Spur Gear 47T Savage-melt

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sky4max

sky4max

Member
Messages
28
Location
Fort Collins,CO
hi

this what happend to my gear, the temp was around 220-240,

I think what melt it is when I tried to climb a rack, the track could not get up and the tire did not spent so the gear spent insted of the tire or getting up the rack,

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here are my Q
http://hpisavageforum.com/forums/newthread.php?do=postthread&f=18
 
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wow, seeing this alot. could it be aluminum shoes causing heat and no venting in stock clutch bells?
 
my guess is the stock shoes slip ..creates enough heat to melt the gear...I have had clutch problems to .. seems the aluminum shoe upgrade is a must "DO" for the Savage ....are you checking your engine temp at the half tank and lower? ...you may be running 220 at full tank but 280 or more at half tank ...mine was running 45 degrees hotter at half tank than full...savage half tank lean...
 
I have to agree with frddyj. I have seen this a few times when my mesh was not right. It just eats the teeth down on the gear.
 
i had the same problem and even when the mesh was right it still eat them up. so i checked the engine plate and found where it was broke i 2 places.
 
I was at a buddy's house last weekend bashing around and his did the exact same thing. He went in to price some new gears and 10 minutes later mine did it too. I haven't checked my truck out for cracked plates or loose engine mounts or anything yet. It's got about 3/4 gallon through it at this point. Just gonna throw a new plastic gear on it and go like hell:Xfingers:
 
Your slipper may have gone loose. If not, then the gear mesh was set incorrectly. It's great to use a piece of between the CB and the spur to set the mesh. You want a very slight wiggle when holding down the clutchbell. Make sure to locktite the engine plate so it doesn't loosen up when your bashing. Running in grass can create lots of resistance on your engine too, which may have caused the heat.


BTW: Don't go with a metal spur gear. You want your spur gear to be the weakest point in the tranny. Chances are, if your mesh is wrong at the CB and spur, then the damage will transfer down the tranny line. Plus you need to run a hardened clutch bell.
 
Metal spur gears are okay to use, it's just that if something were to go wrong, like the engine moving, the damage can transfer down into the tranny or the diffs. I was lucky that my actual CB was the weak spot in the case of me having a metal spur gear on. The CB was completely shaved off from either having a bad mesh or driving in high grass, which caused lots of resistance. I did buy a hardened CB, but now that I replaced the spur gear with the plastic type, I might switch it for a vented one. Another alternative to metal is delrin. Delrin is almost as strong as metal. Just as long as you get your mesh right, you use locktite, and check that nothing on the mount or the plate is cracked, you should have the delrin gear lost a long time.
 
same thing happened to me. Installed a new K4.6 motor, Savage X transmission with 47t SG on my savage 25. The thing was chewed up in less than 5 mins, happened twice already, gave up and its in the Hobby Shop now.
 
i had the same problem only i was running a dynamite .26 on my savy. i was running it out on the beach not thick sand or anything and i went down the beach for one more pass turned it around hit the throttle and it just reaved out i thought i did something serious. when and looked at the spur and it was completely flat all the way around. the next day went and got a metal one and i have never had a problem it runs great now. the only problem is the motor is a pain to tune but i did the seal mod so hopfuly it fixes it
 
I'm gonna throw a few solutions out there for a stripped spur. On my X I went through like 3 spur gears, almost all a different failure. The first spur was destroyed because the slipper clutch was too loose causing heat from slippage that melted the bronze bushing through the spur. The second spur was stripped without the help of heat, the engine was removed to replace the first spur gear and when the lash was reset the engine was misaligned (crooked) on the plate and although lash seemed correct the poor alignment allowed the teeth to be removed. The third spur was damaged but not completely destroyed after running the truck through some tall grass like I stole it 😀, after shutdown I dropped the truck on the ground and noticed no movement between the cb and spur gear upon closer inpection the cb had gotten hot enough to melt the spur gear and was still quite hot to the touch. After turning the spur so that it didn't melt to one spot things cooled down enough to keep it's shape and I actually ran another tank through on that same spur. So to summarize the fixes were, check slipper and make sure it's good and tight (and the spur is not already melted from the slipper clutch side), check your engine alignment on the plate by examining the screw slots and make sure the gaps in the slots are uniform (you can use small 2-3mm allens in the slots on one side while setting lash to hold the engine straight while tightening the screws that hold the engine down.) As far as the hot clutch bell melting the spur I have no surefire solution but I believe that a vented clutchbell or just eliminating the extra load from tall grass or pulling a sled may be the solution. Good luck.
 
