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formula offroad, Mkll twin build, pic heavy

Old 12-17-2012, 01:39 PM
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mooman007uk
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Default formula offroad, Mkll twin build, pic heavy

with a bit of time on me hands and a borrowed, from a buddy, mini lathe/mill combo i started on foff Mkll build...
will be powered by an obr 57cc fullmod twin dialled for torque,
4130 chromemoly tube chassis, 4 link suspension and solid axles front and rear[8D],
kalee tires as they weigh half of what rampig ones do at 740gr, shaved and i think the hpi 5t sand buster paddles glued on,
either drop pitman arm steering set up or toying with the idea of piston to piston hydraulic steering...i'm on the hunt for an oddified tonegawa ps050 if anyone has one or knows of one.
pipes will be hacked up pocket bike exhausts.
motor will be mounted up front lengthways with a simple pinion and spur with jack shafts. splined driveshafts from a honda hru216 mower for centre shafts.
aluminum and steel body panels

just 'bout covers it.

first up the hardest part...axles. been trying to figure these out since my last build...was coming up short until i scrapped aluminum and started thinking good ol' steel.. then i came to me,so procured the needed machine and got started.
using rampage centre diff spool and pinion front and rear.

started with this...each one is a half...

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ended up with this

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machined a vertigo 5b rear hub as a pattern to get the correct bearing position for mesh

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milled holes

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then set about making pinion bosses from aluminum as well as wheel hubs and steel hub flanges

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so far so good, only manged to bugger up one pumpkin half...the last bit too...3 1/2 hrs machining down the drain...being a small lathe 1mm cuts are the max even with carbide index bits.

next was to determine how big the thing is going to be and came up with 20" from end of hex on the wheel adapters, 26" with tires and 26- 28" wheelbase axle centre to centre,,should look scale then with the 8x5" kalee tires.

so cut some thick walled 4130 tube and voila axle housings

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now working on the rear axle shafts...using pig/5b outdrives welded to cut to length hurrax shafts, will be no pins or cups to break, one solid shaft...one all the bits are finished i'll take them to the local foundry to reset the desired hardness and temper.

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the fronts will be hurrax cvds mated to pig outdrive

so axles are just a postman (for some hex sleeve i need), bit of machining and welding away
rear axle with shafts weighs a hair under 1.5kg (3.3lbs) which = a rampage tire, so with 2 kalee and the axle it= 2 pig trotters....the whole build i hope to scale at no more than 18kg (39.6lb) wet, hopefully get in around 16kg.
now that i've been working on these i reckon i've figured how to make the pumkins from aluminum which would enable cheaper and easier production...however i need to test these first then do up a set of alloy protos and test those...hope to bring affordable solids to market if there is enough demand for an outsourced production run to be worthwhile.

can't start on the chassis until my engine comes and that can't be sent until OBR gets their awaited delivery from rcmk..still 1-2weeks[&o] but at least i'll have everything i need here by then so should only take a week or two to complete...think i'll end up power coating this one as well.
Old 12-17-2012, 03:13 PM
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Lars from Norway
 
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Default RE: formula offroad, Mkll twin build, pic heavy

Oooh yes, i like this build already! Make it even more pic heavy please
Old 12-17-2012, 03:23 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

looking good mooman, like the way the axel looks, will look great with the 4 link system, are you gonna use m5 or m6 rodends,
got my axel nailed for my trophy truck 2wd build, not having a mill or decent lath so i made it out of sheet, running a mcd dif and hpi outer hubs,

weighs a ton but somewhere to start
Old 12-17-2012, 06:09 PM
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mooman007uk
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Default RE: formula offroad, Mkll twin build, pic heavy

M6 ends...same as on my current one, from vx bearings best ones i've found so far regards durabilty and 20 for 4 price is good too...tried others and the inserts come out. was thinking M8 but that's a bit OTT i thought. trying to keep it light.

nice fab job stigg, my sheetmetal skills aren't the greastest and still yet to pick up a good tig or set of bottles for the fine welding, my industrial hobart mig doesn't like to feed finer than .030
Old 12-17-2012, 10:53 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

Very nice work and interesting axle approach.
Old 12-18-2012, 08:35 PM
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Default RE: formula offroad, Mkll twin build, pic heavy


I'll be watching this with interest.





