JRX-2 cheater + JRX Pro

[K Rob]

Having had a JRX-2 back in the day and having a few other vintage cars I decided to get one. Was a bit of a mess but tidied up okay.
I then decided I wanted to drive it but I have nightmares thinking back to the problems I had with the original gearbox (seemed to be forever eating diff thrust races).
So thought I would experiment a bit and found a XX retro fit box which I knew would be reliable, unfortunately it's not a straight fit due to the diff sitting so low. Didn't want to cut the JRX chassis so just made a up a 2mm plate to raise everything else up.
Worked a treat and had the added bonus of making the battery slot on the bulkhead higher to take Lipos.

And it's now a racer

Still suffers power on understeer but added plenty of weight up front and gone to shorty which helps. Cracking fun
Had to fit a rather ugly bulkhead brace as I bust the original and they're not cheap

Also got a JRX Pro sitting on the shelf with hydra drive (yes I know this came along later but it just looks so good!!)

[matt1ptkn]

I always thought that the retro fit XX transmission was a direct bolt on fit. That is not the case? What didn't fit?

P.S. Buggies look great!

[LosiXXkid]

I always thought that the retro fit XX transmission was a direct bolt on fit. That is not the case? What didn't fit?

P.S. Buggies look great!

It is a direct fit on the molded chassis such as the Jr.2 but not on the the JRX2's flat graphite chassis. Here's the recess in the transmission section of the molded chassis.....

Losi Jr.2 045c.jpg (45.29 KiB) Viewed 3742 times

Losi Jr.2 045c.jpg (45.29 KiB) Viewed 3742 times

[matt1ptkn]

Gotcha. I didn't remember that the molded chassis had the recess under the transmission. Its not often that I remove a bullet proof LRM from its chassis.

[LosiXXkid]

Having had a JRX-2 back in the day and having a few other vintage cars I decided to get one. Was a bit of a mess but tidied up okay.
I then decided I wanted to drive it but I have nightmares thinking back to the problems I had with the original gearbox (seemed to be forever eating diff thrust races).
So thought I would experiment a bit and found a XX retro fit box which I knew would be reliable, unfortunately it's not a straight fit due to the diff sitting so low. Didn't want to cut the JRX chassis so just made a up a 2mm plate to raise everything else up.
Worked a treat and had the added bonus of making the battery slot on the bulkhead higher to take Lipos.

And it's now a racer

Still suffers power on understeer but added plenty of weight up front and gone to shorty which helps. Cracking fun
Had to fit a rather ugly bulkhead brace as I bust the original and they're not cheap

Also got a JRX Pro sitting on the shelf with hydra drive (yes I know this came along later but it just looks so good!!)

Just in case you haven't seen this thread....

http://www.rc10talk.com/viewtopic.php?f=27&t=24503

[K Rob]

I hadn't seen that one - cheers. Will have a read.
Raced against DerbyDan at the recent Iconic RC Revival - but neither of us were using JRX-2's.

[RCveteran]

I run a shorty Lipo pack in my racer JRXT pushed way forward to middle almost up to steering servo, helps keep car much more neutral and counter the understeer you are finding. I am hardly a top driver but it is the most balanced JRX I've come up with yet.

http://www.rc10talk.com/viewtopic.php?f=27&t=40033

[K Rob]

Looks awesome! Interesting you've looked at moving the cells around. Mine was definitely better with the shorty forward compared to a standard length pack.
A friend has just made an alloy chassis for his JRX2 and has offered to make one with a cut out for the gearbox - I'm seriously considering it! Could also get more kick up at the front to bring it in line with the Pro chassis.

[DerbyDan]

I hadn't seen that one - cheers. Will have a read.
Raced against DerbyDan at the recent Iconic RC Revival - but neither of us were using JRX-2's.

Hi Kieth - I thought I recognised your pink & blue paint scheme!

Your JRX2 looks great.... I'm sure you'll enjoy running the 5-link car.... I think mine is my favourite of all the vintage buggies that I have run so far, they seem so easy & dependable to drive + I love the way the original car looks It's quite apt that you now have a JRX2 since (as I'm sure you know) CML were the original UK distributers back when they were first released.

Your fitment of a XX retrofit gearbox is probably a wise move as it pretty much future-proofs your car, since the XX box will certainly handle any wind motor you decide to throw at it. My LRM gearboxed car is upgraded with the Thorpe nylon layshaft & alloy diff gears - along with a twin plate slipper (XXKW/XXX) which I think 'should' now prove more durable (I did a year's worth of racing with just the slipper on std gears before the diff gear gave up). But it's always in the back of my mind that at some point one of the other gears will eventually strip. The hottest motor I've so far run in the car is an 8.5bl (Orion Vortex).

PS; what meetings are you likely to do with the 'new' JRX2?

[RCveteran]

Derby, are you running the dual ball bearing LRM Differential? I've never had one give up yet?

[DerbyDan]

Derby, are you running the dual ball bearing LRM Differential? I've never had one give up yet?

The diff gear that I stripped was one with the centre bearing - the rest of the gearbox was standard LRM (aside from the slipper assembly & top shaft). The gear finally went after a whole year of regular running with an 8.5bl motor (I don't know what motors you are using) & on mostly high grip tracks.... I was actually surprised that it lasted that long since I knew the diff gear was a known weak part - I even received at one point a box of old JRX2 parts from a friend, which included a whole bunch of pre-stripped diff gears, all left over from the brushed motor days.

I've only done the one meeting with the JRX2 with the replacement Thorpe upgrade diff & layshaft gears (the 1st Revival meeting in 2014, where it won the 2wd race of champions race) so perhaps not a true test of long-term durability?

[RCveteran]

That explains it, mine never see lower than 13.5bl motor. When I get to the track the one I go to is too small for more. And I can barely drive a 13.5 as it is.