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JennyMo

The Mega-bug! - aka. 'Sinclair' [the C5] Scorcher

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Just realised looking at the title I have no idea where the C5 bit  or Sinclair comes in. I know what a Sinclair C5 is but would have expected something base on one of the three wheelers? Now there's a thought!. Or am I just being DIM:huh:

 

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Class 5 Baja Bugs, or C5s, are heavily modified off-road racers based on VW Beetles.

And if you are building a C5 Baja Bug, why not name it Sinclair in honor of that other famous C5, the little 3 wheeler?

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On 6/19/2019 at 11:47 AM, Busdriver said:

Just realised looking at the title I have no idea where the C5 bit  or Sinclair comes in. I know what a Sinclair C5 is but would have expected something base on one of the three wheelers? Now there's a thought!. Or am I just being DIM:huh:

 

Hi Bus' - only slightly dim ;o) - TurnipJF has basically summarised my thinking here...

Class 5 [ie. C5 in the title] refers to the SCORE racing classification for VW engined open-wheel vehicles/buggies - in other words, the Beetle-based Baja (and Southern California) desert race vehicles that the Sand Scorcher was based on.

Giving this build the name 'Sinclair' simply follows the theme of giving my vehicles a 'name' together with an AKA as a pun or word-association* - in this instance, because of the Sinclair C5 as you surmise (since for Brits in particular) if you say 'C5' you immediately think of 'Sinclair', and vice versa.

*eg. Desmond (The 2.2) referring to the class wheel size of that crawler and a pun on Desmond Tutu of course;  and the HiLux Step(in)side Love (AKA Cilla - Black) Dually (AKA Ali G.- "Ma Julie"). 

Jx

 

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On 6/19/2019 at 10:45 PM, TurnipJF said:

Class 5 Baja Bugs, or C5s, are heavily modified off-road racers based on VW Beetles.

And if you are building a C5 Baja Bug, why not name it Sinclair in honor of that other famous C5, the little 3 wheeler?

Yep, pretty much ;o)

Jx

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All now completely clear. Need to think outside the boxmore:rolleyes:

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Sometimes bigger isn't always better... at least where wheels & tyres are concerned.

Having built Hoppers HiLux recently with some puny 85mm diameter tyres, and also bought a set of 1.55 wheels and relatively modest 98mm tyres for another [current] project I'm working on, I've had a rethink with regard to this currently dormant build - and rather than go for another set of 1.9 wheels [as I did with the SRB Cage Racer] and some typically oversize tyres, took a punt on these lovely aluminium Rough Rider/FAV wheels from Hong Kong (via Ebay), which as it turned out, really need the corresponding Tamiya tyres to seat in the machined rim grooves properly...

 

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photo. RCLover alloy 1.7 wheels, and scale M2 acorn nuts from Locked-Up RC, mounted on M2 x 10mm set-screws to create wheel studs.

 

I think this is probably just the incentive I need to dust off this project in the New Year... car 72 will roll again!

 

Happy Christmas everyone!

Jenny x

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2021* Project dust-off...

*only a whole year later than planned above!

 

Is it time yet?

i-jnmjPtT-XL.jpg

Soon...

Jx

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Yay! Glad to see more progress on this build. Looking forward to the next instalment!

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Still slow progress on this one I'm afraid... what is it with me and SRB based builds that they seem to take years?!

A quick recap: As I conceded at the bottom of the previous page way back in June 2019 - ultimately my original plan to try and build a live rear-axle/trailing arm/mid-engined version of the Sand Scorcher was fraught with packaging difficulties, so when the time came to finally revisit this dormant project I would instead endeavour to fabricate a more traditional floorpan/plate style chassis (out of aluminium sheet, as I had done with the SRB Cage Racer), and at the same time see if I couldn't incorporate some kind of trailing arm suspension at least - as would befit an original Beetle, and put a [more realistic] twist on the usual Sand Scorcher...

Actually, to be fair I have made some reasonable progress - cut a prototype chassis plate (full floor for the Beetle body), and have been putzing around with an internal cage (a pre-production test print from @Pintopower and his latest Sand Scorcher full interior project - check it out, it's awesome!) - and still trying to figure out what kind of transmission combo is going to work best with the Kyosho Beetle trailing arms I really want to use...

This was my initial MK2 plan - an Axial SCX10 II transmission, turned 90°, and a pair of ball-joint drive cups (from a Tamiya 1/14th tractor) on the end of the output shafts - ie. similar to an ORV Frog/Brat layout, but with the motor at the rear:

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I reckoned that would work, at least technically - although the rear of the chassis would need to be folded up say 30°, otherwise the rear cylinders [of the engine cover] would be scraping on the ground...

i-jLFwnBD-XL.jpg

 

The only problem with that is it then made the engine itself very high - not really scale?

