Project: X

[-BEZ-]

Its been a while since I have had a fresh project to get my teeth into and with winter coming up there no better time than to start.

 

Project Outline:

 

I get my RC buzz now from making stuff go super fast, but that always comes at a price of a car that is a one trick pony. So It got me thinking .... how can I go fast and still have something I can thrash about dirt tracks and carparks etc.

 

After having a ponder I decided I wanted to build a rally cross car. Something that will go over 100Mph and slide sideways on dirt for as long as I want it too.  The easiest option would be to buy a TC chassis and one of the many replica bodies available on the market, but easy isn't fun and small chassis's aren't good for chucking ridiculous amounts of power at, nor are they that good for taking a beating when things go a little pear shaped.

 

So with the basis of the project lined up it was time to start considering the various options available on the market. It didn't have to be a super agile racing thoroughbred, parts needed to be easily available and at sensible prices. The most important requirement was it needed a drive line strong enough to take 8 cells of lipo insanity ........ yes that's 8 cells .....muhahahahaha. 

 

 

About the Chassis being used:

 

My search took me to the Hyper GT from Hobao (Distributed by CML), built off the solid Hyper SS franchise and with the parts availability and support that would keep me parts when they need replacing. I have to admit out of a lot of shells on the market I have taken a liking to the design of the Hyper GT.

 

Out of the box the chassis is not laid out for a overkill power system, but that's where the "project" comes into it. Modifications to the stock chassis will include:

• Saddle lipo trays (similar to what castle did with their early brushless conversions - Trays built into chassis guards)
• Redesign of the motor mount for relocation of motor to allow space for the above lipo trays
• New ESC mount for MGM 25035-3
• Reinforce the body with a purpose built rollcage /nerfbar configuration to reduce flex at high speed.

I'm sure there will be other challenges as I go though the project but for now those are are the immediate challenges.

 

 

About the Electronics being used:

 

ESC

For me the controller of choice is an MGM X2 Series in this case a 25035-3 which has had additional waterproofing as I want to use this all year round and additional power caps fitted to cope with the extra length of wires a saddle pack arrangement produces. The ESC can run at a constant current of 250A and can work with a input voltage of up to 35V. 

 

Motor

For now I will be using my old trusty 1515 2200kv can which is fitted with ABEC 7 ceramic bearings. Once I am further through the project a better daily KV will be something in the 1600-1800KV range.

 

Steering Servo

As I plan to run all year round the sensible choice was a waterproof servo, The Savox 1210SG while being waterproof it doesnt sacrifice power at an impressive 20KG.  I've always had great success with savox servos and Im yet to break one even with all the crazy stuff I have done with my cars over the years. (I hope I haven't just jinxed that as I have had a gear set for my 1256tg in reserve for over 3 years) 

 

Radio Gear

Ive been using a Spectrum DX3R pro for what seems like forever now and when paired with Spectrum's MR3000 rx I get range than is beyond my sight. Being a marine receiver it has the added benefit of being 100% waterproof, not only that is its the same footprint as their micro receivers which is a bonus.

 

Lipos

Currently I will just be using what I have available and they are 2 x 5000mAh Turnigy Nanotech 65-130, I don't have a lot of faith in their advertised power output but they are good for 250A so thats perfect for this project. I plan in investing in some SMC lipos down the line, or I may go another route. Either way I will do a write up on the differences when I get that far.

 

 

So the other day a nice box arrives from CML with the Hyper GT and servo, It felt like Christmas ......... I cant help it I always get excited about a new project.

 

HoBao Hyper GT: First Impressions (unboxing)

 

 

First impressions going over the car are really impressive, gone are e-clip hinge pins (I really hate those), so far I'm yet to find a single eclip thats always a promising sign in my books. The shocks are sturdy and so much prettier than the previous Hyper 7 shocks. Although the Hyper GT shares the same chassis as the SS buggy the shocks are shorter as you don't need so much additional travel for a on road car, It also helps the body sit lower on the chassis.

 

Overall the car feels nice and sturdy the arms look like they should stand up to a fair amount of abuse. The shock toers feel nice and chunky and the finish is good. Hinge pin plates appear to be stamped but to be fair they look strong enough and are made well. they are fitted with multi position blocks so you can alter the toe and caster angles.  

 

 

Wheels and tyres come unglued which is a huge bonus as that means they can be taped to help deal with high power systems. With this project I will be using GRP tyres as I know from previous experience they are good for over 110Mph. That said I will be taping these up and running them to how well they perform out of the box, I really like the fact that they come with a low profile foam insert to help keep the rotational forces as low as possible.

