Speedy's RM01 Lancia Stratos Build Thread

[speedy_w_beans 4272]

The crowd has spoken and demands a RM01 Lancia Stratos!  (Build Thread Vote)

The goal:  A simple, low-CG, pan-style, M-compliant RM01 chassis underpinning a detailed low-nose Lancia Stratos shell from HPI.

The assets:  A fresh RM01 Tom's 84C kit, a fresh Lancia Stratos shell, some wheel and tire options, and the option to try F103GT front knuckles and axles in place of RM01 axle stubs.

Also, it helps to have a RM01 Mazda 787B already built for measurements and test fits of parts modifications.  

Will you be entertained?!?!

[svenb 3778]

Good luck with the build you jammy so and so

I put a HPI Stratos body on a M04, bit fiddley with the separate rear bumper but looks great.

[Fabia130vRS 2098]

I like the RM01, need to get one at a point of time in my RC collection.

 

if you recently had a look at my F104GT mini build, F103GT uprights were a tight fit. But, the GPM hex adapters with bearings Jug has pointed out, I have orderd them and F104 carbon reinforced uprights. In order to fit touring car rims.

[speedy_w_beans 4272]

41 minutes ago, Fabia130vRS said:

If you recently had a look at my F104GT mini build, F103GT uprights were a tight fit. But, the GPM hex adapters with bearings Jug has pointed out, I have orderd them and F104 carbon reinforced uprights. In order to fit touring car rims.

I just looked at these to see what they're about, and they seem attractive.  One question on my mind is how does a front wheel not wobble or bind with these?  If the axle nut is loose enough to let the wheel spin, then what forces the wheel to stay true to the hex?  If the axle nut is tightened so the wheel is forced true to the hex, how much binding or wear is there on the face of the wheel?

 

[yogi-bear 2321]

18 hours ago, speedy_w_beans said:

Will you be entertained?!?!

I will be entertained!!!!!

[Fabia130vRS 2098]

22 minutes ago, speedy_w_beans said:

I just looked at these to see what they're about, and they seem attractive.  One question on my mind is how does a front wheel not wobble or bind with these?  If the axle nut is loose enough to let the wheel spin, then what forces the wheel to stay true to the hex?  If the axle nut is tightened so the wheel is forced true to the hex, how much binding or wear is there on the face of the wheel?

 

Well, that also came to my mind and I wouldnt know until they arrive in the mail.

[ThunderDragonCy 7878]

9 hours ago, speedy_w_beans said:

I just looked at these to see what they're about, and they seem attractive.  One question on my mind is how does a front wheel not wobble or bind with these?  If the axle nut is loose enough to let the wheel spin, then what forces the wheel to stay true to the hex?  If the axle nut is tightened so the wheel is forced true to the hex, how much binding or wear is there on the face of the wheel?

 

If they are the adapters GPM sell to hex convert the DT series buggies, they have exactly those problems and don't have the best reputation. I would avoid and come up with another option for hex conversion if one exists.

[Grotty Otty 868]

Looking forward to this! If you're using those GPM adapters they are useless for the very reasons explained. They don't stay true as you can't tighten the nut to keep them square as they'll then bind. I've looked at gluing them to the wheels but that would make one bearing inaccessible should it wear but would keep them square to the axle. 

[speedy_w_beans 4272]

So, just some preliminary thoughts to winnow the options...

• In terms of wheels and tires, standard RM01 wheels and foam tires look like they're out.  I downloaded HPI's Cup Racer manual last night, and it's pretty clear the model originally had MX60/60D tires on it.  RM01 foam tires are ~54-55 mm in diameter and look a little small.  M-chassis 60D slicks look about right.  This also means the Yeah Racing M-chassis tires are out; they're 55 mm in diameter, as are Sweep Racing MN25s.  So this leaves me with the Cross wheels and Tamiya 60D slicks to work with.  Not a bad combo once we get some paint on the wheels.