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Looked kind of kewl in a Hot Wheels way perhaps though?

i-DCfk7RK-XL.jpg

 

So then I thought, why not flip the whole engine/transmission around 180°, so it's more mid-engine, and also rotate the whole transmission a bit so the gearbox had more clearance (since the fold in the chassis now has to point down a bit, rather than up)...

i-gHcHz6M-XL.jpg

photo. this current layout utilises short [40mm] TL-01 dog-bones to Wild Willy 2 stub axles - note. the bearings in the Kyosho trailing arms are actually 1050s, and need to be more narrow too - ideally 3mm wide (rather than the usual 1150 size which are 4mm wide).

 

So with that decision sort of made, it was time to swap the butchered red Monster Beetle body for a genuine [re-re] Scorcher shell:

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photo. the narrow rear end tucks the Rough Rider rear wheels into the arches for a more scale appearance I felt?

 

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photo. the AMPro prototype Sand Scorcher cage - the finished version is even more detailed (including sun visors!), but this rough-cut will be perfect for what I've got planned.

 

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photo. so this is how it's been sitting for the past couple of weeks while I debated the next step...

 

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...and ultimately I decided to rotate the gearbox a little further backwards (from approx 45° to now 90°) so it mounted vertically - which was ultimately neater and also gave even more room inside, but of course this lifted the motor/engine correspondingly higher - to essentially the same location as it would be in a Frog/Brat... typical eh? - had I known I'd come almost full circle with this project, then maybe I should have just kept the Fro-Sco after all?!

And something was still bugging me about the overall transmission layout too - while the dimensions of the lower part of the gearbox is perfect [to fit between the trailing arms with the short dog-bones], unfortunately the Axial casing contains a huge spur gear and pinion for the initial reduction... similar [internally] to an SRB gearbox of course, only in that instance the motor itself is more completely integrated in the overall gearbox...

This lead to the inevitable conclusion, that actually, Tamiya had it pretty well sorted all along... darn it, it's off to eBay I go, again!

cont.

 

 

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cont.

So what have we got now Jenny?

i-4ggVbHh-XL.jpg

photo. a load more parts - including a shorty servo, which ought to tuck neatly under the bonnet with a direct steering linkage. note the E parts bag is actually from a Frog/Brat - and includes some rubber drive-shaft boots which I hope will work well with this trailing arm layout, plus some extra gear grease and tools - always handy.

 

Fortunately an SRB rear gearbox is pretty simple - so much so having build one previously, I didn't even need the instructions really - it's pretty self-explanatory: two case halves, six 1150 bearings, and the three sub axles/gears all go together, plus the two clear plastic cases - one to hold the motor in place, and the other to cover the spur and pinion gear (which I already had, since you get two with an SRB kit - and I'd used the faster gearing in the SRB Cage Racer, leaving the higher torque cogs available for this Bug build, which I felt would probably be more appropriate anyway?)

So using my own scale hex hardware, I had a complete SRB transmission for around $50 - not bad in the grand scheme of things I thought?

i-BGVgNBP-XL.jpg

 

With that, it was simple enough to re-drill the rear of my aluminium plate chassis to accept the SRB gearbox assembly, and I sprayed the clear plastic parts with a base coat of aluminium silver, in preparation for the final scale engine detailing later:

i-NKmpdp4-XL.jpg

 

The other things I'd bought recently were a pair of seats (the pukka Axial version, they really are the best quality and come complete with Corbeau decals too), plus a pair of 80mm long Gmade aluminium bodied RSD reservoir shocks - which are a bit of overkill technically, but are going to look great either side of that scale engine I feel!

i-XL66Gtm-XL.jpg

So that is where I'm up to as of now... in reverting to a traditional SRB gearbox it is still going to be a proper rear-engined car in the traditional Beetle sense (albeit transversely in this instance), but now motor and scale engine cover will be mounted lower than it was in the previous iteration - so less Hot Wheels as it were - while equally not being mounted unrealistically high either as it would be with the SCX10/Frog style mid-engine location. It also leaves plenty of room for a battery in the rear compartment - although as with the SRB Cage Racer, I'm still going to have to get creative with regards to a tower to secure the top of those huge shocks.

