RC10Talk - The Net's Largest Vintage R/C Community

Hello,

This is my first post here. I thought you might like to see the my JRX2 build. This car was definitely raced in it's past but was found second hand by my brother and I in the early 90's. It ended up in the loft until a couple of weeks ago when I came across it and decided to rebuild it. This is how I found it. I also had a box of spares which has helped. The car itself has few nice upgrades since before my time. RPM front arms and an RPM front bulkhead with more castor. The shock absorbers are Schumacher I think and never fit properly. The shocks are in great condition so I will be keeping them and mounting them properly.


I decided I wanted to build the car mid motor and keep the 5 link. I rotated the gearbox 180 degrees and began to work out how to make it work. I needed to allow for some inboard toe with the inner hinge pins. I ended up cutting what was the rear hinge pin block in half and removed enough material to narrow it sufficiently to angle the pins in. I then used a piece of aluminium to set the width and used the original screw holes to secure it. The second set of holes that line up with the gearbox mounting screws were elongated slightly so everything can screw together. The picture will make more sense.


The lower rear shock mounting was a bit tricky. I used the original shock tower spacer I had to move the tower back slightly. I found some second hand Schumacher shock standoffs which worked perfectly on the top. I used the original Losi standoff/ball joint on the lower shock and mounted to an RPM rear arm. This is the best solution I could think of and seems to work pretty well. The back end of this car always had a lot of play. I wanted to reduce this as much as possible so I decided to replace the forward rear arms and the 5 link arms with ball joints and titanium turnbuckles. I could only get M3 ball joints so these had to be drilled out to 1/8". This has worked perfectly. I now have a totally adjustable rear end with virtually no play what so ever. And it looks cool.

For wheels I have chosen to go with Associated B4. The fronts are fitted with the standard spacer from the rear axle and narrow nyloc wheel nuts. This brings the width to a maximum of 247mm. The rear uses the same spacers plus a set of 7mm hex adapters. The maximum rear width is 246mm with the setup. I've added a front bumper from eBay and replaced all of the ball joints with new balls and new RPM cups. I am waiting for one last pair of turnbuckles for the rear castor links to arrive. I have ordered a Power Clutch from A&L and a JRX-Pro body set. Both of which are coming from the states.

Nice work there. If you plan to leave the motor plate that way, you may want to use a reverse rotation motor. Keep up the good work!

I like it.

matt1ptkn wrote:Nice work there. If you plan to leave the motor plate that way, you may want to use a reverse rotation motor. Keep up the good work!

It's a small job to switch the moterplate over... as I told him on oople
But making a new one instead of cutting the old plate would make sense: that way you can add some material and have it line up with the chassis on the bottom. And sell the old one for funds

Any sensorless brushless will run without problem in reverse direction too, unless it's got some physical timing built-in but that should be clear from its specs

Yes, I will look into swapping the motor plate to the other side when the slipper arrives. Hopefully soon.

Loving how this is coming together Daniel - I've often wondered how the JRX2 would work as a mid-motor.... or if 5-linking a regular modern mid motor chassis would improve rear end traction but maintain good power-on steering... i.e best of both worlds?

Looking forward to seeing how this progresses - I trust you will eventually race this car against modern buggies?

DerbyDan wrote:Loving how this is coming together Daniel - I've often wondered how the JRX2 would work as a mid-motor.... or if 5-linking a regular modern mid motor chassis would improve rear end traction but maintain good power-on steering... i.e best of both worlds?

Looking forward to seeing how this progresses - I trust you will eventually race this car against modern buggies?

Yes I would like to race it but have no experience as of yet. Likewise I would be happy for someone like yourself to give it a run.

Cool idea and some nice re-engineering there. I dig a modded vintage mid-motored RWD car, they were few and far between back in the day. I modded my Optima Mid 'OptiMutt' chassis to be a mid-motored RWD car, too.

It was considered more as an oval racing mod (conversion kits for the rc10 appeared quite early already).
Yet other 2wd cars had mid motor kinda per accident as rear motor was considered the best solution for 2wd offroad buggies.
For example the raider. But the raider is basically a redesigned rocky and that leads to most other mid motor designs: 2wd as a cheap alternative for the 4 wd version already using mid motor.

MRP must be the first to have offered a kit wih both rear and mid motor options in the box. Unfortunately the quality of that car was far below it's competitors

I built a mod motor jr for oval racing years ago, but mine used the H-arms vs the 5 link. The trans conversion is very easy to do and I used the stock motor plate (modified). I know I still have the plate here, but I can't find it. But this is what I did:
By doing this, you're still able to attach the motor plate to the chassis for a little bit more stability...without having to fabricate a new piece.

Thanks for the input. The power clutch arrived from A&L. This morning I installed the clutch and swapped the motor plate to the other side. All fairly straight forward.

Wow, that is turning out really well! It's threads like this one that make this site so great.

What are you going to do for a body?

Thanks. I have a JRX-Pro body set coming from the USA.

Well I was late to the party on this thread. I sure I have a cut motor mount here somewhere you could of had. DOH!!

Car looks good, You've taken your time and thought things out which is refreshing. Curious to see what you do with body.
I bought a Mid motor JRX from ebay years ago and it had a DAHM's pathfinder body which looked trick

Very nice work, and you have inspired me. I have one JRX2 that has some kind of custom longer chassis that is specifically, and only, drilled for an RPM battery strap. I have been letting this car sit (hang on the wall that is) for a while, but I think I might work on my own mid motor conversion inspired by you. I too have often thought of replacing the plastic 5-link with turnbuckles and ball links (or at least threaded rod).

Excellent work so far, I really like it.

Can you give just a bit more detail on exactly what is required to mount up the B4 wheels? That is an interesting mod. Also, Associated has B4-style rears now that are specifically set up for the "Classic" Rc10 rere, which use a cross pin and a 3/16 axle. I have a set I am about to dye for another project, perhaps I'll see if they directly fit the JRX2.

Looking forward to more progress.