Check your mill mount screws all the time, I took mine out for a bash session yesterday, did the same thing to it as well, after it cooled down and i got it hope to tear into it i noticed that the mill was a lil loose, all 4 screws were loose & it was obvious that it had been loose from start, or during the bash session. I'm sure there was other factors that played into it as well but that is .02 of it. On that note, i run a stock 4.6X, got a 52/17 in it to run until i can get a dif set-up, slight mod to the mill plate, but hope it holds up!
 
I see this more and more the first day I broke in my savage X the spur gear was destroyed and the mesh was good
 
Stay with the plastic 25 spur. MEtal spurs can cause damage if you don't know how to properly mesh them. Think of it this way, if the spur doesn't go, something else will. Probably something more expensive too. I snapped my engines crankshaft using a metal spur. I would rather have a few melted spurs than a ruined engine. I have been running an Axial .28 and the same 25 plastic spur for over 5 gallons now.
 
Savage model 25 has a 52 tooth spur I believe. 25 is the truck model, like: Savage 35, Savage SS, Savage X, etc.
 
Badhabit75 said:
25? I'm lost on that on FX, My stock savy is a 47/17, just curious what you mean by 25, can you explain please. ty
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He's talking about the Savage model. Unless you have the first version of the Savage that came out (Dual slipper type), the S25 and X use the same type of spur gear. So stick with the plastic spur gear. If there is a problem on the spur gear, the damage will transfer down and probably hurt something more costly to replace. It's gonna be a killer to replace too. I like to keep my spur gear the weakest point in my transmission. It's cheap and easy to replace. I make sure the mesh is good every run and I haven't gone through one yet since my rebuild.
 
I wasnt gonna comment on this caz i dint wanna cause controversy, but on the other hand, wanna get best info out there to peeps who need help.

The metal spur on the XL & X ss is an 'upgrade' for many reasons. Truggies also use a metal spur on the center diff without a slipper clutch w/o issue.

Stay with the plastic 25 spur. MEtal spurs can cause damage if you don't know how to properly mesh them.
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If you 'don't know how to mesh' & run a composite spur gear, the spur will melt from excessive heat or strip the teeth off from mis-alignment. A metal spur gear is more forgiving to both of these conditions.

Think of it this way, if the spur doesn't go, something else will. Probably something more expensive too.
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Slipper clutch makes this virtually impossible. Unless you eliminate it.

If there is a problem on the spur gear, the damage will transfer down and probably hurt something more costly to replace. It's gonna be a killer to replace too. I like to keep my spur gear the weakest point in my transmission. It's cheap and easy to replace. I make sure the mesh is good every run and I haven't gone through one yet since my rebuild.
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damage cant "transfer down" beyond your slipper clutch in either direction unless you eliminate the slipper. The most damage you will prolly do is toast your slipper pad which is $4 usd for 2 pads.

A bud of mine (who you all know well) broke his mill plate in 3 places while running a metal spur & dint damage his spur or anything else. a composite wouldve been toast.

so again, please don't take offense to this posting, I'm sure the r/c companies did a lot of r & d before they designed an upgrade that would caz damage and make their phones ring with angry customers.

running a composite or Metal spur gear is a matter of Preference as is most things in this hobby; Adjust your slipper correctly, use a racing/vented clutchbell and you will love a metal spur!
 
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frddyj said:
so again, please don't take offense to this posting, I'm sure the r/c companies did a lot of r & d before they designed an upgrade that would caz damage and make their phones ring with angry customers.

running a composite or Metal spur gear is a matter of Preference as is most things in this hobby; Adjust your slipper correctly, use a racing/vented clutchbell and you will love a metal spur!
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very well put frddy and i agree totally. i have had probably about 6 or 7 savages.......(and working on my 8th!) and i have never had a problem, with a metal spur. i have have problems with the plastics.......but that was because i was jumping the hell out of the thing and had the slipper tight as it could go (a big no no.....especially on big air stuff). but it's all in preference. however....because you have a bad experience on one gear...you should always consider the variables........ i.e. did i have the motor mount tight? was the motor alignment on the gear straight? is my engine mount cracked? is the motor plate warped? questions like thesee. but this is just my 2 cents........................................
 
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