1/8 Porsche 908/03

[ScratchBuilt]

Hello!

More progress on the rear suspension this week. The first task was to assemble one of the driveshafts so that I could check the suspension geometry. I drilled and pinned the spider joints to the donut, trimmed the length of the outer shaft section, and pinned a small spigot to the outer CV joint.

To locate the outer CV into the upright I sleeved four different sizes of styrene tube together, starting at 1/2" and working down to 5/16". A small piece of 1/8" x 1/4" box-section fits exactly into the 5/16" tube, and the CV spigot fits into this! Rather than being 'buried' inside the upright (as they are on the 917), the 908's CV joints sit outside - so there's still plenty of room inside the upright for the stub-axle, etc. Here's what it all looks like:



The big job this weekend was to check the geometry and make sure that everything was going to look as it should...which (to start with) it didn't. You can see on the photo above that the driveshaft is sloping upwards at a noticeable angle - too much. So, I raised the chassis to ride-height then set the upright to the corect wheel-centre height - the lower wishbone ended up just off level, but the driveshaft was still at the wrong angle. Solution: two small 1.2mm spacers underneath the main gearbox mountings to bring the inboard ends of the driveshafts up. Problem solved:



The mounting for the rear top link is (for now) a temporary fix until I'm happy with the geometry. Chances are it will end up staying, with extra reinforcement, etc, to suit - but I'm not going too far with it just yet.

The problem of how to attach the top link and radius rod to the top of the rear upright remained. On the real thing there is a large joint attached to the top link which has a built-in attachment clevis for the radius rod. Trying to make this small enough and strong enough would be tricky, so I used the same method as for the lower wishbone - glue a styrene clevis onto one of the RC car balljoints:





So, everything fits together and there is enough flexibility to allow for final adjustments. If necessary I can move the top balljoint forwards to reduce the angle of the link, but I think it will be okay as it is. The radius rods are just plain 1/8" diameter styrene tube for now, but will eventually have tapered ends, etc, to add a little detail. The lower wishbone is also still in mock-up form until the layout is finalised.

...and that's about it for this week. The next step is to do enough to hang a wheel on the upright, and make sure that I can get it all together without the tyre trying to foul the bodywork. Then I can start building-up and reinforcing the uprights, top link mountings, etc. When it looks like the rear suspension is okay, I can return to the front end...and then sort out the brake discs, calipers, wheel locators...

Cheers!

SB

[Macio4ever]

I have just discovered this WIP then lost my conscious...

Now is OK.

I am speechless

Awesome...

[bmwmech1]

Looks great, as it always does! You're getting close to having to start planning your next build... I'm still in for the exploded view, before you final assemble it all! The number of parts you have made is mind-numbing, truly a masterpiece!

Garey

[Pascal D]

Unbelievable !!!!

The amount of detailling is incredible, and as always your workmanship is first class.

Greetings

Pascal

[Shovel]

I completely agree with Pascal.
What an incredible piece of craftsmanship this is turning out to be.


Can hardly wait to see more of this great work of art.
Mark

[ScratchBuilt]

Hello again!

Nothing too dramatic to report this week - just putting together the top link mountings for the rear suspension:







Not the greatest photos, but they give you an idea. The time-consuming part was shaping the filler-plates to go around the main mounting - lots of patterns made from cereal packet cardboard for these! More greenstuff was added to fill the gaps and give a similar feel to the rest of the chassis - this will be filed and sanded once fully hardened.

Later there'll be a small addition to the top of the chassis above the top link for the anti-roll bar mounting - this will conceal the end of the tube you can see in the last photo. I've also got to add the bracketry for the top damper mount - but not just yet!

Garey - the next project? I'm trying hard not to think too much about the next project, but I guess it's impossible not to think about it! As things stand, I think it's a three-way fight (but all Porsche!): 936, 956, or 935-78. All three have their own challenges, but the main attraction is that any of them would look so good in 1/8 scale! Fortunately, it gives me an excuse to keep finding reference material for all three cars - whether it's books, models, kits, or online photos. I just hope that they publish another Porsche Archive book sometime soon - the one for the 917 is worth having just for the chassis drawings! I reckon the 908 should see me through most of 2010, though...

Cheers!

SB

[jaykay640]

Great work!

If you look for reference to do the Moby Dick this link here should have a lot of useful pictures. By the time they're done you might be done with the 908/3 as well :-)

http://www.freisinger-motorsport.de/...Detail/19.html

[tony126c2]

These pictures are a delight...a piece of art!

[bmwmech1]

Originally Posted by jaykay640

Great work!

If you look for reference to do the Moby Dick this link here should have a lot of useful pictures. By the time they're done you might be done with the 908/3 as well :-)

http://www.freisinger-motorsport.de/...Detail/19.html

Killer link, I bookmarked it too! Never know when I'll pull out the Tamiya 935 and turn it into a Moby, Lol!

Garey

[bmwmech1]

Originally Posted by ScratchBuilt

Garey - the next project? I'm trying hard not to think too much about the next project, but I guess it's impossible not to think about it! As things stand, I think it's a three-way fight (but all Porsche!): 936, 956, or 935-78. All three have their own challenges, but the main attraction is that any of them would look so good in 1/8 scale! Fortunately, it gives me an excuse to keep finding reference material for all three cars - whether it's books, models, kits, or online photos. I just hope that they publish another Porsche Archive book sometime soon - the one for the 917 is worth having just for the chassis drawings! I reckon the 908 should see me through most of 2010, though...

