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On-road car servo mount: angled vs. straight?

Posted: Mon Jun 09, 2014 1:02 pm
by Coelacanth
I've seen on-road touring & pan cars with angled and straight servo mounts and was wondering what the pros & cons were, and how or if it affects steering functionality? It's just an observation as the RC12L3 I'm working on has an angled mount while the 1:10 Lucas Agitator has a straight mount. I'd install an angled mount on the Agitator if it either wouldn't make any difference or might improve steering. Suggestions?

Re: On-road car servo mount: angled vs. straight?

Posted: Mon Jun 09, 2014 2:46 pm
by THUNDERSTRIKE1
Either option works.Angle mounted seems to allow for tighter areas where electronics are really close.Plus ive yet to bust an angle servo yet compared to flat mounting one.DON :lol:

Re: On-road car servo mount: angled vs. straight?

Posted: Mon Jun 09, 2014 2:53 pm
by ChisaiKuso
Coelacanth wrote:I've seen on-road touring & pan cars with angled and straight servo mounts and was wondering what the pros & cons were, and how or if it affects steering functionality? It's just an observation as the RC12L3 I'm working on has an angled mount while the 1:10 Lucas Agitator has a straight mount. I'd install an angled mount on the Agitator if it either wouldn't make any difference or might improve steering. Suggestions?
I would suggest keeping the servo flat because of the Agitator's front suspension design. Associated's Dynamic Strut front suspension, on the other hand, is typically setup with an angled servo.

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From an old post on RCTECH:

The AE dynamic strut front suspension is designed to run with an angled servo. In this configuration you have zero bump toe and an a significant amount of Ackermann.

On asphalt this is a good thing. It makes the inside wheel turn in hard on low speed corners giving you more steering.

On carpet this is a bad thing because the traction is much higher. You do not need as much Ackermann. All Ackermann does on carpet is hurt corner speed and make the car hook into corners because its dragging the inside wheel past its optimum slip angle.

Running the servo flat generates a lot less Ackermann. This reduces wheel scrub and increases corner speed. The thing to watch is the bump toe. The front suspension was not designed to accommodate a servo in the flat configuration so you have to compensate for this.

This is done by running taller ball studs on your steering spindles. If you run the middle holes on a small Kimbrough servo saver with medium height IRS ball studs on the spindles you will have a small amount of bump toe in. If you run the holes closest to the servo output shaft you will have zero bump steer.

If you do not do this your car will go horribly pigeon toed as the suspension compresses and this will kill your lap times.

So...

Asphalt: Servo Angled

Carpet: Servo Flat (with corrected bump toe)

Re: On-road car servo mount: angled vs. straight?

Posted: Mon Jun 09, 2014 2:58 pm
by ChisaiKuso
THUNDERSTRIKE1 wrote:Either option works.Angle mounted seems to allow for tighter areas where electronics are really close.Plus ive yet to bust an angle servo yet compared to flat mounting one.DON :lol:
Either option may work, but track conditions are the deciding factor on which option works best. (It has nothing to do with fitting electronics into tight areas.) :wink: