Just picked one of these up – an aluminium ride height gauge for RC buggies. This particular model passed me by when it first came out – turns out it’s a cracker!
I’ll take a brief detour into the history of Rayspeed – and why it is now a dead brand. Rayspeed was the “personal” brand of Shinnosuke Adachi when he drove for Yokomo. They released a load of really useful bits under it, in particular the pistons for the touring car shocks which became an essential, and also a few bits for the Associated B4 to “Yokomo-ise” it – the Rayspeed rear hubs are still highly sought after. But then Adachi moved across to Kyosho, and Yokomo killed off the Rayspeed brand. Good luck connecting to the www.rayspeed.jp site! Some of the parts have had equivalents released under the Yokomo brand (like some alternative B4 hubs and some new touring springs), but most haven’t. You’ll need to search hard for old stock!
This means that the RS-32 is being sold off by CML Distribution’s “End of Line RC” website – www.end-of-line-rc.co.uk – for a tenner.
A brief look now at why this is such a handy tool…
This is more than just a ride height gauge. As you can see from the slip of paper above, it is also a compact camber gauge. Three sides are machined for 0, 0.5 or 1 degree. Also interesting is that the gauge measures from 20-25mm (for 1/10th) then jumps to 28-32mm (for 1/8th perhaps?) – although you are a bit stuck if you want to run 26 or 27mm ride height!
The aluminium tool itself is surprisingly chunky and very well finished, as you would expect from the Yokomo factory.
This is going to make consistent setups a lot easier for me to achieve. I know that eyeballing the arms and driveshafts is a common way of setting off-road cars, but I much prefer the accuracy and repeatability of a gauge.
And it even comes with a little sticker sheet too!
Well, turns out I do need to make a parts order – albeit not the one I expected…
Managed to get across the the Caldicot club tonight – www.caldicotrcracers.co.uk. Friendly folks and an enjoyable track , which the Yokomo handled well from the start.
Unfortunately, the big crossover jump caused me a problem in the second round – the car went full-throttle-crazy after landing mid-race and crashed into the wall. This was bad enough… but then the marshal mistakenly put the car back down on the track! It charged flat-out the wrong way across the crossover, took some massive air and cartwheeled at frenzied speed into a pit table, knocking it down. Very spectacular – and miraculously the car itself was unharmed, apart from a tell-tale bent shock mounting screw. Turns out the receiver crystal had failed from the impact of the landing.
So, with some alternative crystals, I went out for round 3. Car was going well again, grip was good even with very worn tyres, I was actually leading and enjoying a good duel with a faster driver who was making mistakes trying to catch up. Unfortunately one of these mistakes meant he caught the edge of an obstacle, and flipped over into my path. Bang. Goodbye front shock tower.
Looking forward to getting the car fixed and going back across the Severn Bridge for some more racing!
After much fine tuning (ahem) during the NE indoor regional series this is the setup I settled on for the B-MAX4. Takes the edge off the steering and adds some positivity to the traction while retaining the great ride quality.
I won’t try and sell it to you with race results as they are poor by most people’s standards but good by mine!
First of all, an apology. I have mislaid the camera case which has the USB cable in it so there are no pictures. I’m more gutted by the fact that the case also contains all our memory cards from the last few years…
Moving swiftly back to the topic of the Yokomo B-MAX4, I finally destroyed the rear bevel gears at the Teesside regional meeting at the end of last year. I really should have bought some new ones but foolishly thought I could make the damaged ones last. In the end it compromised my last few qualifiers and my final, although not as much as the marshal who, ready to leap into action like a tiger, decided to lean over the top of a jump and obstruct my view throughout.
As an aside, buying the replacements turned into an epic. In brief, don’t expect CML Shopatron to supply the parts they say are available.
All in all though I enjoyed the Teesside meeting, despite the track being a bit narrow in places, mainly because it didn’t have any of the “big air” obstacles that seem to have become fashionable, and it added up to one of the better “racing” tracks I’ve experienced for buggies in recent years.
I also learned a little about setting the B-MAX4 up. Fundamentally, the car does not have enough roll stiffness for UK conditions so becomes edgy at the limit unless you fit the rear anti-roll bar (standard in the champions pack, I’ve tried a few and keep coming back to 1.1mm), and stiffen the front end (I prefer to use Associated blue springs, combined with Associated silvers on the rear, although you can get a similar balance by running the kit front springs mounted in the outside wishbone hole – although this limits droop and makes the car worse on the bumps). Other cars on the market can acheive extra roll stiffness by running an angled link to raise the roll centre, but on the B-MAX4 you can’t as there are only two camber link positions, neither of which gives a very angled link.
Using this basic setup at today’s Jarrow regional gave a well balanced car, although the tyres were excessively worn as I couldn’t be bothered to buy any new ones! As a result I was down in the D final rather than the C that I usually manage.
To get a better fit with the AE springs, get hold of the Tamiya spring bottoms from the 501X (#51282, use part X4), these let the springs sit a little lower for more ride height adjustment.
Gear mesh yet again
Once again I had problems with the gear mesh at Jarrow. This time I had gone too tight, resulting in a plume of smoke and a burnt out motor!
So, having now gone too loose and too tight, I think I am in a good position to advise how to get it just right (rather like Goldilocks!)
1. Get some extra, fine shims. 0.1mm or less. Yokomo do some but these may be hard to find in the UK, I used the ones from TOP Racing, supplied by Much-More UK. You need 12mm ID for the diff, and 8mm ID for the input gear. You can also use some 5mm ID ones on the opposite side of the input gear to take out the slack if you like.
2. Shim the input gear so it has the broadest mesh possible with the diff gear without rubbing it on the edge. The kit setting should be a good starting point, or maybe 0.1mm less.
3. Unfortunately, the mouldings of the top and bottom gearbox halves are not identical (at least not in my kit). So, put the input shaft and diff gear in the gearbox half with the tighter tolerance. If you set the mesh in the half with the slacker tolerance, the gearbox will tighten up considerably when assembled and cause you problems (such as the aforementioned motor cooking!).
4. Shim the diff so that the mesh is as tight as it will go while still rotating smoothly. There should be no backlash, small high points in the mesh should bed in after one run. Make sure all the side-so-side movement of the diff in the gearbox half is taken out with more fine shims, but make sure the diff still rotates smoothly.
5. Assemble carefully and check that the transmission rolls over smoothly. If any axle or gear seems to bind, disassemble and re-shim. Don’t expect the transmission on this car to spin, the tolerances are too tight for that, probably in the interests of durability. Unfortunately these tight tolerances put more load on the motor, it does get rather warm under the shell.
And one last tip
The only other issue I have had with the B-MAX4, and it is hardly a major one, is bending the front shock mounting screws, probably when the exposed threads catch the track surface during rolls and crashes. After a big impact these are close to shearing off.
A very simple solution which seems to have worked is to put a 2mm spacer on the screw before fitting the lock nut, this means that the round edge of the nut hits the ground first instead of the sharp edge of the screw. Despite landing on the roof and rolling a few times today, the shock mounting screws remain resolutely unbent.
That’s all for now. Hope these tips help you out, let me know if they do.
A belated update on what I have been up to with the B-MAX4 for the last couple of weeks…
Thursday 27th November – Longbenton club meeting
This was the shakedown. Longbenton is mostly a touring car club so the track was flat as a pancake and slippy (it’s a wood floor in a school hall). But I managed to get five 5-minute runs under the cars belt (or should that be shaft?) with no issues, which was what I was hoping for. Grip was terrible (using worn Schumacher minipins) so it was difficult to make any real judgements on the handling but the car did seem to have better turn-in than my Durga would have managed.
Now although motor temperature didn’t seem to be an issue and everything accelerated and braked as it should have, I still wasn’t happy with the drivetrain. It still seemed tight and made some pretty crunchy noises under acceleration. Cue a bit of late-night wrenching…
My foolish transmission modifications
Disclaimer: In no way am I suggesting that you do this. I’m just blogging it as a record of what I did, some of it has already proved to be a mistake, hopefully you won’t make the same ones!
With file and Dremel in hand I launched my onslaught on the centre transmission. The aim was to get the spur gear to spin freely when the top cap was on. First of all I removed some material around the edge of the bearing housings on the top deck…
…then I removed some more material from the top cap itself…
Now after these mods the spur spins freely with the cap tightened down – although in truth I removed a little bit too much and there is a small bit of unwanted vertical movement on the spur now as well. Thankfully there hasn’t been any damage (yet).
Next, I tackled the shimming in the front and rear gearboxes. On my on-road cars, and also with my Lazer ZX-5, I had set the bevel gears to have a small amount of backlash, this gave a super-free transmission and never caused any damage. So I did the same with the Yokomo.
One thing to take note of here is that the moulded gearbox halves are not identical, so a setting that may feel right with the top off will feel wrong once assembled.
Another thing to note is that Yokomo only supply relatively thick shims to set the mesh (around 0.2mm), whereas most other manufacturers give you some 0.1mm shims instead. So, when I set the gears to have a little backlash, the rear gearbox in particular was a bit too loose. I was a bit worried about whether the gears would last.
My fears would prove well founded…
Sunday 30th November – South Shields NE indoor regional
First impressions of the track for this meeting were not good for me – a couple of (excessively) narrow sections and a tall double-level tabletop are not the kind of thing I race well on (I prefer wide tracks and no “big air”), although there were some nice gym-mat ripples that rewarded a good line and a bit of throttle control. First practice revealed a lip on the down-ramp of the tabletop that was kicking the Yokomo up very badly regardless of how I took it. More often than not the car would end up on it’s roof. Fortunately the host club made a change to the tabletop and the lip would not cause me any problems during the racing proper.
I did have a mechanical failure in practice – I tried the “big air” route over the tabletop, landed off the track, and busted the sacrificial gear in the servo. Fortunately I have a couple of spares. The car itself was undamaged and I decided not to risk the “big air” again (shame that wasn’t the case for the other people in my heat who would take the big air and land on top of me from time to time…).
First round was spent getting a feel for the car on kit settings, managed 17th-ish in round from a field of about 45, roughly what I normally manage at these meetings, and quite pleasing considering I was on well worn tyres. There was a lot of carpet on the track and the car seemed to dig in a little on turn-in, wagging the inside rear wheel through the last corner, and getting hung up on the approach to the big tabletop. This was costing me a lot of time – partly my confidence in the trajectory of the car, partly my confidence over big jumps. It took me until the fourth and final round of qualifying to get a good line over this obstacle (gently up the first part of the up-ramp, throttle up the last third, land in the middle of the lower second section, gently down the down-ramp and kiss the apex of the left-hander at the bottom) but I was still a bit slower than most.
In the second round of qualifying I took off the rear anti-roll bar, this improved the balance overall and made the car a little more confident over the bumps (the car was very good over the bumps already, very settled), however the front end was still digging in.
For the third round I tried to stiffen up the front end with some heavier oil (up to #450 from #400). Unfortunately part of the track had got knocked out of place and the bumpy section had become viscious, so I made a lot more mistakes. I still managed to set a quicker time but everyone else was going quicker too and I was only 24th-ish in the round.
In the 4th and final round of qualifying I went back to the #400 oil in the front and managed to get a 14-lapper. Unfortunately the slack rear gearbox mesh decided to call it a day and the once-silent car ground it’s way around the last few laps. And despite going nearly a whole lap faster than I had gone at first, everyone else had also gone faster and I was still only 18th-ish in the round.
Thankfully, the damage to the gears was not terminal, and I re-shimmed the gearbox for a nice tight mesh again. I also noticed that a balljoint on the rear suspension had almost completely unscrewed itself so tightened it up.
Lining up 3rd on the grid for the C-final, I made a terrible start, completely missing the apex of the first corner. Luckily that gave me the inside line at the next corner while others tussled and I was momentarily up to 2nd again. Then as I rounded the right hander after the second set of mats, the back of the car looped around and I ended up off the track and last. The sudden lack of rear grip caught me out a couple more times early in the race, but I slowly managed to work my way back up through the field to finish fourth, just outside the trophies (again!).
The loose rear end was a bit of a mystery to me – it was either the tyres finally going past the point of no return, or the re-shimmed rear gearbox, or the tightened suspension link. Whatever the cause, it meant that the meeting ended in a rather disappointing way.
Revisiting the gearboxes
I have since re-shimmed the gearboxes – this time I have got hold of some fine 0.1mm shims with 8mm and 12mm inside diameter (I have used the ones from TOP Racing), cleaned out all the chipped teeth, and set the mesh to have no backlash and still turn smoothly. Fingers crossed these will hold out at the regional this weekend because I didn’t order any spares!
I’ve also got a couple of setup ideas in my head, main one is to try the front shocks on the outer hole on the wishbone to stop the front end digging in. According the the spring chart at Petit RC the Yokomo black is a similar rate to the Associated silver – and most people in the UK run the stiffer Associated blue on their B44’s and 501X’s.