55 mm foams (too small):

60 mm slicks (about right):

• In terms of body width vs. chassis track width, the rear measures 175 mm across the tops of its wheel arches.  The front measures 166 mm across the tops of its wheel arches.  Meanwhile, with Cross wheels temporarily placed on the chassis the rear measures 162 mm across outer wheel lips.  The front measures 159 mm across outer wheel lips.  This seems to make reasonable sense -- HPI used to recommend +6 mm offset wheels for the rear and +3 mm offset wheels for the front.  If we did that today the chassis track width would increase to 174 mm rear and 165 mm front, just 1 mm less than the body shell at both ends.  For body wheelbase vs. chassis wheelbase, the body measures 210 mm from the tops of the front and rear wheel arches.  The chassis measures 201 mm to the centers of the axle stubs.  I'm thinking some spacers and longer cap screws on both sides of the rear axle should take care of the chassis width issue.  I'm debating whether to drill new holes for the front uprights or make some new front uprights to adjust both the front chassis width and the wheelbase (210 mm body vs. 201 mm chassis at the moment).

RM01 with M-wheels temporarily fitted (162 mm rear, 159 mm front):

RM01 standard wheelbase (201 mm):

Rear axle stub and cap screws (kit stock - add spacers and longer cap screws?):

Front upright position (kit stock - drill new holes +9 mm forward and +3 mm outboard or make new uprights?):

• Measurements of F103GT knuckles, RM01 knuckles, and RM01 uprights led to some interesting discoveries.  The F103GT knuckles are 15.8 mm tall; the RM01 uprights have a 15.8 mm space for knuckles!  The only problem is there is no room for movement then, and therefore no front suspension.  However, the RM01 knuckles measure ~11.16 mm tall and the F103GT knuckles could be trimmed down to ~10.92 mm, therefore fitting on the same kingpins with the same e-clips and springs.  However, the F103GT axles trail the kingpins more and therefore push the front wheels back relative to the kingpins; there is a risk the wheels might rub on the kingpins and we have to add even more to the wheelbase.  That might put us back to considering other options with the stock RM01 knuckles and axles.  The front definitely needs more thought than the rear.

F103GT knuckle height:

RM01 upright space:

RM01 knuckle height:

F103GT "trimmed" knuckle height:

RM01/F103GT axle trailing position comparison:

Kingpins relative to 35 mm ID wheels (not fully seated, w/ chamfers, unique to this wheel):

Kingpins relative to 34 mm ID wheels (fully seated, no chamfer, more typical of Tamiya M-chassis wheels):

[speedy_w_beans 4272]

@Juggular was asking in the voting thread whether the HPI body has the extreme curvature near the rear wheel arches; this is his image:

The answer is really in HPI's own photos; there's some, but not quite the same:

I'm leaning a lot more towards doing a road car ("Stradale") than a rally car; the RM01 chassis is not up for rallying at all!  You'll notice there isn't quite the extreme wheel offset or tire width in the rear of this car.

 

[scollins 154]

Paul, this looks like a great project! As I mentioned to you earlier today I hardly get onto the forums for TC.... lots of reasons for this,, mostly due to my desire to stay away from the computer after coming home from work being on one too much all day long. I am excited to see what you do on this one. Two other things,,, the curvature of the body can be modified with a heat gun and bending over a large wooden dowel (but be careful) and as for the VW Amorak it was on my doorstep when I came home from work today, thanks! I will post my tweaks to it as soon as I can. It did snow this past Saturday for the first time in our neighborhood but nothing accumulated!

[speedy_w_beans 4272]

I was tinkering with the front suspension tonight to see if the F103GT knuckles could be used.  I grabbed a RM01 kingpin, F103GT knuckle, and axle/bearings/cross pin/hex to do a quick test and see what sort of clearance there might be between the wheel and kingpin.  The answer was pretty encouraging.

