Losi JRXS-Nice Features
I have had some time to study the JRXS design features in depth now. I have not driven it yet. I still have some things to do to it and the body.
1 The 4-40 diff nut is a large size and seats in hard plastic. This is a great improvement over the tiny diff nut seated in weak plastic that Losi has used previously on its kit. The plastic T-nut that holds the opposite side outdrive on has a good long bearing area on the threads. It should hold up. It is not nearly as higly stressed as the diff nut which has to be made quite tight to prevent the ball diff from slipping.
2- The outdrive cups are huge, full circle rather than slotted, and beefy. Anyone that uses a one-way or locked diff will appreciate this. The two cups can be purchased together without a lot of other hardware. The fact that they are not slotted probably tripples their strength.
3- The Diff Tubes are large diameter, increasing torsional stiffness. The front and rear pulleys are on opposite sides. Both of these facts should reduce toque steer or the car pulling to one side when you hit the throttle trigger hard. (Give me a torque steer report if you have noticed or not noticed this)
4-The Spur gear will be so easy to change when things get broken in well. Only one C-clip holds it. In stock a spur gear change might be neccesary to fine tune the gear ratio. If you run outside you might want the newly released 48 pitch gears or a handfull of the fine pitch spurs. The little rocks won't so easily destroy the bigger pitch. Having the gears exposed is a detriment in my book though. Nothing beats the XXXS on loose outdoor tracks for the sealed drivetrain and great top speed in stock. The XXXS is not so good in stock, though, on a high grip track.
5-Chassis Stiffness is easily tunable in 3 stages by removing supporting posts. I was enlightened by racers of this thread.
6-Center pulley allows for a center one-way and front one way. Hard to do this on a TC4 or XXXS.
7-The stiffness and strength of a part increases markedly the shorter it is by several powers. I'll look up the exact figure later. These short arms and short drive axles should be much stronger than the longer parts on other chassis especially those on the TC4. You might instead break the Caster blocks, though. (please give me an A-arm breakage report.)
8-When a male threaded fastener breaks it usually breaks at the area right between end of the threads and the smooth shaft of the bolt (or ball stud). On the JRXS, having the ball ends on the shocktowers as female nuts that are fastened on by socket head cap screws, removes this weak junction to a safer place, by the head of the bolt. The head is not stressed by crashes in this application. A standard ball stud here is more likely to break off. I have not had this problem too much on a touring car, but it sure is a problem on the inner rear camber link ballstud on the truck.
9-The pinned chassis plates. This should prevent the chassis from staying twisted after a crash. This really screws up the handling.
10- The starter subject of this thread. The JRXS has true constant velocity drives for the front axles. Lightweight MIP drive axles for the rear.
Don't like
the front mounted motor. I have already had to add a ton of ballast to the back. The new rear motor kit will probably be out at some great cost no doubt.
Do not like the open gears outdoors.
Chassis is not wide enough to protect my GTB controller
Don't care for ball pivots on any heavily loaded suspension point in a 1/10 scale RC vehicle. The inner A-frame pivot mounts on the Losi are nice in that you can adjust antisquat and kickup without a new part, but they will probably develop slop even though they don't really need to move at all. Ball pivots on the uprights that support the axle ends all have increased friction over pins. Fortunately the Losi JRXS does not have these. (Give me a report on wear of the pivot ball area if you have one, it may not be a problem at all.)
Now whats that third body post in the front good for if you don't perforate the body for it. Roll overs are the least of our concerns.
The front airdam on the Skoda II body which I ran on the TC3 split right in the middle on the first impact. It does not really need to be so angled or maybe it was just too cold.
More to come when I run the car.
Last edited by John Stranahan; 12-22-2005 at 06:31 PM.