Kyosho Ultima SB Dirt Master and Schumacher Cougar Classic

[Superluminal 3750]

29 minutes ago, BuggyGuy said:

So it sounds like those step 29 parts add a bit of strength.

Well spotted! I think ive read something similar that arms and uprights can be strengthened with a grub screw inserted into the spare hole positions on other kit chassis so may be a similar principle here!

[skom25 1245]

On 5/8/2023 at 2:08 PM, Superluminal said:

 

Yeah, im using shock shaft pliers on the turnbulckle shaft. I think its a combination of the plastic being incredibly strong (a good thing long term) and the shape of the cup which has two spikes on it - it requires quite a lot of force to thread them onto the shaft even with a blob of grease. It would definitely be kinder on thumbs if it was moulded with a flatter or smoother shape.

I think i might invest in a m3 tap or theTamiya thread forming tool seems to be welm rated although the horse has bolted for this kit.

I was a bit gutted about the servo - it looks really well made and was just a few quid shy of £50 so is about double what i normally pay for servos - i assume i just got unlucky and will try another to see if that is good. Its the time thing thats worse! Im out next weekend and i cant do anything mid week because of work so its a whole two weeks gone by on it.....bahh!

Hold on! If you want to buy tapping tool for turnbuckles, you need two. One side has right thread, on the other is left!

[Superluminal 3750]

You're correct! Left and right handed thread ones would be required.

[Superluminal 3750]

Managed to get some super glue in the week so can carry on with this for a bit more.

Next step is one of my least favourites normally but this wasnt too bad - ball diffs.

Step 19 and 20;

I used some hop up aluminium parts here to replace the kit plastic ones.

Cleaned the parts with IPA and the superglue is used to glue the pressure plates of the ball diff to the drive plates with the castellated end.

I used some old tamiya ball diff grease i had. The parts are very similar to the TA02 ball diffs ive built before - i generally prefer gear diffs as ive no idea whether ive tightened it the right amount (it just says adjust screw to compress disc sprinfs) but it feels nice and smooth.

Bag C next;

Step 21 - 

Screw the side plates onto the diff pully. 

And thats the diff done.

[Superluminal 3750]

Bit more this afternoon.

Step 22 is the dreaded Schumacher universal.

The kit comes with a tool made of the same FRP material as the shock towers. The metal pivot piece needs to pop into the holes in the prongs of the drive shaft and the tool is used to facilitate this. Unfortunately, the plastic is extremely hard and the tool has sharp edges and it requires a badword of a lot of force to install them. I warmed the shafts first in a cup of water from the kettle which i think may have slightly helped, but some time and very sore hands later we have these.

Which then attach to the diff.

Step 23 - starting on the gearbox. Assembly of the spur gear shaft.

Step 24 - fit some aluminium top hats and some bearings to it.

Step 25 - the gearbox sides.

These are made of some brushed finish stainless steel. Im also fitting the hop up aluminium eccentrics which are used to adjust the drivebelt tension.

Wasnt too keen on the use of very small self tapping screws on these parts, would have preferred the design to have a threaded bush or nut on the otherside.

Step 26 and 27 is join the halves together and fit the belt that connects the spur gear shaft to the diff.

Step 28 - fit the remaining screws and the other eccentric.

Step 29 - fit the drive pin and spur gear which is held in place with an o-ring.

And thats the gearbox assembly completed.

[Superluminal 3750]

Last bit for tonight. Step 30 - attach the gearbox to chassis. Theres also a plastic motor guard.

I must admit that im not really a massive fan of pozi screws. They dont feel anywhere near as nice to do up as JIS or hex heads as they feel like they want to slip on the driver more than other profiles.

Parts bag D;

As well as all the plastic you have to keep picking out about a million staples.

Step 31, rear hubs.