Based on the measurements taken Monday night, I opted to trim some F103GT knuckles using a miter box and fine-pitch hacksaw.  The result was pretty good.

They both measured ~11.2 mm tall instead of the original ~15.8 mm, so I took the slightly larger one and test fitted it with e-clips, the spring, and a front upright.  Looks encouraging...

Installing a 35 mm ID wheel showed clearance all around; it spun freely and steered freely with no issues.  Even the standard 34 mm ID wheel from a Mini Cooper Racing kit spun and steered with no interference.  Jackpot!

So now the vision seems clear.  I will make spacers and hex adapters for the rear axle, and I'll use the trimmed F103GT knuckles up front.  In the interest of preserving the lower chassis plate, I may design and print some some new front uprights to create the wheelbase and width needed up front, then flip the ball connectors to the other side of the servo horn.

Bonus!  I found some gold wheel nuts in my stash of parts, so they should go nicely with the wheels once they're painted gold as well.

[Jason1145 3986]

There I was thinking it was only me who liked matching 🥜!

Begs the question though... what will become of that lovely Toyota shell?

[speedy_w_beans 4272]

On 10/24/2018 at 4:29 AM, Jason1145 said:

Begs the question though... what will become of that lovely Toyota shell?

Good question indeed.  No answer for now; it'll join the other unfinished body shells in my stash and wait for some future love.

I'm using most of the standard RM01 kit contents with the exception of the foam tires and wheels, body shell, antenna tube, and decals.  Lots of black parts on a black mat...

Based on the previous investigation and experimenting, the additional parts are now limited to Cross wheels and Mini Cooper Racing 60D tires, F103GT knuckles, bearings/axles/cross pins/hexes, and a spare ESC from the same Mini Cooper Racing kit.

I have a few more things on order, too, but nothing delaying the start of the build:

• A high-torque servo saver to replace the kit biege servo saver.
• 42 mm aluminum turnbuckles to replace the kit 32 mm turnbuckles for a wider front suspension.
• Different axle stubs with (hopefully) better blue anodizing to match Tamiya's anodizing.
• One-piece foam inserts for the tires.
• An oversized urethane bumper to be shaped specifically for the Stratos shell.
• Some thicker wheel hexes (7 mm) just to try them.

Hopefully most of this stuff shows up soon.

Time to get started!

[Fabia130vRS 2098]

I like how this is well explained.

 

may I ask you just this, 

so the rear axle, with wheel adapter and diff, they are 12mm hex and the overall width is 162mm?

 

so basically I could order RM01 rear axle parts and istall them on my f103gt motor mount, is the rear axle of a f104 and rm01 same? 

 

 

Edit:

just searched out Tamico for the rear axle RM01 parts.

110€ it will be to have it on my F104gt Mini.

[speedy_w_beans 4272]

6 hours ago, Fabia130vRS said:

so the rear axle, with wheel adapter and diff, they are 12mm hex and the overall width is 162mm?

so basically I could order RM01 rear axle parts and istall them on my f103gt motor mount, is the rear axle of a f104 and rm01 same?

Unfortunately not quite.  The RM01 wheel hexes are 9 mm, so I have to make an adapter to expand it to 12 mm for the regular M-chassis wheels.  Overall width remains 162 mm by doing this, but then I will add some spacers to extend the width to 174 mm for the Stratos shell.

Not sure if the rear axle of a F104 and RM01 are the same; I can measure the width of the RM01 axle when we get to that part of the build.

I think it's fun and interesting you and I are starting from different kits but are driving towards similar outcomes.

[Juls1 1661]

So your also making a off road rally version too right? You gotta have it both ways!

thinking M04, mid engine, rear drive, lots of different possibility’s. 

[speedy_w_beans 4272]

3 hours ago, Juls1 said:

So your also making a off road rally version too right? You gotta have it both ways!

thinking M04, mid engine, rear drive, lots of different possibility’s. 

Ha, maybe in a distant future project!

