Bloody Mary in 1/8 scale scratch build

[Jo NZ]

The engines used in the final version, the JAP (for J.A. Prestwich) KTOR engine are more usually found at the front end of the Morgan 3 wheeler or mounted in a Brough Superior motorbike. It can be easily recognised by the external ohv valve springs.
Luckily there are still drawings available for most of the engine (only because the microfilms were found in a gutter!) so I started by trying to make a cylinder barrel. The fins are a problem (getting them deep enough) but I could use a slitting saw on a rotary table, which would take forever (four barrels to make!). I tried a shorter slot using a lathe tool. I'll try it in place to see whether the fin depth is going to be seen. Here's the engines in situ



And the trial cylinder - note that I miscalculated the pcd of the head bolts, so there are grooves down the bottom of the cylinder....





It looks like it should work, although I will probably cut the head fins full depth.

Now the chassis - I found some cedar of the right size (it scales out to about 3.75" by 1.8") and used brass sheet for the corner gussets



The front springs are quarter elliptic and cord wrapped.



The leaves are cut from 0.4mm brass sheet, the wrapping is crochet cotton (found in the sewing box).
I discovered on about the fifth look at the photo (after I'd wrapped it of course) that I'm short by one leaf. There should be another long leaf on top of the one with the eye....



Jo

[JunkGTZ]

Seeing the original front suspension doesn’t make a soul confident that it handled well or was safe racing up hills, but the fact that it was run until 1959 says one of two things. Either it actually functioned much better than it looked, or it was owned and driven by a succession of very crazy people! This is going to be fun to follow. You’re off to a great start.

[Jo NZ]

The front suspension is actually from a GN. Mary held several hill records over the years, so was pretty quick - all in the hands of John Bolster. I suppose that with a solid (chain driven) rear axle you wouldn't have too much time to worry about the front end...

[ThierryD86]

Taken my pop-corn cone and a pint of cider and will stay stuck in front of the screen...really blown away by these promising starts...Thanks for sharing, Jo NZ

[Jo NZ]

Thierry, you're welcome. I must revisit your Bugatti Thread, as I need quite a lot of chain (bike chain). There is a chain drive between the motors, then from the rear motor to the gearbox, and then from the gearbox to the back axle. Has anyone ever taken a photocopier apart? I think that there might be small size roller chain in some of them.

[Jo NZ]

Now for the front spring mount. Not the most common type!
The parts



The bit that looks like a boat and the slotted T are silver soldered to make the bottom clamp plate. Everything seems to hang off this, which is why I've silver soldered it



This bracket is important as it is the sole support for the friction damper/bottom radius arm, the hydraulic damper and the brake lever



I made some M1.4 threaded rod to hold it all together. The rods are soft soldered into the bottom clamp plate

[YHOR]

Great job I kept thinking about how he made the engine cylinders. For the grooves, what type / size of blades did you use? And the other question I have is, how did you calculate the diameter of each fin?

I hope to see how the cylinder head will be done, it will be a challenge.

[Jo NZ]

Great job I kept thinking about how he made the engine cylinders. For the grooves, what type / size of blades did you use? And the other question I have is, how did you calculate the diameter of each fin?

I hope to see how the cylinder head will be done, it will be a challenge.

The grooves were made with the tool that you can see in the second picture - I ground it to be as thin as I dared! The fins were produced by using the measurements for the largest and the smallest, and tapering the block before I cut the fins.

The cylinder head is still a thought in progress....

[Jo NZ]

The chassis is painted and the springs are wrapped - along with the knot on the nearside spring



The front axle is a tube with caps that are machined square and drilled to accept the kingpins. I've made mine vertical, I've seen drawings with the kingpins vertical and also with positive or negative camber. It's easier if they start vertical, I can set the camber on the hub



The brackets to attach the springs and lower arms to the axle are fairly complex. Here's where I am so far...

[Roger Zimmermann]

Interesting construction! I suppose you could do the tool for the fins thinner ; breakage is always possible, unfortunately.

[Jo NZ]

Thanks Roger. I needed to get the clamps precise as they have to match, hence the milling.
Starting to free the clamps from the channel



The first clamp pair



Spring to axle. Bolts are 00-90 to the axle and M1.0 for the clamp

[Stu238]

Hi Jo, looking really good. Making great progress. So looking forward to seeing more.

Keep up the good work.

Cheers,
Stu

[Jo NZ]

I'm back!
I've moved house to a different town (it's warmer), got most of the new house fixed up (broken power sockets, switches, new appliances, heating, curtains, fume extractors etc.) and built a new workshop in the back of the garage. It's a bit bigger than the last one, big enough for a larger lathe (Emco Compact 8) which has also needed cleaning and derusting, new bearings, quick change toolpost, quick release nuts etc. In spite of the original condition it's come up very well.
So... back to Bloody Mary:

I needed to build a jig to angle the chassis correctly. It's not parallel to the ground, but angled up at the rear



This allowed me to build the "cockpit" (it's made from 1" planks) which IS parallel to the ground



Next - the pedals. Not a particularly conventional set, but they are in ABC configuration



Mostly made from 0.4mm brass sheet











The more I look at the pictures, the more I realise how complicated 30 years of development (bodging?) can be....

[Roger Zimmermann]

Welcome back!
Interesting arrangement for the pedals...