Im really enjoying how unique this kit is. It has lots of features that ive not seen on anything else before. Having built quite a few Tamiya and Kyosho buggies you get used to their suspension and drive shaft arrangements and they all follow a similar formula even on new kits. This is nothing like them!

Step 32 - more universals. My poor hands.

This is the outer part of the drive shaft which slides over the inner piece on the diff so instead of a dog bone arrangement movement is accomodated by a telescopic motion - very clever!

Fitted into the rear hub.

Step 33 - attaching it to the chassis.

Just when your fingers and thumbs thought they could have a rest.....more turnbuckles.

And the smallest e-clips ive ever seen.

Step 34 and 35 are a repeat for the other side.

And so is 36.

Step 37 - rear damper stay and wing mount.

The shock stay itself is FRP but a black colour. Seemed unusual as the other pieces in this material are normally the greeny colour.

Screwing it the chassis was a bit fiddly as the hump on the gearbox for the spur gear shaft is exactly where your screwdriver needs to sit to tighten the lower two screws.

And thats it for tonight - the next stage is the rear shocks.

[davidwj95 152]

This is a really interesting read and I love all the detail and photos.  I was choosing between these two cars and went for the cougar. It was delivered last week.  I'll be starting the build soon.

[ChrisRx718 4470]

Are those really self-tapping screws just cutting their way into the aluminium? I wonder how that is for longevity?

Like you say really interesting to see a manufacturer doing something we're all familiar with very differently!

[Superluminal 3750]

20 minutes ago, ChrisRx718 said:

Are those really self-tapping screws just cutting their way into the aluminium? I wonder how that is for longevity?

Like you say really interesting to see a manufacturer doing something we're all familiar with very differently!

I think the plates are stainless steel as they feel a bit weightier but yeah, they just have to self tap into the plates. Theyre not very thick though so you arent cutting a great deal of thread into them with the screw. They feel pretty secure for now but not sure how many goes you would get at removing and refitting them.

[Superluminal 3750]

Theres been some choice words this evening. Ive built lots of dampers from Tamiya and Kyosho before but these were a bit "challenging".

Step 38, 39 and 40 will be a bit of an almagam of the three stages.

Rear shocks first.

Starting with the damper bodies.

The first part is to install the larger red o-ring into the bottom of the damper then install the small red o-ring / black plastic spacer / small red o-ring into the brass collar. This then sits inside the damper up against the first red o-ring followed by the clear plastic washer. This is then held in by a circlip. You absolutely need circlip pliers for this - ive got some really poor ebay specials and struggled to get these in. I found it really difficult to squeeze the circlip and then push it into the damper with enough force to compress the o-rings down enough for the circlip to pop into the groove. I got there in the end by getting it approximately in place and then using the tip of a small screw driver to press it down as the prongs on the circlip pliers were contacting the plastic washer. It worked but it was very fiddly.

The other thing the manual goes to great pains to mention is to install the circlip with the rounded side in - I couldnt tell what this was, as close as i looked even under torch light i couldnt see a discernable difference so its 50/50 if i put them in the right way up.

Next is the piston assembly and rod end.

The yellow pistons dont have any holes in for damping, just a slight notch in one side to allow the oil through. There was a ring of moulding flash around them that needed filing off as they were a bit catchy on the inside of the cylinder when i first test fitted them.

The white plastic spacers are fitted internally on the piston shaft and the black o-rings externally as bump stops.

And then i noticed this.......

The small FRP tool first introduced when building the driveshafts is actually a tool that fits the turnbuckle ends. At no point in all the other stages you build all the numerous turnbuckles before this does it ever mention this tool!! I was tightening them by hand until my thumbs were so painful i ended up wrapping the ends in a teatowel (although i have got ultra soft office working, no manual grafts lady type hands) @davidwj95 when you build yours, save your hands and use the spanner on the turnbuckles. And make sure you get some small circlip pliers.

These are then filled with oil which is 400 CST and comes in a small plastic bottle.

The filling arrangement and bladder at the top is fairly standard like a Tamiya cva.

