Savage three speed bulletproof transmission Mod

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frickenjoey

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If you have a Savage with the 3 speed and a high powered modded engine there is a good chance you are going to end up shelling out the gearing of the Savage 3 speed transmission. The biggest problem is the output gears are very thin and the first gear is still plastic. We can fix that with just a few parts and a couple you many have laying around already! The full time to do this mod if you have all the parts is only a couple hours and it will greatly increase the durability of your truck.
**DISCLAIMER** I did not think up of this mod. I am just giving it to you with the consent of the guy that actually DID come up with it. On this site and a couple others he is known as SV250. Jimmy, dude you rock, thanks for letting me post this.

Parts listing for the BP tranny Mod:
  • HPI86098 29T Idler Gear (From old 2 speed)
  • HPI86084 32T Drive Gear (From old 2 speed)
  • SSAV3344T Steel 44t 1st gear (made by Hot Racing)
  • HPI77065 (optional but recommended) High Speed 3rd Gear Set
  • Few washers of various thickness with an inside diameter of 8mm or 5/16
Here are the parts you will need for the Mod


60a94c3a-246e-4a49-9307-9c47c6b1b309_zps312e8f6e.jpg



So getting started you will need to cut this collar off of the 29t drive gear using a Dremel or hacksaw. I used a hack saw since I was out of cutting disc for my Dremel.

IMG_8988_zps197e2882.jpg



Once I had the collar removed I cleaned the surface up by lapping it with a medium then fine wet stone. That is optional as long as you have it cut flush. I just did it to make the job look cleaner and making sure the gear was good and true.


IMG_8998_zps54a75f77.jpg



Next on the back side of the same gear you will need to grind in the back of the gear approx. .5 to .75mm. This lets the gear sit down on the shaft enough to get the “C” clip retainer on the gear. It is better to make a couple passes at it than to take off too much.

IMG_9010_zps6d4a9eb1.jpg



Pull the old 1st speed drive gear off. Swap the drive hub held on by three screws over to the new steel gear. Remember to use locklite (Blue or green) since the screws are going into metal.

IMG_9005_zpsb74d3d85.jpg



Put new 1st gear back on shaft, drive pin and put new wider drive gear on shaft. If the C-clip will not install you may need to shave a little more off the back of the gear as discussed earlier.


IMG_9011_zps5a6bfe2f.jpg


At this point if you are going with the optional Higher 3rd gear flip the gear pack over and remove the centrifugal clutch and replace the gear as well as the one on the top shaft. Reinstall everything as per the instructions in the high speed gear set ensuring you reinstall the clutch the correct way.


IMG_9006_zps794a48de.jpg



Now is time for the idler gear in the bottom of the transmission. Pull off the C-clip remove the old skinny gear install the chunky gear.
Notice the difference in the gear size?


IMG_9014_zps9aee7748.jpg



Note the direction of the collar on the old idler gear. The new gear and shaft just gets flipped 180 degrees end for end.

IMG_9013_zps5a846a95.jpg



Direction of the collar is reversed on the modded transmission


IMG_9026_zps6e697546.jpg



There are a couple things you will need to do before you reinstall. You will need to shim the gear to take out the slop in the shaft and help keep the gear in proper alignment. You will put the washer on the side closest to the gear. The side with the shim will be installed on the forward side of the transmission. Make sure you have most of the slop taken out of the geartrain with the washer. Mine took about 1mm thick washer.

IMG_9021_zps44c33b3c.jpg



Drop in the new gear set on top of the shaft and make sure everything lines up properly. I put another washer on the back of the bearing on the forward side of the gear set to help alignment and take out more slop. You can do this as need. No two transmission will be exactly the same.

IMG_9027_zps03a5d512.jpg



Alignment of the drive and idler gear are almost perfect!!


IMG_9025_zpsb5e0a94b.jpg



Once this is all done put the entire transmission back together and check for smooth rotation and you have no binding in the gear train and you now have the ultimate bulletproof 3 speed transmission!! :tank:
 

frickenjoey

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With the higher speed 3rd gear set you get at least 5-8 mph over stock 2 speed gearing. The shifts are a little closer so the acceration is much smoother keeping the engine in its powerband better. This mod inproves the strength of the 3 speed set up.
 

sv250

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Nice write up. Much better than the one I did. The pics are fantastic. Good job.

