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JennyMo

SRB Cage Racer - aka. Mjolnir (the heavy metal Hammer)

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Unlike Groucho Marx, there is one club I've always wanted to join... if only to revel in all it's machine threaded, hex-headed, high metal content and scale suspension glory!

Of course until 2010, there was no way I was ever going to spend so many hundreds of pounds on a used Rough Rider or Sand Scorcher (never mind the crippling cost of a still NIB!), and even when the re-releases were launched, I still baulked at the the £300 or so it would cost for entry into this exclusive club...

More importantly perhaps, for me modelling has always been about trying to create something unique - so I've never really had the desire nor the patience to build a box art model (or at least a variant on the theme) - which until recently I thought was the only way to really do an SRB kit justice?

That said, I've always felt there was a lot of potential in using the front and rear subframes as part of a custom build - and for a while have had an idea in mind that would tie everything together in a Baja Racer stylee... it's just it seemed trying to source the suspension & gearbox parts on their own would cost almost as much as a complete secondhand vehicle! - and of course after a friend of mine who bought and built a re-re Rough Rider in 2010, had described how much fun it was to assemble, I knew I would also enjoy the fresh out of the box, breaking blister pack joy of assembling brand new components from scratch!

Fortunately, I finally managed to snaffle a NIB rere Rough Rider on Ebay in the USA at a great price ($225 USD - noone else bid!), perhaps because it had the gold body which may not appeal to most people?

Anyway, I considered this kit was a cheap enough way to get everything I would need brand new, and subsequently be able to sell a lot of the unused parts on as spares to recoup some of the cost...

So, this is what was waiting for me when I arrived at Lisa's house:

P1010089_zps12cdcd79.jpeg

Together with the rere Rough Rider kit, I also snapped up a couple of Jack Osbourne figures and some more Willy driver sprues... and brought with me from the UK a set of Pajero wheels and tyres I've had for ages, and another Twin Hammers cage set - which I'd already assembled with stainless hex hardware...

Sounds like a crazy concoction perhaps, but you know it might just work - so let's get this build-party started shall we?!

Jx

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First up, it was time to unbox the parts I'd need:

Sweet!

P1010091_zpsf365a679.jpeg

Building the front and rear assemblies was actually pretty straight-forward, in fact I was surprised how simple the SRB kit actually is compared to more involved newer [designed] models...

Love this!

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I knew from the beginning that I would be replacing the stock torsion-bar springing with more scale shocks that have internal springs, so elected to build the suspension with just the bushing... It takes some nerve to cut up some perfectly good torsion bars - no going back now!

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I want to try and make this as 'scale' as possible, so elected to fit some 1.9 hex wheels and tyres (using a set of hex/pin adaptors for the rear axle)...

P1010097_zps0c4e9d4e.jpeg

Fortunately using the Twin Hammers cage as an integral part of the structure means I can mount longer rear shocks directly to the cage (I think 70mm front and rear will work well), and my plan is to actually have double shocks at the rear...

Don't worry, I have a cunning plan for fitting the hex front wheels too ;o)

P1010098_zpsb7c07018.jpeg

I think you can see where this is going already?

Jx

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So this is where I'm up to so far:

P1010096_zps889aedae.jpeg

The wheelbase is likely to be around 25mm longer than standard (at 275mm), so that the rear twin-shocks line up nicely with the mounting holes on the cage - and also just because it is better proportioned that way anyway... I still think there will be room in the rear for one of Toykid's scale engines ;o)

I really like the proportions of the front end so far, although some work is going to be required as currently the suspension towers foul on the cage (I'd hoped this would have fitted nicely between them) - of course one option is to widen the front track slightly by using longer K&S tubes between the uprights - it is only a matter of about 5-8mm.

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At the back there will be plenty of room for twin shocks:

P1010105_zps90ec3811.jpeg

My plan is to design (and have lazer-cut) a new alloy chassis plate to tie everything together... it will be similar in concept to the Radshape alloy chassis, but be squarer/wider in the centre section so that cage can bolt directly to it, and it is also likely to have a folded step in it either side (angled at 45°) to create a raised sill (also helping to strengthen it) while the battery (a standard 7.2v pack if desired) will fit longitudinally down the centre...

P1010100_zps4735ccb4.jpeg

I also hope to have enough room in the cockpit for Willy to ride in an Axial bucket seat (or maybe two), and will use a small servo with direct steering up front...

