Horatio
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I've started this thread to make it easier to find all the info in one place.
It all started here with DaniC's post - how to adjust servo saver:
https://www.corallyforum.com/threads/easiest-way-to-adjust-servo-saver.459/
Back in the day, around 2022, Danny and myself measured up our springs and looked for spring manufacturers that can make bespoke springs.
Lee Spring were selected as the manufacturer of choice. Primarily because they make the right spring, but also because they have global reach.
Speccing a simple compression spring is more technical than people realise.
The primary issue with the stock spring is rate is insufficient for the level of force that is generated through the steering. Not only that, but the stock spring rapidly gets weaker during use.
The forces that the steering mechanism has to deal with increase with wheel/tyre weight, rpm, surface speed, higher specced servos, higher BEC voltage and the type of terrain.
Note the rate in this spec sheet: 24.343 N/mm
This means that to compress the spring just 1mm, 2.4kg would need to be applied.
Also note the material choice. Music wire is about the best material you can engineer a spring from as the rate will be consistent over time.
With the stock spring, to get any steering authority at all, I had to really clamp down the servo saver spring until there was very little space between the coils.
The disadvantage is obviously that with very little compression space left, there is virtually no saving action in the event of a 'tumble wumble'.
Having insufficient steering authority isn't an option at 70mph.
So, here's the Lee Spring on the right:
It's wound from thicker wire, with a slightly larger height and diameter. It's an interference fit onto the threaded Servo Saver shaft.
The stock spring can be compressed between the tips of my fingers:
Where as the new Lee Spring cannot be compressed between your fingers. I have a grip strength of 50kg and it wasn't happening!
Here's how the Lee Spring should look correctly fitted:
Note the spring is properly seated on the thumb screw and squarely located into the saver.
Fitting: compression to the spring is required as the thumb screw is carefully - and squarely - introduced to the threads to avoid cross threading. Once the first few threads have been positively engaged, continue clamping the spring until 2 visible threads can be seen.
The linear force of the spring against the thumb screw means that it will not loosen over time.
Since the release of the LE, there are already people experiencing issues and people suggesting additional wheel nuts and threadlock as a fix.
Do not apply threadlock here (for obvious reasons)
Do not apply an additional wheel nut.
To manage expectations:
Unit cost of Spring from factory: £3.66
Admin charge for orders below £30: £12.50
Should an ebayer (such as myself) buy a batch of 10 springs, please bear in mind eBay fees, postage, packaging will all need to be factored in to the final selling price.
The shipping costs:
Shipping from the UK to different regions attracts different costs. Springs have to be sent in shipping bags. Sadly, such bags also cost money.
Please do not expect people to supply these at the buy in price and then incur loss, because this is unreasonable.
Fitted as described, you will have much greater steering authority as well as saving action in the event of a crash.
One cannot expect an upgraded servo with >45kg of torque to perform any differently to a bog standard stock servo, if it is limited to the stock spring which yields at 3kg in either case. It's common sense.
Yet people with floppy servo savers still wonder why their new servo doesn't cure the problem. It was exactly the same story with Savage community over 20 years ago.
Servos can fail without warning for a multitude of different reasons. Gears can fail and magic smoke can (and does) happen.
The single biggest problem is incorrectly set end points, and sadly, certain RTR radios do not facilitate this adjustment. Combine this with running servos at their maximum voltage
and the first spike causes failure. Especially on cheaper, unbranded servos.
Over the years, I have bought just about every brand of servo - Acoms, Futaba, KO, HiTec, Sanwa, Protek, AGF RC.
My mindset - if you buy cheap, you buy often.
So, my personal recommendations for 1/8th size vehicles remain:
AGF RC 81BHMW
Protek Black Label 170 SBL
Protek Black Label 170 TBL
I run a 170 TBL in my Baja 5B for throttle/brakes and I have to dial it back on any surface I run.
I run a combination of Protek SBL and TBL in my XT8 and it has such a direct and positive feel - it's scalpel sharp in its response. Perfect centering, which is extremely important - especially when racing.
The AGF RC 81BHMW is comparatively new to me, but I started using them in my Kronos XTR, running the BEC on 6V. 4 years later - it's still as good as new. In the UK, it was supported by King Cobra Racing and more recently - SMD Direct.
I also use one in my Sworkz T2E - it's a great rig and the steering is laser accurate. The AGF is waterproof, HV, brushless - it's very, very good and half the price of a Protek.
I'm about to pull the trigger on a low profile AGF one for my 22x-4 - the A62BHS - with 0.058 speed. Basically faster than anything I've ever used, so will prefer it tamed on 6v to be perfectly honest!
Ensure your servo is OK for BEC use.