Need to stickey this. I know a ton of people have done it. I would like to see how it holds up to a Flux.
 

frickenjoey

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Thanks man, just trying to do justice to your mod. I did put in a sticky request for this, hate to see it get lost in the mix since everyone can benefit from it. I would like to see how it would do in a flux as well. Just have to rig up a mechanical brake linkange like the nitros have. Might have to try it.
 
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Extreme RC Mods

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Great job on the write up and pictures Joey, this truly is a great mod and is well worth the effort :)
 

Greywolf74

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Yeah I think it deserves a sticky. One day i might do this mod myself.

Do you find that the speed is harder to keep working properly than the 2 speed? I know sometimes if I go dickin' around with my 2sp losi XXL transmission getting it to shit again in the exact place I want it to is a PITA. Just wondering if this would be even more troublesome.
 

Snook Man

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Do you find that the speed is harder to keep working properly than the 2 speed?
It’s really just another shift point to adjust, but the 3rd gear shift point adjustment is a little more critical/sensitive to any adjustment than the 2nd gear shift point because of the higher rpm’s of the primary shaft at the shift change.
As long as everything is working properly, setting the shift points with average gearing is not that difficult at all and stays pretty consistent.

If/when you start re-gearing for really fast speeds then the 3rd gear shift point becomes an issue due to the extra rpm’s of the primary shaft and the increased centrifugal force exerted on the primary clutch pawl. The spring in the clutch is only so strong and you have limited adjustment of the shift point until it locks out. The spring rate and weight of the clutch pawl was designed for a certain rpm range of the primary shaft and once you increase the rpm’s over the design a heavier rate spring and/or a lighter weight clutch pawl are needed to compensate or you end up with a shift from 2nd to 3rd that occurs too soon, or a complete skip of 2nd gear altogether.
 

frickenjoey

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Thanks. It is a fairly simple mod (as you know) once you get the couple little things on it figured out. I was just a little annoyed when I realized I had no cutting disc for the dremel. But I made do with the old trusty hacksaw lol
 

Alexander_0_1

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Are HPI gears baked/heat treated......if I sent a set out to get cooked do you think they would be smaller on return...would I have too much play in the gear mesh

So far I've done 2 of these so far, they're freakin sweet,
 

DreamMachine

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You can heat treat them and Quinch in motor oil. It will make them stronger. The savage gears are sinterened which is powder compressed at with high heat.
 

Alexander_0_1

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Can I bake them myself, how hot does the baking have to be....I have a kiln, do you think that would work, I also have a rose bud tip for my cutting torch.....or should I opt for sending them out
 

Alexander_0_1

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Ok now I have to ask has anyone made these gears out of carbon steel, I'd buy them.

---------- Post added at 2:15 PM ---------- Previous post was at 2:11 PM ----------

I wonder what that might cost?
 

DreamMachine

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I'm sure you could have them made.

If you want to heat treat them, you need to get them to the color of the rising sun(800-900F), then quench in oil. You can then put them in the oven between 350-400 for about an hour to finish the process. Oh leave the gears in the oil until there about 120deg then put in the oven. This is how I would treat my gears.
 

Alexander_0_1

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Ya think so?, sounds like extreme BP transmission project....I'm gonna have to make a few calls about having gears made out of carbon steel.

---------- Post added at 6:35 PM ---------- Previous post was at 6:33 PM ----------

Other than integy who else might make a centre transmission case
 

Alexander_0_1

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Sweet

:D I found a company willing to make my carbon steel gears but they want pics and dimensions....does anyone know if carbon steel is going to be too heavy
Also where can I get the information he wants without ripping down a transmission:D
 

FoRdLaz

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Thanks frickenjoey for the awesome pics and how to BUT I've picked up a mistake - cos I wasn't paying attention and messed up my 29 tooth gear:

"So getting started you will need to cut this collar off of the 29t drive gear using a Dremel or hacksaw. I used a hack saw since I was out of cutting disc for my Dremel."

It's not the 29 tooth needing cutting but the 32!!!
 

jamalc6996

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Great write up. I just purchased a 3 speed transmission for my savage and will be doing this mod.
 
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