Some ideas/brainstorming for a 1/7 scale on road car build
 

Was cleaning up and found my Hot Bodies Lightning Street and decided it was time to make something out of it. Maybe use it to jump start my rc interests again??

Anyways, the LS (lightning street) is basically a HB buggy with a longer chassis. It has a 2 speed center spur with 46/42 gears. Single mech brake setup and regular buggy 43/13 diffs. Uses 1/8 buggy wheels with 17mm hexes.

Looking at my motor inventory I have a few options. A 2200kv flux motor, 1521 1y neu, 1717 cc motor, 1521 2y and 1521 2.5y.

I do have the RCM 2 speed adapter and a few losi and rcm pinion gears to use with it, 26/30 would mesh with the center gears and be the highest gearing I can swing with off the shelf gears. 16/20 would be the lowest gearing.

Would use a MMM and a turnigy 5k 6s 40c lipo. I have those at hand.

With the 2200 and max gearing I get 104 in 1st gear and 131 in 2nd. Might be overgeared for that motor. Lowest gearing gets me 64 in 1st and 87 in 2nd. Do we think the 2200kv flux motor will pull this gearing? I know the 1515 sized motor is quite potent and this car will not be much heavier than a truggy with alot less wheel/tire weight...

I like the 2200 flux motor as it can be easily adapted to this chassis by attaching it to a flat plate and then threading that plate to accept the nitro motor screws. The other motors would require some sort of L bracket or maybe get mike to make me a center diff bulkhead to fit?

I could go to the 1521 1y and gear up and get similar speeds with moroe motor power. Unless I can find a suitable esc the 1521 2 and 2.5y are out. TThe 1717 could be used, but I have it earmarked for the 6x6 lst...


1521 1y with mn and max gearing on 6s:

min gearing: 46 1st, 63 2nd
max gearing: 75 1st, 95 2nd

The more powerful 1717 would be about the same, as it has a similar kv, and would likely pull the max gearing in 2nd, as long as the MMM can handle the load. Pretty sure that 40c turnigy can swing it, if not I can make a 6s2p 6400 pack that will.

Thoughts???? Insults???

A 1/7 car, a 1717 motor... I'm starting to notice a pattern. Too bad the MMM can't handle 7s LiPo. Maybe the ICE HV 170? :whistle: :mdr:

Kidding aside, the car is 4WD right? Based on how easily a 2200 lights up the tires on 6s in a 1/8 4WD car (my GTP geared for ~75mph) I think it would be right at home in a 1/7.

On road special
 

For what you are leaning towards I would think the 1717 is out just because of the added weight issues. The 1521 should be right on track for descent speeds for an onroad vehicle, and still give you plenty of power to play with. There are several ESC choices that would do you right, but figuring out exactly which one would work best for your taste will be your toughest decision for sure. Maybe a very capable size MGM would be good for the job if you can work the setup issues and aford the cost. If so I would have two of them so you have a backup on hand. Remember James if things go right we should be in Prague, Czech Republic soon.

FYI By the way I still have not seen those motor mounts for the Neu 1527.

Strange, mailed them out the next day after we spoke. They did go in a small envelope, so maybe that takes longer to get to you?

Ok, so I will try the 1515 2200 motor 1st. Need to get all of my gearing options together and make an order with Mike. Turns out I will need but the 16t and 20t gears for the 2 speed adapter....

Will mock it up and take some pics. Guess the servo, esc and motor will go on one side and put the battery on the other. Still think the battery will be heavier than the other components combined.

So should I mount the battery at the front of the back? I am guessing the front, maybe?

I like to mount everything closer to the front. I've found it helps increase steering, especially on power. Then again I like alot of steering because I like getting sideways.

I thought the same thing. I have always liked to put the weight over the front tires as much as I can, as it seems to help steering, especially under power. You do have to use a stronger steering servo, but I have quite a few jr 9100t servos.

I also will run mech brakes, so I will need to mount the brake servo somewhere, likely just in front of the center diff on the motor side.

Pics will be up tomorrow, had pc issues all day today at work...

I think the lightning would be an awesome platform for what you want to do. As far as weight distribution goes I agree with the battery going somewhere toward the front of the car. Can't wait ti see some pics of this thing!

Ok, did a mockup. Will need to move the steering servo over to the motor side, will likely make a servo plate that will hold the steering servo and the brake servo. Esc will go next to the motor at the back, as in the pic.

The motor is not the correct one but it gives some idea of placement.

Battery tray will go where the steering servo currently is. Will overhang the chassis slightly in the middle due to the spur location. If I had a slightly shorter battery it would fit infront of the spur and behind the steering cranks but oh well...

Current 2 speed setup is 42/49, mocked up with a plastic 49t gear, the other gear shown in the photo is a mgt steel 49t spur that I need to have modded to fit the 2 speed assy. I was going to run 18/25 pinions, but the 42/25 gearing would be over 110mph with the 2200 motor. Will stick to 16/20 gearing and run the stock 46t 1st gear spur and have top speed around 90mph.

