspect the internal antenna will rob more than a few feet of range but I dont mind. Ill test it for range before I set out on running the neighborhood pets/kids over. Id like to stay with a regular style antenna but the tubes dont last a day with the type of use my truck sees. I have the stainless roll bar on the way and im going to cut a piece of lexan to fit length wise between the diagonal roll bars and then drill and wind the antenna wire up it. Mines an FM also, so well see how it does.

What are your thoughts on the "self leaning" issue. Its never really given me problems and it seems like a pain to run the header tank, but I like the idea of having the truck running while upside down and also getting a little extra run time. I dont like the idea of leaving fuel in the header tank all the time(which is what most people seem to do) or having to come in all the time just to make sure the primary tank doesnt run dry and introduce air into the header tank. I think ive come up with a way to have the header tank prime without having to take off any fuel lines(using a 3 way valve and the extra fitting on the header tank) If it works Ill post up some photos. I was also thinking about drilling a hole into the top of the header tank and installing a small relief valve so i could pinch off the line to the carb and then force most or all air out of the header tank. I dunno... just some ideas I had.