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Servo and chassis questions

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C

Cyclop3000

RCTalk Racer
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  1. Bashing
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Hello, I have a couple questions on upgrades...

1- Would the HPI SF-5 servo be a good high torque servo to upgrade a .21 savage, or should I invest a little more in a better servo? I am planning to get a new engine and want to upgrate the servos.

2- Would the XL extended chassis be a good upgrade to my .21? I am trying to see what effect this would have on performance...is there a reason to use extended chassis? And if it's worth it, what other parts would need to be upgraded at the same time...such as dogbones I guess and such?

Thanks!
 
for your steering or throttle/brake servo?

SF-5 SPECS:
Length: 2.15" 54.5mm

Width: 0.79" 20mm

Height: 1.5" 38.1mm

Weight: 1.64oz 46.5g Voltage: 4V-6V

Torque: 314 oz/in 8.9kg/cm

Speed: .20 sec/60 degree (6.0V)


for your steering, i believe its a good upgrade.
 
The SF-5 servo has 124 oz/in torque so it would be OK, not great. I run the JR 9100T for the steering, which may be a bit overkill, but when it comes to steering servos that is all I run in all my rigs. I would go for something that has at least 150 to 180 oz/in to really get good performance. I have run Hi-Tech servos in the past and they offer great performance for the price. Look at the HS-5645MG, I have used them in my Inferno and rock crawler and it was a great servo for about $50.00 and it has 165 oz/in torque. The SF-5 would be a good servo for throttle/brake as I think it is good to have a servo of at least 100 oz/in for the brakes on a heavy rig.

As far as the XL conversion, I did it to mine right away after only running the truck one time. With the larger 40 series Proline tires that I run the truck was very unstable at high speeds, but after adding the XL conversion it is WAY better. By far the best mod I have done so far, and I think it looks much better as well. The only down side to the XL chassis is that there are only a couple bodies that I think look right, I have the ProLine Ford F650 body that is made for the LST, XTM Mammoth etc, and it fits perfectly. I also have the Dodge Mega Cab and Chevy Silverado, both for the LST as well and they fit good, but not as well as the F650. Wheelies aren't as easy with the added length either, but I prefer to be able to mash the gas and go, not wheelie.

HPI sells the XL coversion kit, and it comes with the new TVP plates, longer rear driveshaft and a new motor plate. I didn't need the motor plate as it was the same as the one that came with my Svage X SS kit, but you may need it for the older Savage. That's all there is to it. I think I paid about $55.00 for the conversion at my LHS.
 
supradude26 said:
The SF-5 servo has 124 oz/in torque so it would be OK, not great.
Click to expand...
You may be thinking of a different servo:
SPECS: Length: 2.15" 54.5mm
Width: 0.79" 20mm
Height: 1.5" 38.1mm
Weight: 1.64oz 46.5g
Voltage: 4V-6V
Torque: 314 oz/in 8.9kg/cm
Speed: .20 sec/60 degree (6.0V)
Quoted from Towerhobbies.
 
Ah thanks for the info. The goal here was to replace the stock steering (SF-2 I think) with the SF-5, and put the SF-2 on the throttle/brake.

Ok I just saw the extended plates for cheap on eBay so I was wondering...the lack of bodies is indeed a pain in the bottox, as I really like my bodies and put a lot of time into them.

Hey Boutch, on a change of topics I see in your sig you are using the OS 30...I was thinking of an OS 30VG as well what do you think of the engine?

Soooo...with an engine of this type in mind, would an SF-5 be enough (I am aiming for enough...not necessarily "the best") or should I aim at better, as posted above? I have a bunch of upgrades to buy since my old .21 is almost stock, so I want to put my money where it's worth it.

Thanks!
 
I wouldn't personally go with something any less than 150oz for steering or less than 120oz for t/b in a MT. The stronger/metal geared servos just flat out last longer.

I really like the hitec 985MG. $70 with good specs and last a long time. Tower doesn't list it, but it puts out 172oz @ 6V. I really like those servos. Not a whole lot of money, but still a decent product. It's also sealed with o-rings to help combat wet running.

It's what I used to use on my revo for steering and t/b. Now I just use them for t/b on my savage and aftershock. I had a spare nice JR digital servo that I"m using for steering on the savage and the aftershock runs two servos stock that do a decent job. I like the dependability and sealed aspect of them, especially as a t/b servo since they are almost always standing up and are prone to getting water in around the servo output shaft. These have a o-ring on the output shaft.

As for the longer chassis, I have a hot bodies chassis that is 1" longer than a 21 and I really like it. Handles much better and is less twitchy. Also gives you a bit more room between the engine and rear tower to avoid the shocks hitting the header and fuel tank.

I'm not sure what bodies fit it though and I'm in need of a new body. I think I have the parma exciter body, but I'm not sure. I need to pick up a new one before spring as mine is totally shot.
 
And what about those cam steering servo savers kits (I guess somewhat like on the XL)...is this of any use for the steering servo? Does it really makes a difference/helps in steering or should I just stick with the servo saver my stock .21 has?

Thanks and sorry for all the questions...it's been 5 years since I last took apart my savage...so much has changed since hehe. When I bought my savage 21, the 25 didn't even exist haha ;)
 
The cam version is best. It allows for adjustment and doesn't get all mushy after a short while like those servo mounted ones. If the cam one doesn't come with bearings, order bearings. Helps make it more smooth and keeps slop at bay as time goes on.
 

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