Old 12-22-2012, 01:01 PM
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mooman007uk
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Default RE: formula offroad, Mkll twin build, pic heavy

rod ends arrived yesterday so got the front hub arrangement sorted, they'll be connected with a bar across the front and hoping my idea for hydraulic ram steering works out as planned. also looking into making an air over oil springless shock set upwith remote rezzies...









and made a bunch of spacers and machined the pumpkins, next will be a bit of welding and axles are finished...whoo hoo....now i need my engine to hurry up



Old 01-11-2013, 04:14 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

Moo!  I am excited here now.  How much are you going to charge me for one of these rear axles when complete?    Minus the diff ofcourse.  Also should any 5th scale diff work as well for e.g  the carbon fighter diff - similar to the MCD?

Thanks again 

Glenn.
Old 01-11-2013, 04:52 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

Wow I would say alot of time looking at the quality of the work. VERY NICE!!!!
Old 02-04-2013, 03:45 PM
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mooman007uk
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Default RE: formula offroad, Mkll twin build, pic heavy

engine, killswitch and ada manifolds arrived today...just waiting on the obr full mod top ends and cooling head
at least now i can start the chassis layout



also started on the tires..850gr removed so far...now have to grind them flush and glue 14 paddles on each

Old 02-10-2013, 09:00 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

been busy, got the axles all done, shafts welded together

front shafts...kaylee flm cvd's cut one side with hex welded on the end...the long side i machined some 4140 down and added the needed length with hex cup on the end...nice and true





had to machine the inside hub bearing hole deeper to line the cvd pin and hub pivot point up



welded the axle housings and put them together..made some stand offs for a proto vertigo/nutech carrier and had to machine some off the centre of a cy clutch case so it'd sit flush



.also made an engine mount rail





next i got the chassis floor outline done then set to work on the driveline

first i machined down an old hurrax fr hub i had laying around





now i can use a hurrax cvd to mount my gear cluster...however it was 7mm too long to fit the cvd shaft and nut so machined material off himoto 30t gear, square, back of large gear hub, cvd shaft where it meets the bearing so the shaft poked thru more





end result all fits,



next was to mount the hub...steel welded to frame on the bottom and aluminum bolted to the clutch carrier on top











then spent about 3 hrs modifying the lawn mower splined shaft, hub, jackshaft etc only to find the lawnmower cvd when shortened didn't give me enough wheel travel/articulation so scrapped all that, moved the chassis/motor forward and bingo the cvd from cluster when lengthened will clear the front of the motor, it'll have a mm or 2 clearance to the coil at full axle twist..

rear shaft set up is easier as it has lots of room to play with

as soon as i finish mounting the rear gear set i can build up the chassis and get the 4 links done
Old 02-14-2013, 09:08 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

rear jack shaft done, brake discs will mount on the square nut...shaft is 2 piece







got the front driveshaft done





cut and turned down a hurrax cvd and cut the end off a rampage drive cup...just need to weld it all up now




with the driveshaft sorted time to tackle the front four link...takes bleedin ages making all the brackets the same both sides and then making them fit symetrically,...much grinding and filing and a bazillion measure and remeasures later









just the front bottom brackets on the axle to do and then can start on the back.
you have to stay 4 steps ahead all the time making sure things are going to work, how much space they need etc, so half the day is figuring stuff and half making parts...tank goes out back, servos, batt and brake setup goes in the passenger side, hpi filters will stick straight out the side off the carbs, last was pipes. was going to mod pocket bike exhausts but figured to get the most from obr full mods vrc pro is the only way to go...i've made them fit in all sorts of strange spaces before....looked down at the 5b sidepipe on my nutech and looked too easy....mocked it up with a toxyc manifold, will fit perfect stacked on top each other, so got another one coming, a bit of manifold modding on the second pipe is all i need to do...pics give you and idea...







