Page 1 of 2
Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 10:15 am
by Lizardking
Hi, I recently started working on a vintage Losi JRX truck I got on ebay some time ago. The transmission had a clicking sound when I got it so I set it aside for when I had time to work on it. I finally cleaned up and took the tranny apart. The clicking sound was not the tranny but the motor. It was missing the brushes and the spring was clicking on the commutator when rotated
. Pretty easy fix. Since I had already taken the tranny apart I cleaned it and rebuilt the diff. Side note - how many concave washers does this thing have!?
However when putting it back together I came across a piece that has me scratching my head. It is sandwiched between the spur gear assembly and the slipper clutch. This thing adds 19g of rotating mass to the drivetrain and I see no discernible use other than decoupling the drivetrain from the motor (which is what the slipper clutch is for). When turned it has a viscous feel to it. It says Losi Patent Pending on the side.
Aside from that mystery part I am still deciding if I want to rebuild it back to a buggy or keep the truck format. I really dislike the crude body posts for the truck version. I don't know if they were home made or early mods. The car does not have the 5 link suspension system but does have the holes for it. The rear A arms were replaced for RPM ones. Maybe I can put a buggy body and keep the truck tires for a vintage truggy build.
I’d love to know your thoughts. Thanks!
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 10:21 am
by Lizardking
Additional photo of the chassis for good measure. It had a cirrus CS-248 servo on it. Not sure if the holes were drilled or were there from factory.
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 10:22 am
by RC10resto
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 10:44 am
by Lizardking
Thank you! This hydradrive is working and as far as I can tell its not leaking. Not opening it up now! Also not putting a powerful motor on it, don’t want to destroy it. Amazing Losi basically invented an RC torque converter back in the day.
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 11:02 am
by Dangeruss
Lizardking wrote: ↑Sun Aug 04, 2024 10:44 am
Amazing Losi basically invented an RC torque converter back in the day.
Losi basically repurposed a rotary damper back in the day. Hydra-Drives are awesome... but they work nothing like a torque converter.
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 11:52 am
by Lizardking
It is a fluid coupling. In principle they work the same no?
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 1:11 pm
by Lizardking
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 2:12 pm
by Dangeruss
Cool you found the instructions. MarkyDents posted 'em here too:
https://www.rc10talk.com/viewtopic.php?t=46326
Regarding their operation, they're both fluid couplings but they operate on opposing principals...
The Hyrdra-Drive's straight vaned impeller and housing use fluid viscosity to dampen the energy between the motor and transmission.
Increasing or decreasing the fluid weight is analogous to tightening or loosening a standard slipper clutch.
A torque converter uses curved vein impellers and a stator with angled blades to create
torque by
converting fluid flow into mechanical force.
It does this by pumping fluid across the 35-degree blades of the stator, comparable to spraying water at a fan blade.
...the Hydra-Drive is designed to absorb torque while a torque converter is design to produce torque.
Re: Help Identifying Losi JRX2 part
Posted: Sun Aug 04, 2024 7:07 pm
by RogueIV
Lizardking wrote: ↑Sun Aug 04, 2024 10:15 am
Hi, I recently started working on a vintage Losi JRX truck I got on ebay some time ago. The transmission had a clicking sound when I got it so I set it aside for when I had time to work on it. I finally cleaned up and took the tranny apart. The clicking sound was not the tranny but the motor. It was missing the brushes and the spring was clicking on the commutator when rotated
. Pretty easy fix. Since I had already taken the tranny apart I cleaned it and rebuilt the diff. Side note - how many concave washers does this thing have!?
However when putting it back together I came across a piece that has me scratching my head. It is sandwiched between the spur gear assembly and the slipper clutch. This thing adds 19g of rotating mass to the drivetrain and I see no discernible use other than decoupling the drivetrain from the motor (which is what the slipper clutch is for). When turned it has a viscous feel to it. It says Losi Patent Pending on the side.
Aside from that mystery part I am still deciding if I want to rebuild it back to a buggy or keep the truck format. I really dislike the crude body posts for the truck version. I don't know if they were home made or early mods. The car does not have the 5 link suspension system but does have the holes for it. The rear A arms were replaced for RPM ones. Maybe I can put a buggy body and keep the truck tires for a vintage truggy build.
I’d love to know your thoughts. Thanks!
What you have there is a JRX-2 with a JG mfg Monster truck conversion mount kit.
- 1_7658f3563254227682d078595b95d227.jpg (34.94 KiB) Viewed 1029 times
- 1_7658f3563254227682d078595b95d227.jpg (34.94 KiB) Viewed 1029 times
JRX-T Wheels, RPM JRXT rear arms, later model JRX bellcranks, and a incredibly nice condition slipper/Hydra Drive upgrade.
