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Juhunio

49400 30th Anniversary 934 RSR Rebuild

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You my friend are far too organised 😲

It's a great looking chassis init? 😉

I built mine with all the bits scattered everywhere! Used titanium on mine for a wee bit more bling👍

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31 minutes ago, svenb said:

You my friend are far too organised 😲

It's a great looking chassis init? 😉

I built mine with all the bits scattered everywhere! Used titanium on mine for a wee bit more bling👍

It's ridiculous really isn't it? Just beautiful

Is there a Titanium set that works, or is it a case of bit-by-bit?

Just in case I ever fancy taking it apart and rebuilding it again like :lol:

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1 minute ago, Juhunio said:

It's ridiculous really isn't it? Just beautiful

Is there a Titanium set that works, or is it a case of bit-by-bit?

Just in case I ever fancy taking it apart and rebuilding it again like :lol:

No specific screw kit for it unfortunately, think I used a tb03 vdf pack and a few extra 8mm csk. 

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Next step is every boy's favourite....ball diffs!

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The hop up aluminium diff joints also include and require an extra wee spacer between the bearings. Unclear why, but I've put it in, so we'll have to wait and see :huh:

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I like to liberally grease all the necessary holes, then carefully push the balls in one by one

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Then grease and attach the diff plates

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I remember from building the ball diffs in my DF03 that it was a good idea to give the diff springs a couple of squeezes before you build and tighten the diff, so did the same here

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It might seem obvious, but I find it much easier to slip the lock nut into the plastic holder before you slide it into the diff joint

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I went with the same approach as the DF03, tighten them up as much as possible then back off a quarter turn to avoid over tightening. They went together pretty easily, I remember having real trouble getting the diff screw to bite into the lock nut on the DF03 but no such problems here

And they're done :D

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A quick test-mounting in the lower bulkheads before moving on to drive belts and upper bulkheads....tomorrow

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Lovely 👍 

Hop up ball diff balls!? 

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7 hours ago, svenb said:

Lovely 👍 

Hop up ball diff balls!? 

Thanks!

They’re a hangover from the DF03 where the ball diffs are a known weakness. Consensus is to upgrade various bits including the diff balls, from kit parts to something like these ceramic nitride. Possibly unnecessary in a TC but they come in packs of 20 and I had ordered a spare so they were lying around anyway...

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Fitted the belts this morning, and fell into the trap of following the pictures rather than what my eyes can see

The ball diffs have one side where the bearing is fairly flush to the diff pulley, and one that is spaced away from it. The manual illustration shows both the 'flush' sides facing you when you install the diffs

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One end went in fine, but try as I might, I COULD NOT get the diff at the other end to sit in the lower bulkhead. I checked and rechecked the orientation in the picture against what I held in my hand, and it LOOKED right. But it just WOULDN'T FIT.

Until...

It then dawned on me. The reason it wouldn't fit is because the diff pulley couldn't get low enough to allow the belt tension adjuster to sit in the bulkhead. It was sitting on top of the deck instead of in the recess cut into the deck. For that to happen, I had to turn the diff around, with the 'flush' side facing away and the 'spaced' side facing me. And then it all became obvious..

The pulleys on the spur gear are one atop the other, so the belts run on different planes. Which means the diffs need to be offset from each other to create those different planes. Which means one must face the opposite way to the other, enabling both diff pulleys to sit in their recess and the belts to run smoothly.

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It's all so obvious. But each time I look at that illustration in the manual, I'm convinced it's showing me both diffs facing in the same direction :lol:

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With that head scratcher sorted, I was able to move on to the Upper Bulkheads

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Work building the shiny blue palace continues, with suspension mounts and front and rear centre braces

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Can't see any obvious difference between parts 1 XD and 1 XC, can anyone shed any light?

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The construction of the centre braces is pretty amazing, just about nicking under the drive belts and screwing smoothly into the motor mount

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I'm loving how this is coming together, it looks almost architectural in places

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That's all for today, got to make this one last! 

Seems like I've used a lot of blue bits so far, started to worry I might be running out! But fear not...

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Still plenty left :D

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I seem to have a random spare bit. It's 10mm across, 4mm deep, but doesn't tally with anything in the manual:

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It also doesn't look like it belongs to the front direct coupling or centre one way that were in the box with the car

Anyone have any ideas that can help me identify it?

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What an amazing build, looks truly stunning so far ! But I do wish Tamiya wouldn't insist on putting 4WD chassis under classic 911's  

Keep up the good work and keep the updates coming !

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10 hours ago, Nick G said:

What an amazing build, looks truly stunning so far ! But I do wish Tamiya wouldn't insist on putting 4WD chassis under classic 911's  

Keep up the good work and keep the updates coming !

