OrcusOmega's Mid-Tank mod on an XL

[orcusomega]

I have this in a few locations throughout the board (replies, my project builds, etc) so I thought I would put it all into one thread, and hopefully this will help someone!

Well today I started the first steps in the tank relocation, by moving the revceiver and battery to the back. This is also posted in the How-To section, but wanted to add it here too:

=======================================
OK, few caveats:

1) This is my first how-to, so be gentle
2) My truck is a Savage 25 with the XL TVP's - this gives me the room to move the battery box behind the motor - so I don't know if it will work for everyone
3) Where the battery is mounted will block your access it you use a roto-start - just keep that in mind.

So this is how I moved my receiver and battery from the front of the truck to the rear, in preparation for a mid-tank mod coming soon. My mission was to do it as cheap as I could using crap I had lying around as much as possible.

Parts List:
1) 2 aluminum bulkhead braces
2) 2 servo wire extensions
3) one T-Maxx battery box
4) one motor mount brace
5) one receiver box (Traxxas #4924 - no idea what it is out of)

To start things off, I needed to figure out how to mount a horizontal brace from TVP to TVP without drilling - I did not want to weaken the TVP at all, and it seemed there HAD to be a way to make this work.

When I lined up the brace between the TVP's, I saw that the spaces cut out where different from side to side, so I had to find a place on each side where they were the same. Once I did that, it should be a matter of putting something there to hold it in place - right?

After I found a place on both sides of the TVP's where I could attach the brace and keep it even, I needed a way to keep it from moving around too much - I happened to have a few diff braces lying around from my XL diff conversion, and I used them to hold the brace in place front to rear. All put together, it looks like this:

You will notice that the brace is significantly below the top rail of the TVP, and so did I, especially when I looked at how wide the T-Maxx battery box was, but it worked out perfect. I drilled a few holes in the bottom of the battery box to line up with the holes in the mount, and the flat bottom of the box keeps it in place well (just remember to use locktite on all screws where metal is on metal).

Put together, it looks like this:

Why a T-Maxx battery box, when there are so many other ones that are smaller? Well, I like the T-Maxx batt box because it holds everything, including a port on the top with a rubber plug that you use to recharge the battery pack. When you are done, pop the plug back in and there is no leakage of water, etc.

So now I have the battery moved, but I still need to move the receiver. This is where the Traxxas radio box comes in. Since my LHS pretty much carries only Traxxas and Losi, shopping the rack for parts is hit-or-miss, but this worked out well. I just toolk my spektrum receiver, velcro'ed it to the top of the case, routed the wires for the battery and servo.

I spent a bunch of time trying to figure out how to mount the box to the back, but decided on zip-ties - cheap, easy, and doesn't require me to drill holes or fab up crazy brackets.

The finished product (still need to tuck wires)

Hope this helps someone!

Bob

 

[orcusomega]

OK, next project, now that I have the battery box and receiver relocated is going to be converting it to a mid-tank, again on the cheap. I took some measurements, and the OEM radio box is roughly 2 7/8" wide by 5" long, and the mounting holes are NOT even - there is a pretty decent rise between the front radio mounting hole in the TVP and the rear hole - something that is solved with the FLM TVP's and their servo plate, but I want to make my own. and make it to work on any TVP that uses the standard radio box. I know FLM makes a nice unit - those that have them LOVE them - but I can't justify the expense of everything, especially waiting for them to be in stock... so I am going to scrounge together quality parts, and put together what I hope will be an awesome setup that will not only hold the OFNA 1/7 scale 250cc tank, but also provide additional reinforcement for the tank, etc.

