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Jahay
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06.02.2010, 12:11 PM

that can looks quite kl... should use it on a motor...

Have you made any revisions to the savage slipperential/motor mount?

BB16 i dont know why, but i am having so many bad thoughts that on a bad landing, the motor would rip from the motor mount as its only held on via 2 screws (2 small screws). Would there be any other way of mounting some form of plate under the motor and attatching it to the motor and mount in some way which still maintains flexibility?
   
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RC-Monster Mike
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06.02.2010, 12:53 PM

Jahay,
fear not the stregth of m3 screws - each metric m3 threaded screw has a tensile stregth in excess of 165000 psi. This equates to hundreds of pounds of force when tightened and is more than sufficient for the task at hand. :)
   
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Finnster
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06.02.2010, 01:33 PM

@ Jahay: Everyone mounts the motors like that, and I haven't heard of any damages. I've had bad enough landings on my truggy the chassis flexed and bent up far enough to slap the rear of the motor, yet no damage to the motor mount. (did sever a servo wire running underneath tho.)

I would also strongly recc using the steel mod1 spurs. Not only are you looking at easily stripping plastic (vs steel) the smaller pitch will make it even weaker. The spur is $27, yet the pinion is $10. Replacing a pinion every now and then is much cheaper than the spur, plus nothing ruins your day like stripping a spur, and then sitting waiting for the new one to ship.

The CD mount is back in stock and I just ordered one. I was planning to mount it on an FLM skidplate, but the ext one I wanted is OOS.

I cant tell from the pix on the skid plate tho how clean it will be. On the RCM site, the pix of the FLM skid show little relief machine work. OTOH, some pix on FLMs site show quite a bit of machining. I'm assuming the FLM pix are more recent revs of the part, so not sure how this will effect it.


Lastly, does anyone have any ideas on dogbones? Even if I kept the rear stocker, the f would have to have a longer one.
   
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Jahay
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06.03.2010, 07:25 AM

Thank for restoring my confidence in this method of motor mounting mike!

Thanks finnster for the info. I will prob just run the steel spur then...

I didnt like the idea of mounting the CD to my skid plate and as i am not using an FLM Chassis it would make it difficult anyway. I would probably mount the motor in a similar way but mount it to the TVPs via braces or attatch the cd mount to a plate and attatch the plate to the braces.

Has anyone got any pictures of what the universal mount looks like from underneath and where the screw holes are located?

Finnster GCM were going to make my custom dogbones for me. Im quite happy with the ones they use with their DB-17 xxl conversion and they have held up without any signs of distortion so far. Here is their site.... http://gcmachine.ca/index.php/fabrication/index
   
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JERRY2KONE
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Instrustions - 06.03.2010, 07:42 AM

Mike's RCM universal diff mount comes with a paper template that you can use to make the four holes for mounting it in the chassis or whatever plate you use in your configuration. His design provides you with 4 = M3 screws that screw into the bottom of the mount to hold it in place. For personal reasons I tapped mine out to M4 to use 4mm screws for my project. I love overkill when it comes to strength. The kit is quite simple and easy to set up and even modify if you need to. All-in-all it is a great setup and it is perfect in resolving tranny issues by elliminating the tranny all together. I have mine setup with an HPI lightning hardened diff with an RCM savage aluminum cup with a 44t steel spur and it is very smooth.


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Finnster
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06.03.2010, 10:15 AM

Quote:
Originally Posted by Jahay View Post
Thank for restoring my confidence in this method of motor mounting mike!

Thanks finnster for the info. I will prob just run the steel spur then...

I didnt like the idea of mounting the CD to my skid plate and as i am not using an FLM Chassis it would make it difficult anyway. I would probably mount the motor in a similar way but mount it to the TVPs via braces or attatch the cd mount to a plate and attatch the plate to the braces.

Has anyone got any pictures of what the universal mount looks like from underneath and where the screw holes are located?

Finnster GCM were going to make my custom dogbones for me. Im quite happy with the ones they use with their DB-17 xxl conversion and they have held up without any signs of distortion so far. Here is their site.... http://gcmachine.ca/index.php/fabrication/index

All you need are the FLM or HPI 74mm cross braces that go across the TVPs. You could mount it directly to the braces (which I may do) altho atm I am leaning towards mounting on a skid plate that is attached to such braces and bolted directly into the TVPs. I have some electronics and a rear steering servo I want to protect from rocks and sticks. Plus I'm thinking it would give a bit of flexibility in mounting location.
Either way requires a bit of modding, but Savs are really easy to mod w/ the TVP structure. Just a 4mm hole thru each TVP and you can install a brace wherever there is space.

Thanks for the heads up on the custom bones.

