Kronos XTR Easiest way to adjust servo saver?

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KnowAir said:
Need some measurements of the stock spring so we can source a stiffer one🤔 sounds kinky🤣🤣 but yeah, I'm sure we could find something if we had some specs to start with? I'm too lazy to take apart mine since it's working atm..
Click to expand...
Same here! I was hoping you'd take yours off and give me some measurements!!! 🤣
 
I 100% agree that the problem is with the spring.

During my first few outings, it wasn't a problem. Running sticky road tyres over the last few runs seems to have weakened the spring.

With the current design, if you preload the spring tighter to remove the excessive amount of 'give' - you end up with the spring compressed with too little space between the coils to afford any saving action.

This is just like the Savage all over again! 🤣

The Monster Pirate spring was much beefier and solved the problem. We need to do the exact same thing for the Kronos.

Faffing about with all the alloy parts under the sun isn't going to help if it still relies on the same spring.
 
In the coming week or so I'll try to take it apart and take measurements of the spring (unless @KnowAir beats me to it!). I'll post back here and then we can start searching for alternatives.
 
So... I took my servo saver assembly apart.

Rather than poke things through holes and scrape off the anodising in the process, I just took it apart and lifted the assembly up from the top.

This necessitated removal of the front Brace, the top plate, the trackrods (from the ackerman plate side) and the front upper wishbone pivots. About 18 screws in total.

As KT mentioned in one of his videos (he whinged about it quite a lot) - the servo saver posts are keyed into the chassis. So working from the top makes sense.

There's no point mucking about. It's 18 screws. They're tight - many of them thread-locked into place. Use hand tools. 2mm button heads thread locked into place require some torque - so use quality hex tools, otherwise you'll be chasing your tail with rounded out button heads. On the plus side - I didn't need to use any heat and I didn't bloody any of my knuckles, so as jobs go, it's actually OK.

Did I mention 18 screws? 😂 Now that we have that out of the way, here are the dimensions.

IMG_20220606_140637.webp
IMG_20220606_140908.webp

The servo saver started to feel vague when it looked like this:
IMG_20220606_141218.webp

Note the 2-3 visible threads at the end.
IMG_20220606_141433.webp

With 4 visible threads, the servo saver is much more positive, but there is very little Angular saving action between the coils.
IMG_20220606_141625.webp
IMG_20220606_141655.webp

4 threads = 3.9mm when measured from the end of the threads to the collar.

For now, this will have to do. But a beefier coil spring would be better, with less preload and more space for some saving action. 👍
 
Horatio said:
So... I took my servo saver assembly apart.

Rather than poke things through holes and scrape off the anodising in the process, I just took it apart and lifted the assembly up from the top.

This necessitated removal of the front Brace, the top plate, the trackrods (from the ackerman plate side) and the front upper wishbone pivots. About 18 screws in total.

As KT mentioned in one of his videos (he whinged about it quite a lot) - the servo saver posts are keyed into the chassis. So working from the top makes sense.

There's no point mucking about. It's 18 screws. They're tight - many of them thread-locked into place. Use hand tools. 2mm button heads thread locked into place require some torque - so use quality hex tools, otherwise you'll be chasing your tail with rounded out button heads. On the plus side - I didn't need to use any heat and I didn't bloody any of my knuckles, so as jobs go, it's actually OK.

Did I mention 18 screws? 😂 Now that we have that out of the way, here are the dimensions.

View attachment 2472View attachment 2473
The servo saver started to feel vague when it looked like this:
View attachment 2474
Note the 2-3 visible threads at the end.
View attachment 2475
With 4 visible threads, the servo saver is much more positive, but there is very little Angular saving action between the coils.
View attachment 2476View attachment 2477
4 threads = 3.9mm when measured from the end of the threads to the collar.

For now, this will have to do. But a beefier coil spring would be better, with less preload and more space for some saving action. 👍
Click to expand...
You're the man!! Thanks so much for doing the "dirty work" even though it's not actually dirty (pristine actually)!!
 
Probably also worth noting the 2 shims between the underside of the top plate and the top of the servo saver steering posts. They're just dying to fall off and get lost in the carpet/workshop floor.

In future, I'll leave the posts attached to the chassis - so make that 16 screws. 😂👌

KnowAir said:
You're the man!! Thanks so much for doing the "dirty work" even though it's not actually dirty (pristine actually)!!
Click to expand...
You're welcome. It's just one of those - 'I'll get round to it...' jobs.

Well I want my truck to steer - especially at >60mph speeds, so I'm on it. I'm hoping someone here will find a perfect spring replacement/upgrade.

IMG_20220606_135712.webp

To be fair, I cleaned it prior to taking pictures.

My cat is now lying all over the carefully laid out screws.... 🙀
IMG_20220606_144836.webp
 
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Horatio said:
Probably also worth noting the 2 shims between the underside of the top plate and the top of the servo saver steering posts. They're just dying to fall off and get lost in the carpet/workshop floor.

In future, I'll leave the posts attached to the chassis - so make that 16 screws. 😂👌


You're welcome. It's just one of those - 'I'll get round to it...' jobs.

Well I want my truck to steer - especially at >60mph speeds, so I'm on it. I'm hoping someone here will find a perfect spring replacement/upgrade.

View attachment 2478
To be fair, I cleaned it prior to taking pictures.

My cat is now lying all over the carefully laid out screws.... 🙀
View attachment 2479
Click to expand...
Too funny..my cat (and dogs) always seem to do the same!! :ROFLMAO: :ROFLMAO:
 
Horatio said:
So... I took my servo saver assembly apart.

Rather than poke things through holes and scrape off the anodising in the process, I just took it apart and lifted the assembly up from the top.

