Hopup vs Homebrew - a CC01 project thread

[Mad Ax 9313]

So I found this:

Some alu angle bracket that I've used to make chassis.

Cut and filed, I made these:

Initially I installed them over the axle, as seen here, to try to increase clearance under the lower link, but they made the right height too tall and there was no way to bring the shock mount lower without making some messy assembly.

[Mad Ax 9313]

Here, the ride height problem is obvious:

So the next idea was to flip the mounts and cut off the extra meat.

Now they fit much more like a stock setup, and very much like those on my scaler but less tidy and much easier to make:

I'm using full-size hex heads on this as they're all I have that fit.  Ideally I should get some round head screws to increase clearance.

[Mad Ax 9313]

Final assembly looks pretty neat, I think.

The eagle-eyed among you will notice that I haven't replaced the top links.  I'll get to that later.  I should also make some covers for the bottom links (it's easy with alu tube), to stop the links getting hung up on stuff.

You might also ask why I rushed the rear mounts when I could have done something much tidier.  The truth is that I don't anticipate this 4-link setup remaining in place.  I have bigger plans for the rear axle, which will have to wait until after the current setup has had a chance to compete against the Junfac kit.  I want to get a baseline on a "typical" homebrew 4-link before I make further changes.

Next update will show installation of the Junfac front skid plate and 4-link kit on Hopup, just for completeness, but will have to wait until I actually get around to such things.

[Mad Ax 9313]

OK.  Been a bit of a slow few days with certain jobs taking way longer than planned, but I did find time to get the Junfac 4-link kit fitted to Hop-up.

Apologies for the poor quality photos - the famously changeable English weather has changed again, leaving us with darkened skies and intermittent heavy rain, so I've had to keep the workshop roller door shut.  There seems to be something wrong with my striplights because I don't seem to have any light over the workbench.

Anyhoo - here's the Junfac kit.  Note that it comes supplied with a skid plate, but I won't be fitting it this time around as we are specifically testing 4-link homebrews against hopups available from the shops.

And for those of you who can't remember what a standard CC01 underside looks like, here it be:

Kit opened and parts sorted.  2x long links, 2x short links, 2x axle mounts, various screws and locknuts, some grub screws for the links, and some rod-ends (with spares).  Quality looks and feels good.  The links are blind-drilled to around 6mm with M3 threads and the rod-ends allow around 6mm thread depth - in my experience that's quite short for an off road link, but the CC01 is lighter and less torquey than some more dedicated crawling hardware, so I hope they hold up OK.

Grubs fitted and rod ends assembled

[Mad Ax 9313]

And fitted.  Took about 30 minutes.  I will admit I had to look at some online photos (there are no instructions included) to work out how the link mounts went onto the axle, and I don't know if I put the washers in the right place.  Also I had to guess what length screws to use where, and keeping everything symmetrical, I was left with two odd screws for the main link mounts.  It didn't matter how I divied up the screws, I would always have to have an odd length left-to-right in one location.  Officially, if I fit the skid plate, I will have to replace the screws on the lower links anyway (the skid plate screw doubles as a link mount screw), so it's not a big deal, but it just leaves me feeling a bit uncomfortable, like when a sock has inexplicably spun around in a trainer and you're not sure if you need to walk backwards or upside down.

I actually really like the axle mounts.  I've seen some other versions which are big and clunky but these are very neat.  Being bolted in two places, they don't twist in use and should be strong enough for regular CC01 use.  Great ground clearance too.  As I mentioned earlier, I think the stock CC01 axle is odd in having no shock mounts, but this looks like a neat solution to the problem.  An option of shock mounting holes allows for a bit more shock angle too, for a more progressive spring rate.

Without the skid plate fitted, the Junfac kit suffers the same hang-up point as a stock CC01.

[Mad Ax 9313]

Finished trucks side-by-side.  Wheelbase is identical.

Homebrew sits very slightly higher thanks to my custom shock mounts.  Homebrew also has slightly more shock angle because I drilled it that way and didn't provide an option for lower shock position.  I opted not to move the shock position on Hopup.  To be honest I doubt it will make any noticeable difference at all.

Here's a close-up of the Junfac link mount.  You can see how good the clearance is.  Way better than I expected, and way better than stock.

By comparison, here is the underside of Homebrew.  My lack of nice dome-head screws doesn't help but even so, my solution pushes the lower links downwards instead of projecting them forwards.

