Losi JRX2 rebuild

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JohnE
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Losi JRX2 rebuild

Post by JohnE »

Starting a new winter project, after rebuilding two early 90's RC10's and a B4 (I think I have too many cars) I decided to take on a 5 link JRX2. When I was racing I had a Losi XXX and a XXX kinwald car which I thought were good quality cars but I don't know very much about the JRX2. The only thing I remember about it from when it came out and I was 12 was that one of the fast guys at the track I was racing told me 'Its a good car, after all it comes with a graphite chassis'. Needless to say I was not sold on it back then.

I found a semi-complete car on eBay that was half converted to a truck but it was a 5 link car and looked to have the original wheels and a new body.

Here are some pictures of the car when I bought it, overall I was pretty happy with it other than it seemed like someone dipped it in motor oil and then a bucket of dirt. Also the amount of play in the rear suspension was a joke. I couldn't see how someone would drive it like it was.

It has a few bonus items like a Tiken speedo, a nice Trinity motor and a set of Trinity wheels and tires that are in pretty good shape.
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JohnE
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Re: Losi JRX2 rebuild

Post by JohnE »

Spent last weekend taking the car apart, besides it being really really dirty most of the parts were ok. The transmission and gear cover are in really good shape but the rear suspension is going to need some serious help as the lower rear links have a ridiculous amount of slop. Also the shocks seem to leak a lot but that is for another day.

Soaked all the plastic stuff in degreaser and hot water and the cleaned up pretty well, I was surprised that some of the parts are black and some are gunmetal-ish which seems like it will be a problem down the line.
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Re: Losi JRX2 rebuild

Post by JohnE »

I got a kick out of the steering, the servo was zipped tied to the chassis but after reading the instructions it seems like this was an improvement over just double sided tape. One of the steering arms was broken and replaced with a 3D printed one but was put on upsidedown so the whole steering rack was on an angle.

Also found a bunch more motor oil/dirt under the front end
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Re: Losi JRX2 rebuild

Post by knixdad »

How's the LRM Transmission case? Not everyone has been gentle with the top right screw and it gets cracked there a lot.

And the loosey-goosey suspension was great for rutted, lumpy tracks. A ton of slop would not even be noticeable.

The steering rack: It's funny but I have gotten at least 2 different JRX2s with the same exact issue.

Leaky Shocks: Which ones do you have? The bodies have a little variation and the original caps don't seal right with some. Or the old spring loaded caps rust out. Or wrong O-rings. Or missing the spacer between the 2 O-rings. Or ruined threads.
I miss brushed motors in that hazy, everything seemed better when I was a kid, kind of way.

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Re: Losi JRX2 rebuild

Post by RCveteran »

As to the different color plastics, Gil Jr. was really into plastics, if I recall a plastics engineer by education. Hence you will find several types of plastics. In one of the recent videos released by Horizon Hobbies (on you tube) interviewing Gil Sr. he made a comment how Jr. was driving him crazy with the different plastic specs he wanted for the different parts when they were in prototype stage.

They both hated the Graphite chassis and could not have been happier to leave it behind. It created production issues, I think Gil Sr. said something the affect "I hated how my business was held hostage by some guy in Florida making the chassis in the same video series.

Who was that guy is the question?

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Re: Losi JRX2 rebuild

Post by JohnE »

knixdad wrote: Mon Dec 27, 2021 8:57 pm How's the LRM Transmission case? Not everyone has been gentle with the top right screw and it gets cracked there a lot.

And the loosey-goosey suspension was great for rutted, lumpy tracks. A ton of slop would not even be noticeable.

The steering rack: It's funny but I have gotten at least 2 different JRX2s with the same exact issue.

Leaky Shocks: Which ones do you have? The bodies have a little variation and the original caps don't seal right with some. Or the old spring loaded caps rust out. Or wrong O-rings. Or missing the spacer between the 2 O-rings. Or ruined threads.
The transmission case seems pretty good, I took it apart and cleaned it all up. There are no cracks that found and the bearings are pretty good. I don't know a lot about these cars and am slowly finding out that spare parts are pretty hard to find, I replaced a bunch of stuff and most of it ended up being 3D printed.

The shocks seem original to the kit, I have the manual and the car looks like it had the original shock cartilages which have 1 o ring

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Re: Losi JRX2 rebuild

Post by JohnE »

RCveteran wrote: Mon Dec 27, 2021 9:19 pm As to the different color plastics, Gil Jr. was really into plastics, if I recall a plastics engineer by education. Hence you will find several types of plastics. In one of the recent videos released by Horizon Hobbies (on you tube) interviewing Gil Sr. he made a comment how Jr. was driving him crazy with the different plastic specs he wanted for the different parts when they were in prototype stage.

They both hated the Graphite chassis and could not have been happier to leave it behind. It created production issues, I think Gil Sr. said something the affect "I hated how my business was held hostage by some guy in Florida making the chassis in the same video series.

