Yokomo YZ870C First Run

Here's a video of the car's first run. Boy was I impressed. The car tracked straight, accelerated hard and steered really tight. I dare say in the right hands this car will stand a good chance making it to the A Main in the local races!

enjoy!

Project Losi JRX-2

You know how it all goes... see a pic of a cool RC car... google more pics... search forums for more info... and before you know it, you're spending hours working on the same cool car yourself!

Been about a week since my last post with the picture of that cool Losi JRX-2 buggy and guess what I've been working on? lol!

I bought 2 used JRX-2s a long time ago and I basically cleaned one up to be a shelfer and built the other one intending for it to be a runner. Back then I couldn't find a shell for any of the two cars and after hunting on ebay for the longest time for one I finally gave up and the cars were left aside.

I've since discovered wonderful resources for vintage cars like Mr Lexan's cool repro shells and I've also acquired my Sherline CNC setup and it was finally time to build my own JRX-2 with some personal touches!

Starting Off...
The first thing I wanted to do was to use some modern shocks on my buggy and in my opinion Kyosho makes one of (if not the *best*) shocks available today so their velvet shocks were the shocks of choice. Their 3" front and 3.5" rear shocks seemed the exact length needed for the car so I picked up a set.

On the JRX-2 rear, the lower end of the shocks didn't use traditional spring retainer and rodend due to the unique 5-link suspension of the car; instead the spring retainer features a unique "C"-shaped bottom end to attach it to the lower suspension link. While the setup works and is undoubtedly cool, I wanted to work out a way to use the standard shock end. After all, I intend to run this car and it would be unfortunate if I was sidelined because I damaged a shock end. :)

Here's the new lower link which I machined. It allows me to use all the standard shock parts and it "wraps" round the rodend so everything's nicely protected. It is identical in length to the stock lower link and the shock mount positions are maintained too so geometry is retained.








Shock Towers...
After mounting up the rear shocks everything looked good, but it seems that this setup resulted in a bit less droop than the standard shock mount would've provided. To solve this I designed a new shock tower with revised upper shock mount positions to drop the shock down by 3.5mm to regain the droop I lost. The tower is made from 3mm thick carbon fiber sheet so it should last a long time.




Since I was going to cut stuff anyway, I cut out a front shock tower at the same time. While it retains all the stock holes, I added one more upper shock mount hole and 2 more upper camber link holes. One of the camber link holes is there to allow me to swap to a RC10B4 upright with minimal changes to the upper camber link angle of the car. The 3mm towers should work well - not to mention CF always looks good!




Batteries... where do they go?
I started this project with the intention of using lipo stick packs in standard configuration but I when I tried to fit even my smallest 4000mah lipo packs into the car they were a very tight fit in the rear battery retainer. The newer lipo packs are also longer than the ni-cad packs this car was designed for... back to the drawing board.

After much thought, I decided to go for a slightly more unique setup on this vintage car... saddle packs! The idea is simple - the car was designed to fit a much heavier ni-cad battery lengthwise towards the rear of the car. Swapping to a lighter stick lipo in the same position would move the weight balance further front in the car. Using a pair of saddle batteries in the rear will move the weight bias backwards, thus bringing the balance closer to that of a JRX-2 running a standard ni-cad.

I don't like cutting new holes in vintage car chassis unless I really have to, so I designed the lipo trays to mount where the 5-link suspension block mounts to on the chassis. They fit the saddles nicely in the rear of the car and also feature 3 different sets of mounting holes so I can adjust the position of the batteries forward or aft to fine-tune the weight bias of the car.




Next problem... what's going to hold the batteries in place? I needed a battery strap and some way to mount the strap on. After a variety of designs scribbled on paper, I ended up re-designing the suspension mounts to incorporate a battery mount on it. Now I can fit a battery strap down with thumbscrews so I can accomodate batteries of different heights.




Wheels & Tires...
I wanted to run current tires on this car so wheel and tire testing began. Front tires weren't much trouble as standard B4 fronts worked fine. The rears were more of an issue... Standard B4 tires had too much offset and would not even fit on as they would hit the suspension links. I had a pair of Duratrax Evader and CRT.5 wheels with less offset but although they fit, they made the rear end far too wide for my taste.

I finally decided to drill holes on my axles to move the axle pin outwards to allow me to run B4 rear wheels while maintaining rear width. Now I have a full selection of my current tires to run on this car.

As she stands now...
Here are a few pictures of my JRX-2. I've still got to paint up a shell but she's almost there!



Hope you like the build-up so far!

JRX2 next up?

Just saw this pic of a JRX-2 from a post on rc10talk.com. Man the car looks sweet.

I'm currently debating whether I should prep one more car for the run in December - and if so, if I should work on an AYK BOOST, SG COYOTE or a JRX-2...

But this car really looks so good!

Yokomo YZ870C - all ready to race!

Finally my Yokomo YZ-870C is ready to run, finished up some final mods and also a body shell for the car.

