JRX Pro SE runner build

[DerbyDan]

My next 2wd runner/racer project is also a JRX Pro SE (been saving up parts for a little while), so i'm following this build thread closely..... & taking notes!

Your car looks immaculate (like new) - I'm looking forward to hearing how it performs on track!

I've run my LRM gearboxed JRX2 with an 8.5 brushless set-up - which has proved reliable with the addition of a slipper & some Thorpe gears - but like you, I'm planning on going XX Retrofit for my build to be doubly sure on reliability.... & I would like to go hotter on the motor for the Pro SE. Out of interest - do you know if the standard length XX driveshafts can be used for the Pro SE that is equipped with a Retrofit transmission?

[Splat!]

Thanks for the info on the wheel setup!

I just got a set of those Jrx2 towers yesterday- SO nice! The carbon weave is really fine, never seen anything like it. The towers are easily double the thickness of the stock so should be way stiffer.

Wonder if that guy will ever make chassis plates !

[sixdub]

Out of interest - do you know if the standard length XX driveshafts can be used for the Pro SE that is equipped with a Retrofit transmission?

Sorry for the delay, I've been ill for over a week.
Getting back in the saddle now.

I'm not sure if the XX dogbones will work or not. If you have some you can measure, I can compare to my retrofit bones.

Thanks for the info on the wheel setup!

I just got a set of those Jrx2 towers yesterday- SO nice! The carbon weave is really fine, never seen anything like it. The towers are easily double the thickness of the stock so should be way stiffer.

Now you are going to make me spend more money on this "low cost" project.

[sixdub]

Got a few minutes to work on the buggy today. It's obvious I will have to deal with the front droop/shock length.



I mounted a XXX v-wing using xxx4 mounts attached to the rear tower. I screwed up the hole layout, so I'll have to replace the tower and correct the layout. A good excuse to order the carbon towers from Ebay...

[sixdub]

DerbyDan - I measured the retrofit dogbone pin to pin. Approx. 61.7mm.



Corrected the front droop with 5mm of internal limiters.



Getting the front track width correct (~250mm) with the B4 wheels was a little tricky. I started with Losi GTX front axles A-1022, but that ended up being too wide. As I don't have access to a lathe to reduce the shoulder length on the GTX axles, I decided to shorten the axles on the kingpin side and drill new kingpin holes. This allowed the width to be just under 250mm and I made up the difference with shims on each side.





The 10-32 axle nuts won't fit on the recess of the B4 wheel, so I am on the hunt for some small pattern lock nuts. In the interim, I'm using an axle spacer between the outer bearing and axle nut.



The rear width is perfect with the addition of some Custom Works .125" spacers.

[LosiXXkid]

Thanks for the info on the wheel setup!

I just got a set of those Jrx2 towers yesterday- SO nice! The carbon weave is really fine, never seen anything like it. The towers are easily double the thickness of the stock so should be way stiffer.

Wonder if that guy will ever make chassis plates !

Well, I guess there's only one way to find out............, and a quick email should do the trick!

[LosiXXkid]

Thanks for the info on the wheel setup!

I just got a set of those Jrx2 towers yesterday- SO nice! The carbon weave is really fine, never seen anything like it. The towers are easily double the thickness of the stock so should be way stiffer.

Wonder if that guy will ever make chassis plates !

Well, I guess there's only one way to find out............, and a quick email should do the trick!

Email sent.

Awaiting response.

[matt1ptkn]

I was going through my Losi parts this weekend, organizing. The XX and XX Retro Fit Transmission dogbones are the same. They even use the same part numbers (A-3081). Only difference is that one says XX dogbone and yoke while the other indicates XX retro fit trans dogbone and yoke.

Something else I noticed recently, my retro fit trans came with short drive cups. There is just enough meat for the dogbones to engage. I have several other sets of outdrives for the XX, and they are all slightly longer, maybe by 1-2mm. Anyone else ever notice this and are there different part numbers for different length XX/retro fit trans outdrives?

[sixdub]

I was going through my Losi parts this weekend, organizing. The XX and XX Retro Fit Transmission dogbones are the same.

Good to know, thanks!

Anyone else ever notice this and are there different part numbers for different length XX/retro fit trans outdrives?

Maybe you have a some xxx-nt "monster diff" outdrives A-2905/A-2906? They look very similar to the xx outdrives. Does the diff have the separate aluminum center male part or is the male part machined in one outdrive?

[matt1ptkn]

My XX retro fit transmission diff outdrives do not have the male piece attached. There is the separate aluminum piece that fits in with the diff screw assembly. I therefore assume that means that someone swapped in some XXX pieces? I roughly compared the outdrives in my XX retro trans to my XXXT outdrives, and they do look very similar, if not the same. At least I have some of the proper outdrives on hand. Which leads me to a question: I have the metal dogbone outdrives as well as the molded plastic outdrives for the plastic sliders. Which is better between metal dogbones and plastic sliders?

[sixdub]

The aluminum center (A-3072) is correct for the XX retro trans. The dogbone outdrives are A-3073.

In my opinion, dogbones are the better choice for brushless power.

[sixdub]

Woot!

[DerbyDan]

DerbyDan - I measured the retrofit dogbone pin to pin. Approx. 61.7mm.

Thanks for measuring those for for me - so it would appear that the XX dogbones are the correct/same length - that's good to know since I have a fair few of those I can use - as well as a slider set-up if I prefered

Your JRX Pro SE build is coming along very nicely - Its going to soak up the bumps great with those big bore TLR shocks fitted! BTW I found a decent amount of droop to be beneficial in maintaining stability when landing off jumps with my JRX2.... but maybe not quite the amount that you had when you first fitted your TLR shocks!

[sixdub]

Thanks for measuring those for for me - so it would appear that the XX dogbones are the correct/same length - that's good to know since I have a fair few of those I can use - as well as a slider set-up if I prefered

Your JRX Pro SE build is coming along very nicely - Its going to soak up the bumps great with those big bore TLR shocks fitted! BTW I found a decent amount of droop to be beneficial in maintaining stability when landing off jumps with my JRX2.... but maybe not quite the amount that you had when you first fitted your TLR shocks!

Glad to help!
I hope she runs well when I take her to the track in a few weeks.

I started swapping in Todd's (Vintage RC) carbon towers today. Couldn't work long, just got the old front tower removed.

[LosiXXkid]

Thanks for measuring those for for me - so it would appear that the XX dogbones are the correct/same length - that's good to know since I have a fair few of those I can use - as well as a slider set-up if I prefered

Your JRX Pro SE build is coming along very nicely - Its going to soak up the bumps great with those big bore TLR shocks fitted! BTW I found a decent amount of droop to be beneficial in maintaining stability when landing off jumps with my JRX2.... but maybe not quite the amount that you had when you first fitted your TLR shocks!

Glad to help!
I hope she runs well when I take her to the track in a few weeks.

I started swapping in Todd's (Vintage RC) carbon towers today. Couldn't work long, just got the old front tower removed.

My new JRX-2 CF towers are great!