Who was that guy is the question?
I agree about the colors, I can't understand why some of it is dark grey and the rest is black. I tried to keep the car looking original so I had to paint a bunch of stuff after a few failed attempts to dye parts with Rit dye.

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Re: Losi JRX2 rebuild

Post by JohnE »

I planned to work on this car as a winter project but ended up getting most of it done in about a month. I didn't take a ton of picture along the way but here are some.

I rebuilt the gearbox which was in pretty good shape, the bearings and gears were all fine so I really just cleaned it and rebuilt the diff. I was surprised how free it was once i put it together, it didn't bind at all. The drives shafts are ok but there is some slop in the pins to metal axles but it would still work.

After I rebuilt the transmission I ended up finding a slipper kit for it made by Factory works (used to be A&L right), it looks pretty cool and came with a gear cover.

The first problem is that the kit uses a different style top shaft than what this car has, mine has a pressed on brass top shaft gear but the kit requires the JRX pro style gear that is seperate. I found another Factory Works (A&L) kit that has nice derlin gear. The gear fit the A&L shaft so I am good to go
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Re: Losi JRX2 rebuild

Post by JohnE »

Few pictures of the finished gearbox, it looks pretty cool with the slipper.

I put a robinson 85T spur gear on it since it looks better
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Re: Losi JRX2 rebuild

Post by JohnE »

Here is the competed front end

I put new arms on it, they are 3D printed but are new. The ones on the car were ok, the were scratched a bit but also were bent like they were sitting in the sun too long. The c hubs and steering arms are fine, just cleaned. I put new ball cups on it and a new reproduction shock tower. I also put a 3D printed jrx pro bumper since it looks nice.

The shocks leaked a ton so I bought the newer style Losi XXX shock cartridges. The shock shafts looked ok but I put them in a drill with some metal polish and they look much better. Tried to polish the shock bodies but they didn't look right so I ended up spray painting them silver which looks better than I thought. Also replaced the hose clamp spring collars with 3D printed ones.

I found a ball bearing steering rack on ebay that is 3D printed but seems ok. It has a Hitch servo and Kimborogh servo saver, had some extra RC10 servo mounts that I painted black and drilled two more holes in the chassis to mount.
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Re: Losi JRX2 rebuild

Post by JohnE »

Finished rear end

I replace all the suspension links with 3D printed ones since it was all I could find. I ordered white ones since I have been messing around with dying parts with Rit Dye which worked pretty well for me with some old wheels. Tried dying them black which didn't really go to plan, I left them in the pot for about 2 hours and they went to a dark blue/purple color. Since I wanted to make the car look as original as possible I wanted them to be that grey/gunmetal color of the drive shafts. I ended up painting them with gunmetal Tamiya acrylic paint, kind of cheating but it looks pretty close. They still have that rough surface of 3D printed parts but it's ok.

Rear suspension blocks were fine so I put in new bearings, cleaned up the rest of the parts and put everything back together. I did add some new ballcups and pivot balls for the suspension. When I was taking the rear bulkhead apart one of the wing tubes snapped in half which is a bummer but at least its under the body. Rear shock tower is new and the shocks have painted bodies and newer style cartridges like the fronts and 3D printed spring collars. Found a new set of nylon wheels nuts, I like the look of the white plastic

The gearcover came with the slipper kit so that is new.

The motor came with the car and I am not sure what wind it is, I did take it apart to clean the com and put in new brushes. It runs pretty well so I left it in the car. The spur gear is a 85T so I guessed an put in a 22T pinion
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Re: Losi JRX2 rebuild

Post by JohnE »

The car came with the stock wheels, the fronts were in pretty good shape and as a bonus the original front tires were in the box and didn't look like they were ever used. The rear rims are ok, the outer lip is pretty scratched up but at least they are not painted or cracked. I ended up buying a new set of kit rear tires which cost almost as much as a tire for my car. I did put foams in the front and rear tires
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Re: Losi JRX2 rebuild

Post by Frankentruck »

That's coming together nicely. That motor coming with the car certainly is a bonus.
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Re: Losi JRX2 rebuild

Post by JohnE »

Cut out the body and mounted it up along with the wing, I will be honest I wasn't a huge fan of this car even after it was back together but after I put the body on I changed my mind. I like how the body covers the whole rear end, it's pretty sleek.

Not sure exactly what I am going to do for paint and colors but I started playing around with some stripes
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Re: Losi JRX2 rebuild

Post by JohnE »

Overview shot showing the electronics

The car came with a Tekin Pro Tempret speedo which goes with the Trinity motor so it stays, I added extensions to the motor wires so I can direct solder them to the motor. I still use an Airtronics M8 so I found a receiver that works with my radio and happens to be semi period correct. The servo is a Hi Tech metal gear with a servo saver.

It should run in the condition it's in but i haven't run it yet.
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