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Old 08-16-2016, 10:17 PM   #901
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Default DIY Motor Cooling, and drift wheels



I "fabricated", if you can call it that, a little fan mount for the front of the chassis. It's made out of a small plate of stainless steel, drilled and bent to fit between the motor plate block bulkhead and kick plate. It's pretty rough right now, I wanted to see if it would work. I will clean it up later. But for what it is, it is functional. I sourced the power off the receivers unused 3rd channel. My esc has a capacitor for the Rx, so it should not be a problem.

It also fits nicely under the lexan body too.

You can also see my DIY drift wheels made from 2" ABS plumbing pipe hacksaw mitred and pressed onto HPI rims I salvaged from my worn out x-patterns.
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Old 08-17-2016, 01:31 AM   #902
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You could cut open the grille on the Lexan body to improve airflow to the motor. That bumper and skidplate do a pretty good job of blocking passive airflow to the motor.
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Old 08-18-2016, 11:02 PM   #903
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Yet another set of tires from an eBay/amazon seller I received today.

This time with a different tread pattern, directional radial. These things are oversized compared to USGT, and the last set I have. They are the same diameter as the Tamiya rally blocks if not a tad larger, and have a very high sidewall. The rubber is very soft, rims look decent. I got 3mm offset with these ones. Foams are soft. Tires are pretty squishy. I foresee a lot of side wall deflection on hard cornering. I have yet to try them, paint? Glue for sure.

You can see the size comparison in the image below.



Is there a technique to cutting foams more more optimal traction/wearing?

Lots to do tomorrow, I rebuild the front end with the carbon arms and shimming madness. The current slop is unacceptably annoying, when you know it's there.
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Old 08-19-2016, 12:09 AM   #904
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Man, you are burning through tires at a fearsome pace. You're clearly driving that car a lot more than I drive *any* of mine.

I've heard of cutting wedges out of truck and rock-crawler foams to make them more compliant, but I've never heard of cutting touring-car foams. You might be able to do something like putting a firmer foam in the outboard half of the tire and putting a softer foam in the inboard half, or something like that.
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Old 08-19-2016, 12:31 AM   #905
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Man, you are burning through tires at a fearsome pace. You're clearly driving that car a lot more than I drive *any* of mine.
I haven't burned through my China eBay tires yet but at the rate I *was* driving I was fearful of not having a set to roll on, so I ordered a bunch. At 5$ a set, I can drive like a maniac, and not really worry about eating into real money that racers spend on tires.

This hobby can be expensive, especially when your consumables can cost ~30-40$ every 6-10 runs? I am driving my tires off the rims before retiring them

If I can salvage rims (and not have them disintegrate into empty marshmallow goop in acetone), it should be even cheaper by 1-2$ by buying only tires!

I am buying tire sets to compare treads to see which one I like most. Then I can have a goto when I actually run out of tires.

I have one car. A couple sets of tires. And I drive it pretty hard and often on weekends. Ive seen your garage in posts. It's like Jay Leno's, a car for every mood. 😄 cars on rotation instead of tires on rotation in my situation.

I dig the China tires worn into slicks. Ride USGTs have super low side walls, which make them very predictable. These new tires I think would be good for rally like road stages, since they are squishy and act like suspension. I bet they will balloon like crazy.
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Old 08-20-2016, 07:36 PM   #906
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I've run a couple of packs on these new oversized radial tires. They are a little too big for the wheel wells of the HPI BMW GT body and rub a little. So I ran the Subie. I think the outter diameter is in 68mm+ range.

The tires grip pretty well, they even make a little screeching sound when G-ing out. They have an extra cushy property about them. Like under inflated, high sidewall tires on a real car. Floaty. They add a little ground clearance. Definitely not racing competition tires, but race your friend tires sure!

So far the tire wear is barely noticeable. I actually think I have a slight bit of outer edge wear, from positive camber, because of my ring of death paranoia.

I found another empty parking lot near my house. It has smooth asphalt, with a slight glaze. I did some full throttle parking lot bashing, drifting. T'was fun. Dirty as F though. When I picked up my car, it was like coal dust all over.
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Old 08-23-2016, 11:46 PM   #907
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Old 08-24-2016, 08:57 PM   #908
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Default Steers more one way

Hey, I noticed, that my car steers more to the right than left.

The car drives straight, but I can do donuts easily to the right, but cannot do them to the left.

Is there any way to correct this? My servo is centered. Limits on Transmitter are at 0. I know the electronics side of my car is slightly heavier, so that might be a thing?

I am going to see if my turn buckle screws are the same. But other than that, any suggestions?

Thanks
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Old 08-24-2016, 09:09 PM   #909
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Originally Posted by 4roller View Post
Hey, I noticed, that my car steers more to the right than left.

The car drives straight, but I can do donuts easily to the right, but cannot do them to the left.

Is there any way to correct this? My servo is centered. Limits on Transmitter are at 0. I know the electronics side of my car is slightly heavier, so that might be a thing?

I am going to see if my turn buckle screws are the same. But other than that, any suggestions?

Thanks
The culprit is usually left and right balance. Right side is probably heavier than left.. When turning right the chassis tucks in and turns where as when your turning left, it's not as heavy on that side so it goes wider
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Old 08-24-2016, 09:10 PM   #910
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Quote:
Originally Posted by 4roller View Post
Hey, I noticed, that my car steers more to the right than left.

The car drives straight, but I can do donuts easily to the right, but cannot do them to the left.