 

 

In the box you also get all the body accessories: wing, wing mirrors, body clips, foam donuts for the body posts (I'm very impressed these were included in the kit) It might not sound like much but there is nothing more annoying that a body shell cluttering down the road.

 

 

Also included is a simple tool kit, you can never have enough allen keys and nut wrenches in this hobby, I like the fact that the Hobao wrench also has the turnbuckle wrenches cut out of its body.

 

So after loosely fitting the tyres to the rims and putting the wing on the body to get an idea of what it looks like in the flesh I ended up with this:

 

 

 

 

Some more pictures of the chassis and body in better light and after fitting GRP's, servo and motor into place:

 

 

 

 

 

 

 

Now for a couple of pics with the body:

 

 

 

 

 

 

 

The first hurdle to over come will be how to make the smaller GRPs not look so lost in the precut arches of the body.  I'm sure I can print some kind of wheel arch to help with that. The rear wheels are a bit lost inside the body, but thankfully HoBao do a range of extended 17mm hubs. (i only have +2mm fitted currently, but im hoping to try both the +4mm and +6mm to get a better fit to the body.

 

But I have to admit its going to be one good looking RC once its finished, that's if the early impressions are anything to go by.

 

 

That's it for now, but more updates will follow soon

[froggy8]

that looks well nice

[kiza1208]

Looking good BEZ only skim read it as its to much reading for me to do at the mo lol. I like the sound and look of what your doing.

What paint job you going with?

[-BEZ-]

ohh paint jobs good question ....... well I have to in mind currently take my fancy:

 

 

 

and:

 

 

[jony nitro]

I just read it! Then you let me down! You said Nano tech, but then I smiled you said SMC at last a proper lipo, great work

[kiza1208]

I'm liking the look of the 1st paint job. Would look good on something better than a Subaru.

[Noj]

Interesting project. Always liked the look of the GT, and for the money, I reckon it's excellent value.

[-BEZ-]

The cars are fantastic value for money. At the moment the kits are

[Noj]

One of the best vfm cars on the market, IMO.

Interested to see how you cram saddle packs in...

[-BEZ-]

Chassis review cont.
 
I have managed to dedicate some RC time to the project today, my current task is to strip the chassis down in prep to measure parts prior to designing some new parts to take the chassis help me cram in 8 cells of lipo insanity.
 
While I'm going through the car bit by bit I will be continuing to write up my review of the chassis.
 
Lipo Tray
Ok so its not the most exciting part of a RC car but its a very important to get it right. HoBao have done a pretty decent job of designing their tray. Its nice, simple and sturdy.  If I had one tiny grumble I would personally like a longer tray for fitting soft case lipos. This doesn't mean soft case packs wont fit it just means you will need to be more savy when choosing a lipo.
 
From what I have found is the tray is optimised for fitting 2 x 2cell hard case packs (race packs) when staked up the tray is designed to stagger the packs for easy access to the bullets.
 
Tip: When mounting 2 hard case lipos on top of each other use a strip of non slip material between the cells. This will reduce the chance of the upper cell sliding over and potentially damaging the bullets of the lower case in the event of a heavy impact with the ground or other immoveable objects.
 

 

 
I dug out one of my 4cell 5000mAh nano tech packs but unfortunately it was a tiny bit too long. That said you could be clever and carefully trim a section of the front of the tray without removing the edge to fit a longer lipo in the tray. This is a 5000mAh 65-130c nanotech lipo laid on the tray:
 

 
As you can see from the pic above tiny amount of trimming and it should fit like a glove.
 
Tray internal  dimensions: 140mm long (you could gain an extra 10mm with some delicate trimming) x 48mm wide x 34mm to 13mm deep sides 
 
Brushless Motor Mount
Normally with brushless RCs you tend to get a pathetic excuse for a motor mount that looks like it has been chucked together with no thought in the design. Its not uncommon to have very restricted gearing or find it difficult to access the pinion. I'm pleased to say for the first time ever I'm actually impressed with a stock motor mount. 
 
Key points:

• The mount is a beefy 10mm thick on the motor side and is milled down to 9mm over the diff half.
• The motor is attached to a plate and that plate can be slid up and down to allow a maximum pinion size of 24t (with that gearing its tall enough to make any off the shelf 150A ESC hot under the collar so to speak) Picture below shows 22t pinion fitted ( I tried a 26 but that was too large to mesh)
• O-ring inset into the bearing holder on the diff half, this provides a nice firm hold of the centre diff when fitted.
• Ergonomic design, 2 screws located on top of the mount to adjust the mesh, remove these 2 screws to remove the motor from the chassis for cleaning.
• Mounted to the chassis with 3 M4 bolts, this thing is not going anywhere once bolted to the chassis.