While the bubbles were settling in the oil i moved onto the fronts.

Bag E; the last bag.

Steps 42, 43 and 44

The principle arrangement is the same as the rears.

And so too is the piston. Where it differs is here all the spacers and o-rings are all installed externally (the parts are labelled incorrectly in the manual but its clear on the drawing what goes where)

And instead of the ball ends on the rear it has a different open eyelet with a threaded metal ball nut thing. This needed pressing in. I tried numerous sets of pliers but i couldnt get it through - it spent most of its time firing the two parts out of the jaws and around the room. In the end I got them in with a tool ive never used on an RC car before.

And before filling they look like this.

The fronts use a different heavier weight of oil.

Waiting for the bubbles to disappear.

Bladders in and top caps on. They feel nice and smooth.

Step 41 is mounting the rear shocks first.

Theres a plastic top hat, a plain plastic washer and a nut to hold them on. They were very straightforward.

The fronts on the other hand were not.

Step 45...

This comes with a parts tree of a plastic spacer cone, a ball and a washer for the top mounts. Unusual as all the other kit plastic parts come pre cut.

The nyloc nut holds the top of the damper to the mount and the cap screw is supposed to thread into the metal ball installed into the rod end earlier which sit inside the suspension arm.

However.

This screw is much longer than the internal thread of the metal ball nut. Which means it then needs to pass through this and start forming a thread in the plastic suspension arm on the other side. But both these parts being threaded separately means the cap screw starts to bind on the metal part instead of cutting the new thread on the other side. The whole thing had become hideously jammed up and i couldnt then extract the screw and the gap is too small to get any pliers into. In the end I managed to use the very thin spanner that comes with Tamiya hop up turnbuclkle kits and jam it in the gap which held the ball in place so i could remove the screw. The way that i got them on in the end was to insert the screws first to form a thread in the plastic, remove the screw and fit the damper. Hold the ball in place with the spanner and tighten the screw until it just makes contact with the now threaded hole in the other side. Back the nut off a few turns until the screw is now tightening into the hole and this clamps the hole lot together. 

In hindsight, there is absolutely no reason for this ball to be threaded, it would be better being drilled out with a 3mm drill as its still secured in place with the screw in the suspension arm that passes through it.

And done. Except the nyloc at the top is too close to the top cap to get a spinner on it and i had to use the Tamiya spanner again and turn it a million times a millionth of a degree each turn.

They feel lovely and plush now they are on but i was definitely low on patience by the end of it. Its also worth noting that if you are building one of these for the first time there will be tools that you may not normally have in your RC toolbox that would mean you cant carry on with a stage until you get them.

I'm a bit hobbied out now this evening.

[davidwj95 152]

Thanks for the tip, I'll definitely be referring back to this thread as well as the manual when I build mine.  I'm still deciding what electronics to go with.  I have a 90's stock motor and speed controller in my spares box so might go with those at first. 

[Superluminal 3750]

Tonight - the last bits and easy street compared to last night.

Step 46 - mounting the motor, pinion and gear cover.

Nothing taxing here. The pinion is a 23 tooth steel Schumacher pinion and the motor is a Reedy Tru Stock. I know nothing about this motor, only that I bought it on ebay a while ago mainly because i liked the vintage look of it and no one else had any bids on it. It says Roar Legal so assume this and the name mean it was for a controlled motor racing series at some point?

Steps 47 and 48 are the battery mounts.

The battery strap is cut from black FRP plate the same as the rear shock mount. I didnt end up using the two plastic end stops as they are too short for a Nimh battery stick.

There are different length posts for different battery sizes but no mention of Nimh batteries in the manual. I used the longest posts.

These screw to the underside of the chassis plate.

Battery is nice and secure once the knurled knobs are fitted to the strap.

Last bit - stage 52 (i skipped a couple as those were cutting out the body that i did last week. My favourite bit - wheels and tyres.