So, first thing I had to do was take the measurements - and they came up as 2 7/8" wide by 5" long. When at the local hardware store, i went looking for aluminum plate, but all they had was crap - nothing I could really use. I did some digging online and found OnlineMetals.com - and they have a great process. Pick the metal (I picked 6061 Aluminum plate), specify the dimensions and number of pieces you need, and they cut them and ship them. As a point of comparison, the FLM servo plate is $14.00 + shipping for one plate. Admittedly, it is all cut out and drilled, but I don't need all that for what I am doing. What did I pay? Including shipping, I paid about $25 - FOR 5 PIECES Why 5? I have 3 Savages -and I am going to experiment with making a top-plate to hold the tank more stable when being bashed - apparently folks are having issues where the 250cc tanks can't take the abuse. So I am thinking of taking a piece of paper, cutting it to fit just over the top seam of the tank, and making a top plate - but we will see how that works out in the end Of course, when it came time to place the order for the plates, I ordered 3 7/8 and not 2 7/8, so the price is likely to be less (and now I need to cut 1" off the side LOL)

OK, so here's the running parts list so far:
1) 1"x1"x4' aluminum angle iron (Lowes) $3.00
2) 2 7/8" x 5" x2.5mm 6061 aluminum plate - $6.00
3) Two Ofna 250cc tanks (one spare for now) - $15/ea

This weekend I will be working on more of the specifics - so I will post them when it is all gathered!

Bob

 

[orcusomega]

Build continued last night, even though I don't have all the materials

I scrounged through my ever-growing box of parts and was able to put together most of a Savvy out of spare parts so that I could start mocking up what goes where.

I used an old aluminum bulkhead plate to start lining up where the braces, etc will go and I found I have a lot more room than I thought I was going to have

I am pretty sure that means I am doing something wrong I also don't like the location of my relocated reciever case, so I will be making a new servo case out of aluminum angle and using Durafix to weld it together (with a lid, so I can remove the receiver, BTW). That will be in another post

So, after I lined up the aluminum skid with the steering towers, I realized that there were a few other locations I would be able to use to add extra bracing, as well as having a bunch of space under the plate along the inside of the TVP - this is where the custom receiver box will go.

I also bought more materials today. When I was going through my box of screws I found I was short a bunch, and since I have another build project coming for a buddy of mine, I figured a trip to Lowes was in order again. While there I got the larger machine screws (TVP cross braces, steering, etc, as well as the coarse thread for plastic as well). Again, more detail to come. Suffice it to say I was able to get 100 of just about every type of screw on the Savage for about $20 - much cheaper than the screw kits they sell on eBay

I will post the sizes, and whatnot when I get back to the house.

Bob

 

[orcusomega]

So last night I put more time into the mid-tank mod, and I am 99% of the way there - just waiting on more parts!

The purpose of this update is to remove the radio box, relocate the servos in preparation for the arrival of my aluminum and 250cc fuel tank.

The first thing I did was grab an old set of TVP's, bulkhead, and trans to start mocking up the fitting, etc. After trying to figure it all out, and in doing so, keeping the angles on the steering rod so that they won't bind, I found a space was in order. To do this, I took an old engine mount brace, drilled it out for the M4 screws, and cut out the middle section. This allows me to provide the lateral support for the bellcranks, but still have room for the steering rod in the middle.

Now, I had to make a way to mount the servo to the side of the TVP, and consider the pattern of the TVP and how it will interfere with the mounting options. Since I am using an XL fram, the big X on the side limits where I can drill out for solid mount points. In the end, I needed to create the mount (made from 1x1 aluminum angle) and add counter-sunk screw holes so that the servo and screws would not interfere with each other.

Once that was done, I needed to make another mount for my throttle servo. Remember, I mentioned that this is getting ready for the mid-tank, and I don't yet have the aluminum plate or the tank. So, what I did is use another piece of aluminum angle, and make another mount to hold the throttle servo until the rest of my goodies get here. When they do, this servo will be relocated to where the stock fuel tank goes.

Linkages need to be tweaked a bit and I will be getting a more sturdy steering rod at the LHS, but this is what she looks like - let me know what you think!

Total cost of this part of the project (mid-tank mod) to date:

1) radio box (~$5)
2) two servo wire extensions ($3/ea)
3) 3' 1x1x1/8 aluminum angle - $2
misc screws and crap I had lying around.

Comments welcome!

Thanks,

Bob

 

[orcusomega]

Few minor updates - pictures to come soon!

I added the rubber isolators to the steering servo as well as the throttle servo, just to keep things from vibrating to pieces as Alex pointed out. I also grabbed a set of linkage pieces from the LHS to make things even more sturdy (the linkages in the pictures are ones I used to make a mount for my air cleaner to keep it out of the spur gear, so they prolly wouldn't hold up well to the task of steering without separating).

