****Official**** Corally Kronos/Shogun/XTR Thread

[horatio]

6 hours ago, Tug said:

60C isn't hot, it'll only cook if you exceed 80C.

Pre-fan, it hit over 160°F. So it's probably only medium rare. 😅

[horatio]

So it's been a while since I posted here, but I've had some decent sessions with it over the past couple of months. It's a ton of fun!

 

One area of the truck that needed a tweak was with the servo saver. It becomes quite apparent with big, grippy tyres that the  servo saver spring is too weak to achieve consistent steering. Yes - you can tighten it up, but then there's very little (if any) saving action left in it. Frankly, the spring rate is just not optimal for this weight of truck. 

 

What to do? 

 

Replace the spring. 

 

Over on another forum, a bunch of us discussed this problem and I suggested we look for getting a spring made to spec, with a higher rate. That's exactly what we've done. 

 

 

The stock spring was tightened about as far as it could go for on road use. This offers little little give, because there was no space between the coils. 

 

 

I can compress the stock spring completely with my fingers. 

 

The new spring on the other hand looks like this:

 

 

The spring shown here has a much firmer rate, it's slightly longer, the music wire is thicker and it's an interference fit into the composite servo saver arm. 

 

 

Stock spring on left, bespoke spring on right. 

 

 

The specs for the new one were carefully considered following careful measurements of the stock item. 

 

 

With these dimensions, we could figure out how much bigger and thicker we could make the replacement. 

 

During testing, it became immediately apparent that the steering now was not only more positive, but more predictable, faster and centered with more precision. The result is 100% consistent lock.  See here:

 

 

My first batch are now virtually sold out.  If people want the same - just let me know. I'll get another load soon. 

 

When you consider how much money people spend on fancy steering servos, with mega torque and speed - it seems futile when the servo saver wastes any effectiveness the servo may have. 

 

You need this spring! 

[Kpowell911]

You definitely  have a point! Stock servo savers are usually poor

[horatio]

1 hour ago, Kpowell911 said:

You definitely  have a point! Stock servo savers are usually poor

Yes. None more so than the pitiful arrangement that Savage had out of the box. It literally had no steering at all. Steering more series of suggestions - it was implied rather than actually applied to the wheels.  To get steering, you literally had to take an OFNA monster pirate steering assembly and use that. 

 

Yet before getting the servo saver changed - everyone put in super duper high torque servos. They even used 2s Lipos to up the voltage.

 

Result: zero difference. 

 

So why is this? It's the same for Arrma Kratons as well, only for them they don't have the luxury of an adjustment collar. 

 

It seems like such an obvious oversight. You never have this problem on racing buggies or truggies. 

 

Perhaps bashers don't need to steer? 🤣😂

[Kpowell911]

5 hours ago, horatio said:

Yes. None more so than the pitiful arrangement that Savage had out of the box. It literally had no steering at all. Steering more series of suggestions - it was implied rather than actually applied to the wheels.  To get steering, you literally had to take an OFNA monster pirate steering assembly and use that. 

 

Yet before getting the servo saver changed - everyone put in super duper high torque servos. They even used 2s Lipos to up the voltage.

 

Result: zero difference. 

 

So why is this? It's the same for Arrma Kratons as well, only for them they don't have the luxury of an adjustment collar. 

 

It seems like such an obvious oversight. You never have this problem on racing buggies or truggies. 

 

Perhaps bashers don't need to steer? 🤣😂

I think RC companies in the RTR business cheap out so much with servos (not just Traxxas, I cant think of an RTR “basher” with a suitable stock servo) they purposely put a weak and sloppy servo saver to stop the stock servo failing the minute you turn a corner under stress. 

[horatio]

15 hours ago, Kpowell911 said:

I think RC companies in the RTR business cheap out so much with servos (not just Traxxas, I cant think of an RTR “basher” with a suitable stock servo) they purposely put a weak and sloppy servo saver to stop the stock servo failing the minute you turn a corner under stress. 

 

I kinda get that for the RTR stuff - "let's not keep having warranty claims on the $15  servo we supply - so we'll put in a spring so weak that it doesn't have to overcome anything greater than 1kg/cm". With predictable results! 

 

But why supply the same spring for rollers like the XTR and EXB, which isn't supplied with any electronics? 🤔

 

To be fair, the spring on the XTR was OK for stock tyres on loose stuff.. But take it on grass or tarmac with big sticky on road tyres - there's an obvious problem with vague, wandery steering. 

 

I have night/day difference on my XTR now. So much easier to keep it tracking in a straight line, which for me is important if you run next to kerbs or within the confines of a track. Steering that centers is important! 

 

Another slightly weird thing was the excessive amount of toe out the truck came with - mine had 3-4° which is waaaaay too much. This combined with the soft servo saver meant that high speed runs were a wing & a prayer job! 

 

I've set mine now for 1° toe out, for responsive steering at the entry of corners, whilst still having consistent straight line tracking. 

[horatio]

Visiting this thread having just gone over a few sets of my 1/8th wheels.

There is nothing to lose by balancing your wheels, though it gets increasingly difficult to balance wheels the smaller they are. 

IMO, it's better to take reasonable steps to ensure your wheels are as balanced as possible, because besides the obvious improvement in performance, having a car that has less vibration will also reduce wear and improve bearing life. 

To do a good job, you need a wheel balancer, blutac, pen, golfing lead tape and a digital balance (scales). 

I use blutac on the rim - in the usual way - putting the right amount of blutac opposite the heavy side of the wheel. Mark this with a pen. (often on off road tyres, you'll notice the heavy part of the wheel is where the manufacturer drills the vent hole in the rim) 

Once the wheel is balanced as accurately as possible, I then remove all of the blutac and weigh it on the digital balance. I replace the blutac with the same weight of adhesive lead tape. After a bit of experience, you get to know how long a strip of lead tape you need for any specific weight. It's just a matter of practice. If I'm dealing with very small amounts, I often leave the blutac on the scale - let's say it's 2g. I'll add my length of lead tape to the scale and until I get the length I need to total 4g in total - then put the 2g of lead tape on to the wheel. 

The reason why I prefer lead tape on the rims is because blutac and putty attract a lot of dust and crap. Also, because lead is denser, you require less volume of it to achieve the same result over putty. It's neater and less likely to fall off. 

Some of my wheels require 8g of weight to balance them! On a set of wheels hurtling at 60mph - that's a lot of unwanted vibration if it's left unbalanced. 

My truggy wheels have been balanced with a putty that sets hard and this has also worked well to be fair. However, I still prefer the the lead tape - it's cheaper and readily available. 

[horatio]

And now for balancing wheels - we can use these! 

Edited June 5, 2023 by horatio

[horatio]

So - what's happening to all you Kronos/Shogun/XTR owners out there? You all still driving or is the platform yesterday's news? 

[Stormbringer]

We've just not been out with them to be honest 

[horatio]

Yeah, I've not been out for while with mine either. The weather has been terribly wet. Perhaps I should take up RC boating....🤔