HPI Savage X SS 4.6, Duratrax Warhead EVO and Traxxas Revo 3.3 Hop Ups, Tricks, Tips, and Parts Reviews

How to rebuild a hitec 645 brake, throttle, steering servo schematic

If you have ever done like I did and went with a bellcrank that didn’t have any provision for a steering servo saver on it, you may have encountered exactly what I did here. The Gears on this Hitec HS 645 High Torque Steering Servo didn’t stand a chance with no servo saver in the linkage.

The first thing you need to do is to take the 4 phillips head screws out of the bottom of the servo. They are as long as the whole assembly and hold the OTHER side of the servo in place. Once these 4 bolts are removed, CAREFULLY remove the top plate, the side of the servo that is covering the gears on the top of the servo where the servo horn fits on.

Underneath the plate, you will see a set of gears. These servo gears are put together in such a manner as to slow down the speed output of the motor and to govern the movement of the servo horn. Chances are, if you have broken your steering servo, be it metal gear or plastic gear, the middle gear will be missing some teeth as shown below.

You will need to obtain a gear rebuild kit - contact me and I’ll tell you where to get one cheap. They run about $14 and are readily available (because lots of people strip this little servos!).

To aid with the removal and replacement of that middle gear, carefully pull the center pin out, then slide the center gear out, swap the new gear in there, and replace the pin. If you moved that large gear, the one with the servo horn spline on it, make sure it is centered and facing the right way!!!

Dig a little grease from the assembly and smear it on the teeth of the new gear…otherwise, you’ll have to go find some electrical lube (I don’t know, will diff lube work?!)

Put the cover back on and install the 4 phillips head bolts back in…reinstall the servo, hook up the linkage, and check for side to side balance…then go break it again

Below are some pics, one of the stock Savage X plastic gears (white), the other with BROKEN metal gear teeth, another of the little “pin” I’m talking about, and finally the end result.

Am I satisfied or dis-satisfied with the Ofna Jammin X1 CRT RTR? Come back in 9 days and I’ll let you know!

Note to self: contact Jammin at jammin@jamminproducts.com

Duratrax Warhead Steel Spur Gear Released!

The long awaited Warhead Steel Spur Gear has finally been released. After months of spent plastic spur gears among warhead owners, the release of the steel spur gear will have a great impact on the radio controlled monster truck. The resale value will increase as will the new value as their durability is greatly strengthened with this new steel spur gear.

This coupled with the recent release of the aluminum servo saver for the warhead will surely bring the Duratrax Warhead back from the depths of failure and mockery among rival enthusiasts LOL

With the steel spur gear, you should definately make sure you have a hardened steel clutchbell as well. A regular clutch bell will get worn in under 3 tanks if used with a steel spur gear.

Looks like Duratrax heard our complaints!

Stop the presses…since writing this up, I have learned a great deal about shimming savage differentials. I learned, for one, that the procedure described below is INcorrect. The small shims shown do absolutely nothing for the issue at hand, which is to #1) tighten up the play inside the diff cup and #2) tighten up the play with the crown gear and the pinion gear.

I highly recommend that you check out this article for the proper procedure on how to shim savage differentials: Here is the link to the article

Just keep that in mind when you read this…

How to Rebuild, Shim, Strengthen and Race Lube a Savage X Differential - Using an Aluminum Differential Housing, axle Shims, O rings, and the Differential Lube of your choice…

If you don’t want to end up like I did last weekend, busted up with a stripped out spider gears in the rear end differential, you might want to strengthen up your differential. Here’s How I did it…

Here’s My Savage X after 10 minutes on a nice mud track - the stock, plastic differential coupled with a bad gear mesh did a real number on the rear end and left me with no truck to race…

This is the culprit that brought down my Savage:

The first thing I did when I got home was to get on the computer and start ordering parts. I was determined that this would not happen again. If it does happen again, I’m going to an Ofna Rear End, which is apparently very very strong.

Here is a list of the parts that you will need:

1) HPI Savage 4-Gear Differential Gear Set (you’ll need one cup for front, one for rear)

2) Nova 7075 Aluminum Alloy Differential Cup for Savage

3) Mugen 5,000wt Silicone Differential Lube (for Rear differential)

4) Mugen 7,000wt Silicone Differential Lube (for Front differential)

5) Mugen 50,000wt Silicone Differential Lube (for coating the outside of the differential assembly)

6) BRP Axle Shim .250x.309x.014″ (get 2 sets)

7) HPI O-Ring 5×8x1.5mm Savage 21 (6) (get 2 sets)

8) HPI O-Ring 6×9.5×2mm Black Savage 21 (8) (for the cups where the dogbone goes in, for cushion)