Remember, my receiver is currently installed in a radio box on the outside of the rear shock tower - well I am not too crazy about it being there and not taking a big hit one of these days.

I started fabricating an aluminum mount that will go on the other side across from the steering servo inside the TVP's that will hold the receiver in place and in a much safer position - the aluminum angle will act like a skid plate on the bottom protecting the receiver box from anything that might come up from the bottom. I like this setup better. since it helps keep the weight low (it doesn't weigh much anyways). Also, this will be made from the same 1"x1" aluminum angle (I am getting my money's worth out of this $3 or so piece!). Another member mentioned that the aluminum as a complete box may cause interference, so this will be just a basic tray to keep it in place and will me mounted to the TVP to keep it from bouncing around. I already have padding inside the box to minimize vibrational damage, so I should be good to go.

With all the moving around of stuff, I started making my throttle servo mounts too. Considering the amount of work I am doing with aluminum, and some of the things I am planning on doing with my up-coming 1/5 scale conversion, I am seriously considering a table-top band saw from Lowes - $100 is a good price considering what I can do with that once I get it. Since there will be a lot more custom aluminum work on the 1/5 scale, this is likely something I will pick up at bonus time.

I will get some more pics tonight...

Bob

 

[orcusomega]

Well, last night I got the rest of the goodies installed. The plates arrived from OnlineMetal.com, and they are awesome - well as awesome as I asked for, seems I messed up and ordered 3 7/8" x 5" plates instead of 2 7/8" x 5, but that's OK, I have a hack saw and I know how to use it

So I started off removing the temporary throttle servo I installed the other day to make room for the tank plate.

Once that was done, I took the plate, and cut it to size, drilling holes in it for the steering braces. Alex, I think this is the part I didn't explain the other day - this plate will give it the lateral support that the brace is missing since I cut it in half. Then I used another old motor mount brace to support the rear of the plate, trying to keep the plate as low and level as possible.

This worked out real nice - I just had to add one washer on each side on top of the steering bellcranks to make a little more room for the steering linkage. The results I think were pretty good:

NOW ALL I NEED IS MY *&*&#$*^**#$*( TANK! (grrrrrr):sniper:

Ok, with the plate done, I moved to the back to make a mount for the throttle servo. This was easier than I expected - again, using the 1x1 aluminum angle. I measure a piece big enough to stretch across the opening and use the existing holes for the OEM tank mounts, and notched it for a servo:

I thought this was too clunky, and when the pull-start line droops, the rubber boot rubs on the edge of the aluminum bracket. So I modified the plate a bit to make it more esthetically pleasing, and shortened the ear of the mount so that when the servo is mounted, the rubber boot rests against the smooth side of the servo, protecting the boot and the line inside!

Now I need to just iron out the wrinkles with the throttle/brake linkage, and we are good to go -- OH YEAH AND WAIT FOR MY &*&*^#$^ FUEL TANK...

Bob

 

[Pope]

looking good

 

[Hypnotiq]

looks great man.. gave me a few ideas for my mid tank build! Thanks!

 

[orcusomega]

No problem! I got a lot of good ideas from you and Bank in Shout this morning - thanks to you too!

Bob

 

[orcusomega]

Well, I was worried my tanks wouldn't arrive in time, so I ordered one from Tower yesterday - and guess what arrived today? The tanks I was worried about No worries at least I have them and can get them installed in time for our bash on Sat!

Tomorrow I will get them installed, and get the mounting plate figured out - more pictures to come. I also will need to make another plate - I sent my only complete one to Hypnotiq! LOL

Bob

 

[Bankrupter]

good stuff. I am waiting on the the 4ws truck !

Never fear spare parts... Now if you crack a tank (hard but can be done) you got a drop in no wait!

 

[Hypnotiq]

I also will need to make another plate - I sent my only complete one to Hypnotiq! LOL

Bob

Thanks alot bob! Cant wait to see your finished product!

 

[farmawi]

cant wait to see your product finished bob
nice build

 

[orcusomega]

Thanks for the support guys!