Here's a shell that the used car came with. Gave it a good wash and trimmed up some of the cracked areas and it actually came out looking like a decent basher shell. I was told by a friend this looks like a "Eagle" shell from Parma. It looks like it was purpose made for this car given the way it fits with the under-tray.



I like the design of the shell very much although the paint on this one could have been a lot better. Funny thing is, "cab-forward" buggy designs were present even in the vintage era - though I must say the execution seems so much more aesthetically pleasing than the current crop of Bulldog and Punisher shells. lol


As I gave the car a once over I noticed quite a bit of slop in the suspension, particularly where the hingepins go through the bulkheads. I thought of machining some front and rear hingepin braces to take up some of the slop, but the wonderful guys at RC10talk.com suggested this solution - longer hingepins, a couple of balls and a turnbuckle. Nice!


Here's a pic of the car ready to run with lipo batts and a black can motor (requirement of our local vintage event). I also wussed out and changed the elegant stock bumper for a larger RPM one which offers more protection.


Okay so the nice basher shell comes off and here's the car with the Protech shell it's supposed to run - done up in the same paint that I run on almost all my race cars. I got this shell from Mr Lexan and I must say his work is very good - lexan seems to be of excellent quality and the body is well made with proper overspray film too.


Fresh paint, JC tires to fit 2.2" JConcept Caliber tires, RPM bumper, vintage AE gold shocks...


One more pic to go!


Drop me a comment if you like this restoration project.

YZ-870C update - lipo trays, body shell...

The last 2 days have been very unfortunate ones with regard to my tools... for some strange reasons, accidents have resulted in 1 broken carbide end mill, reamer and machine tap... and 1 messed up drillbit as well.

At least through it all there's been some progress on my 870C. Slow and steady she goes!

Manage to mill out new lipo battery trays as well as stand offs for thumbscrews to hold down the batteries. The tray on the right of the car can be flipped over to swap the battery position for weight adjustments.




Batteries mounted. Barely visible is also the servo mount plate that I made. I didn't want to drill any new holes to mount the servo so I used the existing holes in the chassis originally used to attached the chassis "spine".



Also trimmed out the shell and undertray. Took a bit of fiddling and trimming to get it to fit right especially with the new top-deck mounted. Here's a pic with the shell and Pro-line Caliber tires all round. Starting to look like an 870C now!



Gonna mask up the shell and get it painted.



Some stuff still to finish... wingmount wire, cut and paint wing, glue tires, rebuild shocks, install electronics.

If time allows I'm going to try to mount a rear brace to the hingepins also, not to strengthen it but to remove some of the slop. lol!

Vintage SG Coyote 2WD Buggy!

Won this on ebay last week and the postman delivered a nice big box today!

It's a buggy made by an Italian company - probably sometime in the 1980s - called a Coyote. The Coyote was actually a 4WD buggy but it wasn't unusual for companies back in the day to "convert" a 4WD buggy into 2WD simply by omitting the front transmission parts from the kit. This was the case with the 2WD Coyote.

The Coyote wasn't exactly a very well known buggy, but like many buggies in its time it boasted some very interesting and unique features. I hope I can cover some of these as I build this New-In-Box kit, hopefully in time for our vintage run in December. :)

Here's a picture of the NIB kit. It's awesome enough to receive vintage buggies in the mail, but the feeling of receiving a NIB ready to be built can't be beat!


The buggy pictured on the box is actually the 4WD version as the front drive shafts are clearly visible. It was obvious that - other than the giant number "2" on the box - this car was simply a repacked and rebadged 4WD kit. Even the list of features printed on the box says "TWO FOUR WHEEL DRIVE" as if to highlight the split personality of the car. :)


Here's a picture of the side of the box with the "Technical Data" of the car. Again, the car pictured is a 4WD version.


Upon opening the box I'm greeted with SG's version of blister packaging. While it is a far cry from the awesome Tamiya blister pack presentation (which often highlighted many of the performance parts in a kit), the Coyote's packaging is neat and functional.

Check out the manual too - boldly declaring "4WD"!



Lift up the blister and all the various parts of the car are neatly packaged. Also visible is the lexan shell which on first impression looks very well made and feels quite substantial.


Here's one quick pic of the manual - as stated before it is a manual for the 4WD version of the car with no obvious notes for how the 2WD car should be built. I'll figure that out during the build itself. :)




I look forward to building this kit soon but I will have to first measure and count the many self-tapping screws included and order up some more "modern" hex head screws.

Tune in for the build to start!

Finally a top deck for my YZ-870C

One more car to finish up for the vintage event and that's my Yokomo YZ-870C. Some of the great folk over at RC10talk informed me that the front bulkhead was prone to breakage especially where the front shock tower was attached. Their advise? Fashion a top deck to support the back of the tower to take some of the load off the bulkhead in the case of impact.

Took quite some time to measure up everything carefully but I'm very pleased with how it turned out!




Front of top deck with shock tower support. :)

Mudblaster and Yokomo 834B shells...

So it appears white is the new black. lol!

Short post with quick pics.

Mudblaster with painted shell... she's ready for the vintage event!



And here's the stickered up 834B. It's a basher shell so just trying to get it to look a tad cooler...

