Savage Diffs

[JasonB]

Now that we have the bullet proof diffs, the only weak part of the diff is the 10x16x5 (B032) bearing. I've tried milling down the stock diff case to accept the 8x16 bearing and that works, but this weakens the shaft and it snaps off after a few packs.

Solution: After much digging, I found out the Vorza Flux diff case will fit perfectly. It's actually a Hot Bodies part number from Lightning Series truck (HBC8019). Yes, this is a plastic diff case, instead of aluminum, but it has a steel ring at the end that accepts the 8x16 bearing. The diff case is very rigid plastic, and seems like it will hold up well. An added bonus is that the plastic will not let the screws back out. I've had hit or miss success with loctite on the stock diff case because of grease getting into the holes, but that will never be an issue again. The Savage diff internals fit perfectly, however, you will need to sand a few thousands off of the length of the cross pins to get them to slide in easily. Everything fit nicely and the diff is smooth as silk. I am very happy with this upgrade and will never use the 10x16 bearing again.

Based on what I've read, the Kyosho Inferno and Hot Bodies D8 diff cases and internals are also direct drop in parts; I have not yet confirmed this.

Here's another tip: If you've ever wanted to reverse the direction the motor spins and still go forward, reverse the diffs. All you have to do is grind off the little tab inside the bulkhead and then you will have the option to install the diffs in standard or reverse orientation.
Benefits:
1. Motor spins reverse direction which will cause the pinion to push up against the stop if it ever loosens . . . no more pinions falling off.
2. The reason I decided to try it was that I noticed that my truck was running quieter in reverse than forward . . . probably due to wear on the transmission gears. Now I'm using the other face of the gears so I'll get more life out of them.
3. It's cool to have options.

[josh9mille]

sounds like a good way to get rid of that stupid bearing! Let us know how the plastic case holds up.

[E-Revonut]

If you want to reverse the rotation of the motor just hook the esc up to CastleLink and reverse the rotation

[Jahay]

please let us know how the plastic case holds up... im worried it will allow flex and cause gears to shred...??? but nice1!

[bruce750i]

Yes it would, or swap a motor wire. What he was referring to was running the center drive line in reverse while the rc moved forward.

[ozzynichols]

wouldn't running the motor in reverse also help eliminate the slipper nut from coming loose?

[lincpimp]

Originally Posted by ozzynichols

wouldn't running the motor in reverse also help eliminate the slipper nut from coming loose?

That and flipping the diffs to ensure the truck goes the correct direction when the motor rotation is changed.

[JasonB]

I'm calling this mod a success.

I've got 2 dozen runs or more on these diff cups and there are no visible signs of internal gear or cup wear. For me, the Vorza cups are a very good upgrade that is actually less than half the price of the stock cups (win win).

Results will probably vary depending on your driving style. I am heavy on the throttle, do some mild jumping, but generally don't do hard starts and avoid back flips all together.



__________________________________________________ ______________________
One other thing I did to my diffs that may seem weird and perhaps even a little crazy . . .
After several months of use, the bearing holder on the BP ring gear wore down to the point that it was slipping inside the bearing. Fix: after shimming the diffs, I put a very thin coating of red loctite on the bearing holder before putting the bearing on for good (I was careful not to get any loctite inside the bearing). The red loctite prevents the bearing from slipping on the ring gear and all it takes is a slight amount of pressure with a couple of flat head screwdrivers to pry the bearing back off when it comes time to change it out. I did this to the cup side bearing as well to prevent it from ever getting worn down.

If the bearing ever seized up, this could be a problem, but most likely the inner sleeve would just detach from the raceway and free spin, as I have seen happen a dozen times before with the 10x16 bearings. No telling which part would give out in the highly unlikely scenario of the bearing locking up and not falling apart (probably the sacrificial lock pins inside the cup but your guess is as good as mine). Try this one at your own risk.