If I was to use the 1521 1y I would run the 49t spur for 1st and the 18/25 pinions. If the 2200 cannot handle the load I will have to switch it up. Will require a much more elaborate motor mount...

So I will stick with the 2200 for now. People say they are great motors, and I did have good success with one in an lst on 5s... Seeing this thing shift into 2nd gear around 55mph will be interesting. Will need some serious brakes, thinking a high torque servo for the brakes, and another for steering. Luckily I have a few jr 9100t servos laying around!

http://i206.photobucket.com/albums/b...p/DSCF4616.jpg
http://i206.photobucket.com/albums/b...p/DSCF4617.jpg
http://i206.photobucket.com/albums/b...p/DSCF4618.jpg
http://i206.photobucket.com/albums/b...p/DSCF4619.jpg

Starting to look interesting. That will be one hell of a beast.

I hope so...

Just curious. What motor is that in the pic? Think I could make out 1521?

And also, where'd you get that 2 speed pinion adapter? I really need to get some of those.

Motor is a 1521 1y finned. 1600kv and it has enough power to move my 12lb lst around geared for 45mph or so.

The 2 speed adapter is from the rcm store. Uses lst pinion gears, or (preferably) rcm pinion gears. The rcm gears are hardened and superior to the losi ones. Great products, tailor made for conversions like this!!! Thanks Mike! In your face Tower Hobbies!!!

Need to order some from mike, just want to make sure that the sizes I need will fit with the flux motor installed and not touching the rear center bulkhead.

Looking good... Might I recommend relocating the steering servo to the left side so that the battery can go in the front right to offset the motor?

Ok, I am not quite with it today.

For some reason I thought I could swap the steering bellcranks and put the servo on the other side...WRONG

So I got the motor out of the flux, set it up on the same side as the steering servo, and found some small pinions, 18/22, for the 2 speed adapter. It all fits, with room to slide the motor over for the smaller 16/20 gearing I need to order.

Also, the brake servo will fit behind the steering servo and in front of the centerfront bulkhead. So good to go. Battery fits a little better on the opposite side, and the MMM looks lost behind it. I do need to figure out some sort of tx/bec mount or box.

Only issue is that the rear brace off the rear diff bulk will need to be moved to clear the motor. Looks like I can swap in a longer turnbukle and run it slightly diagonally and mount it on the other side of the rear center driveshaft.

Forgot to take pics but will do that in the morning.

Manufacture a new steering link, perhaps? :neutral:

I would have to make an ackerman plate too, and the arc of the mount points of the bellcranks would be very weird if I swapped them. I will stick with putting the motor and both servos on one side, and the battery and esc on the other.

Here are some pics with my current configuration. Think this will be the final one, so I will get to making the motor mount plate.

http://i206.photobucket.com/albums/b...p/DSCF4623.jpg
http://i206.photobucket.com/albums/b...p/DSCF4622.jpg
http://i206.photobucket.com/albums/b...p/DSCF4620.jpg

Instead of using a longer turnbuckle for the rear chassis brace, how about moving it to the outside of the mount. I know the mounting screw won't be double shear then, but it is only for onroad. Although if you have a longer turnbuckle lying around... Looks nice though, never knew Hot Bodies made a 1/7, thanks for sharing.

Setup.
 

Hey James. Your setup looks pretty clean to me and practical to. The only issue I see so far is the battery center diff gear spacing. I will assume that you plan on using a battery tray of some kind to keep them from coming into contact with each other. That could be one ugly incident. Looks good James.

How radical are you thinking about getting? There seems to be quite a bit of real estate on that chassis. Any thoughts to maybe moving the center diff back a few inches and offset towards the batt side, that flips the motor around too, and you could bring it and the battery closer to the center line of the chassis?

There seems to be some space around the nitro motor mount holes where you could fit the CD in. Makes mounting the rear brace a bit trickier tho. F brace could move to other side of driveline, which is fine as the brake servo goes back w/ the CD, and there may be space in front of the motor. Just a wild thought. GLWTB.

I was thinking this, just use a longer screw and put a sapcer in the space that is left so I can run the screw thru both tabs. Might do this as it is easier than digging up another turnbuckle.

Yep, will have a full height sides battery box with velcro straps, I aften put a piece of al on the outside of the box just in case the box breaks and gets too close to the spur.

If I was going to make another chassis I would do just about what you have said. I would have the center drive at the back, and use a long center dogbone to get power up to the front diff. The motor would sit in the middle, pinion facing rearwards, and possibly offset the center drive so the battery could move in closer to the centerline. Even balance side to side would be nice, and I would like the ft to rear balance to be about 1/3 of the way from the front of the chassis, for more forward bite under acceleration.

Might do this at some point, but sticking to the center drives and stock chassis on this one. I do plan to make the motor plate big enough to go under the center drive and act as a brace. Something similar to the xray truggy chassis brace Mike makes.

