Savage BL Conversion - Page 2 - RC-Monster Forums

lincpimp · 04.20.2009, 01:27 PM

Quote:

Originally Posted by spiftacu1ar

Wait, ur saying it comes with a 46t spur, not a 48t.... SNAP. I have it setup for use with the neu-castle finned motors (42mm diamter), but the diamter is actually less than that up front at the end bell. I don't remember what diamter I made it, but it is the right diamter for the front of the castle motors. I hadn't orgianlyl desgined it to sell... BUT, if there is enough interest, and my design ends up being much different than mikes, then I may sell them. Let's see what mike has to offer first though.

I did the math,and with the neu-castle motor, the closest mesh you can get is one with 48:9, not 46:9. 46:9 is a tad high for the savage anyways. In fact, 48:9 is a tad high too. 50:9 and 50:10 are ideal ratios.

If I do decide to sell these, I will be fabricating them at the techshop, as it is too expensive for mew to have someone else fabricate them if I sell them (i.e., I have to mark up the marked up price, which will make it insanely expensive). If I fab them myself, I can sell them at a reasonable price. Also, I can change individual ones for different motors and hole patterns, as only the main plat would have to change. The "cup" part would be the same for all of them.

Another cool feature I didn't mention is that the screw hole for mounting the motor is completely counterbored, and the cup goes on top, leaving enough space for your allen wrench, but not allowing the screws to fall out. This means you can easily remove the motor and put it back in without having to reseat the screws. This makes changing motors and pinions easy while leaving the gearbox in the truck.
I don't know if that makes sense, so if it doesn't I'll try and get soem pics of it.

EDIT: It can handle 50:12. An easy way to see if the gearing will work is 48:9 + 6 teeth anywhere. (you can add 2 to one side, and 1 to the other, or 3 to one side, and none to the other). Mod 1 gearing works out such that increasing either the pinion or spur by 1 tooth will increase the distance between the shafts by .5 mm (it increases the mesh diamter of that gear by 1mm). I have my ratios set as follows. Based off the distance for 48:9, you can go in an additional 1.5mm (on only one side, so a total shoaft movement of .75). Round 1.5 down to 1, for a 1 tooth reduction, (but the motor may interfere with the cup). You can go out an addition 6.5mm (shaft movement of 3.25mm), so round 6.5mm down to 6 for 6 additional teeth possible (You will still have about 1mm between the motor and chassis if the motor is ALL the way out to 6.5mm, which it never will be, because it won't be in mesh with anything there.

I made a typo above, which I will fix. The max distance is with 50:13 or 48:15 (both of which are WAYYY too high for a savage). Basically, although I didnt have intentions of selling, I kept speed demons in mind jsut in case I do decide to sell.

Hmm, good info.

Given your info, it looks like your design will handle 46/16 gearing. Since you have designed it to fit the neu/castle motor, it will fit a smooth can neu just fine. I have a special project that will use a 1527 2y motor (625kv) on 10s lipo, which makes for low motor rpms.

I was going to lock the X tranny locked in second gear, and use 47/23 gearing, but I am not sure if the tranny can handle it. That motor can make some torque, and the vehicle will not be light. Not sure if I would use a std diff, or Mike's slipperential.

As for your question on the bearing to bearing dimension, it should be the same as a losi 8 diff (I think that is the diff with the smallest spacing). Mike made the diff to fit most 8th buggies, and it requires shimming between the bearings and the bulkheads to fit some of the brands. I would make yours to fit a std hotbodies/ofna/kyosho diff, and the slipperential will fit (may need shimming) and will alos allow the largest number of available diffs to fit. I would most likely use a hpi al diff cup with a kyosho plastic spur, as the plastic will provide some shock protection, and run a bit cooler than steel on steel. And I could grease it since your design is sealed.

My other question is are you using stock chassis holes to mount it? Or do you plan to drill the chassis? Either is fine with me, as I would make my own tvps...

spiftacu1ar · 02:00 PM

It is currently designed to use the stock tvp mounting holes. HOwever, a neu 1527 is too long and won't fit in the space alotted. I currently have mounting holes to have it mount at the front 2 holes of the stock transmission mounting holes. I can make a second set of holes to have it mount in the 2 rear which would allow you to use the neu 1527, but it would also limit battery space.

To give you an idea of the size of the gearbox, the entire thing sits inside the TVP. Nothing hangs over the side, sticks out the bottom, or even the top, so its pretty small. Smaller than even the kershaw designs DD gearbox. The whole thing is smaller than the stock savage tranny.

EDIT: also, what is the distance between bearings on the standard hotbodies/ofna/kyosho diffs?

lincpimp · 04.20.2009, 02:36 PM

Quote:

Originally Posted by spiftacu1ar

It is currently designed to use the stock tvp mounting holes. HOwever, a neu 1527 is too long and won't fit in the space alotted. I currently have mounting holes to have it mount at the front 2 holes of the stock transmission mounting holes. I can make a second set of holes to have it mount in the 2 rear which would allow you to use the neu 1527, but it would also limit battery space.

To give you an idea of the size of the gearbox, the entire thing sits inside the TVP. Nothing hangs over the side, sticks out the bottom, or even the top, so its pretty small. Smaller than even the kershaw designs DD gearbox. The whole thing is smaller than the stock savage tranny.