It all started here with DaniC's post - how to adjust servo saver:
https://www.corallyforum.com/threads/easiest-way-to-adjust-servo-saver.459/
Back in the day, around 2022, Danny and myself measured up our springs and looked for spring manufacturers that can make bespoke springs.
Lee Spring were selected as the manufacturer of choice. Primarily because they make the right spring, but also because they have global reach.
Speccing a simple compression spring is more technical than people realise.
The primary issue with the stock spring is rate is insufficient for the level of force that is generated through the steering. Not only that, but the stock spring rapidly gets weaker during use.
The forces that the steering mechanism has to deal with increase with wheel/tyre weight, rpm, surface speed, higher specced servos, higher BEC voltage and the type of terrain.
Note the rate in this spec sheet: 24.343 N/mm
This means that to compress the spring just 1mm, 2.4kg would need to be applied.
Also note the material choice. Music wire is about the best material you can engineer a spring from as the rate will be consistent over time.
With the stock spring, to get any steering authority at all, I had to really clamp down the servo saver spring until there was very little space between the coils.
The disadvantage is obviously that with very little compression space left, there is virtually no saving action in the event of a 'tumble wumble'.
Having insufficient steering authority isn't an option at 70mph.
So, here's the Lee Spring on the right:
It's wound from thicker wire, with a slightly larger height and diameter. It's an interference fit onto the threaded Servo Saver shaft.
The stock spring can be compressed between the tips of my fingers:
Where as the new Lee Spring cannot be compressed between your fingers. I have a grip strength of 50kg and it wasn't happening!
Here's how the Lee Spring should look correctly fitted:
Note the spring is properly seated on the thumb screw and squarely located into the saver.
Fitting: compression to the spring is required as the thumb screw is carefully - and squarely - introduced to the threads to avoid cross threading. Once the first few threads have been positively engaged, continue clamping the spring until 2 visible threads can be seen.
The linear force of the spring against the thumb screw means that it will not loosen over time.
Since the release of the LE, there are already people experiencing issues and people suggesting additional wheel nuts and threadlock as a fix.
Do not apply threadlock here (for obvious reasons)
Do not apply an additional wheel nut.
To manage expectations:
Unit cost of Spring from factory: £3.66
Admin charge for orders below £30: £12.50
Should an ebayer (such as myself) buy a batch of 10 springs, please bear in mind eBay fees, postage, packaging will all need to be factored in to the final selling price.
The shipping costs:
Shipping from the UK to different regions attracts different costs. Springs have to be sent in shipping bags. Sadly, such bags also cost money.
Please do not expect people to supply these at the buy in price and then incur loss, because this is unreasonable.
Fitted as described, you will have much greater steering authority as well as saving action in the event of a crash.
One cannot expect an upgraded servo with >45kg of torque to perform any differently to a bog standard stock servo, if it is limited to the stock spring which yields at 3kg in either case. It's common sense.
Yet people with floppy servo savers still wonder why their new servo doesn't cure the problem. It was exactly the same story with Savage community over 20 years ago.
Servos can fail without warning for a multitude of different reasons. Gears can fail and magic smoke can (and does) happen.
The single biggest problem is incorrectly set end points, and sadly, certain RTR radios do not facilitate this adjustment. Combine this with running servos at their maximum voltage
and the first spike causes failure. Especially on cheaper, unbranded servos.Over the years, I have bought just about every brand of servo - Acoms, Futaba, KO, HiTec, Sanwa, Protek, AGF RC.
My mindset - if you buy cheap, you buy often.
So, my personal recommendations for 1/8th size vehicles remain:
AGF RC 81BHMW
Protek Black Label 170 SBL
Protek Black Label 170 TBL
I run a 170 TBL in my Baja 5B for throttle/brakes and I have to dial it back on any surface I run.
I run a combination of Protek SBL and TBL in my XT8 and it has such a direct and positive feel - it's scalpel sharp in its response. Perfect centering, which is extremely important - especially when racing.
The AGF RC 81BHMW is comparatively new to me, but I started using them in my Kronos XTR, running the BEC on 6V. 4 years later - it's still as good as new. In the UK, it was supported by King Cobra Racing and more recently - SMD Direct.
I also use one in my Sworkz T2E - it's a great rig and the steering is laser accurate. The AGF is waterproof, HV, brushless - it's very, very good and half the price of a Protek.
I'm about to pull the trigger on a low profile AGF one for my 22x-4 - the A62BHS - with 0.058 speed. Basically faster than anything I've ever used, so will prefer it tamed on 6v to be perfectly honest!
Ensure your servo is OK for BEC use.
Last edited:
Facts! Cheers buddy. 
