Alex B's WCS 1989 build

[Alex B]

In keeping with tradition I'm making a thread on my latest Yokomo build, thanks to the work of Cheng Fan's amazing reproduction parts, some new old stock Yokomo parts, some old parts including some that I actually used in my 870c as a child from the Alex B parts bin, MCI racing, penguin bodies and some others that I find myself in a position to be able to build my very own replica Yokomo WCS 1989.

It was this very car that I drooled over as a young teenager and convinced me to ask my parents to get me the Yokomo 870c over the far more popular, at the time (in the UK at least) Schumacher CAT XLS for Christmas 1989.

Along with the official 870c rerelease by Yokomo it is going to be an enjoyable winter.

I'll update this thread in due course and hopefully I'll finally finish my WCS 93 build https://www.rc10talk.com/viewtopic.php?t=26696

[Alex B]

Shocks are vintage associated 0.71 for the front and 1.02 for the rear. I only had some blue anodized shock caps in the parts bin so these were given a quick rub down then primed using Tamiya plastic primer and them painted with a Tamiya black.

The white plastic parts are from FAN RC, but I've since retrobrighted some original Associated parts which came up great. One problem I had with the springs I'm using was they were slightly larger diameter than the shock retainers (not a FAN RC issue as the originals are the same) to fix this I used some black Yokomo shock spring centring collars, I also used some Yokomo white collars on the spring retainers to prevent the springs rubbing on the shock bodies. The original Associated parts have this little guide built in.

This is not quite keeping with Masamis Yokomo as he used spacers, I do have some of those and I might change to them in the future but I'm not going to be that precious about it. The screws are titanium and were procured from AliExpress.

These shocks (in this size at least) are getting harder to come by and expensive but will so be available from FAN RC in the near future.

[Alex B]

For this build I will be using original Yokomo parts where I have them, in the case of the front and rear shock towers I managed to get a NIB ZC-710S front tower, the rear is one I ran on my original 870c back in the day, which from recollection was a genuine Yokomo part. As you can see from the photograph of the actual car mine is different as it has several more shock and wing mounting options. If anyone can shed some light on the tower that would be helpful.

[Alex B]

The bumper is homemade from 3mm 'kydex' I used a heat gun and wooden spoon handle to achieve the bend. It is grey because I ordered white kydex sheet but was sent grey, either that or I'm colour blind .

I've used a nylon bulkhead for mock up purposes but I'm waiting on some FAN RC aluminium ones which I'll use in the final build.

[Alex B]

A couple of small updates.

I mocked up the rear suspensions arms and hubs. Fan RC provides some nylon and and metal washers of this I used 1 large nylon and 1 metal washer for the rear and 3 metal washers for the front. I total you will need 4 of the metal washers and one of the larger nylon washer provided in the Fan RC kit. The hub extension has very tight tolerances on the fixing holes so I ran a 3mm drill bit by hand just to ease assembly, I fixed them with M3 x 6mm titanium screws. The hingepin length is the same as the length used at the bulkhead side.

The tolerances, quality and fitment of the parts is very good. No issues thus far.

[Alex B]

The front arms went equally as smooth. I'm using Kyosho Optima C hubs (Part number: OT204) and Kyosho Optima Yeah Racing brass knuckle bushings (Part number: KYOP-014GD) the steering knuckles are fixed with m3 x 8mm titanium screws, I had to shim out a little bit of play using a washer - I'll probably get some proper M3 shims when it comes to final assembly as the washer I used was a tad too thick and was causing a little binding.

The Kyosho Optima C hubs come with a small nub on the top which you will need to file off.

[Alex B]

Thought I would do a mock up of the chassis, all fit together perfect. I'm still waiting on a 2mm gear adapter so used a 3mm slipper and layshaft for the mock up. I also found a alloy heatsink layhaft cap in the parts bin - I might keep this on but strip the anodizing, not decided yet.

[Alex B]

Finally got the Fan RC bulkheads in, they really are a well made bit of kit.

[Alex B]

I'm using titanium hardware I got from Aliexpress, I had to 'adjust' the countersinks as the chassis is made for the Associated alloy 8-32 screws which have a 100 degree countersink, I'm using the alloy ones for the battery posts. Those alloy screws are available from JC Racing if anyone is interested in a set.

[Alex B]

Detail of the layshaft - using the 2mm belts and pulleys. Using a M5 nylon nut on the front pulley as Masami did on his car back in 89

[Alex B]

2mm drivetrain installed. The caps are from my original 870c they did not have the upper chassis mounting holes so I had to drill and tap them. They were in quite rough shape having yellowed quite significantly over the years but some Core RC green metallic paint sorted that out. The diffs are from a later YR-4.

[Alex B]

Front, rear and steering detail which are all from Fan RC. Originally I was going to use Kyosho C hubs but found they were giving horrible bump steer which I think was caused because the Kyosho hubs have additional caster so I reverted back to some original Yokomo ones. I think I'll get the Yokomo re-re arms and c-hubs when they become available next year. The hubs are original Yokomo works 91. The ball joints are original alloy Yokomo ones which I originally got for my WCS 93 until I found the correct ones. All the white ball cups are Fan RC.

[Alex B]

Front and rear suspension detail. The shocks are original Associated 0.71 and 1.02 stroke. The Fan RC kit comes with new reproduction shock towers but I used some original Yokomo ones I had. I had forgotten how much of a pain e-clips were...

[Alex B]

Underneath shot of the completed chassis and suspension, the bumper is hand made from grey 3mm Kydex.

[Alex B]

Completed chassis. The sticker on the upper chassis is from the Schumacher Masami CAT XLS kit. The battery posts are Fan RC and don't come drilled so I had to drill them for the r-clips, the nylon material is really hard and was a pain to drill - I ended up heating a small drill bit and melting the material to create a pilot hole, that was probably the hardest part of the build.