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-   -   OS's CFX Killer (http://www.rccrawler.com/forum/tamiya-tlt-crawlers/598123-oss-cfx-killer.html)

OSRC 04-26-2018 06:10 AM

OS's CFX Killer
Been having a lot of fun wheeling around my little CFX. I've had all kinds of ideas on modding it for better performance, but I kinda like it as it is too - the challenge is part of the fun.... so what to do?

Let's build a new truck! (any excuse to mess with random parts really...) Similar dimensions and still using a CC size body but with the performance mods I wanted to incorporate into the CFX. Sure, let's go with that.

I used this truck as the base and started mocking up a lower driveline that incorporated OD...with such a short WB, I think OD will help tremendously. Started messing around until I had a layout I liked. Proof of concept...kinda. Compared to the CFX in the background, it's much lower COG-wise.

The chassis could have worked, but I wanted to incorporate some changes, and the old one was getting holier than the pope after being modded so many times so I cut up a new one. Really, it was just an excuse to cut up some metal.... incorporated the shock mounts and straightened out the back.

The tried and true HPI reduction...used a piece of ABS to span the chassis and mount it. Seems solid, though delrin would have been better - I might come back and make an aluminum mount later that's a bit stronger.

Mounted up a Hammer t-case set up for OD. Little more OD than I would prefer, but should be ok with the kinda tiny tires. My trans ratio is only 10.89/7.41 front/rear with this setup though - definitely need more reduction somewhere. I kinda have a plan....

Axles are my last pair of TLT's with all the goodies from back in the day... MIP's, clocked C's, HD lockers, etc. I was debating a set of MST axles since they have better steering, and are the perfect size, but the TLT's were doing nothing but gather dust and the MPA axles were $100. So TLT's it is!

Front axle mounted up...it's tight, but it all shoehorns in there. Went with a 3 link w/panhard so I could drop the motor as low as possible.

On the rear axle, I swapped the truss for a Dinky link I found in my stash for more clearance.

Tight back here too, but it all works. I was worried about the driveshaft angle, but it seems ok.

Ordered a few parts, so I'm kinda stuck at the moment.

While I was waiting for them to come in, I started messing with other stuff. These old Outcroppers are going back on - they are not comp level tires to be sure, but there's just not a lot of great tires at or under under 100mm, and these seem to work pretty decent - inline with my driving abilities anyway, so using them for now...I did open them up with a dremel a bit which should help. Modded tire on the left

Pretty much it until the UPS guy gets here. "thumbsup"

grob23 04-28-2018 06:47 PM

Re: OS's CFX Killer
watching this one like a hawk! stoked to see another tlt build!"thumbsup"

OSRC 04-29-2018 07:55 AM

Re: OS's CFX Killer
Parts came in yesterday....if I can tear myself away from 'Dega today, might get some work done. :)

OSRC 04-30-2018 06:10 AM

Re: OS's CFX Killer
Made a little progress yesterday before the race.

Took off the HPI trans to hook up the gear reduction and found out 2 of the three screw bosses broke off. Very strange, never had that happen before. Broken one on the left... thankfully, I have a spare that I swapped over.

I needed more reduction, so I put a 4:1 RC4WD unit inline with the HPI giving me a total trans ratio of 29.6. Should be in the ballpark, if sill a little tall. Used a Tamiya mini motor to power it all, though have room for a full size can if needed.

Mounted up in the chassis. Kind of an odd trans setup, but it's fairly compact for what it is

Squeezed a steering servo in...had to bend the panhard and add some offset rod ends, but it all clears just barely. The panhard and steering links look off, but that's just due to the bends. I get full movement with no binding and no bump steer. The MIP's give a whole lot more travel than the stock TLT parts - it's right at the same angle as the CFX at full lock.

Wheels and tires back on - got a roller! The 8-holes were already drilled out to fit over the MIP's, so left them on there. They are weighted inside - weight down low is critical with such a short WB rig, and I don't know of any way to add weight to a TLT axle, so the wheels got some lead. The Outcroppers are a little stiff being an older compound tire, so dremeled a bit on the inside of the tire to thin it out and put a super soft foam in. Feels pretty good on the bench. We'll see.