Re: Help Identifying Losi JRX2 part
Posted: Mon Aug 05, 2024 9:05 am
by Dangeruss
RogueIV wrote: ↑Sun Aug 04, 2024 7:07 pm
What you have there is a JRX-2 with a JG mfg Monster truck conversion mount kit.
JRX-T Wheels, RPM JRXT rear arms, later model JRX bellcranks, and a incredibly nice condition slipper/Hydra Drive upgrade.
Isn't it though? An early Pat. Pend. one with the white fill & bleed screws too, plus a sweet Losi fluorescent motor mount... The whole truck is actually pretty cool.
My thoughts... it needs a set of RPM front arms
I love a good truck conversion but you're talking a pair of JG body mounts and JRX-T wheels being the difference between it being a truck or a buggy so... why not do both?... pull the mounts and wheels and run it as a buggy then when the mood strikes, bolt on the mounts/wheels/ period body and go truck racing.
Re: Help Identifying Losi JRX2 part
Posted: Mon Aug 05, 2024 10:48 am
by Lizardking
Thanks everyone for the responses!
The truck had a JG sticker on the graphite plate which i removed while cleaning, so it makes sense it was a JG kit buggy to truck conversion and not hand made by the previous owner.
The truck body it came with was waaaaay beyond repair, full of cracks and barely held together with aluminum tape … so I tossed it. In keeping with the spirit of restoring the unit to its age-accurate state, I went ahead and ordered a JRXT Junior T truck body from Sabula Tech as well as the slipper gear cover. It already has the truck wheels which are in great shape and I prefer the stadium truck look. Going to a buggy would require not just the body, but sourcing the buggy wheels and maybe even the 5 link suspension If I’m feeling like a completionist. I can always do that in the future, or simply wait for buggy with the 5link to show up on ebay. Will post new info/pictures as I progress.
Re: Help Identifying Losi JRX2 part
Posted: Mon Aug 05, 2024 12:07 pm
by Lizardking
RogueIV wrote: ↑Sun Aug 04, 2024 7:07 pm
Lizardking wrote: ↑Sun Aug 04, 2024 10:15 am
Hi, I recently started working on a vintage Losi JRX truck I got on ebay some time ago. The transmission had a clicking sound when I got it so I set it aside for when I had time to work on it. I finally cleaned up and took the tranny apart. The clicking sound was not the tranny but the motor. It was missing the brushes and the spring was clicking on the commutator when rotated
. Pretty easy fix. Since I had already taken the tranny apart I cleaned it and rebuilt the diff. Side note - how many concave washers does this thing have!?
However when putting it back together I came across a piece that has me scratching my head. It is sandwiched between the spur gear assembly and the slipper clutch. This thing adds 19g of rotating mass to the drivetrain and I see no discernible use other than decoupling the drivetrain from the motor (which is what the slipper clutch is for). When turned it has a viscous feel to it. It says Losi Patent Pending on the side.
Aside from that mystery part I am still deciding if I want to rebuild it back to a buggy or keep the truck format. I really dislike the crude body posts for the truck version. I don't know if they were home made or early mods. The car does not have the 5 link suspension system but does have the holes for it. The rear A arms were replaced for RPM ones. Maybe I can put a buggy body and keep the truck tires for a vintage truggy build.
I’d love to know your thoughts. Thanks!
What you have there is a JRX-2 with a JG mfg Monster truck conversion mount kit.
1_7658f3563254227682d078595b95d227.jpg
JRX-T Wheels, RPM JRXT rear arms, later model JRX bellcranks, and a incredibly nice condition slipper/Hydra Drive upgrade.
WOW these JG conversion kits are going for insane prices
https://www.ebay.com/itm/233266322528?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=zUVcHIL1Sqa&sssrc=4429486&ssuid=ZcaOjJwxR96&var=&widget_ver=artemis&media=COPY
Re: Help Identifying Losi JRX2 part
Posted: Mon Aug 05, 2024 12:17 pm
by jcwrks
Kit appears to be incomplete based on pics, and the price is rather steep.
Re: Help Identifying Losi JRX2 part
Posted: Mon Aug 05, 2024 1:28 pm
by Lizardking
Truck came with 3 sets of these batteries. Need to clean them and see if they hold a charge after all of these years.
Re: Help Identifying Losi JRX2 part
Posted: Tue Aug 06, 2024 6:10 pm
by Lizardking
Printing the body mounts from a 3d file I found online. Will show results.