I started working on the new tank mounting plate, and changed the design a bit. The new one is looking like it will allow the tank to sit down into the plate about 1/2" - this will keep the COG down, lighten the weight of the mounting plate, and hopefully provide more support for the tank overall. I picked up some aluminum round stock to use for the mounts, and started a prototype custom mount for the tank. Instead of having it sit in a cutout and have just two pedestals for mounts, I am going to have a plate supported by 4 posts, with the tank sitting on that, so that the small mounting holes that are on the tank don't support the whole weight, they just keep it from moving around. I am also going to leave a small tab on this plate where a fuel filter can be easily attached, and easily accessed.

Here is the template - I only got one picture of the paper template, I will be transferring this to the aluminum plate hopefully tonight.

This is the outline of the tank right UNDER the seam, so that the tank gets full support all the way around. Does it need it? I don't know, but I am having a lot of fun trying to figure everything out

Bob

 

[Divey1130]

I have an XL and was thinking of doing something very similar to yours. Very nice write up so far with detailed instructions. 250cc tank is exactly what i had in mind for a longer run time or even bigger. With the XL's you have so much room up front to put a larger tank. Anyways good job and can't wait to see the final master peice. Terry

 

[Combuster]

I have an XL and was thinking of doing something very similar to yours. Very nice write up so far with detailed instructions. 250cc tank is exactly what i had in mind for a longer run time or even bigger. With the XL's you have so much room up front to put a larger tank. Anyways good job and can't wait to see the final master peice. Terry

the xl has the same amount of room in the front as any other savage it is extended to the back

 

[Divey1130]

^^ Woops your right. I would like to do a duel tank for more run time.

 

[orcusomega]

Last night I put the last bits together to get this thing done in time for tomorrow's bash - was up till 2 am doing it, but its done at least!

After finally getting the tank, I found an interesting problem - the tank was longer than the 5" plates I had ordered - so I needed to add a little diving board to the end:

From there I added the mounting posts. I don't know if you can see it well, but I drilled the posts off-center on the top, and centered on the bottom - so that the posts could be rotated to make subtle changes to the width of the mounting positions to move the tank a bit side to side, front to back, etc.

While doing all this, I found out something pretty cool, actually. The mounts that I was fighting with in the rear at the trans were not necessary. The 1/8" plate was thick enough to be rigid, and the fact that it rested on the trans and front bulkheads, with mounting screws into the bell-cranks, made the platform ummovable. And I tried! I am going to keep an eye on this, but if it works - that would be AWESOME. I left the bulkhead brace on the back of the plate @ the trans for rigidity, but also if need be I can put the screws into the sides through the TVP's - the holes are already there, but I wanna see how it holds up

When mounted, the tank sits low, but I would like to figure out at some point if I can make it even lower. 250cc is a lot of fuel that can throw off the center of gravity when sloshing, so maybe if I get bored sometime over the winter I will try to come up with another idea here, but for now, it will get me ready for Sat's bash!

Completed (missing pressure line off muffler)

I will beat on her like a government mule tomorrow and let you all know how well it worked out.

All told, the overall project was fairly inexpensive, but mostly because I have the means to make my own parts. Here's the breakdown:

1) plate aluminum - $5
2) 1x1 aluminum angle - $3
3) 3/8" diameter aluminum round stock - $2
4) Ofna tank - $14
5) RC10GT Receiver box (not arrived yet) - $7
6) Traxxas battery box - $10 (I had one, but if you had to buy one...)

When you add in the misc bolts and screws that I had on hand, this whole thing should cost no more than $45 or so - not a bad deal when you consider how much more consistent the motor will be without the mid-tank lean, as well as almost doubling your run time (this is important to me, since I run a 4.6HO - thirsty little devil). I did decide to add the RC10GT receiver box, but it did ot arrive in time for the bash so everything is all wrapped in balloons for water-proofing and ziptied out of the way for now.

Comments welcome!