 

[Mad Ax 9313]

To summarise - I have not had a chance to drive either car yet.  Hopefully with my daughter returning to nursery tomorrow, I'll get back some lunchbreak time and be able to get out to the woods for a bash.

I had honestly expected the homebrew solution to be superior.  It's hard to imagine how that could be the case - if you have access to end-to-end CNC machined parts, you can make a better solution than someone chopping up angle-bracket with a hacksaw.  However, I had unfairly assumed that Junfac were just another company who solve problems by throwing anodised parts at it rather than looking at it in detail and coming up with a workable solution.  What they have is a very good solution, and ultimately it looks and feels stronger than my design, with significantly improved ground clearance (where mine is slightly reduced over stock) and a well thought-out part that doesn't fall into the trap of some other ebay options.

It has given me some great ideas on how to improve my design.  I can't copy it directly because I can't make parts from billet aluminium, but I can investigate moving the link forwards to get more clearance under the axle.  Ideally I'd love to attach the shock to the top of the axle also, but that's a problem for another day, when I really start hacking into the back end.

Stay tuned for a side-by-side comparison and more updates to the cars, including a robust solution to the problem of lower link ground clearance....

[Mad Ax 9313]

Quick update - I took Hopup and Homebrew out for a quick test-run in the woods during yesterday's lunchbreak.  A sharp shower came in just as I was setting out and wetted the ground nicely.  The terrain there is a mix of gravel on the track section, and heavy clay on the mud sections, with lots of big roots just under the surface to make things tricky.  A long dry spell meant lots of dust, and recent showers have turned it to a gooey paste that looks sticky on the surface but offers absolutely no traction.  This is where the budget tyres really showed their weakness and, to be honest, were the weak point in the test.

Otherwise, there is surprisingly little to report.  Neither truck excelled, and where one truck struggled, the other did also.  If one truck got stuck on a high spot, the other truck would get stuck just the same.  If one truck grounded out trying to hit an incline, so did the other.  In fact I'm not sure I got any better performance than I would have with a stock rig.  (I should probably go get a stock CC01 just to prove this point).

The biggest hang-up point on both chassis is actually the centre gear housing, which hangs down in the middle of the chassis.  There is no aftermarket solution for this and no home-brew mod that I can think of that doesn't involve drastic chassis alterations and possible alternative transmissions, which is way beyond the scope of this project - for now.

No pics on this adventure as it was raining.  My camera is waterproof, but wiping drops off the lens in muddy conditions is asking for trouble (the wife gave me her old TG-3 for her birthday because she'd just bought a used TG-5.  The first time she used it, she got grit on the lens, which she tried to wipe off with a cloth.  Hey-presto - one utterly ruined lens...) and trying to drive with one hand and shoot with the other while also trying not to fall over on the mud is no fun.  Next time I might try bringing a friend along and having a crawl-off - see which of us can lose the other over tough obstacles, then switch rigs and see if the same route feels easier or harder.

Before that though it's time for the next round of mods.  Hopup will be getting the centre skid plate, which should help lots with the new lower link bolts getting hung up, and Homebrew will be getting a fairly substantial mod to the underside which should give it drastically improved clearance.

It would be really really nice to replace the cheap Kong tyres with grippy rubber and heavy alloy wheels, but 2 sets of premium wheels and tyres would completely blow my project budget.

[Mad Ax 9313]

OK - managed to get a bit more done yesterday.  My first plan was to think up some solution to my rear link mounts hanging up on the stones, but I figured I was going to rip it all apart to mod the chassis soon anyway, so I thought the best place to start was to fit the Junfac skid plate to Hopup.

So - this is where we started

[Mad Ax 9313]

The Junfac skid plate mounts over the lower suspension mount at the front and the link mounts at the rear.  This is what it must fit on at the front.

I figured this wasn't ideal since those little round mouldings will push the plate lower to the ground, most critically creating a hang-up point around the leading edge of the plate.

I broke out my trusty Dremel and took a the mouldings down to the plate.

Now I've bought myself an extra mm of clearance.

[Mad Ax 9313]

Now when resting in place, the skid plate sits proud.  It's obviously bent to pretty accurate measurements, but it shouldn't be too hard to bend out later.

With the rear spacers resting in place, there's a clear slant to the plate.  That shouldn't me a serious issue, because it's sloping the right way and the truck should ride over anything that is that 1mm too high, but I figured if I could save some clearance here too it wouldn't hurt at all.