Need to figure out some sliders, electronics and battery mounts and a bumper of sorts, then tear it down for paint.

goobs 05-01-2018 03:01 PM

Re: OS's CFX Killer
I have 6 of those HPI gru's in trucks and another 4-5 on the shelf. i love them.
i have had one out of all them being used break a nub like yours did. all others are fine.
nice to see these older rigs (parts) still get love.
keep it up "thumbsup"

OSRC 06-20-2018 07:17 AM

Re: OS's CFX Killer
Get a little more work done on this little guy...

Bent up some 2mm aluminum and made some boatsides. Plan to make some steel sliders to cap off the ends.

Perfect fit under the Tamiya body, and a nice place to mount electronics.

Bumpers back on...rear is a modified Sawback front bumper.

Zip tied in the old battery tray...not quite sure where I want to put it yet

With all the electronics mounted, it's pretty low profile.

Now onto fabbing up some sliders and getting some paint on. Have to tear down the entire chassis and spray it black as well.

cartronicshn 06-26-2018 03:22 PM

Re: OS's CFX Killer
Very nice build, i should try and do a rebuild to my last tlt axles i have left which coincidentally i have mounted the fj40 tamiya body from the cr01.

OSRC 06-26-2018 05:29 PM

Re: OS's CFX Killer
You should! TLT's for life! :)

I've driven this round the shop a bit, and I'm not sure on the overdrive. It's too much imo... drags the rear tires noticeably. I'll get it out for a test run though first before making any changes. Do need to get my paint shop set back up and spray some color first.

OSRC 08-01-2018 07:24 AM

Re: OS's CFX Killer
(2 months later)

Everyone is out building VST's, and here I sit playing with TLT's still. :)

SO finally got my paint area cleaned up and ready to go. Been a while since I totally pooch-screwed a body, and I was due for sure. Mission accomplished! My airbrush had a heck of a time spraying the white - not sure if the paint was old or what. But I didn't have much left to begin with, so the white got very blotchy. Unfortunately, the black backing layer really bled through....the white looks terrible. Not to mention the sub par masking job that bled here and there. Of well, what's done is done.

Some of the black is overspray, but sadly, not all of it.

Decal time. If you've ever done one of these bodies, you know it's an extreme exercise in patience. Each window is 2-4 tiny, uncut decals that take forever. Hopefully the decals hide some of the paint disaster... hopefully.

2mtech 08-01-2018 07:38 AM

Re: OS's CFX Killer
That has to sting a little. Looks like it would have been a really unique paint scheme. Can always reshoot on the outside and try to recover?

JatoTheRipper 08-01-2018 08:03 AM

Re: OS's CFX Killer
Building VST's? Did you mean MST there or is a VST something I'm unfamiliar with?

Too bad the paint didn't work out. That's heart breaking. And this would have been a rare non-blue paint job from OSRC! Sad. Hopefully it looks OK with the decals.

OSRC 08-01-2018 08:30 AM

Re: OS's CFX Killer
VS4-10 T breaker one-niner. Too many letters, I get myself confused. :)

2mtech 08-01-2018 10:06 AM

Re: OS's CFX Killer
You should run that body over to Jato, you know he loves to paint. :roll:

OSRC 08-03-2018 05:55 AM

Re: OS's CFX Killer
Ha! Let's not get crazy!

Paint and decals done finally. Holy cow, does this thing take some time to decal up.. Since I'm running TLT's and a Tamiya body, decided on a modern Rough Rider theme. Think it came out OK - would be far better if I didn't screw up the white but I can live with it.


Drive-wise, it has a very low COG with the motor hung as low as possble so it's pretty stable. Those old Outcroppers are still pretty grippy and make cool whooshing noises when they spin on the rocks.