These are secured into the hubs with cap screws. At first i was a bit concerned about getting a positive location on the castellated surface of the wheels and hubs but if you just gently tighten the screw the give the wheel a couple of wobbles theres a nice reassuring click as it engages and you can finish tightening the screws.

And done....

And a test fit with the body. This will be held on with velco once painted.

Well that was certainly a different experience to building the Dirt Master - a much more involved and complex assembly. It feels incredibly strong and robust though - like it could really take some abuse (Tamiya kits in particularc always seem to have an underlying brittleness too them)

Apart from the servo saver only being fit for the bin and some issues with the damper mountings I can really recommend this if you want a longer and more challenging build to the norm, you will just need to make sure you have all the tools needed in advance.

 

 

[Superluminal 3750]

Going to jump back onto the Dirtmaster now. Where it was left was the servo I had originally bought was too big and didnt fit and the new low profile replacement seemed faulty on my servo tester (disco lights and general wigging out) - the too big servo worked fine on the tester.

So i took it back to the shop last week for a replacement. He tried it on his shop servo tester and it seemed to work fine!!! Gahhhhh. Apparently.....im not an expert, especially when it comes to elastictrickery.......that some servos need a higher voltage to operate and my tester with its puny little AA batteries wasnt enough. He's servo tester on the other hand appeared to be powered by the thing IronMan has in the middle of his chest. I explained then that I had also tried it in the car with my 1060 esc and usual Absima receiver and that it also hadnt worked. What it turns out is that I needed to buy a capacitator with a servo plug on it to plug into the receiver in a spare slot and this should make it work.

So today, a big bit sceptical i must admit, I tried again.

Freshly charged battery;

The servo and its new three pounds ninety nine pence capacitor. Plus my weedy battery pack that the servo laughs in the face of.

Set up to test before fitting;

I put the capacitor into the channel 3 slot.

And it works!!!!! So this is a thing is it? I just assumed by now everything would be fully cross compatible / plug and play etc etc on electronics. If the servo needs this then im not sure why it doesnt come with one or have one built in.

Anyway, ive stuck everything in and gave the tyres a quick spin up, theyre not glued yet and with a very tiny squeeze of the throttle they both ballooned and came off the wheels. The tyres are super soft but these cheap and cheerful brushed kyosho G15 motors are pretty pokey!!!

Here it is all double sided taped and cable tied in. Not the neatest of jobs.

What i cant find is a convenient place to locate the on/off switch that can be reached without taking the body off. I like the way Tamiya mostly designs in a slot for their switches to poke through somewhere. Not the end of the world, just need to think about painting it now.

[Superluminal 3750]

Over the weekend I painted the Dirtmasters body and driver and put the stickers on tonight. I want with Tamiya Cobalt Green as I had half a can left over from the Tamico Vaillant 934 from a couple of years ago. I masked off the rear cockpit section and window frames and painted these black as I didnt fancy attempting the stickers for this. The decal scheme evolved tonight after I ruined two of the main kit stickers, the one for the wing and the nose. I applied the wing one but just couldnt get the two notches aligned and it to sit square, in the end I'd messed with it so much it would stop lifting so i binned that. Im not sure whether its there pre-cut makes them harder to apply but i had the same with the Optima re re (to the extent i sold the shell because i was so fed up with it and bought a javelin cage instead) and also the Turbo Scorpion. I tried cutting around the outside of the nose one, snipped the upper piece of the backing off and applied it, but again couldnt get it to apply centrally. 

In the end I went for a completely different approach. I used the left over stickers from my re re Ultima and Turbob Scorpion / Tomahawk hybrid and some vinyl pinstripe tape which I dont think looks too bad.

The driver figure is from the Kyosho Beetle and was trimmed to clear the esc and receiver and is attached to battery strap with foam tape.

[Re-Bugged 10152]

Very nice mate, the driver looks right at home in there too 👍🏻😎

[Big Jon 684]

That lovely Schumacher is in desperate need of a good hardware kit. Is it a mix of standard and metric, too?

Shumachers have the strangest hardware choices. Slotted screws, Torx, Pozi, I seem to remember square drive (?), just a weird assortment. Are there any kit-specific special screws?

[Kowalski86 3034]

So between both kits, which would you say you like the most? 

I've always felt that the Shumacher Cat was more interesting than the Cougar, but I understand that the breakaway a-arms were a pain to setup.

[Superluminal 3750]

4 hours ago, Big Jon said:

That lovely Schumacher is in desperate need of a good hardware kit. Is it a mix of standard and metric, too?

Shumachers have the strangest hardware choices. Slotted screws, Torx, Pozi, I seem to remember square drive (?), just a weird assortment. Are there any kit-specific special screws?

Yep! Its a complete mix up ofevery fastner imaginable - mostly imperial size pozi but a few metric socket screws too. I didnt notice anything kit specific but theres a few areas like the motor plate that rely on very small self tapping screws and i dont think you would get this thread on a stainless steel socket cap or button head screw if you wanted to upgrade to hex screws throughout.

[Superluminal 3750]

4 hours ago, Kowalski86 said:

So between both kits, which would you say you like the most? 

I've always felt that the Shumacher Cat was more interesting than the Cougar, but I understand that the breakaway a-arms were a pain to setup.

Difficult to say really because they are so different. I think i preferrered the Cougar build just because it was so unique. With the Kyosho you could almost picture in your head in advance exactly what the next step would be as it uses a fairly well established arrangement of parts that you have built hundreds of times before. The Cougar on the other hand......that felt like in each bag you were given a completely random selection of parts that you then had to manually fashion into an rc car component and its only until the parts are assemebled does it become clear whats going on - despite the frustrations it was very enjoyable. For a "simple" 2wd buggy theres a lot in it!

[Superluminal 3750]

I think ive changed my mind on preferring the Cougar 

After painting the Dirtmaster just a single colour i thought id try something different with the Cougar and push the boat out a bit. For these two builds i didnt want to buy any more paints so have been using what I had left over. In the end I decided that i would paint a scheme using blue, silver and gunmetal. The blue i had was translucent light blue and i like the way these translucent paints look when backed with a metallic. I masked it up - and bearing in mind I am terrible at masking and always suffer bleeds and feathering no matter how much I press the tape down. Started with the gun metal. Removed the main masking on the body - multiple light coats translucent blue, must have been 20 plus. Then backed the whole thing with silver. Of note, theres another of the Schumacher oddities - the masking film is on the underside of the wing for some bizarre reason so you have to mask the top with tape, peel the film off and then paint it. 

And it went perfectly! My mask lines were all crisp and straight and not a single paint bleed, even in the sharp internal corners - it was probably my most successful masking job to date. That was yesterday. Ive left it to cure for 24 hours and today i thought id assemble the body onto the chassis.

Step 50, attach the rear wing. How hard can that be.

So you have to drill some 7mm holes in the wing to pass a plastic spiggot thing through it.

And then theres an o-ring. And some pins and a washer with a slot for the pin to sit in.

What a complete and utter abominable shambles this idea is. I dont belive for a second that the wing can be attached as shown in the manual using those parts. For a start if you fold an o-ring in half it doesnt sit flat in any way shape or form. It instantly twists itself in the middle in the hope of returning into a circle. It doesnt form a nice flat 2D loop ready to pass a pin through. As much as I could manage after many failed attempts was some of the o-ring squashed into the spigot. On the attempt i could manage to pass the pin through the o-ring i could locate one side but just could not for the life of me press the pin home through the hole on the other side as it doesnt sit flat as the slot in the washer angles it. So i thought i would use the end of some tweezers which should just be enough force to press the pin in all the way.

Then the inevitable happened. I slipped with the tweezers and scratched the paint back to the clear lexan. Not on the silver or gunmetal that ive got loads of little paint pots i could touch it up with but on the translucent metallic blue bit.

To say i was gutted would be a massive understatement. There are times in this hobby, more than any other aspect of my life where karma seems to be in play and good has to always be balanced out by bad.

In the end I abandoned the idea of those stupid o-rings and dug out some Tamiya rose washer things left over from my TA02SW FRP chassis and used some countersink screws and nylocs underneath. Its not ideal due to the massive 7mm holes in the wing but its secure for now. I have ordered some white Schumacher stickers to try and cover the chip.

And here it is finished.

You can clearly see the hole in the paint on the wing  so annoyed about that.

And a couple outside where the blue really shines.

[Kowalski86 3034]

4 hours ago, Superluminal said:

What a complete and utter abominable shambles this idea is. I dont belive for a second that the wing can be attached as shown in the manual using those parts. For a start if you fold an o-ring in half it doesnt sit flat in any way shape or form. It instantly twists itself in the middle in the hope of returning into a circle.

Could be worse, could've been the "break-a-way" a-arms on the Top Cat, or the rubberband-strapped spoiler!

[davidwj95 152]

On 5/15/2023 at 10:53 PM, Superluminal said:

The other thing the manual goes to great pains to mention is to install the circlip with the rounded side in - I couldnt tell what this was, as close as i looked even under torch light i couldnt see a discernable difference so its 50/50 if i put them in the right way up.

I'm at this stage of my build now, I even put them under a microscope and it wasn't really obvious.  

[_Ben_ 302]

On 5/16/2023 at 11:07 PM, Superluminal said:

Tonight - the last bits and easy street compared to last night.

Step 46 - mounting the motor, pinion and gear cover.

Nothing taxing here. The pinion is a 23 tooth steel Schumacher pinion and the motor is a Reedy Tru Stock. I know nothing about this motor, only that I bought it on ebay a while ago mainly because i liked the vintage look of it and no one else had any bids on it. It says Roar Legal so assume this and the name mean it was for a controlled motor racing series at some point?

Steps 47 and 48 are the battery mounts.

The battery strap is cut from black FRP plate the same as the rear shock mount. I didnt end up using the two plastic end stops as they are too short for a Nimh battery stick.

There are different length posts for different battery sizes but no mention of Nimh batteries in the manual. I used the longest posts.

These screw to the underside of the chassis plate.

Battery is nice and secure once the knurled knobs are fitted to the strap.

Last bit - stage 52 (i skipped a couple as those were cutting out the body that i did last week. My favourite bit - wheels and tyres.

These are secured into the hubs with cap screws. At first i was a bit concerned about getting a positive location on the castellated surface of the wheels and hubs but if you just gently tighten the screw the give the wheel a couple of wobbles theres a nice reassuring click as it engages and you can finish tightening the screws.

And done....

And a test fit with the body. This will be held on with velco once painted.

Well that was certainly a different experience to building the Dirt Master - a much more involved and complex assembly. It feels incredibly strong and robust though - like it could really take some abuse (Tamiya kits in particularc always seem to have an underlying brittleness too them)

Apart from the servo saver only being fit for the bin and some issues with the damper mountings I can really recommend this if you want a longer and more challenging build to the norm, you will just need to make sure you have all the tools needed in advance.

 

 

Really interesting that a nimh stick battery fits - I’ve always thought you’d need a saddle pack or a shorty 2S.

[Superluminal 3750]

58 minutes ago, _Ben_ said:

Really interesting that a nimh stick battery fits - I’ve always thought you’d need a saddle pack or a shorty 2S.

Yeah it fits fine - If I was going to start running it I would probably put a strip of the aluminium tape around the inside of the body to stop any movement in the wires rubbing the paint off the shell.

[Sogogi 3217]

Its been a while since the build. How’s your experience running the car?