Starting a new project...

[kuskye25]

with those small wheels i bet your torque and acceleration is insane, haha

[LeadFootedRacer]

Per Snook's reccomendations, ive installed a 24t clutch bell on the pro.15 and a 66t spur gear, hoping to return the truck back to a more stock like acceleration/top speed.

[kuskye25]

Per Snook's reccomendations, ive installed a 24t clutch bell on the pro.15 and a 66t spur gear, hoping to return the truck back to a more stock like acceleration/top speed.

oh ok...................

[LeadFootedRacer]

Lower extended rear skid done, built an aluminum rear bulkhead brace, mounted the rear slash bumper, and lowered the body posts. Looks alot better now. Will get pics up later.

[LeadFootedRacer]

New holes in the body posts:


Pinned in the towers:



Body now sits in a more respectable location:


New rear skid:




Bulkhead brace (now also a bumper support mount [yes, there is an extra hole, oops]):


How the bumper fits with the body on:




Doesn't look bad for a 1/10th scale (Slash) bumper and an 1/8th scale (SC8) body. I did buy RPM mud flaps for the Slash, and then realized they are specifically designed to fit the RPM bumper for the Slash. I have not decided wether or not they will end up on this truck. Still have to mount/modify front bumper, clean everything up, paint some parts, and a few other things. Waiting to hear back from UE on the rear dog bone they are custom making me.

[LeadFootedRacer]

This also came in today, which is great, as my assortment of used hardware has pretty much been depleted.

[LeadFootedRacer]

Started the final assembly. Still need to modify the front skid, havent had a chance to get back to the shop. Also waiting on a dogbone from UE. Hopefully in the next week or two.

[LeadFootedRacer]

And there she sits... till I get the front bumper on, and the rear dogbone. Took it out today to make sure everything worked. Ran real bad, but its only 35* out and drizzling. Needs new batteries for sure, servos are pretty sluggish, but other than that, everything checks out. Need to do my toe/camber adjustments too.

[kuskye25]

cool man, i like it a lot, did you powder-coated the chassis

i really like that it makes everything in the center of the truck, itll make for good COG

very interesting build

[LeadFootedRacer]

No powdercoating, just some flat black spray paint. Pretty sure it will was off with the nitro fuel, but it looks sharp for now. LoL

[LeadFootedRacer]

Still no word from UE on my bones. Emailed them last wednesday, they got back to me thursday saying they could do it if provided the length. Gave them a length and havent heard anything. Emailed them again wednesday this week asking for an update and a price, and have yet to hear back. Hopefully they can do this for me.

[LeadFootedRacer]

Anyone know what thread the UE drive cups are? Need to buy some set screws, as the cups didnt come with any. Thats another thing I emailed UE about, and didnt hear back on.

[Kyleb]

I was only missing one set screw from my cups. A regular 5mmx6mm set screw will work/ just went and got some spares yesterday

[NitroTrout]

Still no word from UE on my bones. Emailed them last wednesday, they got back to me thursday saying they could do it if provided the length. Gave them a length and havent heard anything. Emailed them again wednesday this week asking for an update and a price, and have yet to hear back. Hopefully they can do this for me.

What length of dogbone are you looking for (pin to pin)?
I had to order HPI dogbones to fit my monoblock extension.
They're 9mm x 123mm pin to pin I believe.

[LeadFootedRacer]

150mm pin to pin. Ive researched high and low for a pin close, the 142 is the closest I could find, but was too short.

[Snook Man]

Since you’re having trouble getting the correct length bone you may want to try this as a temporary (until you get a bone made) or a permanent solution.

The Revo Center differential pinion (part#5416 ) has a long pinion shaft that can be cut to the length you need to make up the difference with a short dog bone.
The bevel gear face is a little smaller width than the stock pinion but when shimmed well it holds up fine. (I have run this method with .28 BB engine without issues)

Just cut the shaft to the length you need for the bone you’re using and then add a bushing(s) to take up the space between the drive cup and the outer bearing so that no inward pressure from the pinion can be exerted on the ring gear. Then just cut/grind flat spots in the shaft for the drive cup grub screws.
You can easily make up 10+mm in difference.

[kuskye25]

nice mod to help the op out....

[Madd802]

nice build.... Glad i checked it out

[LeadFootedRacer]

Wow. I actually really dig that mod. That gear uses the same diameter shaft and bearings, as well as the same gear tooth count/pitch?

Any particular material I should use for the bushing? I have access to aluminum, nylon, brass, and steel.

How do you "shim" the gear?

[Snook Man]

The shaft diameter and gear pitch with the revo center diff pinion is the same as a stock pinion with the exception of the longer shaft and a little narrower gear face width.
You can use any of those you listed with a 6mm ID for a bushing, just cut it to length so that with the bushing/spacer installed and the cup attached to the pinion shaft there is just enough end play for the pinion to move smoothly.

Shimming a diff is just setting the mesh between the ring and pinion gears so that they are not too tight or too loose , like a spur and clutch bell mesh, only with a tighter tolerance.
If needed: You can shim the diff cup/ring gear assembly left or right in the diff housing and/or shim the input pinion forward or backwards against the ring gear to where there is no binding, very little play and everything turns smooth as warm butter on hot toast.
You need the appropriate sized shims for the shafts or bearings depending on which you shim.

Here is a good read. A little dated but applies to almost all diffs in general.
http://traxxas.com/forums/showthread...g+differential

[LeadFootedRacer]

Will read that. Thanks for the info. One last question before I get elbows deep into this, how would one go about identifying a "blown" or "bad" diff? I had troubles with my other truck when I put the 3.3 in it and upgraded that truck to brushless diffs, and now there is a pile of diffs in my parts box. I have 3 all together, the one I spooled got thrown out after it failed. I know one of these had failed, and the other two were primarily fronts. (One from my truck, and one from a roller)

[Kyleb]

Unless there is metal metal shavings or chipped diff teeth you have nothing to about. Just shim them
So they mesh nicely, with little to no play and they don't bind

[LeadFootedRacer]

I blew 2 diffs, opened them up and there was no evidence. LoL. I kid you not. I knew they were bad when all that would spin was the front tires. But by hand, they appear fine

[kuskye25]

I blew 2 diffs, opened them up and there was no evidence. LoL. I kid you not. I knew they were bad when all that would spin was the front tires. But by hand, they appear fine

yeah what, ive never blown a diff or heard the dreaded clicking and not find evidence...

and im not just speaking for maxx's, ive blown diffs in prolly 10 different vehicles and all different manufactures...

somtimes the flakes/pieces can mix into the grease or lube... and be hard to find

[kuskye25]

Will read that. Thanks for the info. One last question before I get elbows deep into this, how would one go about identifying a "blown" or "bad" diff? I had troubles with my other truck when I put the 3.3 in it and upgraded that truck to brushless diffs, and now there is a pile of diffs in my parts box. I have 3 all together, the one I spooled got thrown out after it failed. I know one of these had failed, and the other two were primarily fronts. (One from my truck, and one from a roller)

wait you put in e-maxx diffs and blew them with a 3.3, ok man you definitely need to start shimming your diffs haha.... properly built bl diffs should last you a long time, so i bet its cause your mesh wasnt good and you didnt fix it when you built them... i tore mine apart after 1 gallon and were like new still, im on 2 1/2 gallons now and i beat the crap out of my maxx....

even non bl diffs hold up just fine... i rarely blew stock 3.3 diffs maybe 2 out of 4 trucks, but then again they were shimmed...

[Snook Man]

I blew 2 diffs, opened them up and there was no evidence. LoL. I kid you not. I knew they were bad when all that would spin was the front tires. But by hand, they appear fine

If there is no evidence of broken/worn teeth on the ring and input pinion and the bearings were still in good shape the problem would be inside the cup.
Did you look at the spider gears? You may have spun the spider pin in the cup or broken a spider gear or 1 of the cup output pinions.

[LeadFootedRacer]

wait you put in e-maxx diffs and blew them with a 3.3, ok man you definitely need to start shimming your diffs haha.... properly built bl diffs should last you a long time, so i bet its cause your mesh wasnt good and you didnt fix it when you built them... i tore mine apart after 1 gallon and were like new still, im on 2 1/2 gallons now and i beat the crap out of my maxx....

even non bl diffs hold up just fine... i rarely blew stock 3.3 diffs maybe 2 out of 4 trucks, but then again they were shimmed...