The only other thing I'm going to have to do to make this all work together is take a hack-saw to the ends of the gearbox casing (where the roll hoop and front lug of the wishbones would mount) in an effort to tuck in the trailing arms as close as I can - as it is, I've had to order some slightly longer dog bones and the rear track is going to be approximately 10mm wider than it was before - although that still ought to be a touch more narrow than a stock 'Scorcher with the traditional A arm rear suspension.

With any luck, the next series of photos you see will be it standing on all four wheels and the [new] drive-shafts hooked up at last!

Jenny x

 

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OK then, we are back in business!

Having waited more than two weeks for some alternative drive shafts to arrive, I'm now in a position to finalise the chassis layout, and see if I can't start bolting stuff together at last!

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photo. Carisma 45mm long dog-bone drive shafts, will require the trailing arms to be moved outwards, increasing the track width.

The reason for using slightly longer dog bones is primarily so that I can mount the trailing arm supports either side of the SRB cast gearbox casing - even then, as the the photo shows above, I'm going to have to hack-saw off the cast supports for the original SRB roll-bar in an effort to snug everything as closely together as possible and not to increase the overall rear track width any more than necessary (note the end result is a track width of 195mm, so essentially the same as a regular SRB using wishbones as I recall?). On the flip side, increasing the dog-bone length/track width means the drive shafts moves through less of an arc, so I will effectively get more travel up and down before there is a danger of them potentially falling out of the drive cups.

Although this increased rear width is going highlight the disparity between the front and rear track width (which I could always address as I did with the SRB Cage Racer, and use longer tubes between the suspension uprights to increase the front track width too), looking at a photo of an old 1:1 Baja Beetle (actually in the Classic class of the Dakar Rally earlier this year), it appears that retaining the narrow [stock?] front end is a thing on these bugs... the handling must be scary!

i-VZtkrw2-XL.jpg

photo. similarly the rear wheels are tucked in as I'd previously envisaged with the different transmission layout, ah well...

So working with what is realistically achievable using this collection of off-the-shelf parts and only some rudimentary workshop modifications (a saw and a file), it was time to finally get the front and rear subframes connected...

i-QstdV7t-XL.jpg

photo. no going back now, this had better work or it's $50 down the drain!

 

After some jigging and careful measuring, it transpired that while I'd got the wheelbase pretty much bang-on, the floorpan section essentially needed shifting forward 8-10mm so that the body shell sat in the correct orientation above the wheels, which ultimately required a 2nd/Mk2 chassis plate to be cut... Fortunately I had just enough 2mm sheet left over to squeeze another one out, now that there was no requirement for the chassis to extend behind the rear suspension mounts:

i-kGwxz8G-XL.jpg

photo. trailing arm rear suspension (from a Kyosho Beetle) - coupled with the SRB front end - about as scale layout-wise as you can get!

 

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photo. prototype 'Scorcher cage from AMPro Engineering - his complete 3D printed chassis/cage/interior combo is superbly scale, however the dimensions of this early mock-up have actually proved even more suitable for my own creation of a stripped-out race car...

 

i-wQ4b39F-XL.jpg

photo. the cage will allow a full cockpit interior, and suitable mounting for scale harness seatbelts too. The rear cage stays also line up perfectly with where the top of the 80mm rear coil-over shocks will need to locate - honestly, it was like it was made for this exact application!

 

i-BhWcKrp-XL.jpg

photo. the money shot?! - rear track slightly wider than I originally planned, but this is going to look awesome with a scale transverse V8 engine hanging out the back! I also really like the squat rear end, although will need raise it slightly to give it any real off-road ability I fear...

 

i-Jprz2hh-XL.jpg

photo. workshop Louis looking pleased with himself, and so he should be... it's taken a while, but the Bug is now finally taking shape!

 

More soon!

Jenny x

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I'm a big fan of this, awesome work. Can't wait for the next installment :) 

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14 hours ago, Re-Bugged said:

Excellent 👍🏻  
Liking the roll cage a lot. 

Yes - I was all set to use another Twin Hammers cage (modified a bit) at the beginning of this thread, but one benefit of putting the project on hold for a year or more (and ultimately using that TH cage set for the Baja Blazer instead) is that @Pintopower had finished his Sand Scorcher kit development, and had this dedicated far more appropriate cage design available.

I do still intend to have some kind of rear external cage-work around and over the engine to potentially mount a spare wheel back there, but factor that on a real racing buggy, that would probably be separate and more sacrificial compared to the main internal safety cage anyway? Fortunately, in using the trail-arm suspension rather than the SRB wishbones, it means there are some additional mounting points at the rear of the gearbox too.

Stay tuned!

Jenny x

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