@ Jerry, thx for the tip on the bottom mounting screws. I may tap mine out to 4mm too. Last thing I want to do is shear or strip a 3mm screw (had enough of these when I had an emaxx....)
   
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Jahay
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06.03.2010, 11:01 AM

I was considering doing that finnster with the braces but it if i can find another way of mounting it i would be happier.

I know this is a silly question, but i have never tried tapping my own holes. I know this would definitely benefit the mount and prevent any stripping. What specific tools would i need to do it?
   
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Finnster
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06.03.2010, 02:02 PM

Quote:
Originally Posted by Jahay View Post
I was considering doing that finnster with the braces but it if i can find another way of mounting it i would be happier.

I know this is a silly question, but i have never tried tapping my own holes. I know this would definitely benefit the mount and prevent any stripping. What specific tools would i need to do it?
All you need is a properly sized drill bit and a hand tap (and the tap wrench to hold it.) You first drill out the hole to the approx size, then run a hand tap down the hole which cuts the threads. Basically looks like a threaded drill bit.

You can get taps all over the place, but small metrics are not so common. I get mine from McMaster Carr, but I'm sure Harbor Freight or any other decent hardware dealer has them. M4x0.7mm and M3x.5mm are the most common sizes in RCs. Invaluable tools to have IMO.

Interesting idea about mounting the CD sideways. I wonder if it would fit inside TVPs tho.. Only 74mm clearance. You would not want to tap the thru hole, just the mount the screws are going into.
   
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JERRY2KONE
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Simple - 06.03.2010, 07:15 PM

Here is a link to one of the cheapest sets I have seen. I have one of these plus a few others. 3mm and smaller taps are easy to break, so I have spare taps just in case. You can find larger and better tap sets, but this is a good starter set.


http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXE224

All you have to do is drill the hole with the matching drill bit according to the size of tap, then tap the hole out with a threading tool. Use a piece of scrap to practice on and make sure you can do it farely well before trying it on your exspensive toy. It's really not difficult at all once you know what you are doing. Keep the drill straight and level to make a good hole to work with. When you use the tap the standard method is to move forward 1 turn and back off 1/2 turn repeating this all the way through until you reach the desired deapth. This will help to keep the hole clean and keep the tap from gauling and getting jammed in the hole, or even breaking off in the hole.


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Jahay
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06.04.2010, 04:51 AM

thanks for the links and explanations, sounds pretty simple.....

Finnster - i was considering using another style of mount used on truggys which mount on its side, but this cause a few too many problems.
- It just wouldnt fit inbetween the tvps properly
- The CD would be way out of line with the diff axles

But i did like the idea of LCG.... This universal mount will be fine though.
   
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  (#41)
JERRY2KONE
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06.04.2010, 06:23 AM

[quote=Jahay;368239]thanks for the links and explanations, sounds pretty simple.....

Finnster - i was considering using another style of mount used on truggys which mount on its side, but this cause a few too many problems.
- It just wouldnt fit inbetween the tvps properly
- The CD would be way out of line with the diff axles

It sounds like all you would need to do is install a set of spacers to get the mount centered where you want it. Something like this should be right up your alley.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDEB4

I use them for all kinds of stuff when things just won't fit right. There is always a way to overcome obsticles.


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Jahay
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06.04.2010, 07:05 AM

nice link... look like some decent spacers.
Thanks for that....

But still the CD mount would not work sideways as its restricted by the side of the TVP.
The upright mount would be the only way. Also having the cd mounted directly in line with the Diffs would prevent premature wear on certain items or would just be better at transfering the power to the wheels anyway.

I was just thinking of ways of keeping the Centre of gravity as low as possible.
   
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mothman
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06.05.2010, 12:42 PM

Jahay, how much are you willing to spend on the mount? I got a quotation from a machinist to machine the mount that BB16 has designed.. if just 1 set to be machined, it will cost about $200. But if 4, it will cost about $100 only.. Let me know what you think..
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Jahay
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06.05.2010, 04:17 PM

mothman i PMed you.
   
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Jahay
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06.07.2010, 08:53 AM

Need a little help guys...

I have decided to finally go with the RCM CD Mount... But now i am unsure as to whether the slipperential is ideal for my use???

Are there centre diffs which i can lock and unlock depending on what sort of performance im looking for? Considering the savage tranny isnt a diff and the same amount of power goes to the front and rear wheels. How do you think a CD would change my handling? I dont want to unload all the power to the front wheels when wheeling?

Is the slipperential the toughest CD out there? Im looking for reliability and although i am not bashing on the slipperential... Im just exploring my other possible options. What CD would fit directly into the RCM Mount without too much shimming and be able to handle up to 9s (although i will be running 6s most of the time.)
   
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