New experience with the JRX-Pro

[fredswain]

The last time I drove a JRX was somewhere around 1991 or so. It's been a while. Since getting back into rc sometime around February I've been restoring/completing the old cars including my beloved JRX2. I had so many spare parts in the end that I decided to build another complete car out of those parts. I decided to go with a JRX-Pro. The only thing I was missing was the graphite chassis. I had an extra Junior 2 composite chassis but I thought it would be nice to have one complete stock JRX variation since the other car is built using all of my favorite parts in the JRX series to be a complete car that never came that way. A little hlep from bearrickster took care of my chassis dilemma. I've been driving and modifying an RC10 since I got back into it and have had lots of fun. Through lots of work I got the car handling pretty well and using modern logic even added weight. It's not bad. The one thing that has given me frustration with it though is reliability. I keep breaking things on it. It's heavy and handles well but it's not capable of getting around the track in one piece. That car is getting rebuilt for strength so I decided to get the Pro going. When I was building the Pro I learned from the RC10 issues and strengthened everything anywhere that I could. The car is a tank now.

I took the Pro for a quick drive outside 2 nights ago. My Trinity brushed motor was acting up so I didn't get any useful runtime on it but the car did run for the first time and it was the first time in 20 years that I had driven a JRX. I ended up thoroughly cleaning the motor and replaced the brushes. Power!!!!! Last night a friend and I went to the track for a couple of hours. This is the same track that my RC10 self destructs on so I was a bit intimidated as to the potential consequences for the new Pro car. I got the car out on the track and immediately could tell that it was very forgiving. It went off of jumps at angles that would have sent the RC10 tumbling into oblivion yet would fully recover on it's wheels and just keep going. It was much easier to drive and I've spent the past 6 months tuning the RC10. This car I just built the way I guessed it should be setup and it's a better handling car that is easier to drive. Now my driving ability still needs quite a bit of practice so I did hit a few issues on the track. At one point I got stuck under a barrier. The RC10 would have had something broken so I was a bit scared to see the carnage. There was none. Remove barrier and drive. Sadly the night did end abruptly when I stripped out the main diff gear. I'm running a modified motor with no slipper. It didn't like it. Fortunately I had 4 more of those gears in my spare parts box so it's all fixed and ready to do. A slipper clutch is going on it this weekend.

I've got to say now I remember why I went to the JRX from the RC10 back then. This car rocks! I don't have anything modern to compare it to at the moment but instead of maddening frustration at the track I was enjoying myself. It's a very good car and I can't wait to get back out there to start dialing it in for even better performance. I've spent 6 months on the RC10 when all I had to do is just drive the JRX. Go figure. I still love the RC10 though and will still work to make it the great car that it was but for personal preference the JRX-Pro is how I like a rear motor 2wd buggy.

Here's a picture of my 2 JRX's without the bodies on. The one on the left is the evolution from my original 1988 car. The one on the right is the new Pro I just built from parts. New bodies are next. I'm running a hacked up RC10 body on the Pro right now.

[sgirouard]

Great write up Fred. I love the JRX2. I've owned 2 in my life and adore them. I turned an X2 into a modern runner except with the 5 link going. A couple things that really help out the old girls.

1. Get some xxx shocks. You'll LOVE IT MORE!!
2. Duratrax evader front tires for 2.2's on the front, your JRX bearings go right into the rims and they work awesome
3. On the rears (for your runner) I believe associated B4 tires work but get another losi guy to confirm. I did something different to put 2.2's on the 5 link that I wouldn't suggest for the H-arm (12mm hex off the strike with 12MM rims that I'm not sure what buggy they're for, the offset was right so I used them)
4. There's an easy slipper mod you can use. Talk to bearrickster, he knows the gear you need to mount any Losi slipper pad. I was running a 3900KV brushless in my JRX2 without issue.

[fredswain]

The white wheels on my Pro are B4 wheels. The rears are just bolted right on. I have RC10GT wide front axles to give me the front offset. That's all I've done. Track width is just barely under the ROAR maximum front and rear so it's perfect. I had a set of the Duratrax wheels but they were narrow and too fragile. I gave them away to a friend.

All of my slipper clutch parts came in today. I am using the Losi hydradrive top shaft with all B4 slipper parts and spur gear.

My shocks use the XXX shock seals but with a twist. I threw out their o-rings and am using x-rings instead plus very liberal amounts of AE green slime. No problems at all. The springs are also the current springs (non big bore of course) and the shock collars are as well. They are very smooth.

The JRX on the left in the picture uses a Pro-SE front end, Junior 2 chassis, and JRX2 rear end and 5 link suspension. The gearbox is the original one with an early Losi friction slipper but will soon go to the Double X retrofit with a more modern slipper. The shocks are the threaded body type and the seals were built the same was as those in the Pro. It's the only way I'll build a shock anymore, regardless of whose shock it is.

[Bongo Fury]

I like the selection of parts on your project car. Nice mix.

Regards

[slow_jun]

Slipper would be nice,



I prefer AE slipper plates as they have much more surface area.did the same on my 22, and it can handle my 8.5T like a peanut.

Or Trinity lightweight plates. Use the hydra topshaft and you can do most of any slipper(AE i mean).

[fredswain]

I got the slipper installed last night. Hopefully no more stripped diff gears. I used the hydra top shaft with the B4 plates, pads, and gear with the Losi spring assembly. It looks just like that picture. I did have some issues until I saw an old manual that stated the gearbox and backplate had to be drilled out to clear the rear slipper plate. All I need to complete the Pro is a new body and gear cover.

[slow_jun]

There was a recent run of pro body c/o Brandon G,you may need to contact him, his pro body is great, with standard gear cover and wing,