I broke out my trusty pipe cutter and some cheap alu tube which is brilliant for making spacers

[Mad Ax 9313]

Fitted and screwed down, the plate easily bends under tension, so no need to start trying to un-bend that nice factory bend.

[Mad Ax 9313]

Even with my mods, the Junfac skid plate costs quite a lot in terms of ground clearance.  The benefit is that it's a smooth surface, so if it hits a rock of root it should slide over instead of hanging up on the link mounts.

It's the lesser of two problems, but the best solution is to have neither problem, and it's that solution that I'll be looking for in my Homebrew update, coming soon...

[schlabinski 250]

Fun thread!  It sounds like you still have some tricks up your sleeve and I look forward to seeing them.  Here's something that I started on many years ago...I wonder if you're up to something similar?

More of that project:  https://flic.kr/s/aHsjS3X1DW

[Mad Ax 9313]

@schlabinski I have something very similar in mind, not quite the same as yours but definitely in the same ballpark.  Just uploading pics now

[Mad Ax 9313]

First of all, I needed to make a link that gave more clearance than my current solution.  Having the bottom link underneath the axle, with a full-head screw as well, presented the ground with a nice edge to catch the truck on.

Here are some random doodlings followed by 30 mins in Fusion 360:

Taped onto a piece of 2mm alu sheet

Holes drilled and bolted into place

And a very rough example cut out

[Mad Ax 9313]

The axle mounts need to be away from the ground, so they need bending into shape.  Some heat from a gas torch and a tap with a hammer gets the alu over without damaging it.  Getting these perfectly symmetrical is tricky and requires lots of patience and lots more luck.

[Mad Ax 9313]

Still a bit of work to do on those yet but it was getting late.

Earlier in the day (thanks to whatever protocol decided my photos should have been uploaded out of order, I have missed a step) I cut the mounts off my chassis tub.  There is officially no going back now.

This is 15mm U-channel.  It fits very nice over the moulded chassis rails.

Unfortunately this is all I have.  Actually I think this came to me attached to my very first CC01, as front suspension mount.  Some more is on order and should be with me tomorrow.

[Mad Ax 9313]

I finished work early and had a bit of spare time, so I got out the gas torch and folded some more aluminium sheet.

These are far from finished - they still need deburring and polishing, but as least they can be test-fitted to prove the concept.

[Mad Ax 9313]

Here they are bolted into place.

I don't have any round-head screws long enough to reach the top link nuts, so for now I have installed full-head screws.  The finished product will probably be countersunk.

[Mad Ax 9313]

Here is a mock-up.  The lower link chassis mounts are just pushed into place into holes I drilled in roughly the right place.  Unfortunately I chose to drill exactly where there's some webbing behind the rail, so I couldn't get nuts on the end for a sturdier proof of concept.  However it gives a good idea of how the finished product will look.

[Mad Ax 9313]

The lower links will probably have to be spaced inwards a little to clear the rails (they bind very slightly as they are) and the shock angle looks a bit extreme - I can always move the shocks to the LWB position.

The whole assembly hung together long enough to get some body-on pics.  Slight wheelbase issue will be solved once the final mounts are fitted and the links are adjusted.  Ride height issue is due to some guesswork about exactly how much height would be gained / lost in the bending of the 2mm sheet, but future suspension plans will allow for more adjustability.

[schlabinski 250]

Looks great!  I appreciate your good pictures and explanations.  My interest in the CC01s goes way back to when the Touareg was released and before many hopups were available, so I always enjoy seeing how people modify these with homemade parts.  I look forward to continuing to follow along here.

[Mad Ax 9313]

After I got back from my Sunday morning motorcycle ride with the SCX10 G6 attached, I figured I should probably try to make at least some progress on my RC projects.  Homebrew had been sitting on the bench for over a week and my wife had complained that she couldn't get to the tools, so I decided to crack on and finish the links so I could put things away.

This is about where I left it last time: a piece of 15mm aluminium C-channel pressed over the chassis rail.

It would need trimming to fit properly, so I marked it in situ and joined up the dots.

60 seconds with the hacksaw and I had a very rough chassis rail.

To make sure the links were perfectly symmetrical, I needed two identical rails.  Easiest way to achieve this is to bolt them together, then file them together.

[Mad Ax 9313]

And here they be:

The back end of the links is going to press up against a plastic moulding on the chassis.  This is how I can be sure the link mounting point is the same on both sides.

In the name of not getting hung up on the trails, I added a chamfer to the front of the rails.

Then I stuck them on the bench polisher.