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Old 01-05-2010, 06:02 PM   #256
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Default JRXS Pro

Hi john how are you? I used to own one of these cars not long ago but decided to get rid of it. IMO this ride is the worst American made TC on the market. I rank it dead last (with the TC3 being #1, TC4 #2, XXX-S #3, street weapon #4 , never ran the TYPE-R but seen it perform). Mind you this is not anything written in stone...just personal experience.

When i say worst i'm accually saying that this car is hard to set-up on different venues...mainly the not-so-"ideal" lots i been racing on these last couple of months. Tell me...why is this car so horrible everywhere but on carpet?!? That's where it seems at home! I got so fed up with this car outdoors that i put it on the chopping block and brought the old Pro3 out from HPI! Why? i have not idea...maybe because of the flex/grip this car has for low bite asphault. The XS-Pro is too stiff. plus it's got those teeny tiny carbon a-arms. why couldn't losi make these things out of something softer? THAT would have helped a little!

Reading thru this colum i learned a few tricks here and there and decided to try some things on a different path. When i recieved the car (used..pre-assembled w/ Todd Hodge.com stickers on the chassis. maybe it was HIS old car?) i could tell right away it was a carpet car. maybe even mod (128 64p spur gear). it sported 6 degree castor blocks with the .035 spacer on the rear block for "kickdown", stock pistons, 25lb springs all round, 1 degree O/S hubs w/ 0 degree rear pin support & 1 degree front, short "regular" arms in the rear..BK arms up front, lowest roll centre all around. think that's it fars i remember.

i threw different asphalt set-ups at it from the Numan to some custom stuff i lucked up and found online. nothing! i felt like the top plates were too thick for outdoors so i plane-sanded them both down to 2 mm. stock they were nearly three (2.87 to 2.44mm VERY inconsistant). this helped but still off. next i tried the flex a-arm trick by dremeling material away from the rear a-arms(mostly the center). this helped. but it still spun out easily(with 2 degree pivot pin and 1 degree hub). after 4 weeks of exhausting practice and trail and error i finally decided to let it go...

when i set the car up to sell as a RTR, i put some 2000 mah ni-cd batteries with it as starters then test drove it one final time to make sure the potential buyer knows it works. I COULD NOT BELEIVE HOW DAILED THIS CAR WAS!!! Call me crazy but the car was on rails!!! maybe it was the extra wieght down the center that did it. who knows! i now have a car i know i can race with!

but alas i have all li-po's now and i'm not going back to nickels so i have to let the car go. at first glance i thought the car was thaBOMB!!! but after getting it home and trying to tune it i find it more of a headache than ANY tourer i've ever owned! Not trying to bash or anything but losi should have recruited more on-road support for this car rather than "convert" a team of offroaders. not to take away anybody's talent from the dirt but let's face it...... Francis was no Baker, Hodge was no Leimeux(sp), and Kinwald was no Hara. If losi would have had the necessary talent and support for on-road as they did for offroad, this car would have made the A-final at EVERY Ifmar world event. much like their dirt vehicles.

too repeat what i said earlier this is not a flame... just saying it's a shame to see such a well designed & thoughtout car fade away to nothing. but then again, was there TOO much thought put into it? or (over the long run) not enough?
I'm pete ....thanx for your time.
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Old 01-06-2010, 10:07 PM   #257
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Quite a post.

On the JRXS
I think if you put some 3.5 2s LiPo power in your top choices that the order might change. We could not get the TC3 "drivable" really on our track with this much power on board.
Torque steer was the culprit. Interestingly my TC5 with a bent motor plate throwing that armature inertia out of alignment was similarly difficult until the motor plate was changed. We abandoned the TC3 as well as the all aluminum TC3 with carbon chassis that is now available. That said, the TC3 is a very good performer on indoor carpet with stock motors due to the low friction driveline.

Note motor power has about doubled to 1 Horse Power now since the low turn brushless.

As far as the JRXS it has some nice qualities. I found no noticeable torque steer. this was aided by beefy torque tubes and equal length outdrives left and right in spite of the center battery. Of Course it also had the nice tru constant velocity LCD front driveshafts.

Grip on asphalt is improved by increasing chassis flex. I did this in a series of mods described in this thread. One was the increased motor cutout described n the previous page. Top and Bottom. One was beveling of the chassis on the bottom. This improved roll clearance and added flex. The fact that I had to do this with 6 mm ride height meant I was developing some cornering forces big enough to drag the edges of the chassis.