Now to go shopping for some shocks - I really fancy those Old Man Emu ones complete with rubber boots... then get the cereal packet and scissors out and template a chassis!

More soon!

Jx

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So I finally managed to do a little more work with the car today, having spent the past few days going round and round in circles trying to spec up the suspension and second guess what other hardware I'm going to need, as despite RC4WD being based only a few miles from where I am in San Jose at the moment, their warehouse is strictly for dispatch and doesn't have a sales counter - boo!

Instead I've had to order everything online, and am now fully committed having spent over $200 USD today on trick parts - including three pairs of Old Man Emu scale shocks, complete with blue boots; various set-screws and hex bolts; plus some Axial Corbeau seats together with some more light buckets and LEDs.

I've also bought a couple of 6mm diameter internally threaded suspension links, as these (I hope) will make perfect cross braces - one to replace the centre tube on the SRB front suspension (I'll explain in a minute), and another that together with a couple of neat ball links, I hope will make the perfect rear shock top mounting...

I also got the tape measure out, and the cardboard and scissors and mocked up the first chassis template to give me a better idea of dimensions...

This is what it looks like with a completely flat chassis plate - and the wheelbase is now 270mm:

P1010121_zps2e67c68c.jpeg

As you can see, I've had to widen the front track (by +8mm) so that the Twin Hammers cage fits between the shock uprights:

P1010117_zps1316a8df.jpeg

Fortunately, while I curse the American insistence on keeping imperial measurements alive (we are engineers for goodness sake!!!), fortunately some 5/16th (in other words 8mm) thick-walled K&S tube was the perfect replacement for the stock upper and lower tubes - allowing the suspension link axle/pivots to still rotate snuggly inside!

Unfortunately, I was not so lucky with the next imperial size/s down - they are either half a millimetre too large or too small - grrrrr) so for the centre tube (while I wait for the proper threaded 6mm replacement to arrive), I have just used some longer screws to hold the original tube in place.

This allowed me to mock up a chassis, to get the wheelbase and cage positions worked out:

P1010116_zpsbda90cf3.jpeg

However, while the distance from the front wheels to the cage is perfect, mounting the cage at the same level as the suspension means the back end is very squat - and while it looks kinda mean, there is no way I can fit 70mm shocks in there if I want to use the most obvious (and strongest) position on the cage that I have in mind...

P1010120_zpsd89da8aa.jpeg

Close up of the ball link mounts - the idea is that with a brace bar between these two, the twin shocks will mount either side of the cross bar, and down to the swingarm each side:

P1010115_zpsfdaae207.jpeg

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It will be a very neat solution I feel... however, the problem is that the rear of the cage needs to be a lot higher (like 10mm) to give enough room for the 70mm shocks.

Now I always envisaged that the sides of the chassis plate would be angled up from the centre to where the cage will attach anyway - not only to improve rigidity, but also to more accurately represent a real skid plate... so it's perfectly feasible to lift the cage the required amount that way... although of course that will raise the centre of gravity of the vehicle a little (and visually), and ironically then there wasn't any need to widen the front track, as the shock towers will actually be under the bonnet part of the cage anyway...

I'm sure I'll get a better idea once the shocks arrive - but what this has proven at least is that a simple (unfolded) chassis is not going to work, unless I radically redesign the rear shock top mountings... of course in an ideal world perhaps I'd get those CNC'd too ;o)

It's still a work in progress...

Jx

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As always, loving your work J

Nice to see these problems arise and then you dealing with them.

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Just had notification that my suspension parts haved shipped... So hopefully they will arrive before the weekend (that are only 3 miles away!)

I have also revised the chassis design to include the raised sills - and hope to fab up a prototype using 2mm styrene and a heat gun... Although that might end up a gooey mess!

More soon!

Jenny xx

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Another fine project! But... it's unlike you to lengthen a vehicle's wheelbase, isn't it? ;)

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So cool Jenny,

If you are in San Jose, we need to get a meet sorted out with you, Jim (aka Shodog) and I to get all our SRB's together. Is your plan to finish this before you go back to the UK?

James.

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I can't wait to see this come together. Your work that I have seen on here is amazing. One day I will have to try one of these complete custom builds. They look like a lot of fun, trying to figure out how to make it all fit together and work.