Using the RC4WD t-case as overdrive gave far, far too much OD to the front wheels. Was literally dragging the rear end up and over stuff. Sometimes that's good, but I had no drive at all in the rear, so the front was doing all the work. That's no good. Motor was super hot after just a few minutes of testing which I hope was due to the axles fighting each other. Going to remove the OD and just set it up as a std. t-case


Too bad there's no "vintage class" of crawlers...feels like I should have a Stampede trans stuffed in here. :) Compared to a newer kit, the steering on this is just laughable. BUT it is fun to wheel regardless. Still needs sliders and think I'll finally break down and paint the chassis.

2mtech 08-03-2018 09:16 AM

Re: OS's CFX Killer
Man, that came out looking really sharp! That's one for the "is that really an RC?" thread.

The white actually looks good too decaled up...just gives it sort of a dirty/driven appearance. A good modeler, like a good carpenter, relabels "boo-boos" as "character". "thumbsup"

Nice job! Hope your regearing solves your issue.

Bananaclip 08-03-2018 09:59 AM

Re: OS's CFX Killer
Man-o-man does these pictures bring back memories..... The TLT started it all for many of the oldschool RCC members including myself.... You might be starting a new trend here my brother....... Great work on the chassis and floorboard/sliders.....

OSRC 08-04-2018 07:47 AM

Re: OS's CFX Killer
Amazing what a bit of time with a Sharpie marker can do to a lexan body...

Speaking of vintage, I've got a few sets of WK axles, Proline 2.2 mashers, a bunch of stampede transmissions, and a few old style chassis laying around. Hmm.... Vintage crawler build? Got the wheels turning for sure.

In the meantime, tore this truck down and sprayed some paint yesterday between storms - pics to follow. Apparently all the rain that should be falling out west is bombing the east coast. This is getting crazy. My pool overflowed last night for the first time ever.

OSRC 08-04-2018 11:54 AM

Re: OS's CFX Killer
Been chipping away at this thing over the past 2 days. First thing I did was get rid of the overdrive. Flipped the t-case, swapped the input to the other side, drilled 2 more holes and it's good to go. Piece of cake! Before and after:

The ABS mount I made might have been strong enough, but there's a whole lot of weight hanging off of it, and I feel better with something more solid. Found some old server rack mounts I brought home from work that were made of 6mm aluminum. Two hours of sawing, filing, and drilling later, I had an aluminum mount instead. The sliders on the boatsides are made of brass. I had a slight mishap with the brazing involving flying magnet shrapnel and took the easy route.

Stripped the chassis down and sprayed everything flat black.

Feeling better about the motor/trans mount...much more solid.

Axles back on and almost a roller

Wheels and electrics. Good to go!

View of the front. The shocks were hydro-locking with too much fluid, and really, really inconsistent with a bit too little. Not a fan of these at all, I cannot get them to operate smoothly for the life of me. Drained out the oil for now so they at least cycle smoothly. It'll be a bouncy test ride for sure. I'll dig into them later to see what I can do.

Side view.

Front axle setup. Great caster and pinion angle from the clocked's c's - they make a huge difference on the TLT axle imo. Motor is as low as possible up front given the short wheelbase.

OSRC 08-04-2018 12:15 PM

Re: OS's CFX Killer
Body back on and ready to go. Swapped the wheels for a set of old white ones I've had in my box-o-parts since ... well, forever. I have no idea how old these things are, but finally found a truck they look decent on.

This body looks great with 1.55's, but all the ones I've tried are just too much offset with the TLT axles. I need a wheel that will narrow the track width as much as possible, so I've been sticking with the 1.9's. Think I've got a good amount of tire coverage with this combo.

Gotta have a flex shot or two. About the same as the CFX/CMX.

Comes in at 5.6lbs and a 53/74 front weight bias. Right where my CFX is - should be an interesting comparison! My only concern is that mini-motor up front. It was way hot on the first test run, so I'll be keeping an eye on it. It's geared way down though, and the motors do fine in my CC chassis, so we'll see how it does here. I've got a regular can 35t on standby.

cartronicshn 08-09-2018 12:43 PM

Re: OS's CFX Killer
:shock:, super nice job on them tlt's, the body looks really good to, anxious to see your final test results i will definetly take some notes from your build for mine.8)8)

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