• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

Steel spur Q's

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
L

lykan

Hardcore RCTalk User
Messages
1,302
Reaction score
1
Points
0
RC Driving Style
Hey all,
I picked up a nice 1'st gen T-maxx. It has a steel spur on it. Looks to be pretty high quality.

I noticed after the maxx gets off idle, about 1/4 throttle. It is really responsive. Hit the gas, and I can kick it sideways in a turn, or do donuts.

Off the line from an idle it's kind doggy. It really has to get a few rpm's uder it's belt before it has any torque.

I know the motor I have on it is a little tired. What I am wondering is if the inertia, or rotating mass of the Steel spur is causing it to be a bit doggy on the low end.

I know I can lower the gear ratio. I also know I can do a foc, and get rid of the steel spur.

I like how it is setup now, I am just wondering if anyone noticed a drop in off idle torque when installing a steel spur. If it is caused by the steel spur I'll live with it, maybe drop a tooth on the CB later. If it is not cause by the steel spur, I will be rebuilding my engine sooner rather than later..

Thanks as always
 
I noticed increased performance with the higher quality parts. I would check the carb settings, gear ratio, slipper pegs, and then the engine for wear.
 
I have a piston & sleeve to put in, but I don't want to do it until it is completely necessary. I guess from the sounds of it, it is time.
 
Well, the math tells you it slows it down. It will give you more momentum, but your take off will be a bit slower. So your pretty much right. As to how much slower it makes it would be difficult to determine.

When I went with steel gears, I changed all the trans gears I could to RRP and the spur. So I added a lot of rotational mass all in one shot. I noticed a considerable amount of low end power loss.

But, the OS 21 RG makes up for most of it!
 
A full on steel gear will tend to not improve the low end. The rotational mass of the spur is increased by the steel. This means it takes more time to spin it up far enough to engage the clutch in the tranny. It also means that it will remain spinning far longer than a plastic gear would after going from WOT to idle.

If you want the best of both worlds, I suggest the double disk slipper set up and ring gears by RRP. This is basically a very vented spur gear and an improved slipper mechanism. It still weighs more than plastic, but only slightly so. I run one on my T-Maxx and there is no problem on the low or high end of the spectrum.

Go HERE and scroll down to the area labeled "Slipper Kits". There you will find what I am talking about.
 
Lykan,

Any added rotating mass will slow down acceleration, but your motor would have to be pretty weak to notice it. To test if your motor is done, take out the glow plug. Rotate the flywheel with your finger. You should feel some resistance or "pinch" when the piston is at the top of the stroke. If not, it is toast. Replace the piston/sleeve, or get a new motor. If there is no pinch when it is cold, the expansion of the sleeve when it is hot reduces the seal to nothing, so no power.
 
Originally posted by scottm
... If there is no pinch when it is cold, the expansion of the sleeve when it is hot reduces the seal to nothing, so no power.
Click to expand...

LOL...Tell that to my two year old Fantom .15FR. It is getting real close to rebuild time, but still has plenty of power in it. I just need to keep the darn pull start from continually crapping out on it.
 
Yeah, its true a worn engine will still run good on top, but bottom and mid power is the first to go. Another sign that it is dead is when it is real hard to start when it is hot, again because of the sleeve expansion.
 
No arguments here, just observing that I have not yet seen these indications from my engine. Been running steel spurs for most of the Fantom's life, and the engine gets good performance across the board. Based on what you are saying, perhaps I am further from the rebuild than expected, but my compression test indicates otherwise.
 

RC Builds

Back
Top