Cheers!

SB

Well, it's interesting that 10 years ago, I would never have thought about building anything in 1/8th that wasn't based on some sort of kit. And the kit offerings were pretty few and far between... fast forward to now and I don't know if there is anything I wouldn't try building in 1/8th... Good subject matter for your next project choices... and you're right, all would be awesome in 1/8th! I should have some more progress shots up tonight, too...

Garey

[ScratchBuilt]

Hi jaykay - yes, I've been following the Moby Dick rebuild on the Freisinger website for some time. Most of the photos of the 935-78 you see in books tend to be the same few shots, so it's good to see one being given the full restoration and rebuild treatment - plenty of chassis details! The tricky part of making one from scratch will be creating what's left of the original 911 bodyshell - there's not much, but it will be fun trying to mould it somehow from fibreglass!

I'm pretty sure Iconmodeler started a thread on this forum several years ago about converting the 1/12 Tamiya 935 into a 935-78, but I don't think it ever reached a conclusion. It could give me a few ideas, though...

You're right, Garey - part of the fun is thinking 'how can I scratchbuild that?', rather than 'I wish someone made a kit of that'. Just as the 956 was Porsche's first ali monocoque racer, if it turns out to be my next project it's going to give me some new challenges too! Can I replicate the chassis tub using fibreglass sheets somehow, or can I create an inner tube chassis and panel it to get the same result? Hmmm...I think some experimentation will be required!

Still, the next model is still some months away, so there's plenty of time for things to change - I see there's a Ludvigsen Library book on the 956 / 962 coming out in early 2011 (I think), so that might just have the one photo or drawing that makes the project possible. A good book on the 936 would be fantastic, but I don't see it happening - a shame, because there was a lot of good stuff going on there from '76 to '81. We shall see.

Cheers!

SB

[ScratchBuilt]

Another update for you...

The last couple of weeks have been a little frustrating, to be honest. After finishing the pick-ups for the rear suspension I turned my attention to the front end - I'd mocked-up all the mountings for one side earlier in the project, and after making a dummy upright I could see where the pick-ups really needed to be. So, new pick-ups all round and I was then ready to start thinking seriously about the uprights...

Which is where the frustration started.

I wanted to add some reinforcement to two of the pick-ups to match the reference photos. However, everything is at an angle to each other, so I managed to spend two evenings getting nowhere very fast trying different ways of joining part A to part B.

A migraine on the third night didn't help to get anything done, either.

Then I spent another happy evening trying to bend some tube for the rear anti-roll bar. End result - scrap tube, more annoyance.

So, approaching this weekend I decided to go through my joblist and set a few targets - and it seems to have worked.

Firstly, I had to add a couple of curved gussets to the pick-ups for the front lower wishbones:



A good chunk of yesterday was spent working on the oil cooler and ducting. Instead of having the hot air from the cooler exiting over the nose of the car and washing over the cockpit, the 908-03 ducts the air down through the floor and out under the car:



It's quite a thin slot in the floor, but I can only assume that the raised chassis floor directly behind does a good job of sucking the hot air through.



Here you can see the angle strip I fitted to locate the oil cooler. A second angle will give me something to glue the fibreglass duct to.

The left-hand end of the duct was removed to allow access to the oil pipe connections:





The basic idea for the pipe fittings had been worked out some time ago, so I made a few more parts to get the pipes exiting at the correct angle.

So, when it all goes together it looks like this:





The final job for yesterday was to modifiy the two tailpipe brackets I'd made a few weeks ago. Nothing too dramatic here, just a case of adding another short length of tube and filling in the gaps with greenstuff. You''ll see how it all looks a bit further down the line.

Most of today has been spent making the catch-tank for the oil system. It's built around a core of three lengths of 8mm box-section, with an outer skin of 0.5mm styrene sheet. The top is built-up around a small length of angle-section (which will mount it to the chassis), with a little extra detailing for the cap. It still needs three small strips gluing around the middle, but it's just about there:



There's a few other jobs going on that I haven't taken photos of yet. I've done the clutch foot-rest, and made a good start on the two ignition coils earlier this evening.

Hopefully this approach will get me back into a good run of work - I find it very annoying when I spend an evening on the car and feel that I don't have anything to show for it. There's a whole bunch of parts that still need to be made, so it's not as though I'm short of things to do! I think the uprights will have to wait until Easter - then I can spend two or three solid days on them, rather than an hour or two here and there. So, what am I going to do this week? We'll see...

Cheers!

SB

[bmwmech1]

Finally... an update! Just kidding, I have been waiting for one, though. I seem to be in the same sort of spot you're in... not made any progress for about 10 days, for a number of reasons. I think your idea of shifting gears and changing what you're working on is the right idea. I have been working on some drawings for the engine block and suspension, to switch from the chassis, for a little break. Your progress looks good, but it always does, right?
I may get some work done tonight, but we'll see... it's still early yet, here.

Garey

[rollin80s]

this is such and awesome build. got me hooked on it that i look at this thread every time i visit here. this is truly an epic build.

[tony126c2]

I love this piece of craftsmanship!

Ton