Ok, little update here. Had some time so I figured out the brake servo mount, and would have cut it to length but the "tires" on my bandsaw have dry rotted, so I had to order new ones.

So I removed the center drive and the other parts and found a nice piece of al, 2/10ths of an inch thick, to use as a combined brace, motor mount etc. Motor will mount to this piece from the underside, as will the brake servo mount and the rear of the battery tray. Will thread holes in it so it can be held to the chassis from the underside thru the stock chassis holes.

Plus the front and rear chassis braces will mount thru it, and it will stiffen the center of the chassis, and help keep the gears mesh correctly. The gear mesh will be set with the center drive and the motor mounted to the plate off the vehicle and then the whole assy will be mounted in. I could cut some "windows" in the stock chassis, kinda like a nitro chassis, just depends.

Heres a couple of pics, had more but the stupid "smart phone" did not save them correctly...

http://i206.photobucket.com/albums/b...231_182821.jpg
http://i206.photobucket.com/albums/b...231_182809.jpg

im looking forward to seeing how this turns out

Me too, should be decent.

Due to the length of your project, I would suggest you find a way to fab up a top plate that connects the front and rear of the chassis to cut out flex. I don't think the front and rear braces, in my opinion are not enough to keep the chassis from flexing.

Kind of like a 1/10 4WD TC right Big House?

Kind of unrelated, but my truggy has a carbon-fiber "spine" so to speak as Big House described, and it has done a great job reducing flex (especially since it's the 6061 RTR chassis, not 7075 Pro). Diggity Designs makes a similar item for the Caster buggy:

http://diggitydesigns.com/D3_Caster_EX_UpperDeck.html

I spoke to Damon about using setups like this, and he said with the reduced chassis flex you will have to change the suspension setup a little, but overall it will be more consistent. You still need to have a little flex, but shock oil and springs are more predictable than a flexing chassis, and they should be doing the bulk of the suspension "work". And especially with a TC I think a stiffer chassis is the way to go, since the surface is smooth and high traction.

The sides of the chassis are bent up and that helps with the flex. The motor mount plate will act as a chassis stiffener, effectively doubling the chassis thickness in the middle. I do not think I will have any problems. I have made top plates before, but that was a flat chassis vehicle that did have flex issues.

Did some work tonight on the center chassis plate. Looks like it will work fine.

Need to order gears from Mike, might as well do that tonight too! Once they come in I can finalize the motor clamps locations and do a few test runs. Also need to make a battery tray, but that covers the construction aspects of this project...

Some pics:

http://i206.photobucket.com/albums/b...p/DSCF4656.jpg
http://i206.photobucket.com/albums/b...p/DSCF4655.jpg

Got some more work done. Drilled and tapped 4 holes to mount the plate to the chassis, thru existing holes. Also mounted the brake servo mount to the plate, used coutersunk screws so the plate sits flush on the chassis.

Waiting on gears so I can mock up the motor clamps and drill holes for them. Will make a battery tray and trim the brake servo plate as my bandsaw tires just arrived (yay). Need to wire up the MMM and make a mount for the receiver, pretty sure I will put it next to the steering servo. Then I get to attemot to remember how to program the M11 to slave the brake servo on ch4... Sounds like alot of fun.

Here are a few pics with the tires and body on.

http://i206.photobucket.com/albums/b...p/DSCF4662.jpg
http://i206.photobucket.com/albums/b...p/DSCF4661.jpg
http://i206.photobucket.com/albums/b...p/DSCF4660.jpg
http://i206.photobucket.com/albums/b...p/DSCF4659.jpg

Looks nice but ESC looks "FET" challenged... Some new super light MMM design?

PS you need to shorten your steering link.

HAHA, yeah, the Lite version 1!!!

The steering link is the correct length, just not attached right now. Not sure if I will continue to run that servo, but I may as I will be running a ccbec and will crank the voltage to 6.5v or so. Not the best servos but I have a bunch and they are fast, reasonably torquey, and have metal gears. Plus they were free.

Just ordered the pinion gears from Mike. He sis not have a 20t 2nd gear so I ended up with a 21t and a 17t. So it will break 90mph in 2nd gear. I think the 2200 should do fine, if it can get a savage up to 60mph it should be able to push this car ok.

lincpimp, i just bought one of these cars and need some help on parts. do you have any of the nitro parts laying around somewhere? In particular i need the motor mount, but any parts lists would help. (I am referencing your post for the clutch bell setup.) I hope to hear from you soon..i live in houston but will be back home in opelousasLA this weekend for easter. would be great if we could meet. thanks

Unfortunately crip, Lincpimp has been taken hostage by his wife and young daughter. He is busy taking care of his wife and new child, and doesn't r/c much anymore. I hate people like that, that do the right thing.(sarcasm)

It may take a few days for him to answer. I suggest sending him a PM, he's a great guy. Hell, at this point he may sell you his car!:yes: