Kyosho Big bore tapered pistons

[sime46]

Small bores rule.

[SimonW]

I've finally decided that 2x1.3 and 2x1.4 per piston is what i will use in my vega front and rear. After filling 1 of the holes in the stock 5x1.3 and not changing the oil weight a quick bench test felt a little too stiff ( pack) and too slow but only just for my taste, on the track the car was alot better than with 5 holes. Past experiences with shocks i thought the 4x1.4 will be close but a little soft so i went for the mid point. HTH's

[RogerM]

Right guys, I am still not in the position where I can say that this is definitively the best setup for either car but we have now put something like 30 hours running (our poor cars would be destroyed by now if any other brand) and 75 hours at the track tinkeing and have settled on the following as the starting base setups for each ... although this may evolve over the next few weeks as we get more and more feedback from other drivers. We have had 28 different pistons to work through and drained about 12 bottles of shock oil between up even being methodical about our testing order. All testing has been done against the clock and so isn't what feels fast it is what is fast (for us at least).


2wd (Scorpion & VEGA tested, sadly no MCS available but I can't imagine it to be far off ...)

4x1.40 front (35wt AE oil as a starting point and tune from there, remember 2.5wt is a big step on the big bores), X-gear Gold springs with staggered ribs / minispikes, Reds with minipins. That is shocks out on wishbone and mid on original tower
For those running Losi springs that is Orange
4x1.45 rear (30wt, 32.5 if you like a livelier rear end) and X-gear red or Yellow springs depending on how much rear roll you like form the car.
For those running Losi springs that is Pink.
That is shocks inside on wishbone and middle on Scorpion stinger tower, 1 in from outside on Vega.

Because the stock RB5 runs much more inclined rear shocks than the mid motor cars I would expect that you will be wanting to reduce pistons 4x1.4 and maybe even then still go up 2.5wt in the oil. Sadly we have not had the opportunity to do much testing with a rear motored car.

I tried 3,4,5 & 6 hole combinations but to get the front end geometry to really work and feel alive, responsive & stable at the same time you need to have a little bit more instantaneous roll than you can get with 5 or 6 hole pistons but not as much as 3 hole pistons give you.
I hate to think how many combinations we put across the cars to arrive here but each time we moved from the 4x1.40 fronts we found ourselves back there a few logical tuning steps later. The rear sort of followed the progression of the front end tuning with the key objective being balance, that said we worked all around the various combinations in that region and kept coming back to the 4x1.45.


With the FS2-sp it was just as mammoth task but at least we had the 5x1.3/5x1.4 setup to use as a base line from last season and the 4x1.2/6x1.2 setup we settled on for the big jump strewn indoor carpet tracks.

After much work it became apparent that the front and rear of the FS2 are so superbly balanced that you didn't have to push one far away from the sweet spot before it started to show up very apparent weaknesses in the setup. That is great because you can get almost instant validation to a change at one end of the car.

Up until yesterday evening I would have said that I was happy with the setup as we finished with it a couple of weeks ago but Nick sent me through some extra pistons to try based on the requests & feedback I'd given him earlier in the week. Cutting a long story short a change of front pistons highlighted that we were too soft at the rear, a couple of hours tuning time later and we had a car that was fast, confidence inspiring and a pure joy to drive ... even let you get away with the odd wheel on a track marker type error at full speed without getting unsettled.

Front 5x1.2/35-37.5wt AE oil with a Losi Green spring (mid hole on front wishbone), 3rd in on tower
Rear 5x1.35/30wt AE oil X-gear red or yellow rear spring (or Losi Pink which is similar to X-gear yellow) inside on LAW43 and middle on tower.

Now I am convinced by the above setup but there were only two of us at the track last night testing and light was failing so I have nobody else to get an opinion from other than what they saw. The comments I got back where that the car looked to be stable and stayed relatively flat throughout the lap and it was certainly quick on the clock too.
It is great over the bumps (with ride height set 18 to 19 ... use 19-20 if track is REALLY rough) and just holds it's line no matter what the surface throws at it.
Be warned, this setup generates a LOT of steering and as such you might find its a bit of a handful until you get used to it then you will love the fact that it will turn inside any other 4wd car out there, nothing will be sneaking up the inside of you in a final for sure
If it is too much all that should be required to calm the nose a little is to stand the front shocks up one hole and/or go up 2.5wt in front oil (try all combinations to find what suits your driving style).
I know I have said this repeatedly but it still holds true, IMHO the Lazer FS platform is as close to perfection as a 4wd car can be.


As I say work is still continuing but I believe that both of the above setups will give very good starting points for your own individual tuning.

I hope to be writing a full breakdown of the trials very soon and hopefully there will be a full on article covering damper tuning on oOple soon

[Gayo]

We have had 28 different pistons to work through and drained about 12 bottles of shock oil

Now that is nuts

I will try your findings ASAP, now where is Nick?

[njc11]

Sounds good Roger...

Im racing tomorrw, just MCS though, so may if i have time try your shock settings!

[RogerM]

Nick,

been trying to find time to give you a call all this week but life has been chaotic .... not helped by all the testing LOL. Will try to get hold of you tonight buddy.

[RogerM]

Originally Posted by Gayo

Now that is nuts

I will try your findings ASAP, now where is Nick?

Well the other options were either guessing or not bothering at all .....

To my mind you either do a job properly or not at all

Now, remember that I am not on the pace of Kev Lee's etc. BUT running those settings on the 2wd last weekend I was able to monster all other cars through the rough stuff and wasn't loosing out anywhere on the infield sections and my times through the runs were very consistent and faster than those I am normally racing for places. I do however need to remind myself that no run is improved by over driving the first lap .... my ability to stick it on it's roof on the out lap was the only thing more consistent than the other lap times

[Nick]

Hi just to say thanks for the orders and the have all been posted Also if anyone need any at the national i will have some with me! See you all at the weekend.

[RogerM]

Hi guys, just a quick update. I've had the week off work and have made it out a couple of times to try some more stuff.
The short story is that I keep coming back to the shock setups listed above, there are other combinations that make the cars feel easier to drive but all seem either slower or less consistent against the clock.

I have found with the above setups all that I am changing for different tracks / conditions are;

Inner ball stud spacing (typically starting at 1mm both ends on the Lazer, 5mm [use the ball studs with the 2mm shoulder to prevent them pulling out] front & 2mm rear on the 2wd)

Upper shock mounting position (in when more roll needed, out when less wanted)

front hub height (run the front AXLE low for buckets full of front end bite, axles up if you want to calm the car down) ... this is a powerful tool, especially on the FS2!



Just to clarify the rear shock tower position on the 2wd; they are mounted at distance apart that is equivalent to the width between the middle holes on the Lazer rear tower.


Hopefully that will help some of you ... lets put the small bores to bed for good

[Nick]

Hi all just to say thanks for all the orders and they have all been posted

Also many thanks to Roger for all the hours of hard work on the shock setups for everyone to use! So far I have heard very good reports about how good the setups are.

Also i have just swoped to a RB5 Vega so will start working on setups as well as soon as i get a set of big bores for the car.

[RogerM]

Nick I will be in touch over the weekend to discuss VEGA big bore setups.

More testing tonight, maybe tomorrow as well ... we aren't standing still on making the big bores quicker around a lap than the small bores .... for me they already are, significantly so!!

[Honeybadger]

So which way are you meant to mount the pistons in the shocks?

Tapered side up or down?

[RogerM]

tapered side down

[Honeybadger]

Originally Posted by RogerM

tapered side down

Thanks Roger, I'm on it now. I'll get the Laser out for a blast in a bit.

[Nick]

Hi all just to say all orders have been posted out yesterday

[RogerM]

Just a note to say that in the brief spell of warmer weather we got I found both cars were a bit too soft on the oils quoted above and ended up +5wt in the front of both and +2.5wt in the rear of both.
Still sure I have the best piston combination in there for both cars.

Going to do a few runs with the DB1 on small bores to get a feel of Kev's set up then will start working on a big bore set up for her.

[tomtom]

Originally Posted by RogerM

Going to do a few runs with the DB1 on small bores to get a feel of Kev's set up then will start working on a big bore set up for her.

You got me interested !

[RogerM]

Some extra testing has suggested that a higher pack setup works better on the 2wd cars (still happy with the Lazer setup once the oil grades where upped a little when the weather warmed up).
Will post details of the revised setups once they have been properly tested by a couple of different drivers.

Work has begun on the DB1 setup.

[Rebelrc]

Originally Posted by RogerM

tapered side down

Makes absolutely no difference at all, fact!

[RogerM]

Originally Posted by Rebelrc

Makes absolutely no difference at all, fact!

Absolutely incorrect I am affriad ... that is how they work, all about the change in effective section along the length of the hole. It's a very common flow biasing tool used in many different engineering genres.