[speedy_w_beans 4272]

There are only 21 steps in the instruction manual, and the parts count is pretty low, so I'm combining steps where it makes sense.

Bag A provides the hardware for steps 1-5, and sprues C, L, and W provide the plastic parts:

It probably took more time to arrange the parts for that photo than to actually assemble it!

That takes care of the rear motor pod, pivot ball suspension, side links, roll springs and roll damper, and pitch damper mount.  I used AW grease for the roll damper.

Bag B provides the hardware for steps 6-10, the front suspension and rear ball diff/axle.  It might be another day or two before I get to it.

[speedy_w_beans 4272]

Bag B contents in position:

The rear axle and front knuckles are built.  I don't plan to use the kit front uprights, and the front bumper will change based on the urethane bumper I ordered, so those parts are loose for now.  I used "Oatey Faucet and Valve Grease" in place of the kit ball diff grease, and I like it better.  Both are silicone-based, but the faucet grease is a little thicker and considerably less expensive.  It reminds me of Associated ball diff grease; the Tamiya ball diff grease is a bit watery in comparison.

Bag C is for steps 11-21, but most of those steps are installing electronics, setting up the steering, mounting the tires/wheels, and mounting the body.  Browsing through those steps I've opted to install the pitch damper and battery holder, but I'll deal with some of the customizations before installing the electronics.

Pitch damper and battery holder queued up:

Pitch damper and battery holder installed:

Hey, it's starting to feel like a chassis!

So what's next?

• 12 mm to 9 mm hex adapters for the rear axle
• 5.5 mm thick spacers for the rear axles (with M2.6x12 cap head screws coming next week)
• Front uprights
• Bumper plate and foam shaping
• Body mounts
• Electronics installation
• Dirt protection for pivot balls / dampers / spur / pinion
• Body work

 

[Re-Bugged 10141]

Wow, you have been busy. Only seems like yesterday I voted for this. Going well mate 👍🏻

[Fabia130vRS 2098]

On 10/26/2018 at 2:51 PM, speedy_w_beans said:

Unfortunately not quite.  The RM01 wheel hexes are 9 mm, so I have to make an adapter to expand it to 12 mm for the regular M-chassis wheels.  Overall width remains 162 mm by doing this, but then I will add some spacers to extend the width to 174 mm for the Stratos shell.

Not sure if the rear axle of a F104 and RM01 are the same; I can measure the width of the RM01 axle when we get to that part of the build.

I think it's fun and interesting you and I are starting from different kits but are driving towards similar outcomes.

Yup, I agree, similar thing happening all over the world, makes me wonder how many people are right now involved in m chassis conversions hah.

a bit disapointing what I have read here about the GPM hex adapters, but it was kind of to good to be true storie.

I am very interested how your hex adapters will look like on the end, I thought if I could make such adapters to fit a 12 &  14mm hex, I am buying the rear RM01 axle combo. 

My plans are to male a comical Senna 190E RCON model with either F104 rubber wheels or TC wheels. But the F104 tire setup would save me all the hassle about the front uprights, just that I would need to make adapters which I probably will glue into the rims and the F104 would give the 190E a dramatical wheels appereance like the comical grasshopper for example.

 

sorrz for the off topic, I want to see the hex adapters first if all

[speedy_w_beans 4272]

16 hours ago, Fabia130vRS said:

I want to see the hex adapters first if all

Ask and you shall receive

The design is pretty straightforward with a 12 mm hex hollowed out by a 9 mm hex and a 9 mm disc.

The parts are 100% filled and printed using 0.1 mm layers for better adhesion between the layers.

They just slip over the existing 9 mm hexes.

I also designed a quick axle spacer.  It's just a 22 mm disc with a center 11 mm cutout and three 2.6 mm cutouts.

I measured the parts along the edges in several locations, and the thickness is consistent to within 0.01 to 0.02 mm.  These were printed 0.1 mm layers as well.  They're ready to go, but I don't have the longer M2.6x12 cap screws yet...