This necessitated removal of the front Brace, the top plate, the trackrods (from the ackerman plate side) and the front upper wishbone pivots. About 18 screws in total.

As KT mentioned in one of his videos (he whinged about it quite a lot) - the servo saver posts are keyed into the chassis. So working from the top makes sense.

There's no point mucking about. It's 18 screws. They're tight - many of them thread-locked into place. Use hand tools. 2mm button heads thread locked into place require some torque - so use quality hex tools, otherwise you'll be chasing your tail with rounded out button heads. On the plus side - I didn't need to use any heat and I didn't bloody any of my knuckles, so as jobs go, it's actually OK.

Did I mention 18 screws? 😂 Now that we have that out of the way, here are the dimensions.

View attachment 2472View attachment 2473
The servo saver started to feel vague when it looked like this:
View attachment 2474
Note the 2-3 visible threads at the end.
View attachment 2475
With 4 visible threads, the servo saver is much more positive, but there is very little Angular saving action between the coils.
View attachment 2476View attachment 2477
4 threads = 3.9mm when measured from the end of the threads to the collar.

For now, this will have to do. But a beefier coil spring would be better, with less preload and more space for some saving action. 👍
Click to expand...
Oh man thank you so much for doing this! Did you happen to take the inner and outer diameter of the spring by any chance?
We're one step closer to finding an alternative spring!
 
DaniC said:
Oh man thank you so much for doing this! Did you happen to take the inner and outer diameter of the spring by any chance?
We're one step closer to finding an alternative spring!
Click to expand...
Outside diameter = 18mm
Inside diameter = 14.4

Sorry - didn't take a photo of these dimensions. I didn't have enough hands!

I did however take a photo of the spring thickness and stated the outer diameter. 👍
 
Horatio said:
Outside diameter = 18mm
Inside diameter = 14.4

Sorry - didn't take a photo of these dimensions. I didn't have enough hands!

I did however take a photo of the spring thickness and stated the outer diameter. 👍
Click to expand...
Awesome!!! Let the search begin! 😅
 
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DaniC said:
Awesome!!! Let the search being! 😅
Click to expand...

Perhaps Airedale Springs (or another UK manufacturer like them) can roll them out for us? The more we need, the cheaper they'll be. 👍

Edit: I'm not sure if my post was visible because of a link I initially put, but headsup to the mods - it's merely a link to a company that makes springs! I'm not affiliated to them in any way.
 
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Here's a few options that might work?

- Arrma RC Servo Saver Spring 12x20mm X-Hard EXB AR340178 - this one says 12mm diameter, I presume that inner diameter, we @Horatio said the inner diameter on the stock spring is 14.4mm, but if the diameter in the post is 11mm or less then this might work? It's also longer at 20mm, but it looks to me like there's room to spare in that regard. Any of the Arrma guys here have you tried this one?
- HPI Racing Heavy Duty Servo Saver Spring 21x12x1.9mm 4.5 Coils HP102522 - similar measurements to the one above.
- Team Associated RC8B3.1 Servo Saver Spring AS-81083 - no measurements, but it's for a 1/8 so maybe...
 
Horatio said:
Perhaps Airedale Springs (or another UK manufacturer like them) can roll them out for us? The more we need, the cheaper they'll be. 👍

Edit: I'm not sure if my post was visible because of a link I initially put, but headsup to the mods - it's merely a link to a company that makes springs! I'm not affiliated to them in any way.
Click to expand...
Yeah, it wasn't visible. Only seen it now!
This option didn't even occur to me! Do you think they'd be up to something like that?
 
DaniC said:
Here's a few options that might work?

- Arrma RC Servo Saver Spring 12x20mm X-Hard EXB AR340178 - this one says 12mm diameter, I presume that inner diameter, we @Horatio said the inner diameter on the stock spring is 14.4mm, but if the diameter in the post is 11mm or less then this might work? It's also longer at 20mm, but it looks to me like there's room to spare in that regard. Any of the Arrma guys here have you tried this one?
- HPI Racing Heavy Duty Servo Saver Spring 21x12x1.9mm 4.5 Coils HP102522 - similar measurements to the one above.
- Team Associated RC8B3.1 Servo Saver Spring AS-81083 - no measurements, but it's for a 1/8 so maybe...
Click to expand...
The springs here - length wouldn't be a deal breaker, but the diameter would be because the springs wouldn't fit the plastic moulding of the servo saver.
 
DaniC said:
Yeah, it wasn't visible. Only seen it now!
This option didn't even occur to me! Do you think they'd be up to something like that?
Click to expand...
That'll teach me for putting a link to a commercial site! 🤣

In response to your links to different springs Danni, I did respond my post is under moderation again because of the links. 🙄

I don't think the length of the springs is a deal breaker, but the smaller/karger diameter would be - because they wouldn't fit the mouldings of the servo saver or the thumb screw.
 
I think what i am going to do, is crank the servo saver down as tight as possible so there is no play. Then replace the servo horn with a hot racing style servo saver directly to the servo
 
Caleb90 said:
I think what i am going to do, is crank the servo saver down as tight as possible so there is no play. Then replace the servo horn with a hot racing style servo saver directly to the servo
Click to expand...
Yeah I thought of that option.... Team Corally also has a few of those types of servo savers. But not sure what the advantages/disadvantages would be.

https://www.corally.com/Servos-Parts/Servo-Savers-Arms/
 
Caleb90 said:
I think what i am going to do, is crank the servo saver down as tight as possible so there is no play. Then replace the servo horn with a hot racing style servo saver directly to the servo
Click to expand...
It'll be hell on the servo, but will definitely get rid of any play. I haven't looked anywhere for a replacement spring yet myself, but am going to look outside of the rc industry and see what I can find when i get a chance.
Now that I have some measurements of what comes stock, maybe I can find something.
 
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