EDIT: also, what is the distance between bearings on the standard hotbodies/ofna/kyosho diffs?

I will pull the center diff out of my hyper8 and let you know, you want the dimesion from the inside of the bearings? Or the out side? I will give you both. Do you prefer inches or metric? My dial calipers do inch, the mertic ones walked off one day...!!!

I planned to mount the setup where the stock tranny is and place the motor pointing towards the back of the truck. Batteries would be in front. This truck will have a 23" wb (long) so I plenty of room. Planned to use the savage xl rear driveshaft in the rear and a custom length shaft in front.

The diff cups that come on the slipperential should fit the stock savage center driveshafts. Most of those dogbones are the smae size on the ends.

I can say that the savage xl have larger ball ends on the wheel shafts than the center shafts have. I have used the lst and muggy center driveshafts and the lst1 wheels driveshafts as center drives. They have a cvd end with 8mm hole, so they work with the savage pinion gears. The dogbone end fits the savage output cups on the tranny, and most center diff cups too. 1/8 scale buggys and truggys are mostly standardized on the dogbone end size.

Dafni · 04.21.2009, 05:41 PM

Here´s the slipperental savage build
http://rc-dc.ch/gallery/thumbnails.php?album=35
stay tuned

spiftacu1ar · 04.21.2009, 06:06 PM

it's not sealed :(. Any word on the dimension between the bearings?

Dafni · 04.23.2009, 03:06 AM

Quote:

Originally Posted by spiftacu1ar

it's not sealed :(. Any word on the dimension between the bearings?

Not enclosed is no issue, just look at truggies and stuff.

Distance between bearings is just like xray, mugen etc diffs. I can measure it up tonight if you want.

spiftacu1ar · 04.23.2009, 03:20 AM

I don't have any truggies, so I can't measure the distance, so if someone could do that, it would be greatly appreciated.

About being sealed, there is a large difference between truggies and a savage. To start, most truggies have a chassis with no holes on the bottom, and the body covers most of the openings. I have a buggy, and there is about a 1/8" gap between the body and the chassis. Very little dirt gets in. On the other hand, the savage chassis is completely open, and the body barely protects it at all. Many people (such as my self) run without a body (I have a nylon rollcage instead). This means there is absolutely nothing protecting the gears from larger debris. If even a small rock interferes with the gears, it will cause a lot of damage. In addition, running sealed allows you to lubricate better, for less overall wear on the gears. Therefore, I want a sealed gearbox on my savage.

Dafni · 04.23.2009, 03:27 AM

Quote:

Originally Posted by spiftacu1ar

To start, most truggies have a chassis with no holes on the bottom

huh, every truggy I have seen has a hole for the spur gear... and this savage has a skidplate with no holes.

trust me, enclosures are not needed. (Remember the MadForce/Twinforce and many other trucks?)
We had a center diff savage like that before, no issues whatsoever, still running stong, with bashing in gravel pits and everything.
It's completly sealed from below anyway, and some lexan sheets behind the TVPs would complete the job...

A direct drive pinion to spur needs no lubrication.

But to each his own

Daf

Dafni · 04.23.2009, 03:29 AM

Hey, the spur/pinion is always open, and that's everything there is anyway, no transmission as such...

crazyjr · 04.23.2009, 11:19 AM

I agree with Dafni, I have run open mod1 spur /pinion on a Gmaxx transmission without problems for over two years.

Dafni, I'm not fond of the losi shocks on there (make it look too bulky for my tatse) but very nice setup, on the level of your revo setups

lincpimp · 04.23.2009, 11:58 AM

Is there a downside to sealing it up? I cannot think of any reason to not seal it up, and the lack or debris will add to the gears lifespan.

While a direct drive may not require lubrication, it will extend the life of the gears... And lube usually keeps stuff cooler, which is always good.

Access to the center diff may be more difficult, but once you have it set correctly it is not really necessary to get to it.

You would not consider running the ring/pinion without lubrication...

spiftacu1ar · 04.23.2009, 12:29 PM

I don't think there is any downside other than increased mass, but then again, we are talking abou brushless here. Increased mass near the front means more traction, which means you can put down more power.

Regardless, I guess this is a thing of what the ed user likes best. I like sealed better, some others might like open better for the weigt savings.

Any word on the distance between bearings on a standard center diff?

BTW: My gerbox is currently less than 200grams, and still has plenty of room to reduce that more. I am going to wait till I have final dimensions before I really lean it out though.

Dafni · 04.23.2009, 12:55 PM

Bearing distance on XRay/Mugen/Slipperential Diff: 32.5mm (32.3 on xray?)

lincpimp · 04.23.2009, 01:01 PM

Ok, measured the diff and it is 34mm from the outside of the bearing to outside of the other bearing. That is a hyper8 diff with a plastic kyosho spur, so it should be the widest spur/cup combo you will encounter. Any slack can be taken up with 16mm od shims.

spiftacu1ar · 04.23.2009, 04:56 PM

Thanks. I have updated my CAD to accept a max bearing to bearing (outside) dimension of 34.3mm. The total mass now is about 218.6grams with room to reduce mass if neccesary.

Anybody know how far the slipper adjustment hole is from either of the bearings. I would like to add an opening to adjust the slipper without taking apart the truck. (kind of like the shift adjustment on the stock savage)