jw4 Smokey's JW4 Formula Four Rebuild Thread

[Mark (smokey mow)]

18 hours ago, alexander72 said:

superb - interesting you can have a bolt at the top but a rose joint is banned still? 

The bolt is in double shear which is a recognised MSA and FIA detail.

the shear area of a rose joint is conversely a lot smaller so there is a significantly greater failure risk, but in my eyes the greatest risk is by tensile failure of the rose joint thead. 

[alexander72]

Cheers M

[Mark (smokey mow)]

A great video from March 1967 of the Vixen F4 and also one of the races at Lydden Hill. 

 

 

[Mark (smokey mow)]

With not much happening with the JW4 at the moment while I wait for the fuel tank to be made I've started looking more at car number two.  I've already got a lot of the parts needed for the build and whenever I've had parts made I've been ordering in pairs but there's still a few bits missing that I'm going to need.

 

The steering rack was a bespoke item for the JW4; I had what I thought was a spare rack for the second car in amongst the boxes of parts but on closer inspection It turns out it was missing the pinion. Luckily I had the original machining drawings but unfortunately gear cutting is well beyond my basic workshop tools so a quick call to JDR and they were able to help out.

 

 

 

[pete g]

will it be ready for crystal palace mark

 

 

[Mark (smokey mow)]

3 minutes ago, pete g said:

will it be ready for crystal palace mark

 

 

Yes, but not the one this year  

TBH there's not much left to do on the first car now, a few brackets here and there and thats about it. The car will be going to the Fordham car show again this year in August after which it will be fully stripped down.  The parts which aren't already plated will be sent away for a polish and nickel plating, there's a bit of welding to do on the chassis which can only be done with the body off, then there's the chassis to enamel paint before final assembly.  

I'd like to think all the above will be done by early next year. That way I'll be able to use the first half of the year for testing, probably at Gosfield and to get it log booked.

 

 

 

[Mark (smokey mow)]

Its once again been far too long since I gave a progress update on this build thread. My summer was largely spent block paving the driveway at my girlfriends house and now I'm mid-way to refitting her kitchen but theres still been a little progress on the JW4.

 

First up was the fuel tank. The JW4 ran two fuel tanks, the main tank was in the nose ahead of the drivers feet and the second smaller lift tank was fitted in the engine bay.  The fuel pump was mechanically driven by a cam off the rear axle and would pump the fuel from the nose tank to the engine bay tank only when the car was in motion.  The fuel would then be gravity fed from the smaller tank to the carb.   As my intention is to only use the car for sprints the smaller tank should be enough for that purpose and i will be fitting a crash box in the place of the main tank.

 

Way back in April before Stoneleigh I'd sketched out some ideas for the tank to try and mirror the design for engine bay tank originally fitted and made plans to see the fabricator once I returned home from the show. Plans however changed over the Stoneleigh weekend when by chance I found a small air reservoir tank on one of the auto-jumble stands that would almost be perfect. It had a few holes that needed plugging and was obviously missing a fuel filler but it had enough potential to be useable for the build. After I got home it was dropped off with Martin at .mjs Fabrication and he set about transforming it into a fuel tank for me.

 

The before and after results.

 

The other major progress albeit not with the car is that I've now had all the drawings scanned for the JW4 and Johnny Walker's other projects.  In the end it amounted to some 250 drawings covering the various cars, prototypes and Karts that emerged from his factory between 1965 and 1968.  Having everything in an electronic format will make things easier for me when sending drawings to have parts made and also searching for drawings as they're currently stored in about 20 tubes.

 

 

[Thrustyjust]

Thats a tidy bit of welding on that tank. 

[Mark (smokey mow)]

I can't believe it's been 4 months since the last update.

i started a major kitchen refurb for SWMBO back in November so that has required most of my attention at the expense of garage time however that hasn't stopped me from doing a few small jobs when time had allowed.

With the first car almost complete and only the chassis left to paint, I've turned my attention to the second JW4, the Carburol Special and who have been following this thread from the start wil recall it's hanging from the rafters.  Like my first JW4 the Carburol began it's life racing in Formula IV but with the demise of the series it was converted by and adapted by it's then owner John Shaply in the mid-1970's for hillclimbs.

Time hadn't been kind and when it came into my ownership the chassis was covered in a thin layer of rust and what other parts I had have all seen better days. The orignal aluminium panelling it carried during it's hillclimbing days has long since been lost but by chance I have a full set of Mk2 JW4 bodywork lurking in the loft of the garage.

The Carburol Special begain its life as a JW4 Mk2 so the plan is to rebody it with this but critically retain all the chassis modifications and bracing that was undertaken by John Shaply. As I'll be building it for the "period look" I'll also be fitting a period engine so the Triumph Twin will be finding a new home.

[Mark (smokey mow)]

With space in the garage currently at a premium the plan is to refurbish all the parts first and then carr out the assembly right at the end.

The first job to do was the front hubs and uprights.  I was suprised to find these were aluminum hubs rather than the cast steel sidecar units which they would have orignally been fitted with. Front brakes are still used BMC mini drums, the backplates were looking worse for wear so I opted to replace these rather than refurbish. Otherwise everything else received a good coat of paint, a regrease and then reassembly.

[Mark (smokey mow)]

The aluminium drums were also looking a bit tired so these were left with a local company for media blasting.

The before and after 

 

[Mark (smokey mow)]

Over the last few evenings I've had a bit of time to escape into the garage to do a few jobs.  I didn't have a set of radius rod connecting forks for the second car amongst the spares but I did have a set that had been part machined in the past.  I'm not sure if these were from the original stock or a later remanufacture but using them would save me a lot of time and expense of getting some made from scratch.

 

This is one of the clevis's on the first car and shows what they should look like

 

 

And this shows what I have to work with.

 

 

First job was to drill down the centre for the threaded stud, to make sure everything was centralised I did this in the lathe.

 

 

Next task was to tap the hole I'd just drilled out to 3/8" UNF

 

 

And finally it was back into the lathe to part them off at the correct length.

There's another two still to make and then the studs need threading to the correct length. 

 

[Mark (smokey mow)]

A little more progress earlier today, I completed a couple of the trailing arm forks and trial fitted them to the rear uprights. They just need a coat of paint and then they're finished.

[Mark (smokey mow)]

Ah this should see the pace of build imorove a bit.  I finally got around to ordering all the various brackets and parts I need for both cars from the laser cutters.  Whilst I was at it I also ordered a few spares so I now have enough bits to also build two more chassis should I feel the urge  this is about half of the order, i ran out of room for it all on the lounge floor !

 

[Mark (smokey mow)]

A little more progress to day. The arrival of the parts from the laser cutters has given me the chance to start pulling together a few bits for taking to the welders.  One part I've been keen to get on with is the rear drive assembly for the Carburol Special as every component for this is missing and so will need to be made completely from scratch.  

The drive housing is a simple fabrication but I still needed to turn the 3-tubes on the lathe and drill and shape the mounting brackets.

The mounting brackets are 1-1/4" steel angle which was first cut to length on the trusty chop saw and then onto the pillar drill to drill the holes.  The corners then needed a radius on them for which the bench grinder was put to use. To help me form the radius by hand I bolt an oversize washer into the hole which I can then use as a guide when grinding away the corner.  

The finished kit of parts ready to take to the welders