If you guys are going to have an SRB meeting, why not drive over the hill to Santa Cruz and do some beach running. I'd love to stop by and be jealous of all of them :)

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Full marks for RC4WD - their postage might be expensive, but they ship quickly and it arrived next day - although so it should, from 3 miles away ;o)

It was a real joy to open their packaging and fit the shocks on at last... I went for the 70mm length front and rear (the longest you can fit on the stock front tower), and had to modify the uprights by removing the rear of the two posts the original torsion springs butt-up against:

P1010123_zps1d690b91.jpeg

Otherwise they bolted up a treat and really transform the looks I feel.

At the rear, I decided to stump up the cash and go for twin shocks - not that they vehicle really needs them, really just for looks - although you might argue that with a rear engined vehicle that is designed to jump over dunes etc. that a 1:1 buggy would almost certainly require twin shocks at the back... However, the RC4WD shocks are pretty stiff already (at least initially out of the box), so I'll have to see how compliant the suspension is once it's running...

P1010124_zps3a3dcb28.jpeg

The twin shock lower mounting was achieved by using a 25mm M3 bolt, plus one of the original spacer/bushes from the OEM damper set - this gives the perfect spacing between the upper shock bodies... at the moment I've simply bolted a second spacer at the top, while I continue my search for a shop in the USA that actually sells metric drill bits* - how they got into space I'll never know?!

*Fortunately the LHS here does have a range of metric drill bits and various taps & dyes with metric thread pitch too.

More once the rear shocks are attached to the cage - I'm really pleased how my cross brace design/idea worked out - it looks to be perfect and very 'factory'... I've also cut a MK2 chassis template, and will ultimately tweak it into a MK3 (mainly just the cage mounting position holes in relation to the folded sill sections) before cutting a prototype from styrene...

Jx

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I don't know whether I should copy this to the 'scale builds' or 'look what the postman bought me' threads too!

So a few more parts arrived yesterday - and it really is starting to look like a car now!

P1010140_zpsb067c1a0.jpeg

A few details and explanations...

First up, I bought another Axial light bucket set - this has a range of lamps in various sizes and styles and is great value for money, as the quality is very high... I used the 12mm round ones on the front:

P1010135_zpsaeb888d6.jpeg

Yes, I am being a brand-tart with this build, so have included the PIAA grille covers ;o)

And at the rear, the larger of the two sizes of oval lamps:

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I'm not sure this will be the final position for the rear lights, but I want to try and combine the high-level brake/dust lights and tail markers in one unit to keep the wiring to a minimum - I had originally mounted them hi-level internally on the roll-cage cross member behind the seats, but feel the seats really need a little more room to go further back.

Talking of seats - yes, Axial again - their scale Corbeau bucket seats - again, great quality for the price:

P1010136_zpsc8520594.jpeg

I know it might sound like sacrilege to scratch builders, but I felt there really was no point in trying to fabricate something like this when they are available off the shelf - especially as the finish is OEM out of the box.

The seats really have transformed the [scale] look of the vehicle I feel:

P1010133_zpsa271dfed.jpeg

Yes, you'll notice I still haven't been able to connect the rear shocks to the chassis crossmember mountings - still can't find a 3mm drill bit here in the USA, and I refuse to use the next size up imperial (1/8th inch) which equates to 3.2mm (and a slack 3.2 at that) - rather will have to wait until I get home next week to do a proper job... I can't believe the sizes here jump from 2.8mm to 3.2mm with nothing in between - grrrrrrr!

So, for now I'll leave you with these:

This view from above shows how much space there is behind the seat for the battery (a regular 6-cell 7.2 Nicad will fit nice and snuggly widthways between the cage) and other electronics:

P1010139_zps58cd20c7.jpeg

Also plenty of room in front of the front suspension should I succumb to a nice [working] scale winch, even if that isn't strictly 'Baja'...

While the side view gives a good indication of the final proportions, once the folded chassis plate is fabricated:

P1010132_zps9fc3aa91.jpeg

Toot toot!

Jenny xx

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That looks awesome Jen, kinda like a vintage rock racer!

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I must admit I wasn't too sold about the original concept, but seeing it laid out like this I'm a true believer again. Praise the Jen! :D

Makes me want to try out some smaller tyres on my Twin Hammers now.