[Jahay]

well im glad you have had success!

as you know i am now taking the plunge!

I definitely think the vorza cups will handle the hard starts and large jumps as there are no on throttla landings... i bet back flips will be fine too!

I have never heard about loctiting the bearings to the cup or ring gear, and i prob wont bother as i the 8x16 on both side should last a long while in my non flexing alloy bulks anyway... But it is a weird though... if it has worked out for you so far, maybe its ok?

[lincpimp]

Loctite seems like a decent idea. We do not want the inner race turning on the ring gear or diff cup, as that will cause metal to metal wear and slop.

I am glad you are having success with the plastic cup. I blew up alot of those in my old savage with the 14xl and 8s. But I never had an issue with the 10x16 bearings... Whatever works, thats ok with me!

[Jahay]

hmmm... well from what i remember of seeing of the old savage plastic cups, these vorza ones seem much better and definitely very solid. Only time will tell with my 9s setup. Maybe they will do all right in the alloy bulks? maybe they may not cope with larger baja wheels i hopefully upgrade to when funds allow. I just dont want the larger 8x16 bearings to fail nor the internals of the diff. Only time will tell.. when and if they do fail or show obvious signs of distortion, i will upgrade to the IRC lightning alloy cups. but for now, these seem very solid

[ljoncp]

Jahay, Im trying to fit my rear bulletproof diff into some GH alloy bulks i just bought (truck is dissasembled) and the GH bulk halves wont close with the bulletproof diff inside. The bulks close up fine without anything in them, but when i try to close them with the diff inside, something is fetching up or rubbing and making it so it wont close. I dont think its the ring gear itself because when i turn the ring gear (while inside the alloy bulks) it does not make the tick tick tick tick sound it would make if the gear was hitting the alloy bulk.

Any ideas?

Thanks

[lincpimp]

Originally Posted by ljoncp

Jahay, Im trying to fit my rear bulletproof diff into some GH alloy bulks i just bought (truck is dissasembled) and the GH bulk halves wont close with the bulletproof diff inside. The bulks close up fine without anything in them, but when i try to close them with the diff inside, something is fetching up or rubbing and making it so it wont close. I dont think its the ring gear itself because when i turn the ring gear (while inside the alloy bulks) it does not make the tick tick tick tick sound it would make if the gear was hitting the alloy bulk.

Any ideas?

Thanks

I had this issue recently with GH bulks and brand new BP diffs out of a XL. Turned out the case was not machined correctly and was not the correct shape to fit one of the diff bearings. One of my cases fit fine and the other required some shaping with a round file. Have a look at the bearing areas on the case when you have the diff in. I had what can best be described as a flat spot. Should have been curved to match the bearing.

[ljoncp]

Originally Posted by lincpimp

I had this issue recently with GH bulks and brand new BP diffs out of a XL. Turned out the case was not machined correctly and was not the correct shape to fit one of the diff bearings. One of my cases fit fine and the other required some shaping with a round file. Have a look at the bearing areas on the case when you have the diff in. I had what can best be described as a flat spot. Should have been curved to match the bearing.

I'll check this out and let u know what i find. Thanks!

[Jahay]

I had this prob with one of my cases too... and when i screwed it up tight and my mesh didnt allow the gears to turn....

hmmm i found that my HD Diffs (original diffs in flux) worked very well and were smooth... when i put my BP diffs in teh GH Bulk.. there was a lot of friction. Many i know who use GH Bulks with brushless systems say it is unnecessary to use BP Diffs as the mesh is always constant anyway.... and i some what agree... but i wanted to use my BP ones which i paid more than $50 for haha

I didnt think i had a prob with my bulk but the mesh was definitely too tight... i attached my drill to the end of the pinion after tightening the bulk up with the shock tower in there) and the gears then used my drill to turn the pinion and spur for a good 5 minutes, the mesh had bed it self in. Now my diff turns extremely smoothly...