Porsche 934 RSR 230mm 'Baby Blue'

[Juhunio 6830]

There are plenty of very detailed 934 RSR build threads on here; green ones, black ones, red ones, kit ones, bits ones, 236mm ones...

So this won't be a hugely detailed step by step, but more the specific points that may be of interest, and I found either interesting or challenging (or both!) when converting a standard 236mm TA02-SW to 230mm wheelbase, making it in theory a better fit for the 230mm body shell as originally intended for the 30th Anniversary Vaillant 934

This build started out as this 84431 40th Anniversary Jagermeister Kit

 

[Juhunio 6830]

The major change was the switch to 230mm wheelbase, using these excellent carbon fibre chassis plates and shock towers from maxspeedparts on eBay. Thanks go to @Superluminal for pointing me in his direction, they really are excellent parts 

He doesn't make the small front (14315027) and rear (14315028) spacers unfortunately, so you either need to use the kit parts or buy some more. I bought some more, so I could use the full FRP set from this kit in my Lancia 037 Rally TA02S to convert it from a bath-tub to a double deck chassis

 Power is provided by a Superstock RZ motor, paired with the 53127 TA-02 Speed Gear Set, working with a Hobbywing 1060 ESC and Savox Black servo

That servo would end up being mounted on these very nice aluminium servo mounts by Precison Geek on eBay

The chassis sits on a set of TRF dampers

And a set of chrome rims with black hub caps (54794). They only come in 26mm width, but a fortuitous and mutually beneficial swap with @ChrisRx718 (my spare 26s for his spare 30s) left us both with the drum-widths we needed! 

[Juhunio 6830]

First step is building the rear ball diff. I used these 3mm ceramic silicone nitride balls which I've used in previous ball diffs and seem to hold up well!

I initially used the 'build it yourself' thrust bearing, but then later on took it out and replaced it with a Tamiya 53136 one piece thrust bearing, to avoid any risk of meltyness 

[Juhunio 6830]

I have an unbuilt Lancia 037 Rally TA02S kit in the loft, which has the nice silver/grey front and rear gearboxes. So I decided to swap them with the black parts from this kit as an extra little point of difference and a nice match with the CF plates

[Juhunio 6830]

The Superstock BZ motor asks for an FDR of 6.5 - 7.5 which is beyond the spur gear in the kit, but bang in range of the 69T spur included in the Speed Gear set. 

I've initially paired it with a 24T RW Racing steel pinion gear to get an FDR of 7.01, right in the middle of the BZ's range with room to manoeuvre up or down if needed

[Juhunio 6830]

When using the option CF shock towers, the holes haven't been drilled wide enough to accept the step screws used to mount the upper arms (same applies front and rear)

So I made some adjustable tie rods to replace the upper arms. The rears are 32mm eye to eye...

the fronts 29mm...

I had turnbuckle shafts and adjusters in the spares box to make these:

I could probably do with trimming a bit more off the adjusters, I'll cross that bridge if needs be

The rear arms were mounted using 3x10mm threaded shafts and short 5mm ball connector nuts into the rear uprights

And then 5mm ball connectors with a 1.5mm spacer on one side and a 3mm lock nut on the other side of the CF shock tower

 

[Juhunio 6830]

That completes the rear section. You'll notice I've already removed the collars from the prop shafts, ahead of the big mod!

[Juhunio 6830]

The front gear diff is pretty straightforward. The only change I made here was to the diff outdrives. Where the rear ball diff comes with the hardened steel outdrives, the front gear diff just comes with 'standard' outdrives, so I added these optional hardened gear diff joints

The front upper arms were attached using the same combination of threaded screws, ball connector nuts, ball connectors, spacers and lock nuts 

Front section complete!

[Juhunio 6830]

Then it's time to attach the front and rear sections to the chassis, which is when the real fun starts!

Firstly, I decided to make first use of my Tamiya drill and thread tapper, and use machine screws rather than self tappers for this part of the build.