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COOOOOOOOOOL!!!!!!!!! :D

This looks like it's going to be a classic stunning JennyMo build. I cant wait to see more. :)

Nump.T

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Love the build. I had the same hard time finding drill bits in metric sizes. I'm even a porsche tech and not one of our tool trucks that come by the shop carry metric drill bits. So I ordered a set of tamiya bits of ebay. Relatively cheap and fast shipping. This seller is located in SoCal, so it might ship fast to you in the north.

http://pages.ebay.com/link/?nav=item.view&alt=web&id=221458015431

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That's excellent, thanks for the link drewbush! I had conceded that ebay was the only way I was going to get some - unfortunately I didn't have enough time this week to order them (and get them delivered) before I head home this weekend... so once back in the UK I'll have access to all my lovely METRIC tools again!

So the project is going to be on hold for a couple of days - and also I've been toying with a different chassis option after all...

While a flat/folded plate style chassis seems most obvious evolution of the original, as the suspension was designed to bolt to a flat surface... I can't help but think it would be even more awesome with a proper aluminium box-section chassis joining the front and rear subframes together, then have a simple flat plate 'floor' on top to mount the seats, and the cage to too?

I've already mocked it up with 6mm (ok, 1/4 inch) box section K&S tube - and although it will mean the cage sits slightly higher, the dimensions are perfect for the height of the cage/rear suspension mounts, and at the same time, allows the original track width* at the front as the top of the shock towers are now below the front part of the cage...

* That said, there is quite a disparity between the front and rear track on the SRB, and I can't help but think that if the front was wider/closer to the rear width, it might handle better, or at least not be so tail happy without a rear differential?

Anyway, if you're read this far, I'd appreciate any suggestions or links to anything similar...

Toot toot - I've got a plane to catch!

Jx

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Jenny , once your this side of the pond get your butt to B&Q . METRIC drill bits and you can get some tube in order to widen that front end . If a jobs worth doing its worth doing well . You just know that you will never be 100% happy with this until its fully sorted .

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On 7/6/2014 at 10:21 AM, bromvw said:

Jenny , once your this side of the pond get your butt to B&Q . METRIC drill bits and you can get some tube in order to widen that front end . If a jobs worth doing its worth doing well . You just know that you will never be 100% happy with this until its fully sorted .

Don't worry Brom' - I have a shed full of metric tools at home, and already have the various diameters of K&S tubing - but then I'm sure you guessed that already ;o)

I'd already widened the front track by 8mm (using longer tubes) in the US, but now I've had the idea to use box section rails for the chassis, decided to revert the front track to standard as it so happens (although I'm sure all SRB owners know this) that the width between the inner faces of the front suspension mounting brackets is the same (52mm) as the width of the inner faces of the box section of the rear subframe - in other words, it means the new chassis rails would be parallel... ideal.

However, doing it that way would mean a regular battery won't fit in the space between the chassis rails (which might be a kind of neat location), so my alternative is to widen the front track a little further to 15mm (which is closer still to the rear track width), and in turn this would allow the new chassis rails to mount outside of the box at the rear (which would give a width between them of of 55mm).

It will make sense when you see it!

I'm going to get that drill out now!

Jx

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Makes perfect sense already Jen - good thinking . Looking forward to seeing some progress photo's

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OK, here are a couple of photos with the box section chassis rails:

P1010325_zps1b91a377.jpeg

As I explained above, by widening the original front track by 15mm, the rails sit inside the front uprights, but outside the rear box section:

P1010327_zpsc6bd59ce.jpeg

I'm really happy with the front width now:

P1010326_zps82eb8270.jpeg

However, having finally drilled the rear shock mountings that I'd assembled on the cage and mounted up the rear shocks, I was concerned there would be too much flex (those twin rear shocks are pretty stiff) - especially as the whole cage will only be bolted to the chassis with 4 x 2.5mm screws along the sill area (and ultimately some sort of front skid plate too)...

I am going to try and fabricate my own cage cross brace using a single aluminium tube (as I like the simplicity of that idea) - however, I feel ultimately I am going to have to fabricate something (metal) that mounts to the rear subframe - sort of like the original hoop but lower, and with the twin shock top mounts incorporated...

One thing is clear, this won't be a quick build ;o)

Jx

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Great concept (again) and it looks like you're making headway. These things are never as quick and easy as we think they should be!!

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