The low budget DIY XL conversion

[Nixpus]

Hiyas!

Last year I did a DIY Savage conversion. And it has actually been holding up pretty well. Driving at rediculous speeds on a pair of Terra pins was/is a pain. But jumping and serious off road is great!! Thus this is what I will try to focus on this time.

The thread from back then is here: http://www.rc-monster.com/forum/showthread.php?t=20862

I have bought a set of XL TVP's, all dog bones, bullet proof diff's (with the easy access housing - god the Alu houses I have now is a pain) & the wheel base widening axles. No fancy 3rd part bling alloy! I was considering the fat Flux shocks... but as far as I understand they are not that great for bashing since they stress the shock tower too much. or?

1st thing Ive noticed is that if I swap the TVP's I can make a window for the motor without much trouble. I need to cut a bit of the center gear box to make them fit but thats no problem. The reason for swapping them is that the motor will be less off center (placed like the flux).

Ive been looking for Lincpimps old build with the super simple mount but cant find it... but I will make something like that.

Motor wise I have the fat EZRUN 4465 2000KV & a KB45-08XL 1600KV... tbh I would like to have a lower KV motor, but as of now I will try to go with the KB and see what a budget motor can do. I will run it on 4-5 cells and gear for around 40mph.

The purpose of this thread? Present an alternative to the pretty damn costy stuff alot of you guys are doing Standard stuff all the way unless thers some 3rd party part which makes a world of difference... ?

Updates to come when Ive got some pictures to show :)

[Nixpus]

One question for the pros... whats the best (or least crappy) budget motor around? Low KV KB45-XL? Feigao? Something else?

Wheres the 4/6 pole cheap stuff?

[sabongi]

KB45 is a bit overkilll, i'd go with a kd-36 74 or 60 http://www.hobbycity.com/hobbyking/s...idProduct=6676

[bruce750i]

Castle's ever expanding line of awesome 4-pole 1/8 scale motors can be found (here in the USA) for a little more to the same amount of cash sometimes(ebay auctions) as other foreign 4-pole motors.

[Nixpus]

I love this forum: http://www.okhobby.com/category.php?id_category=88

55$ to my doorstep in Denmark... 1650 or 1860KV, 4-pole, 2S-5S... looks like a budget winner (too bad I have 2 motors already...).

[simplechamp]

Did you already buy it? I think the 43mm by 63mm might be a bit small for an XL Savage. They are the same size as a 1512 Neu, and in something big like a Savage XL it'd probably be better to go for something 1515 size or bigger.

[Nixpus]

A few blurred pictures of my progress...

Ive got 9mm extra sideways room after modding the standard TVP a little. Plenty of room for a 45mm wide motor like the KB45-XL.




Its the weight optimized race edition... bolted onto the TVP in 6 places. Hopefully it will be strong enough.

[Chadworkz]

Looking good so far! Everything I have read or heard about the KB45 motors has been positive, with the only slightly negative thing being the 6mm shaft, which makes finding pinions a bit more difficult. But, most people either drill out 5mm pinions to 6mm or mill the motor-shaft down to 5mm.

[scarletboa]

Originally Posted by Chadworkz

Looking good so far! Everything I have read or heard about the KB45 motors has been positive, with the only slightly negative thing being the 6mm shaft, which makes finding pinions a bit more difficult. But, most people either drill out 5mm pinions to 6mm or mill the motor-shaft down to 5mm.

i milled the shaft on my kb motor with a standard dremel bit. all i did was hook the motor up to the esc and spun it slow while grinding the shaft to 5mm with my dremel. all you have to do is eyeball it and check the size often with a 5mm pinion gear. then, all you have to do is grind the flat spot.

btw: you will need a custom motor mount. the kb motors have 30mm spacing and 4mm screw threads.

[Nixpus]

Roger roger Scarlet :)

As this is a DIY project the mount will be custom and accept both KB45 and regular screw size/spacing. Btw... you had some less fortunate experience with the KB45's as far as I recall? Do you remember what gearing you ran and if you had heat problems?

Ive drilled 4 holes in the front and back of the can to let heat escape more easily... may shorten its life but thats ok. The shaft was done on a bench lathe (I know... its almost cheating).

The mount will be made out of 2½-3mm hardned steel. I will not weld anything but simply cut and bend since this should be something anyone can do.

[scarletboa]

i had issues with the rotor slipping on the shaft. this can be easily solved with green loctite. i ran mine geared for about 45-50mph and the hottest i got my 1600kv xl motor was 145F in 95F ambient temps.

[Nixpus]

Some progres:

Motor mount ala Lincpimp:


Its 2mm HD steel... I couldn't bend anything thicker. In order to avoid damaging the thread I made in the steel sheet I'll add some M4 screws on top of it. Actually I could just have made some straight holes and added the screws after...

Yes it can wobble a little... a little :) I'll have to add some sort of support in the rear. However it can only wobble vertically. Not horizontally... so it should be pretty easy to fix.

Drilled a hole in the bend line to get the motor as low as possible:


I can mesh 13-19 tooth pinions as it is:


Chassis with battery trays:


Tested it a little around the parking lot with the KB on 3 cells. looked good :)

[Nixpus]

The alu battery trays... yes drilling those big holes did save me a few grams (and I agree it was a waist of time):


The cut out was needed to make room for the center transmission. On my previous E-Sav I had put washers in between the bat trays and the chassis to make room... but I wanted to skip that on this one.

The whole thing from another angle:


This has cost me a few hours of work... the materials can be found pretty cheap either at your local metal shop/smith or at a DIY retailer.

I know its nothing special... but I think its important to show that it doesn't have to cost alot to do a conversion. I'll update if/when I break anything ;)

[Nixpus]

Ran the big fat XL motor for 25 minutes or so yesterday... it is an absolute beast! And actually it didn't seem that power hungry? My drivetime was far better than the stock E-Revo my brother-in-law was playing with (Dang that thing is dull with the titan motors).

Without active cooling (bad idea I know) it did reach 92°C/198F after plowing through ½ a meter of weed up and down a hill... with a 14:1 gearing (another bad idea but I didnt check my final gearing result before running it).

As far as I could tell after letting it cool a bit it was ok. However I will look for a 45mm heat sink and gear down to around 18:1 ;)

The balance of the thing is great. A little nose heavy... but thats good in my book: Better power handling in a straight line + Better up hill climbing. Further more I would rather adjust a nose down landing than a rear bumber first landing. Putting the truck into reverse mid air sounds like a transmission killer? :)

I did one backflip... just to check.

I wonder a bit about gearing and heat. It shouldn't run freely and it shouldnt be loaded too heavily as far as I know... but how do I calculate the optimum? Guess I'll have to dig a bit in the brushless forum for that ansver.

[_dV]

Just gear it down until the motor temp level out and the esc starts to get hotter. Optimum is rather hard to work out theoretically ..lotsa factors that are individual to each machine.