Hicentered

The RoosterFish is my first foray into a TLT 2.2 rig. I have a 1/8 Clod-based crawler behind me but the challenge of a 2.2 comp level design intrigues me. After lurking around the forums for a while I decided to start about here:

TLT diffs, locked using epoxy-microballoons
RC4WD R2 gearbox
Front dig capability
2.2 Moabs on narrow RC4WD beadlocks
Wheel wideners
Approx 60/40 chassis
E-Max shocks (on hand)
55T brushed with Novak Super Duty controller - like my 1/8 crawler
Spectra DX6 and Parkflyer Rx - also like the 1/8 crawler
Hitek 5595 TG servo
Rubicon lid

I always work from detailed AutoCad drawings so I started by calipering the diff/axles from a RockBuster kit and a new R2 bearbox and detailed them three-view in Cad. These being the guts of the build I tweaked the overall layout including articulation check, shock travel and mounting, parts clearances, etc. Once the layout looked OK the details of some of the custom parts could be firmed up. With these printed out I stepped over to the lathe and mill.

I decided to mate the dig feature to the R2 box. The extended output shaft on the R2 begged for a sliding socket-yoke and hex-nut engagement scheme. The collage shows the parts and the assembled gearbox/dig/servo assembly. I will use Traxxas driveline sliders/yokes.

I couldn't find any steel yokes in stock so I reworked the Traxxas plastic yokes by drilling them out and pressing in a knurled sleeve with a 5mm ID. I trued the outside and pressed on a steel band over the outside, cross drilled and tapped them for the cross pin.

Accurately drilling the TLT pinion shafts for yoke cross pins presented the same problem most everyone else hase struggled with. I ended up with the simple drill fixture pictured....not very fancy but simple, quick and very precise.

Tilting the axles for better driveline alignment and ground clearance appealed to me...(IMHO, ignoring caster angle is a crime against nature) so back to the shop to whittle out some aluminum C's with 18 degree offset to retain zero caster angle. The C's are great but the knuckle arms will have to be modified to clear the C's to get sufficient turning and to set up for a better Ackerman ratio. I may have to machine up some front knuckles but would prefer to modify the stock ones first.

So the next items of business will be pulling the details off the drawing for the servo/batt mount, radio deck, links, wheel wideners, etc. and get busy making more shavings.

The chassis will wait for last. It will be simplified to extend only where mounting points are functionally required. The rigidity of the R2 housing itself is part of the chassis design. More pics at that stage.

Acs_guitars

My Feedback: (3)

All that comes to mind is.... WOW. You have some great fab skills, and the tools to use them. If only I had access to the CNC machines at work, QC/QA guys don't have those perks one the job. I look forward to seeing this one progress--- Keep us updated.

nu2THISgame

wow.. thats some cool stuff you made.... thats the BEST dig i've seen yet and those c's ARE amazing.. you should patent those c's cause i have a feeling someone in here is gonna take them elsewhere... i'm keeping an eye on this build...[sm=thumbup.gif]

hands without shadows

That dig is amazing, not hacked together like all the other ones. Have you though of doing a front and rear dig? You could still use one servo, and with the neatness of yours it could fit pretty nice. What are the chances of sending me a cad file of the axle? I want to know specifics and plan the whole build before I "invest" in one.

Anomie

Wow! [:-] Excellent work, I must say. The operation should prove flawless, and your design is outstanding.

xtremraptor

My Feedback: (24)

Very sharp! excellent work...[X(][8D]

rok_ej

Fantastic work with your R2! Are you in the market to sell some of these items? I'd love some metal output yokes for my TLTs. I also like what you've done with your R2 for the dig setup . . . are those extra parts for sale at all? I've got the R2, but not the setup parts you made. If you''re interested, I'm at [email protected] . . .

dezfan

Nice work, I think your clocked axle C's are amazing.

If you ever decide to sell them, they would do very well!

The market for that mod is ripe!

run2jeepn

Found it Dezfan....Man thats some crazy work.

dezfan

I knew you would!

Pretty slick huh!

Hicentered

I managed a few more licks on the Rooster. Accommodating the clocked C's complicated the steering arm clearance and I had to adapt some longer arms to the stock TLT knuckles. Along with that I incorporated some additional Ackerman steering. I could adapt to BTA pretty easily but decided to start with the standard configuration. I can always convert later by just exchanging the new arms on the knuckles and reversing the servo.
I am particularly pleased with how the wideners came out. I think this extender design is preferable to utilizing the hex drive on both ends. I configured them so the end play is reduced in the outer axles. The barrel "nuts" are made from socket head bolts...I prefer the Allen wrench feature. I extended each side 1/2" which gives me a squish-to-squish of 11" with an axle loading approximating the weight of the crawler. The RC4WD narrowed wheels have a lot of offset built in so knowing that 1/2" PER SIDE gives 11" track can be helpful to know.
I have most of the axle assembly outrigging and servo mounting finished and will start on the links and chassis next....the custom parts count is adding up. I wish I could be more responsive to some who have contacted me about making parts but I am not set up for any custom work. All I have is a 45 year old Southbend bench lathe (which I bought new) and a hobby mill.

Anomie

Man, that is some trick work on the wideners and steering alike. Have you considered fabricating the axle housings also? I would think you have the talent, but I understand the time it takes to make all these custom parts. I have to say, the work you've completed so far is excellent.

I can also appreciate your statement about manufacturing parts for other people. I have had a few requests for similar work, but the time is just not there.