 
Motor mount close up - Showing oring, and mount adjuster
 

 
The above picture shows the mount fitted with a 22t pinion
 
Gearing
Stock Spur is a 48t metal spur on the hyper GT.  I will be looking around for a smaller spur  this has 2 benefits; you can go faster and fit a larger pinion without modifying the stock motor mount.  I'm hoping I will be able to find a 44t or there about that will fit, I'm fairly confident there is at least a 46t option on the market. 
 
Well I decided to do a bit of digging online.  I have discovered that the Hyper 9 has an option of a 40T spur, but looking at the part compared to the Hyper 7/ss/gt diff the cup is a different design so that is out of the question. However It makes me wonder if its possible to fit a hyper 9 centre diff to maximise the off the shelf gearing options. I plan to use a 30-35 tooth pinion for high speed runs so having a small supur on the centre diff would be a huge bonus.
 
I think its worth seeing if I can get hold of a hyper 9 diff to see if its compatible with the chassis, I will update this post as and when I find one and most importantly I can answer the question "does it fit"
 
 
Well that's it for now, I have a huge list of parts to sketch out while I wait on a few parts to arrive to sort a couple of issues highlighted in the first post.  I will continue my review of the remaining chassis features upon my next update.

 

In the meantime here is a sneaky picture of a layout I have in mind for the lipos/motor:

 

[-BEZ-]

I seem to be on a roll this weekend with being able to get some RC tinkering time, so again my time has been diverted to the Hyper GT project ...... after all its rude not to give it the love it deserves.
 
I will continue to finish off my chassis review in the post above but in the mean while I want to start talking about the 8s conversion.
 
Hyper GT - 8s Conversion, the beginning.......
 
At the bottom of the last post I made I showed you a picture of the kind of layout that will best benefit a 8cell (or more if you are completely bonkers). Last night I got on a roll listening to some music while tinkering with solidworks and before i knew it it was 2am .... always amazing how easy it is to loose track of time when you get into something.
 
Anyway I finished off the drawings and decided to print out the mount as a mock up and get it mounted to the chassis. Printing is a lot quicker for prototyping parts and less expensive if you make an error ....... that and my cnc still needs finishing ...... forever waiting on parts to arrive.

 

I used some colorfabb XT as its a pretty durable filament albeit awkward to print with. After printing a couple of test peices and tweeking the odd measurement I had slightly wrong (nothing to do with drawing parts at 2am  ) I ended up with something that looks like this:

 

 

 

 

The motor is fitted with a 26t pinion above (I have some bigger ones on order ...... I did have some but stupidly sold them with my DM1 a while back) 

 

?I know the motor is pretty high now compared to stock but with the lipos in a saddle layout and weighing in at approx 500g a side I'm hoping it wont adversely effect the handling of the car when running it about for fun. I will run the car in both configurations to test the effect on the everyday handling of the chassis (updates to follow).

 

I now have 2 huge areas to start constructing lipo trays in. I'm just waiting on a few parts to arrive (side pods etc) so I have a good idea of the space I have to play with. If at all possible I want to try and keep the weight as far forward as possible to keep the chassis balanced.

 

The main tasks i still need to complete for the conversion are as follows:

• Relocate rx box to free up more space
• Find a home for the MGM and design and make a mount for it
• Design and mount lipo trays

 

All in all I have had a pretty productive weekend on the project, I hope some parts will start arriving through the week so I can get back with another update very soon

[heavyleftthumb]

awesome project there pal. looking great. i will be watching this one

[RCbutcher]

Great car one of my favourites atm too but pipo holds me back. I really do want a 100% waterproof carpark basher , drifter , speedster tho. Your the perfect guy to get ob this car.

Shell i like it alot from the front and just like it from the rear.

Tge scooby paint scheme looks alot like monster lol they obviously didnt want to let that go, who designed blocks first scooby?

the evolutions have been called back to japan for faulty brakes and gearboxs not that it matters here lol.

[-BEZ-]

Just to keep things interesting I'm going to keep this particular post updated with what I believe are "Essential Upgrades" for the Hyper GT. Don't expect a huge list here as even with my OCD I'm finding it difficult to find fault with the car as it is out of the factory.

 

There are a couple of small things that bug me but at the same point they are really simple and relatively cost effective solutions.

 

Problem: Wheel Offset

Ok, now this in the grand scheme of things has no bearing on the cars ability, but as I have built a few scale drifters drifters over the years its something that gives the car more wow when the wheels have a more flush fitted look.