9) Great Planes Pro Threadlocker

10) For Differential Gaskets, I just used the old gasket, putting a thin layer of Permatex Silicone Gasket Maker there. If you need to replace your differential gaskets, Ofna makes a compatible set - Diff Gaskets

Below are some pictures of the assembly. Also, here are 2 videos showing you the point of all this:

1) The fact that the stock plastic differential flexes under load and
2) What is meant by “shimming” the differential (I know it doesnt work right now, fixing it)

Here’s that stock plastic differential cup:

A few Notes on assembly:

On the Savage X, the differential is very easy to remove. All you have to do is remove 6 screws, the lower hinge pins, and pull off the differential cover. After you have the diff out, spray it down and clean it up some with some carburetor cleaner. Take it apart, noting how it goes back together!

Once you have it apart, clean up the inside, again, using carburetor cleaner or whatever works for you. Remove all cleaner residue before you go to put this back together, it might break down your diff lube if you don’t.

Take the diff access set looking screw out of the side of your stock plastic diff cup, it’s on the side of the cup. Transfer that screw to the new alloy aluminum diff cup AFTER you put the shims and the inside retainer pin on the shaft. Replace the inside o ring with a new one. Remove the old bearing from the stock plastic diff cup and transfer it to the new aluminum diff cup.

Put the entire gear assembly together DRY a few times, noting any play in the shafts going into the differential. You want a few thousandths of an inch play there. You want a Little play, but want to avoid too much. You are trying to get those spider gears inside to mesh as good as possible. Shim up any play with the tiny axle shims you bought.

When the play is all shimmed up right, put in your hex screw (set screw looking screw) into the side of the new aluminum diff housing. Pour your differential lube into the cup and remember that the bevel gear will displace some of that lube…leave some room at the top.

Put the whole assembly together, locktight the 4 screws, and cinch it down. Note: you can’t use the stock 4 screws, you will be using 4 diff cup screws that come with the aluminum diff cup.

Coat the outside of the assembly with 50,000 weight Lock Lube to catch dust. Also, put some 50k lube around and near the bearings to catch any dust and dirt that would want to enter into the assembly. You will be servicing this differential after every gallon of fuel. Put the entire assembly back into the housing, throw your 6 screws and 2 hinge pins back in and get ready to LIGHT UP THE TIRES because you’re going to be transferring all of that torque to the wheels WAY more effectively now.

FYI, RTR, out of the box, there is virtually NO lube in the differentials…

Comments, questions, hate mail (heheh)? Either comment here, send me an email, or come comment on the Savage X Thread at RCUniverse.

My Ofna Jammin X1 CRT RTR 34962

Well, after careful consideration of the HPI Hellfire Versus the Ofna Jammin X1 CRT RTR #34962, I have decided to go with the Ofna Jammin.

The Ofna Jammin is clearly better made, designed, tested, and less costly in the long run than the Hpi Hellfire.

To find out more about the problems that folks are having with the HPI Hellfire, visit this thread: RCUniverse Hellfire Thread

Thanks to the guys who have helped me make the decision to go with the Ofna Jammin, directly and indirectly. I feel like I’ve graduated . If you are interested in anything having to do with the Ofna Jammin X1 CRT, this is the thread to be on: RCUniverse Ofna Jammin X1 CRT Thread

Read both threads, compare notes, and come to the conclusion that I did. The Hellfire has design flaws, engineering issues, handling issues, and is breaking left and right. The Ofna Jammin stays tight, will SMOKE a Revo for Thanksgiving, and is cheaper…ready to RIP right out of the box.

Check out these Ofna Jammin CRT Videos (scroll to bottom)…notice how well it handles the corners, digs in, and flies with little or no nose down or nose up. This is in stark contrast with the Hpi Hellfire which will flip over on you, cartwheel, etc.

The Hellfire is a more mainstream truggy…HPI is green in the Truggy business!

The Ofna Jammin is for graduates who are tired of BETA TESTING

Here’s more info about the Ofna Jammin Truggy: Product Description

And here’s a pic of my new baby…right out of the box, this is how it looks:

In the relentless pursuit of speed and handling on the dirt track, I’ve done my research and decided to go with the “Nubz” Tire/Rim Combo for my Savage X. I like to bash, but I’ve got a bone to pick with some Revos . Maybe these rims and tires will help?

This is exactly the stance I was looking for - narrow tires that are light and will grip on a small dirt track:

Here’s a pic of a Hellfire owned by the quickster…the only modification most folks are making to the HPI Hellfire is the Steering Servo. Other than that, this truck is an unbreakable, uncaged beast right out of the box!