Modern Runner Issues...need some suggestions

[pmathews924]

After a few months building it I've finally had the chance to run a couple batteries through the old Jrx2, but I'm having some issues and need suggestions...

1. Steering...it doesn't have enough to make it though the tight sections of the course. I'm running the JrxPro front tower, upper mounts are on the inside hole and lower mounts are on the outside of the a-arm. I have it set with about 1 degree of negative camber and zero toe, but it's not getting the turning radius I need to get through the technical sections of the track. Any ideas?

2. Front wheels nuts...I'm using the stock white nylon buts, but with 2.2" prolines in the front and a washer to give them enough spacing, I can't screw the nut all the way down without locking up the wheel. So...I have to back it off a little so the wheel spins freely. Throughout the course of running the track, if I hit something the nut loosens up and I've had my wheel fly off a couple times. Is there a smaller/thinner option to keep the front wheels on? Do they make a flat nylon lock nut that will fit? On my buddy's B3 he's able to crank a lock nut all the way down and it doesn't bind up the front wheel at all...still spins free.

3. Shocks...my rear geometry is good, or was good until one of my shocks stopped rebounding all the way...easy fix, I'll just rebuild the shock. My front geometry is bad however. With the tall Pro tower and the longer shocks, it has too much droop...when the chassis is flat on the ground, I can move the front wheel up about a half inch off the ground when I really shouldn't be able to move it at all. I have a proSE shock tower, but I would need shorter shocks to make it work. I'm thinking about just getting modern shocks that will fit...any suggestions on a modern shock/spring set that will fit the proSE front shock tower?

4. Rear tower...I was running the Pro tower and the top corner of one side broke off, so my only mounting option is the lower inside hole. I'm okay with running the shocks super flat, but I need to get a replacement tower soon. Which rear tower will give me the most steering and durability? Should I get a proSE tower, or find another Pro tower?

FYI...for those of you following my other posts about the tranny, the LRM is holding up great through about 3 hours of track time, and the traxxas bandit sliders are also working really well. No issues whatsoever.

If you want to see pics of the way the car is set up let me know and I'll get some posted...

[JK Racing]

When I ran the Pro/Long front tower, I used the truck front shock bodies and the buggy front shock shafts. Seemed to be a perfect set up, not so much droop and the travel was fine.

Post pictures and your set up, one of the biggest items is post up what tires you are using, and what tires are the "fast locals" using. Tires make a huge difference as well.

For the front wheels, I need to find a link to the wheel nuts I have, basically a 12 point 1/4" nut with a 10-32 thread inside No issues with binding.

[aip47-2008]

http://www.ebay.com/itm/Losi-New-10-32-Low-Profile-Alum-Nuts-LOSA6304-/181240849823?pt=Radio_Control_Parts_Accessories&hash=item2a32cbe59f

[JK Racing]

they look like this:



still havent found the link to the item though...

[DerbyDan]

Some pictures of your car as you are running it would be very helpfull I guess? Also what type of surface/track are you running on & are your tyres suitable.... no amount of suspension tuning can make up for poor tyre choice.

With regards to your steering - is it a case of insufficient lock - or is the front end understeering/pushing-on... which is quite a feature of a 5-link JRX2 to be honest, especially on-power. To combat the power-on understeer i've added a fair bit of weight onto the front end - there's approx 20/5g stuffed inside the front bulkhead with at least another 30g stuck on top!

I would suggest that your nylon wheel nuts are probably well used & not gripping the thread like they once did, but yes they do bind up the bearings if they are tightened right up which means you have to back them off until the bearing is allowed to spin freely - there is a small lip on the inner face which should grip the inner part of the bearing, but this gets crushed if the nut is over tightened. I've got different metric axles on my car that work with Yokomo wheel adaptors but the wheels are secured with regular aluminium nyloc nuts.

With regard to the long front shock tower - the effect that you describe is what the long towers were designed for - greater compression & a little more droop - it allows a wheel to ride over an obsticle (e.g track marking) without upsetting the attitude of the chassis... even if the obsticle in question is greater than the ride height between chassis & the ground. Its interesting that these long front towers were rather a passing fad - and even now cars have more reasonable length front shocks.

When I put together my JRX2 runner - I wanted to experience the car in its more original form - hence 5-link, short shock towers etc - all the geometry is standard JRX2, & I must admit I'm very impressed with how it drives on the tracks that I've used it on (Generally indoors on carpet or astroturf or outside on grass, all surfaces being quite smooth) - so much so that I don't think I'd gain much if I 'upgraded' to Pro-spec shocks & towers?

[Coelacanth]

I've found the same thing as what DerbyDan mentioned; overtightening front wheel lock-nuts always binds up the wheels. I tighten them up, then back them off just enough so they spin freely. They're lock-nuts so they shouldn't loosen off any further.

[knixdad]

Common problem with bearing in wheel Losi vehicles.

[pmathews924]

I was planning on digging into the car and posting some pics after work today but had some BS pop up, so I'll get after it tomorrow night and show y'all what I'm talkin' about.

I raced last night and with the help of the track owner I was able to figure out a few of the issues I was having regarding the wheels and steering...the main problem...proline wheels made for a b4 rub the wheel carrier, so by switching to a different set of wheels he gave me I didn't need to use the spacers. Without the spacers, I was able to get the nylon nuts to stay (sort of) and the front wheels stayed on until halfway through the last lap.

It's gonna be a while before I get my driving and tuning to where I can turn the consistent 26 second lap times from the newer stock buggies, so I raced in the beginner class. It was basically me with my jrx2, a buddy racing a b3, and 3 traxxas slashes. The slashes ran me over so many times that my entire body ripped completely off (it was already torn and taped together behind the front shock tower). One front wheel had a nylon nut and the other had a locking nut because I only had one with me. The locking nut stayed on, but with my body ripped off, the nylon nut wheel flew off halfway through the last lap. Somehow, I was still able to steer the car with one front wheel and managed to finish out the race on 3 wheels and win the 2nd qualifier. It was pretty epic. I taped the body together for the main and finished 3rd. I was super fast through the first two laps, and then my transmitter wheel stopped snapping back and my steering was all effed up. I managed to finish, but it was really hard to control the car. I figured out after the race that the rubber grip on the steering wheel had slid off and was rubbing against the transmitter causing it to rub/drag instead of snapping back. If it weren't for that, I think I would have easily won the main. A little super glue and a few other adjustments and I should get closer to that 26 second lap time I'm looking for...and this is all without any boost which is allowed at our track.

Overall, I'm pretty impressed with the way this old Losi is handling on the track. Give it a few weeks and I think I can be ultra competitive with brand new b4s and kyoshos.

[kfeldt]

Glad to hear you're having fun racing your old Jrx2. I did a little bit of that last year with my Pro. At least, at the club racing level, I think you can be somewhat competitive. I usually ended up mid-pack out of 30-40 racers in Mod Buggy. That said, my B4.2 is definitely faster.

I use some Losi low-profile locknuts (LOSA6303), with spacers, on the front wheels. I haven't had any trouble with them coming loose. You do need to make sure not to tighten them all the way down though.

In terms of setup, I use something close to Brandon G's setup here: http://www.rc10talk.com/viewtopic.php?f=27&t=23199&start=15 . I ended up using lighter springs in the front though, either red or pink. I would also suggest experimenting with the rear roll center until you find a setting you like.

I've also been experimenting with adding a little weight to the front of the car. It does seem to give the car a bit more steering, but I've only driven it on a rough outdoor track though, so I'm not sure how well I'd like it on other surfaces.

Keith

[pmathews924]

I bought a set of the spoked j-concepts wheels that are made for a b4 and they fit much better than the prolines I was running...combined with the new rips fronts the steering was much improved. 10-32 lock nuts hold the wheels on fine and give them enough clearance so the wheel spins free...guess the j-concepts fronts are a shallower. So, I'd consider the steering problem licked after running today.

Only 2 problems left to solve...

1. Shock tower...I need to replace the rear. It's a broken jrxPro tower, filed off, with one hole left (lower inside). Should I get another pro tower, or go with a proSE tower?

3. Modern shocks...I currently have a pro tower on there, but want to run the proSE tower. What's a good, modern shock set that fits that combo well?