Bob

 

[orcusomega]

Well, yesterday was the first shakedown with the mid-tank kit in, and it was awesome!

http://www.youtube.com/watch?v=IC27Q7XzUZA&feature=channel

It flew well, landed (relatively) flat and smooth, ran for ever I did not make it an entire tank of gas without breaking though - I kept breaking rear carriers and linkages because I don't know how to fly But, it was awesome nonetheless!

http://www.youtube.com/watch?v=YVfm1DMj8BY&feature=channel

I did break the battery box, but that was due to a particularly hard, upside-down landing from pretty high up -

http://www.youtube.com/watch?v=NE5r1Cmv4DA&feature=channel

but again - could have been a lot worse! I will be making a few changes to the design of the throttle assembly, and will post pics soon!

Bob

 

[farmawi]

nice vid's Bob....
wish you enjoy your truck without facing serious probs.
have a good build .....

 

[orcusomega]

OK, now that Thanksgiving is over, I was able to get a little more done on the Savage last night.

The last time I was out bashing with Alex, AJ, Ben, etc, I managed to destroy the T-Maxx battery box I was using behind the motor of my XL. Before you rip on Traxxas, it was a pretty bad hit - broke the rear shock tower and two shocks and in all that the box got hit. I was able to zip tie it back together to keep bashing, but it needed a redesign.

In the old design, the receiver was in a balloon and zip-tied to the inside of the TVP up front - done pretty much to get the truck in running shape for the bash. Now that the season is pretty much over, I can revisit it.

So I removed the RX and batter box, and pulled out another Traxxas RX box I picked up early in the process. Initially I had the RX mounted to the back of the shock tower:

I didn't like this layout, and since I ended up hitting the shock tower, it definitely needed to be redone. So I pulled the box out and redid it.

I added a Spektrum SR3300T receiver, power switch, and charge receptacle all to the one box - this will ge mounted behind the engine between the TVP's:

It is a tight fit, but it all fits nice and snug. To cushion the RX, I have it mounted in the box on velcro - holds it in place, but also provides some shock and vibration protection. With the bottom in place (not shown) it all stays nice and snug. The switch is mounted on the top and the charge receptacle is mounted in the side:

The receiver box is mounted behind the engine here:

It is actually farther back than in the picture, to keep it away from the exhaust mmanifold. If it gets too hot, I can put a piece of thermal barrier there to keep the RX box from becoming a little oven or have it start melting.

As for the Rush battery box, I used a piece of aluminum to make a mount that attaches to the bottom two screws on the shock tower running up along the tower. Then I used two screws in the existing holes to attach the battery box to the aluminum plate.

One thing I did different than I have seen in other posts is that I added a n additional screw to the mix - The Rush battery box is nice and small, but the existing mounting points are basically a hing - there is nothing else that will support it in a crash, etc. The weight of the battery in the box then becomes a pendulum - making it likely that the mounting tabs could break off in a crash.

What I did was I added an additional screw to the top of the box to hold it to the aluminum backplate. Two problems with this: 1) there is NO room in the box for any screws to protrude, or the battery box won't close and 2) the back of the battery chamber is not flush on the same plane as the mounting surface. I used a countersunk screww and sucked it all the way down flush with the inside of the box, used a locknut on the other side of the plate to act as a spacer, and then through the alum plate. I had to do it off-center because I forgot to look, and the original hole ended up hitting the tower... Since it is more for support than load bearing, off-center should not be a problem.

I have some motor changes coming soon, so everything is gonna get all mixed around - more to come soon!

Hope this helps!

Bob

 

[Divey1130]

Looking good man. I am going to take your idea (if you don't mind) and also mount the reciever box where you did. I only worry of breaking it after a big crash. I will be getting the FLM tvp's after christmas so I will be moving some stuff around. Like you mentioned with my steering servo and the reciever box. I am also going to redo the throttle/brake linkage and make it shorter. I saw somewhere on here how to do it. Keep up the good work. Terry

 

[orcusomega]

Thanks! I was running through the rx/tx testing last night I and realized that my SF-1 has pretty much bought the farm. I ordered two HS-645MG's, and one will become my throttle servo. I will move the servo mount to my other Savage, and make a direct throttle linkage setup I don't like the mixer at all - so I am going to TRY to go directly to the carb from the servo horn - should be doable, just need to make sure the angles are right

Bob

 

[Divey1130]

Here is the one I was talking about. I'm going to give it a try.
https://www.hpisavageforum.com/forums/showthread.php?t=8612