Time to think about those uprights...

[Badcrumble 4203]

10 minutes ago, speedy_w_beans said:

Ask and you shall receive

The design is pretty straightforward with a 12 mm hex hollowed out by a 9 mm hex and a 9 mm disc.

The parts are 100% filled and printed using 0.1 mm layers for better adhesion between the layers.

They just slip over the existing 9 mm hexes.

Great work, really enjoying this thread.

Could the hex adapter be adapter to accept bearings and fit an ORV axle? I always thought there ought to be an easy way to change the wheels on an ORV. Anyhoo, back to your build... 

[speedy_w_beans 4272]

On 10/28/2018 at 1:17 PM, Badcrumble said:

Could the hex adapter be adapter to accept bearings and fit an ORV axle? I always thought there ought to be an easy way to change the wheels on an ORV. Anyhoo, back to your build... 

I think you're pondering the same question Fabia130vRS did at the beginning of the thread; GPM makes some hex adapters that accept ball bearings, but it seems like they "kind of work" at best.  You really need a rigid coupling between the wheel and the bearings to make it work well, and adapters just don't seem to cut it.  The situation is a little different in my case because I'm just adding to an existing hex (9 mm to 12 mm), and on the front end I'm using F103GT knuckles that take ball bearings and M05/M06 axles.

Anyhow, the latest is I've completed the front suspension design and made some parts.  First I measured the existing chassis plate and the kit stock uprights and captured as many important dimensions as possible.  Here are my notes:

• Rear axle to front upright (rear hole) - 213 mm center to center
• Upright hole spacing, rear to front - 20 mm center to center
• Upright hole spacing, side to side - 46 mm center to center
• Upright hole diameters - 4.15 mm
• Bumper hole spacing, from front upright hole - 6 mm center to center
• Bumper hole spacing, side to side - 61 mm center to center
• Bumper hole diameters - 3.13 mm
• Chassis plate width, front - 70 mm
• Upright camber - 0 degrees
• Upright caster - 4 degrees
• Upright kingpin hole offset - 1.5 mm for caster
• Upright kingpin length - 31 mm
• Upright kingpin, e-clip to e-clip - 12 mm
• Wheelbase offset due to caster - 0.5 mm
• Wheebase offset due to RM01 trailing axles - 3.5 mm
• Wheelbase offset due to caster and RM01 trailing axles - 4.0 mm
• Wheelbase offset due to caster - 0.5 mm
• Wheelbase offset due to F103GT trailing axles - 6.0 mm
• Wheelbase offset due to caster and F103GT trailing axles - 6.5 mm
• (201 mm RM01 wheelbase means bottom kingpin hole is positioned at 205 mm relative to rear axle)
• (210 mm RM01/F103GT wheelbase means bottom kingpin hole is positioned at 216.5 mm relative to rear axle)

I turned all this into a plane template in FreeCAD and then started building objects over the template.  It's a 3-piece design which makes it easier to remove the kingpins and steering knuckles later if necessary.  Instead of removing three e-clips from a kingpin, you only have to remove the bottom e-clip holding the spring, and then undo some screws from the top bar.

Printed parts and initial installation...

The angles might look a little funny, but it's a combination of caster, part shape, and lens distortion that makes the image look that way.  The kingpins are oriented correctly, the wheelbase is 210 mm, and the width with tires/wheels installed is 165 mm (1 mm less than the body shell width).  If I need to tuck the tires in a little more I can replace the 7 mm thick hexes with 6 mm or 5 mm thick hexes.

Getting there...  FedEx and USPS are holding my M2.6x12 screws hostage for the rear axle spacers...  And I still have a servo saver, turnbuckles, bumper foam, and tire foam coming from overseas.

Beyond those other items, I also need to install the kit spacers/washers under the front end and install different S-parts in the rear pod to level out the chassis' ground clearance.