~Reiko

Hicentered

The mechanical parts fit-up of the Rooster is finally done except for the lid. The pics pretty much speak for themselves. I can't find anything that I would change so far but that may prove optimistic when it goes to work. Articulation is 70 degrees which I think is plenty. The chassis is built around the R2 box and the dig adaptation. The chassis is around 45-55 depending on how the split is defined. The CG is just at the top surface of the delrin belly pan. Clearance is 3-3/8 inches, wheelbase 12-1/4 inches, width squish-to-squish is 11 inches. I am running an 8 tooth pinion in the R2 which is probably a bit short....anyone have any comments on the R2 input gear? I found a couple sets of gray Losi's for the E-Maxx shocks which may be too light but they look OK on the bench. I will tailor the spring complement after I see what the torque looks like. I have a rear axle brake drawn up and designed to fit into the driveline but am going to see how it works out with just the disconnect feature. Next task is to convert the Novak ESC for single battery pack operation and make up the wire harnessing.

tjarr001

from your pictures i noticed that your driveshafts werent centerd on the frame. are most crawlers like that? im still waiting on my tlt to come in from ultimate hobbies then im gonna get started on it. are they usually to the side like that due to the way the trany is built? ill be using a evader trany, will it be offcentered like that? thanks for any imput

Hicentered

The Roosterfish is up and running now so the build thread is about complete. The weather hasn't encouraged me to get out on the rocks but I've done enough carpet crawling to get comfortable with the Tx and Rx configuration and settings. The R2 dig clutch adaptation seems especially smooth and positive. The 8T pinion and 55T motor makes for pretty short gearing...I suspect I will want to pinion up some after abusing some rocks.
The photos are shots of the finished rig and some more configuration details. The last photo is the Rooster alongside my extensively reengineered and reworked Clod-based Rockbull II.

Anomie

That is a very nice rig! I was hoping to see the finished product, and it certainly does not disappoint. I really like the way you engineered that coupling, and I have to say it has inspired me to think in an unconventional direction for a drive coupling on my truck. It also sounds as if it will perform well on the rocks, judging by your testing thus far.

All in all, fantastic work [sm=thumbs_up.gif]

Hicentered

FWIW...a little more info on the RF that might be of general interest:
I made up the attached chart for measuring ground speed and checked the Rooster with the W2 box, 8T pinion, 55T motor, 6 cell pack and RC4WD 2.2 Moabs.
The times averaged for 40 foot run was just 19 seconds so the average ground speed was ~1.4 MPH.
I believe the R2 is a 27:1 box with the 8 T pinion and the R-P reduction is 2.7 for a total reduction of ~ 73:1. The 55T motor rpm at 7.2 volts is ~8450 so the final wheel RPM is ~115 RPM.
The rolling diameter of the 2.2 Moabs is just at 4.75 inches. The MPH from the wheel rolling diameter calculates out to be ~1.4 MPH so that the empirical correlation is OK. That being said I feel comfortable in using the chart for comparing pinion selections.
The Rooster has more than enough low end torque and is impressive on the tough pulls but moves very slowly otherwise. I believe I can use a larger pinion and still have plenty of pull-out torque with a better flat ground "walking speed". A 13 T pinion should bring the relative speed up to around 2.4 MPH and a 7 cell pack up to 2.8 MPH which is just about where I prefer my Clod flat ground speed to be.

Hicentered

When I designed the RF I planned on front and rear steer so I made up four clocked C's to get zero caster on both ends. After working up the R2 rear disconnect feature, however, I decided to eliminate the rear steer so that clocked C's there aren't needed. I just finished up some new fixed outer bearing housings for the rear. This was encouraged after I ended up twisting off two axles on the same side while crawling in my favorite boulder patch. The 55T-R2-8tooth pinion drive combination (73:1) on 6 cells is capable of walking through an axle just about any time the throttle is buried with a wheel wedged. The climbing speed is OK, the walking speed is too slow, the torque is great and the motor loafs but stock axles just can't handle the available torque.
Fortunately, since both twisted axles were on the same side of the rig a short and a long one was sheared off. I swapped a good one from the rear and modified the two broken ones to use on the rear by adding an extension to engage the outer axles. I reusing the 2mm cross pins from the broken ball-ends. The aluminum bearing extensions are a direct replacement for the two removed clocked C's and knuckles so that all the stock axle dimensions are maintained. I took the easy way out, turned off the plastic knuckles and inserted them in the aluminum extensions. This way the outer bearings remain in stock spacing and position. The inner axle extesions with the cross pins are carried in a slightly loose fit to the pocket of the outer axles. The outer differential bearings are eliminated.
I am installing an 11 tooth pinion which will drop the overall reduction to ~53:1 but I still going to be careful with my throttle in tight spots...especially with the rear disconnected

Hicentered

After considerable tormenting of the Roosterfish on the rocks it was clear that dig disconnect without a brake feature is of little advantage. Fortunately, the mechanics and servo actuator seems fool-proof so I decided to sacrifice another 1/2" socket to the cause and fabricated the disconnect-brake I had designed earlier but never incorporated. When moved forward the socket/output yoke assembly is locked onto the hex plate screwed to the R2 housing and when moved back it engages an internal hex drive nut on the output shaft. I was able to use all of the original servo multi-linkage parts except for a simplified servo-saver torsion spring interconnect on the shift pawl. To accommodate assembly of the machined output u-joint I pressed the solid cross-pin out of a Traxxas joint ball and replaced it with a 3mm M.W. pin retained by a grub screw. So far, this seems to complete the dig capability I want for the TLT comp rig....no on to a scale trail project.