No. I blew the older unsealed 2 screw diffs with a 3.3, steel cvds, and big joes

[LeadFootedRacer]

Just ordered that revo shaft. With the recent move, things have been slow on the hobby... hope to have more updates soon.

[kuskye25]

No. I blew the older unsealed 2 screw diffs with a 3.3, steel cvds, and big joes

oh ok i gotcha...

[LeadFootedRacer]

Established a new ride height. After the truck was fully assembled, the cut savage springs did not provide enough pressure to raise the skids off the fround. Preload spacers were out of the question, at full compression the coils almost touch. I added another set of stock shocks but with stock red springs and no spacers. Both sets of shocks still running 30wt oil. Hoping to get the rear diff and driveshaft mods done friday so I can start driving this beast and work out the kinks. Setup the front end with -1.5 degrees of camber and a tiny bit of toe in. Once the rear is installed I will set it up the same way for now to see how it does.

Here is a pic of the new ride height. A little high for my liking, but it may settle down a smidgen.

[LeadFootedRacer]

Driveshaft in. Took it for a test run, and everything checks out. Got the tune pretty close and then my failsafe decided that my rx batteries were too dead to keep playing.

Current suspension setup is WAAAYYYYY too stiff. No squat. No body roll. Continuous barrel rolls when turning. All this proves is that my turnbuckles and modified control arms are suitable for the build. Now to figure out how to soften it up some. LoL


Also... would like to say, thanks again for all the pointers and suggestions on this build. The gear ratio snook reccomended gets this truck out of the hole nice and quick for an old pro 15. The revo transfer case gear in the rear diff allows me to run an off the shelf dogbone.

[LeadFootedRacer]

Also need to tune the shift point... shifts really early. I haven't been able to get a top speed run on it yet. Need to work on the handling a little more.

[LeadFootedRacer]

New batteries, replaced a front axle that broke on the last run, aligned the rear, pulled the 4 stock shocks with red springs, leaving 4 stock shocks with the cut savage springs, and out I went. Perfromed very well on pavement. Doesnt try to flip when hard cornering, yet doesnt have a significant amount of body roll either. My driveway is far from flat, and there are no scratches on the underside from bottoming out. I will try to get it out in the dirt this weekend and hopefully get a video of it as well.

[Snook Man]

Good to hear you got it out and running.
Setting up the handling to suit you on a new build when a lot of changes have been involved is always the last, and sometimes the most difficult part.
I spent weeks on a build once just finding the right springs and shock oil to suit me.

[LeadFootedRacer]

Turned full lock, one direction, driving in a circle on pavement, I can hear the tires screaching. It doesnt try to kick out, it just holds the ground. Im hoping it performs similarly in the dirt.

[LeadFootedRacer]

Took it to an open parking lot and really hammered on it. Flipped it once, which was my own mistake. Appears as though the cut black savage springs are working. From a dead stop, full throttle, the rear squats a little, and the front expands a little, just like a real short course truck. It does have a bit of roll in the corners, but all four tires appear to stay on the ground. Jumps speed bumps with ease, doesnt bottom out or anything. Quick out of the hole and top speed is pretty impressive. Tires dont like getting wet, makeds for interesting turns, but again, all this is on pavement. LoL. Cant wait to get her in the dirt.

[LeadFootedRacer]

Back to the drawing board with this one. Going to be redesigning the control arms and making them out of aluminum. Once those are done, hoping to build a new chassis plate with the extension built in. Probably going to move tye battery box to the gas tank location and move the gas tank to behind the motor. Truck seems too front heavy when jumping. Stay tuned for more updates.

[SuperPanda]

looking forward to it. i have a question. why go aluminum on the arms? ... did they break? wouldn't that add more weight?

[LeadFootedRacer]

The truck performs well as is, but when I redrilled the pivot ball holes, my thread quality went out the window. The pivot balls have jumped a thread or two here and there. I have access to cnc machines, so aluminum parts arent hard to come by.

Here is my rough idea of an upper arm at the modified length:

[LeadFootedRacer]

This would be made from 6061 aluminum.

Still need to draw up the lower and quite possibly make a few changes to the design prior to moving on to the next stage.

When I say it performs well, what I am saying is that from a dead stop, the truck will spin all 4 tires at wot. The top speed of the truck isnt a huge factor, as it is designed for short course racing. The plastic arms are also harder to come by, as I modified a set of the narrow style from an early maxx.