Yokomo YZ834B RPS SE Track Test

Here's how the car looked at the last vintage event held in October...



Although it started life as an RPS SE I had returned it to stock 834B specs for the event with the twin-monoshock suspension setup too.

I had a blast with the car but it was far from competitive. The stock wheels/tires combined with the monoshock suspension just couldn't handle the rutted track very well. For the upcoming event in December I wanted to go back to a dual-shock rear setup. So here's the car back in RPS trim.



Basher shell



With the rear independent suspension and the larger, more "modern" 2-inch wheels and tires the car was certainly transformed! It's still no TRF511, but it did much much better. Rough track handling was improved and the car was a lot more settled. There were some wierd steering characteristics but I attribute that to the limited steering throw (leading to a lack of steering) and the front one-way-bearing design (leading to the occasional breaking of rear traction resulting in too much "steering").

I did have problems with the king-pins though. The design of the car uses grub screws in the knuckles to hold the kingpins but because the kingpins are totally cylindrical there really isn't much for the grub screws to hold onto. Coupled with the soft plastic the knuckles are made of, this resulted in the kingpins coming undone easily.

Solution? I machined new kingpins with notches on the surface for a firmer hold. This way, the grub screw doesn't need to tighten all the way down to secure the kingpin, the notch will hold it in... that's the idea anyway.

Here's a pic of the new kingpins (I know... not much to see till I take pics of the pins removed) but they should work well and will be tested soon.

Mudblaster V2.0 bash and hop ups

Here's the Tamiya Mudblaster that I bought in a great second hand deal sometime ago. When bought it the shell was still unsprayed but it was in bad shape especially where the front bodymount had pierced right through the front hood.

After lots of puttying and a tedious paint job, she returned to her former glory ready for more bashing fun!





The above pics were taken just a week ago when I brought the truck out for a run. It was a blast and the car handled far better than I expected it to. Maybe it was the slow speed of the silver can, but the car actually negotiated the track pretty well (see video in earlier blog post).

Unfortunately the joy was short-lived... note to self: take hard-shelled vintage car off track when high-powered modern 4wd buggy comes on the track. The carnage is as follows...


The bodyshell is shot.




After combing the track I find the remnance of the windscreen...




Oh well... you know what they say... crap happens. :)


Although a tad broken hearted, I went home with good feelings of how well the car ran. I decided that I wanted to see what the car could do with a little work - especially in the upcoming local vintage race, the NOOB CLASSICS event.

So off went the cracked up hardbody (to be glued together another day...) and on went a lighter lexan shell. I found the HPI Wheely King shell a perfect fit for the Mudblaster wheelbase. A custom bodymount had to be machined to fit the shell but that's all sorted now.

Also off went the standard chevron threads and in their place a set of JConcept Goosebump tires on HPI star rims. I found a set of these rims at the local hobby store but the fronts were in black chrome and rear were in gold. After a few hours of chrome removal followed with dying, I got all 4 rims a nice black.

Here's how Mudblaster V2.0 looked at the track test yesterday!



The shell's yet to be painted of course, but I think you get the idea of how the truck looks.

A pic with my other buggy I was track-testing, the Yokomo YZ834B RPS SE!




In this body-off pic you can see the custom body mount. I don't like hacking up stock parts unless I have to - moreso when they are vintage parts... so the mount was designed to fit without any modification to stock parts.




How did the truck do?

It ran great, tracked well, felt really good!!! For the whole lap and a half that it ran before I hit a pipe and well...




I thought it was strange that the knuckle would break so easily since it had taken worse knocks than this. I'm guessing either (1) it was one of those murphy law incidences where the angle of the crash managed to break this part or (2) the previous collision that totaled the shell might have damaged this part before this crash did it in.

Disappointed I loaded up ebay to look for the part only to find that it was going for a *mere* SGD80+... not to mention the 2-3 weeks of shipping time it would take to get the part. I was understandably simply "ecstatic"...

So out come the calipers, the autocad gets fired up and the ol' mill gets dusted off. Thanks in part to the very basic design of Tamiya parts of yesteryear I was able to do this...



A new steering knuckle machined out of delrin that has a lot more material for reinforcement than the standard part. I'm hoping that the slightly more forgiving nature of delrin plus the extra material will make this knuckle bullet-proof. I found the stock knuckle to be a tad on the aneroxic side and brittle too.



More testing to follow to see how this baby holds up to the rigours of offroad bashing...

stay tuned. :)

There's a local Vintage RC event - called the NOOB CLASSICS - planned on 12 Dec 2010. It's the first event of it's kind and here's a couple of vintage cars that are doing some laps on the local track! :)

Another Rally Vid!

Here's another vid taken recently by a friend while I was running the Mini rally!

As you can see the car is pretty speedy on a black can motor and it is capable of managing the jumps on the track - although I clearly need more practice!

The nose down attitude in jumps is still something I'm working on - but it would appear the jump timing becomes so much more important so the nose drops at the right time to land on the downslope of a jump. :)

Enjoy the vid.