Old 02-15-2013, 04:01 PM
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Lars from Norway
 
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Default RE: formula offroad, Mkll twin build, pic heavy

Absolutely lost for words here, exept from those i just wrote
Old 02-15-2013, 11:03 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

spot the difference



all the measuring a remeasuring and i overlooked steering lock..2hrs later.



front done, back 4 link done





starting to look like something now









now working on the rear driveshaft and brakes...down the road i'll pick up some used hydros off ebay.uk for now modded rampage ones look like it'll work...hope to get that all done tomorrow as well as th..then on to the steering...should have both pipes and some borrowed 5b rear shocks monday can then finish off the frame...then strip down, finish welding everything and paint...lime green...hopefully my obr top ends arrive next week then could feasibly have it running by next sunday
Old 02-17-2013, 08:23 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

rear driveshaft, brakes and servo mounted











front tie rod







the brakes were a bugger and took bleedin ages...they work good though and should be able to supply enough stopping power with the 5755/digi4 ...hoping to rig up a th cable off the same servo...pipes should be here tomorrow so can start on the top half[8D]
Old 02-18-2013, 03:02 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

Still losfer' words here, but always following with exitement
Old 02-18-2013, 03:40 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

Yeah, what he said







Old 02-18-2013, 09:11 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

pipes were easy peasy[8D] one just had to cut 3/4" off a toxyc vrc manifold and other one cut a twist and weld both are the same length now too, remounted the spring tabs where they needed to go and sorted...rear mounts will come when i get to rear of cage







air filters interfered with each other so a angled shredtack and a bit of trimming the lock ring, fit nicely







started on front end, top tube tacked on



next installment should see the front end done and shocks mounted
Old 02-19-2013, 11:30 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

That looks incredible love the look of front twin engine. The way things are supposed to be. Nice
Old 02-19-2013, 08:41 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

trying to keep it as close to the fullsize configuration as possible, and trying to keep it somewhat scale..it works out to be about 1/4 scale...once it's finished i'll scale it and figure the hp per tonne to see how it compares to 1:1...i should be close to 750hp/t

front shocks mounted and figured the spider web of bracing required that'll still leave room to get the pipes off, clear link arms and driveshaft and fit in a tone servo and linkage just in case plan A steering setup don't work ...took a while to figure so it wouldn't look goofy, few more bits to add and the front end will be super strong







i'll get the front finished tomorrow then just the top and back to do...had to order a bit more steel, hope to have it by weeks end so i can get it done, stripped down and painted...obr top ends arrived today so will throw those on when the motor comes out for final welding...
Old 02-21-2013, 05:07 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

Very Nice!! Subscribed to this one!!
Old 02-22-2013, 12:20 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

Mate looking REAL good....is there some kind of rubber concertina boot that might fit the telescopic shaft? Like a large version of the RC boat rudder rod boots?

Maybe front forks boot of a mountain bike?
Old 02-22-2013, 08:56 PM
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Default RE: formula offroad, Mkll twin build, pic heavy

I have a boot in mind, just have to remember what the hell i saw it on...about 3cm concertina rubber booty, be the perfect size.

so been working on the steering cylinders and having the same issues i had with an attempt i did on a full size lifted 97chevy 3/4 ton pu a few yrs ago, i'd cut out the ifs and 4 linked an f350 dana 60 up front with coils...didn't work then either cos bleedin is a bugger...think i've figured it but need more cylinders...plan b that hopefully will get me by until i figure hydraulics is using cables, easy to insatll and remove later

more chassis work











got the rear part of cab bent up and now i am out of steel tube, more should be here Monday..a bit more bracing up front and a removable cross piece for the top of the hood and finish the rear off...i can mount the shocks while i wait and finish off some odds and ends.

plan b steering, with the tonegawa i'm not worried about having the power for this to work, my concern is snapping a cable when it cartwheels down a steep hill , so this is just temporary...unless it works and holds up then it'll stay...coated braided mountain bike gear change cable with non kink lined housing, supposed to be pretty tough but we shall see



Old 02-23-2013, 10:01 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

I like that push-pull steering system!
Old 02-24-2013, 02:46 AM
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Default RE: formula offroad, Mkll twin build, pic heavy

Excellent built, mate.

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