Thanks very much! Yes, a classic 911 on a rear motor RWD M chassis would be nice 👍 

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12 hours ago, Truck Norris said:

The holes will be slightly further apart on one of them. This fantastic article will explain what they are and how they differ: https://www.thercracer.com/2017/01/tamiya-suspension-mount-ultimate.html

Thanks Truck, that’s a brilliant article to help understand the parts, their variations and their functional benefits 👍

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Great build so far, so much blue I need a blue-light filter :lol:

I was trying to post the link Truck Norris posted above from my mobile yesterday, that page is bookmarked for me since I can never remember what the codes mean without referring to it.

And with regards to making a RWD chassis Porsche, have you ever tried driving a RWD RC car quickly? It's really hard (in my experience) to stop them simply swapping ends under acceleration. Mind you; perhaps that is fairly accurate to an older Porsche?! I built a shortened F103GT for my 934, regrettably its currently sat un-finished. 

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2 hours ago, ChrisRx718 said:

Great build so far, so much blue I need a blue-light filter :lol:

Thanks! If it wasn't so pretty it might make me feel blue!

2 hours ago, ChrisRx718 said:

And with regards to making a RWD chassis Porsche, have you ever tried driving a RWD RC car quickly? It's really hard (in my experience) to stop them simply swapping ends under acceleration. Mind you; perhaps that is fairly accurate to an older Porsche?! I built a shortened F103GT for my 934, regrettably its currently sat un-finished. 

Not yet, I've got an M-06 Beetle but haven't taken it out for a spin yet. Literally!

You really need to finish that 934....

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On 11/19/2020 at 7:58 AM, Juhunio said:

 

It also doesn't look like it belongs to the front direct coupling or centre one way that were in the box with the car

Anyone have any ideas that can help me identify it?

I believe that is a coupling for the rear drive pulley attached to the spur gear in order to use the front 1-way diff. That drives the rear pulley and a 1-way bearing is placed in the other pulley. For use with PN 53841.

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Had a few days away from this build to focus on celebrating Mrs J's birthday, which is ALWAYS an entire weekend, never just the day itself :lol:

But after a couple of early meetings I had some clear time this afternoon to get back to it, moving on to step 7; assembling and attaching the steering

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The steering bridge, arms, posts and turnbuckles are all shiny blue aluminium with the arms and bridge fully ball-raced too. Looks like this will be smooooooth like cool Lester Freeman

Turnbuckles meant breaking out the Tamiya turnbuckle and adjuster wrenches, the saviour of thumbs everywhere

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Here's the steering bridge with all the ball connector nuts attached

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And then all assembled and attached to the chassis. It is super smooth :D

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Then straight into Step 8, which is attaching that lovely 30th Anniversary CF upper deck with a generous handful of tiny little 5mm screws

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Others might not be so bothered by this stuff, but I really marvel at the design planning and engineering that goes into all these kits (well, apart from the MB, what a basket!) and this is a great example. How the front and rear braces just fit in and around the drive belts, how the steering assembly just glides over the belt with minimal but enough clearance, and then how that upper deck just slides in underneath the belts and allows them to flow over, under and through it. It's so smart. 

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On 11/22/2020 at 3:31 PM, SupraChrgd82 said:

I believe that is a coupling for the rear drive pulley attached to the spur gear in order to use the front 1-way diff. That drives the rear pulley and a 1-way bearing is placed in the other pulley. For use with PN 53841.

Thanks for responding, really appreciate the help. You're (almost) dead right, and pointed me in the right direction. Turns out it's actually for the Centre One Way... I hadn't clocked that the instructions are two sided :rolleyes:. I had only checked the first page, which doesn't reference that part...

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But hadn't turned the piece of paper over...well, whaddya know?!?

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All bagged up together properly now, for if I ever decide to use it. 

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What does it actually....you know....do??

 

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The build focuses on the back end for the next few steps, starting with building the rear arms. These will include the titanium coated suspension shafts (53851) that I bought as an extra little upgrade, just because

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As this was bought as a built kit which I then dismantled, none of the plastic parts are on their original sprue trees, which I'm expecting might cause a couple of issues with part identification. 

No such issue with working out which were the front arms and which were the rear, as Tamiya had helpfully included the part number in the moulding! D2 are the rears, D1 the fronts.

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I've not seen that before, or maybe just hadn't noticed because I wasn't looking, but right here right now it's a brilliant little touch that I am very happy about :D

 

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This step includes one of those Tamiya micro-measurements that I think are only do-able with digital callipers; the little 10mm screws have to be screwed through the rear arms, with precisely 1.5mm emerging from the lower surface

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Then on with the shafts, spacers and suspension balls

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The rear arms are attached to the chassis using a 1C suspension mount, and require a drop of the ole' sticky silver gloop on each of suspension balls 

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This is my first build using these suspension blocks, interesting to see how the different widths create a bit of angle (I guess toe-in?) on the arms due to them being more 'splayed apart' at the back than the front

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