JRX Pro Rebuild

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Some updates on this project:

Firstly, wanted to say thanks again to everyone who contributes to these boards. Great community and really helpful information. Secondly, I'd like to send a big F you to the same group. You guys need to clearly warn new folks that this is a total rabbit hole and they are gonna lose all sorts of time researching obscure parts, ogling RC porn, etc. In addition to this JRX project, I also recently picked up an RC10T and an XX4. When will this stop?! My wife is gonna kill me...

So, I've torn down, cleaned and rebuilt about 95% of the car. The body reamer worked great on the tranny case and I was able to pretty easily retrofit the double slipper. I went with Jconcepts Rulux wheels with spacers on both the front and rear. That said, I'm having some trouble with a couple of other things:

1) The steering is binding when pushed all the way to the left and right and I don't know why. I've checked and cleaned every piece of the steering linkage. It does not bind when I remove the steering turnbuckles. Best I can tell, something about the downward pressure of having the steering links attached is causing it. Any ideas?

2) The manual was not clear on which of the two holes to use to connect the hub carriers to the H arms. I went with the top one.

3) I went with a Hobbywing ESC and motor, but I don't think I'm getting anywhere near the top speed I should be. The RC10T I picked up has the same motor/ESC and its much faster than the JRX. Also, the ESC on the pro always has a blinking red light when at neutral throttle. Oh, and the fan is always running at high speed. Could it be defective?

[jwscab]

it certainly is a black hole of time and $$ spent. But it's better than other ways to spend money that's for sure.

can't really help on your first question, just look at each part/assembly separately until you find the problem. you may just be seeing the limit of the steering throw.

I'd probably use the top hole in the hub also, but someone else will know for sure.

the esc is in blinky mode, if the other is not flashing the red light, it is possible that it is programmed for lots of timing, which can improve the performance greatly compared to stock timing. The trackstar combo I have runs the fan all the time, so I don't know if that is correct or not, but I just let it run.
the esc's have a programming card to change a bunch of features.

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the esc is in blinky mode, if the other is not flashing the red light, it is possible that it is programmed for lots of timing, which can improve the performance greatly compared to stock timing. The trackstar combo I have runs the fan all the time, so I don't know if that is correct or not, but I just let it run.
the esc's have a programming card to change a bunch of features.

Ah -- that makes sense. Thanks!

[matt1ptkn]

An issue I've had with steering is if the tie rods are threaded too far into the ball cups. You may not notice any difference inside the cup, but just the slightest intrusion of the tie rod can bind up the ball joint. Other than that, you may be able to try a ball bearing steering set. Sabula Tech makes a printed set.

The different holes in the rear hub carrier is a tuning option. I believe that the top hole is typically the standard choice.

If your ESC is in blinky mode, I'm assuming that you're running a 17.5 motor. If that is the case, you will need to gear up a lot. I've found that 17.5s are powerful and full of torque and in order to reach top speeds, require a much taller gearing setup, ie. a much larger pinion than what would be used on a vintage 27 turn brushed motor. Just be mindful of your motor temps.

Yes it is addicting. I'm sure I could buy my own personal jet if I had saved instead of spent, all the money I've spent on RC since I was 8.

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An issue I've had with steering is if the tie rods are threaded too far into the ball cups. You may not notice any difference inside the cup, but just the slightest intrusion of the tie rod can bind up the ball joint. Other than that, you may be able to try a ball bearing steering set. Sabula Tech makes a printed set.

Thanks. I thought that might be an issue so I went ahead and swapped out the original tie rods for Lunsford tie rods and cups. Same issue. I might give the bearing steering set a shot.

I played around with it a little more tonight and I think it may be due to the ride height. When I compress the shocks a bit the binding goes away. The manual recommends that the front A arms be parallel with the bulkhead, but I'm not able to get the front end that low even with the shock collars all the way up. Should I be using internal limiters? What am I missing?

[jwscab]

Yeah something is binding due to the extreme angle. You'll have to play with some internal limiters in those shocks, but once the car is full race ready, drop it from 10-12 inches to see where it squats. From there you may need to play with spring pressure, you may be using springs that are too long for the front.

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You nailed it. The front springs I have are 2.5". The manual says the correct part number is LOSA5100, but Google tells me that's 1.5" which seems too small. I believe 2" is the right size for the Pro. Am I right? If so I think I'll look for LOSA5132 which are the green 3.5 rates unless you guys think I should do something different.

[jwscab]

I'm not a losi tuning guy but the spring rate sounds about right.

[aconsola]

It's not just the springs that are the problem is is the shock cartridge.
you have the newer double o-ring cart which is much shorter than the original both inside and out. you need spacers inside the shock to shorten them up and spacers outside to limit travel slightly.

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Got it. I'm gonna add a pair of these to each shock.

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Another update -- I added the limiters and green springs. Ride height is now normal and the binding in the steering is gone. Now, I've got decided whether to turn this into a runner or pretty it up and put it on the shelf.

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Took old girl out to the track for the first time. Did pretty well until I broke a male universal shaft. I'm pretty sure this just convinced me that the car belongs sitting on the shelf. Out of curiosity -- is there any way to convert the drive shafts to something stronger (dogbone, CVD, etc) without replacing the entire transmission?

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Should have done a proper search first. I see MIP (MB-100) made bones that fit the H arms. Is this the only option?

[matt1ptkn]

Traxxas Bandit slider shafts are supposed to be a direct fit. They are virtually the same thing as the Losi, but newer, cheaper and tougher.

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Much obliged. Out of the curiosity, would the white super sliders also be an option?