You can first remove the four little standoffs to the battery top plate. Then you can go on a carving mission on the upper plates. U shaped plates with the sides of the U parallel to the long axis of the car seem to have the best flex. I am not sure if I did this to the JRXS, but would If I still had the car. I did do the mod to the upper motor plate.
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Last edited by John Stranahan; 01-06-2010 at 10:30 PM.
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Old 01-07-2010, 10:03 PM   #258
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thanks for posting so quickly. yes the standoffs are removed and i cut the little "ears" off that they mount to. ya i forgot about the torq-steer the TC3 had...HORRIBLE!!! but most of the time, i was faster with a good ole 12 double (REEDY Sonic/TC1) than those crazy 8's and 7 singles. well....there was that custom 10 single flatwire that i had wrapped on a tri-rotor blank

the losi DOES shoot strait as an arrow even on hard launches! thats what i like the most! the car reacts very well too. puts my 38 year old reflexes to the test! my biggest gripe is getting on the throttle @ corner exit. she just loves to spin out. you say you were generating so much grip that you were beveling the chassis?!? Whew! wish our track conditions had that much bite! IMO this car doesn't like long flowing tracks. (altho it can be tuned to perform on them but the window "seems" very small). maybe it's those short arms not able to cope with the G's of long rolling arcs of big turns.

i'd like to try the other mods you posted above and see how it makes the car feel. the hobbyshop has not sold it yet (granted i live in "offroad" country,NC) so i'm gona scoop her up later today and get back too work. until it warms up in these parts, my tire of choice is gona be take-off's. i got some older 27's but with all the cold i think some 22's should go in the box too. the RP 30's and speedmind 32's may not be "cold" enuff.
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Old 01-08-2010, 09:28 AM   #259
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Quote:
Originally Posted by nomaak View Post
my biggest gripe is getting on the throttle @ corner exit. she just loves to spin out. you say you were generating so much grip that you were beveling the chassis?!? Whew! wish our track conditions had that much bite! IMO this car doesn't like long flowing tracks. (altho it can be tuned to perform on them but the window "seems" very small). maybe it's those short arms not able to cope with the G's of long rolling arcs of big turns.

i got some older 27's but with all the cold i think some 22's should go in the box too. the RP 30's and speedmind 32's may not be "cold" enuff.
Corner Exit oversteer
is the biggest problem that guys have on our track. With a ball front diff the cure is as follows: Set rear toe to 2.5 degrees. 0 rear antisquat. Now gradually stiffen the front springs (or lighten the rear) until the problem is resolved. You are adding a little understeer with each change until the oversteer/understeer is balanced. When You have achieved it the car will tend to slide sideways when pushed too hard int he turn. It is much easier to drive this way.
Once you have this set, now add the locked front diff. If you need additional tuning try the normal tuning and also try the reverse. Depending how you use power in the corner the car may respond better to reverse tuning. This is the result of huge torque steer on the outside front when cornering with a locked diff. More load on this tire will sometimes increase your steering.
More grip is developed with lighter overall springs. I am running 14 lb springs on the Losi XXX-S. Somewhere in this range or up to 17 lbs is probably enough on slippery asphalt. The light springs caused the chassis to rub on the edges. I then took a Dremmel and beveled the edge to a rounded knife edge over a 1/2 inch width on the bottom. There is a pic back in the thread.
It still won't grip like a XXX-S on a very slippery track, in the corners, but it is much closer with light springs 6mm ride height, low roll centers and beveled chassis.

That flat wire, I believe, was a development after I measured and discussed wire induction of various wraps on the trinity site, and then postulated square wire would have the edge.
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Old 01-09-2010, 05:52 PM   #260
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Hey john great news!! (thanks for the posts by the way). There's a carpet track here in NC (Rosewood RC Raceway) that's gonna have a carpet on-road race for some of the locals...well....anyone close enuff to run going to the snowbirds this year. normally they run oval only in the winter months so i feel that this is huge! This is my one chance to try the losi out in it's natural habitat. Sure we can only run rubber tyres but at least i can get this car on the rug.

from what i understand, med-low bite asphalt set-ups are really close to what most use on carpet. is this true? i'd like to find something comfortable for 17.5/ball diff up front. doesn't have to be perfect. needs to be something that will work with BK arms in the front only. i'll be using take-off27's for practice but will break out the much more 32's for racing. i wont be using sway bars so i guess traction sauce is gona play a big roll in final grip. i'll be stripping the chassis after church tomorrow. got brand new cutting disks ready to slot..cut...chop...mutallate....and "tweak" this beast till she can flex and twist better than Christina Agullera in a strip club!
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Old 01-17-2010, 03:43 PM   #261
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Old 01-18-2010, 04:34 AM   #262
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hey john congrats on the win!! u got that xxxs working like a dream! i was curious though......have you ever thought about trying the Pro out again or are you completely done with it. have you ever won a race with it? i didnt go to the carpet race this weekend. i didnt wont to change my set-up from the asphalt. the car is feeling a LOT better now. it dosent spin out as easily any more. (and thats with the offset hubs in place. i'm thinking the normal rear hubs will lock this puppy in!) the body may have something to do with it too. (went from HPI mondeo to PF Stratus All Purpose..wing rearward)

as the temps try to improve here, i'm getting closer to giving you a race report. so far i've removed the gtx speedo and re-installed the larger novak SS Plus. this unit is twice as heavy but i need the extra weight and brushless capability. final practice and "race" practice are still a few weeks away but i'll getting closer with every tweak little tweak
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Old 01-18-2010, 06:44 AM   #263
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Thanks.
I don't have the JRXS any more. It was in the top 3 usually.

I think you are right about the rear hubs. Put on the standard hubs and keep the offset hubs for a tuning aid on carpet. Look forward to a race report.
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Old 01-24-2010, 12:51 PM   #264
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no race report today due to rain.
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