Is there any way to correct this? My servo is centered. Limits on Transmitter are at 0. I know the electronics side of my car is slightly heavier, so that might be a thing?

I am going to see if my turn buckle screws are the same. But other than that, any suggestions?

Thanks
Do you get unequal steering at low speeds, or does the problem only occur with lots of throttle? If the latter, it may be chassis tweak or uneven shock preload. Also check that camber settings are the same left to right. Weight distribution can have an effect too, it really depends on how unbalanced it is.
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Old 08-24-2016, 09:48 PM   #911
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Only at high speeds I can tell. Tweak might be a thing, I can try loosening my toe blocks and
Diff and then re-tightening.

I think weight is one contributing factor too. I can't really do much since my battery weighs less than the esc, receiver and servo. I think the xv-01 has a right side bias. One way to test would be to add weight to the left side, but in a game of trying to make a lighter car, that just seems silly. Try I may, to test that theory.

Also, I reduced the toe out on the left, just a little, it seems to have helped. The car can almost do stand still donuts in that direction now. I really need to send the car into a 3 wheel drift to test. Unfortunately my battery just died before I could really test.

Thanks all for the quick responses.

Last edited by 4roller; 08-25-2016 at 07:42 AM.
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Old 08-24-2016, 11:33 PM   #912
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Originally Posted by 4roller View Post
Only at high speeds I can tell. Tweak might be a thing, I can try loosening my toe blocks and
Diff and then re-tightening.

I think weight is one contributing factor too. I can't relly do much since my battery weighs less than the esc, receiver and servo. I think the xv-01 has a right side bias. O e way to test would be to add weight to the left side, but in a game of trying to make a lighter car, that just seems silly. Try I may, to test that theory.

Also, I reduced the toe out on the left, just a little, it seems to have helped. The car can almost do stand still donuts in that direction now. I really need to send the car into a 3 wheel drift to test. Unfortunately my battery just died before I could really test.

Thanks all for the quick responses.
Regarding weight distribution, even though you may not be able to get side to side balance even, you should try to get the cross weight balance as close to even as possible. You can do this by adjusting the preload on the shock springs. A quick online search should give you more information on this topic.
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Old 08-25-2016, 08:04 AM   #913
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Regarding weight distribution, even though you may not be able to get side to side balance even, you should try to get the cross weight balance as close to even as possible. You can do this by adjusting the preload on the shock springs. A quick online search should give you more information on this topic.
Ah ha! Thanks. I looked up corner balance. This may be a major contributor to my issue as I my preload on my springs is basically non-existant. I backed the springs off completely to achieve the lowest ride height for the over sized tires I have. I will try adding a slight bit of preload to one of the corners to see if it changes things.

Thanks!
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Old 08-27-2016, 11:57 PM   #914
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So I found out why my car steers one way more than the other.

#1 Someone (me) set my transmitters left/right EXP to 80/90, so the servo had more right bias. Fixed that.
#2 my servo horn (kimbrough) although was centered on the splines, I found the ball joint was in the furthest top rear position. So I moved it to the center mid position. This helped. However I found that the ball joint is so low, when turning one way the tie rod is hindered by the round part of the servo saver. I added a small plastic spacer under the bell crank ball joint, this helped. I also tightened down the steering block limit screws.

Is anyone not running a servo saver? I feel like trying a solid aluminum arm, I have a metal geared futaba servo, and one guy at the hobby shop said it's durable. I just dont want to know crash my car and then regret life.whats everyones take on servo savers vs solid arms?

Tire update:
My ebay China tires (both pairs) have the ring of death. And one set ripped right through. I tried to acetone them, no dice, it just dissolved into a pile of goopy mess.

Luckily I have 3 more sets to burn though. I am living in a disposable society. Ugh. There is just something wrong about throwing perfectly good rims. Maybe I need to find an alternative to CA glue. Any suggestions? Aluminium rims? HPI rims? Because those two don't dissolve in acetone.

The cross weight topic got me thinking. And I started playing around with suspension. On braking and turning (off power turning) the outer front corner of the car will dive, thus lifting the inner rear, losing traction, and possibly causing the rear end to slide out. To counter act this, we need to harden the front springs, so the dive is lessened. Off power turning is improved, less rear end sliding.

I will lement about on power turning now, and how to (with suspension) counter act spin out. The power solution I had was to reduce punch/torque in the ESC. But sometimes you just one that power at your finger tips.

Anyway. Still loving this car. Except for tire wear, its groovy.

Last edited by 4roller; 08-28-2016 at 05:03 PM.
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Old 08-28-2016, 04:21 AM   #915
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You could probably get away with a solid servo horn on this car; a metal-gear servo will certainly handle the load, though it's possible you could end up breaking steering knuckles in hard hits without a flexible component in the steering system.

If you want to keep using a servo saver, MST makes adjustable servo savers with a wide range of ball-stud mounting positions, so you can get it just right. They come in red, black, blue, purple, and silver; I have the blue ones on most of my Tamiya cars and the purple ones on most of my HPI cars. They also come with 3 different springs; I've determined that the stiffest spring is too stiff and will sometimes cause the servo saver to break when hit particularly hard (I have one installed on a stadium truck), but the middle spring works great.

I use HPI wheels on all my cars that don't have premounted tires. I think they're great. I re-iterate my recommendation for HPI Super Radial tires or HPI V-Groove Pro Compound tires; I'm sure they will wear longer than the no-name rubber used in those generic tires.
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