I was quite nervous of messing it up, but it's an amazingly easy tool to use and the screws then thread in and out very smoothly. I think this will be my method of choice for all future builds! If you can find hex-head screws in the right lengths, obviously!

Again, the optional chassis plates are excellent, all the mounting holes are drilled very accurately

For the rest of this modification, full credit must go to @ruebiracer, as this is absolutely his modification method. And it works a treat 

First, you have to push the copper collars off the prop cups. Easy enough in a vice using a few M4 nuts to push them off, they don't need too much force to pop off

Then I balanced the prop shaft on the prop cups and drew a line to mark the overlap, to get an accurate idea of the extra space needed. Logically it should be 6mm, but it's always worth a double check!

Sure enough, 6mm!

I then used a Dremel cutting disc to cut an extra 3mm depth in the slots in the prop cups, so the shaft could sit 6mm deeper end to end and 'buy' the space I need that way

 

[Juhunio 6830]

That wasn't the end of it! As this pic shows, the profile of the prop shafts meant the front wouldn't quite fit into the cut in the cup, so I also had to cut 2mm off the end of the cup to get it to fit

Here are the 'new' cups with the collars back on

And everything fitted together!

[Juhunio 6830]

That last step was very satisfying, trying new things, using a Dremel for the first time and also first use of the thread tapper. That is one of my favourite things about this hobby, particularly coming to it later in life; the chance for this old dog to learn some new tricks!

But the big test is whether all that extra work has made a difference; does the shell fit the wheelbase?

So I got to break out the Dremel again to work on the body shell. I always use Tamiya Polycarbonate scissors to cut my shells out, I think they're excellent. If possible I then use a craft knife and metal ruler to cut the sill lines to get them as straight as possible

But for this one I then also used the Dremel sanding drums to help finish the wheel arches and all the cut lines. Again, it's an amazing tool and really makes a big difference to the final result

And I'm very happy with the fit, even with the slightly larger treaded tyres the wheels look centred and everything looks in proportion. Phew!

 

[Superluminal 3750]

Looks great - really worth doing with this bodyshell

[J@mes 2326]

Cutting & sanding Poly body wheel arches brings me out in a cold sweat!

[SupraChrgd82 1425]

Might I suggest the use of flapwheels to massage the edges of and wheel arches?  They come in a variety of sizes and drive shanks, both for Dremel and die grinders.  These make perfect wheel arches a breeze.

 

[ChrisRx718 4470]

Coming along lovely. Sorry if I missed it, but did you have a colour scheme in mind?

Edit- I mean, pretty sure it's going to be blue , but what about a livery?

[Carmine A 2046]

EXCELLENT Build and Modifications!! 👌👏👏👏  I've missed out on several great TC Chassis' during my 1993-2008 RC Hiatus. I missed the entire heyday of Tamiya TC Racing in the 90's... Particularly here in the Colonies. 

By next year, when my fortunes FINALLY change, after a 9 year poor spell..... 

I fully plan on experiencing several of these!  There will be several stupid questions - relevant to this Build... Which is the best TA series Chassis?? (I'm likely to stick around 257mm, 190-200mm Bodies) 

The Carbon Fiber Chassis Plates are an obvious improvement, are they only available as a 230mm Conversion Kit, or are other WB's available as well? 

Frankly, seeing your work before, I can't wait to see how you finish that BODY!! 😊😎

[Juhunio 6830]

19 hours ago, J@mes said:

Cutting & sanding Poly body wheel arches brings me out in a cold sweat!

I know what you mean, but it is one area of this hobby where I do feel like I get progressively better each time

Unlike soldering....

[Juhunio 6830]

15 hours ago, SupraChrgd82 said:

Might I suggest the use of flapwheels to massage the edges of and wheel arches?  They come in a variety of sizes and drive shanks, both for Dremel and die grinders.  These make perfect wheel arches a breeze.

 

Top tip, thanks very much! I'll track some down, you can never have too many Dremel widgets 

[Juhunio 6830]

14 hours ago, ChrisRx718 said:

Coming along lovely. Sorry if I missed it, but did you have a colour scheme in mind?

Edit- I mean, pretty sure it's going to be blue , but what about a livery?

I always had a 'road car' look in mind rather than a race car, as I found @Shodog's 934 really breathtaking

So I sold the kit body, wing and stickers and bought a 'Black Edition' body set from Tamico and have painted it in Corsa Grey, which is actually a lovely flat pale blue

I used about 3/4 of a can, in 6 thin coats with an hour in between as it was a nice warm day so it cured quickly

I also got a set of @Truck Norris's window and bumper stickers, which are a flatter black than the kit stickers and look a bit more realistic

[Juhunio 6830]

7 hours ago, Carmine A said:

EXCELLENT Build and Modifications!! 👌👏👏👏  I've missed out on several great TC Chassis' during my 1993-2008 RC Hiatus. I missed the entire heyday of Tamiya TC Racing in the 90's... Particularly here in the Colonies. 

By next year, when my fortunes FINALLY change, after a 9 year poor spell..... 

I fully plan on experiencing several of these!  There will be several stupid questions - relevant to this Build... Which is the best TA series Chassis?? (I'm likely to stick around 257mm, 190-200mm Bodies) 

The Carbon Fiber Chassis Plates are an obvious improvement, are they only available as a 230mm Conversion Kit, or are other WB's available as well? 

Frankly, seeing your work before, I can't wait to see how you finish that BODY!! 😊😎

Thanks very much! I only came into this hobby last summer at the age of 40mumblemumble so I missed the heyday of everything! Now making up for lost time and enjoying the lessons thrown up by each build

Maxspeedparts seems to do parts for a few different kits but at first glance his Tamiya work is mostly / exclusively TA02S in either 236 or 230mm, though I could be wrong and I think that a couple of members here have worked with him to develop parts in specific sizes

And the body work came together really nicely I think 

[Juhunio 6830]

The body is painted in Corsa Grey, which is actually a really nice pale flat blue

I used hardly any of the kit stickers, just the lights, door handles, wipers and grills really.

The window frames, bumpers and body stripes all came from a set by @Truck Norris, which work really well. Top job Truck!

For the rear wing I primed it using Tamiya Fine White primer, then masked off the bits that would end up blue so I could spray the vents and fin in PS Black. Then let that dry, removed the masking, re-masked the black bits and sprayed the rest in the Corsa Grey, two light coats did the trick.

It took quite a bit of fiddly masking, but I'm pretty pleased with how it turned out

[Krustybus 214]

That's very nice! Love that colour

[Carmine A 2046]

PRETTY PLEASED? You should be quite proud of that!! Especially after admitting your "lack of experience" in the Hobby. You're right about the Paint, my first impression is that of nothing but Sky Blue. It's a beautiful choice indeed. 👌 Very simple, yet Elegant.

Your Stance is nearly perfect! We try so hard to get the right fitment of the Tires into the Wheelwells, vertically and horizontally. You've achieved that!!  👌👏👏👏👏👏👏👏👏👏

The Decals by @Truck Norris  look about as good as it gets. The Headlights and Bezels are so good that at least on my Phone, they LOOK like separate molded pieces - NOT Stickers!!

[ChrisRx718 4470]

Looks ace, that. Fair play.

Bugs me that, no matter the chassis, the battery retainers are visible on the 934 RSR  even my custom F103 has this issue.

[Juhunio 6830]

3 hours ago, ChrisRx718 said:

Looks ace, that. Fair play.

Bugs me that, no matter the chassis, the battery retainers are visible on the 934 RSR  even my custom F103 has this issue.

Thanks!

Agreed, it's weird that they tailor(ish) made this shell / chassis combo, as the shell has relatively high sill lines, higher certainly than the 911 RSR which does a better job of hiding the TT02 chassis it sits on

But then it's also weird that they paired a 230mm wheelbase shell with a 236mm chassis, so hey ho!