 

Solution: Extended hubs

As some of you are aware you can usually get bog standard 12 extenders for the majority of 17mm hex hubs. But what I discovered last year is HoBao do a whole range of different offsets for 17mm hubs. In fact they do the following 1mm, 1.5mm, 2mm, 4mm, 6mm, 8mm, 10mm and 12mm offsets (full list here). This is pure RC gold when it comes to getting the wheels to fit the shell properly. For the Hyper GT stock body I have found the +4mm on the front and +8mm on the back seem to have the best look and fit.

 

(Picture below shows from left to right: Stock hubs, +4mm hubs and +8mm hubs)

 

Before: (It doesn't look bad, but there is room for improvement)

 

 

After:

 

 

 

 

Problem: Keeping the dirt out

This is a car that will be used all year round for fun and for going fast so its important to me to be able to keep as much debris out of the car as possible. This will also have the added benefit of protecting the inner workings and more importantly make cleaning and servicing less of a chore after a days bashing,  anyone who owns or has owned a SC truck and run it through mud or wet grass will know exactly where I'm coming from.

 

Solution: Enclosure

The solution is to enclose the chassis with a cover. There are a "breathable" covers on the market that you can fit but my experience has been a bit hit and miss with this type of solution.  Baring in mind the Hyper GT is essentially a Hyper SS the logical solution is to fit a Hyper SS body and Side guards under the GT body.

 

I'm currently waiting on some side guards to come in on a back order so when I do I will update this solution but what I can do for now is show you a Hyper SS body laid over the chassis.

 

 

More to follow on this very soon

[heavyleftthumb]

yeah man that things now got stance

[Alex97]

Any updates on this?

[The Dark Knight]

How did I miss this thread?!? Awesome build so far, nice work on the motor mount

[ta05]

the second idea you had for a paint job is stunning, go for it!

 

The yellow and black work so well together with some stickers to mix it up!

[-BEZ-]

I'm stuck in the abyss of back ordered parts atm, but this thread has reminded me I need to give them a gentle nudge and see if they have had any luck getting the side guards I'm after  

[The Dark Knight]

Cool, will look forward to some updates soon hopefully

[-BEZ-]

Well good news, the side guards arrived

 

They fitted fine, if not a bit snug but the normal approach of fitting all the bolts loosely then tightening up worked a treat. They are definatly a welcom addition to the car and offer the rather exposed servo and rx box a bit of protection.

 

Please excuse the low quality of the pics the camera is rubbish in unnatural light lol

 

 

 

 

 

The plan is to design and print some nylon nerf bars to reach out to the sides of the body then screw from the body into the nerf bars to stop the body deforming under the forces at high speed. I will also be making some other supports to strengthen the body for high speed fun, more to come on that very soon.

 

In the mean while I have to attach myself to CAD and run a few prototype designs off.

 

Fingers crossed the next update will not be to far away

[ajlovering]

Have you painted the shell yet?

[-BEZ-]

lol not yet, thats the last job ........ so I can make sure I have lined up all the chassis/body supports im in the process of designing atm

[-BEZ-]

Oh god its really been a while since I updated this project.

 

I finally have some free time to give this some proper attention most of the time is taken up designing and printing parts for test fitting which munches time like nothing else. It can take an entire day just to do a single lipo tray, but as ever the amount of work put in always pays off

 

So the main push for me atm is to get the lipos mounted in place the solution I chose was to opt for a saddle arrangement. The added benefit is that I can double up the lipo trays to act as supports for nerf bars to brace the body. So Yesterday I set about sorting a design for a tray and optimised it for the Turnigy nano-tech 5000mAh 4s packs I have.

 

I'm keen to get the trays sorted ASAP as once they are done I can do the nerf bars and then get the body lined up and then that can FINALLY get painted lol

 

There are a few tricky bits atm like where to mount the MGM and Rx box but both of these aren't impossible tasks. The MGM in particular is a fiddly fit as with  the extra cap bank fitted it makes it rather long. I have a plan to print a cradle for it in nylon and hang it off the front of the centre diff at present but like most things that idea may well change by the time i get around to it

 

 

 

This is the r/h lipo tray V1 (it needs one hole slightly relocating, however for a V1 prototype it came out pretty much spot on. I'v designed it to fit the contour of the chassis and use any existing bolt holes that are existing so as you see it in the pic no holes have had to drilled to fit this tray which was one of my main goals to create parts that would simply "bolt on". The raised sections on the side have been designed to house m3 nylocks for mounting the nerf bars too, which will simply be ovals as they can absorb forces without over stressing the material.

 

I'm hoping to get most of the parts designed and printed by the end of the week, so fingers crossed the update will be very soon as I'm getting excited about being able to run this soon

[chewbacca]

Tis good to see progress, this thread was the inspiration for "Project Why" my 3s powered Hooligan