RWS Losi XXX-SCT Digital Logbook

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Originally Posted by wyd

Are you keeping up with pennies and nickels (aka Kask Krickler). He is fast whe is asphalt offroad racing but get him on dirt offroad with his 2wd and its a different story.

Mr. Kash's Kyosho is very impressive, it seems so settled on its suspension. I hope to get the XXX that good looking. I qualified 4th, so no complaints. Still a ways to go.

Originally Posted by Sidewayz

Thanks for the excellent logbook by the way. Has me thinking about newbie racing with a 2wd XXX SCT rather than the 4x4 Slash I just bought.

You are very welcome. Just thought I should give back since I've learned a lot here as well.

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More tire weights. Looks like proper race tires run about the same.


Proline Caliber in Soft (m3)


HPI Trepador in D-compound Belted

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The rear pivot block options

Toe___Anti Squat___Part Number____Vehicle
4_______2_________4145__________XXX-SCT front and rear
3_______2_________4126__________XXX, XXX-T rear
3_______2_________4149 Alu_______XXX-T CR, XXX-SCT rear

4 degrees is a lot of rear toe, especially for a paved surface, so I moved to the 3 degree block early in my updates.



So just like they are listed in the table. The stock 4 degree plastic, 3 degree plastic, then the 3 degree aluminum.



The aluminum block bolted to the T-plate. I was going to put lock nut on top with longer screws, but due to clearance to the transmission I chose to just use thread lock and flush length fasteners.



The block from below to give you an idea of where all the screws go. Be sure the block clears everything so it all bolts up flat. There are a lot of flexible pieces that can be bent to fit so take your time to line everything up correctly.

You will notice small plastic wedges come with these mounting blocks. The purpose of these is to kick up the front on the block by putting them between the t-plate and the block itself. From the side view the contol arm pivot pins will now be angled up pointing forward.

Anti-squat is a means of using suspension kinematics to direct driveline torque to resist the rear suspension from compressing under longitudinal load transfer. I can take some additional pictures and explain the concept of there is interest.

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For additional tuning options I installed the rear Variable Length Arm (VLA) hub carriers.



For comparison purposes I've loaded both on a hinge pin.



As you can see the VLA carriers do no impact the position of the output shafts or hex drive hub. There is an additional rear upper camber link position to the outside while the two inside locations are the same.



I pre tapped the ball stud holes in the carrier, which encourages the screws to fall out . So I went with longer screws and a lock nut. I've also added a washer under the screw head to retain the link in the event of a crash.



I don't have a good photo of the two hinge pin locations of the VLA carriers. You can kind of figure out from these shots that you can move the outboard hinge pin between two positons now, effectively lengthening or shortening the lower arm. Changing this changes the camber gain and shock/spring lever ratios.

An additional feature of the VLA carriers is two small spacers that allow for wheelbase adjustments by moving the carrier forward or backwards on the outer hinge pin.

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This might seem obvious, but when you are trying to pry that e-clip off your shock rod and it goes flying under the pit table the last thing you want to do is waste time looking for it.



I found these pill organizers for cheap at the drug store and they work great.
I like the fact you only open one compartment at a time so you can dump out the contents in your hand. They are also see through and fit in tackle box drawers.

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I've seen some comments on diff outdrive wear. As I was working on my rear pivot block I noticed I have some as well. This is the stock diff with 3 race days worth of use. I practice before and between rounds so we'll say 5 hr of actual drive time.



I'm only concerned that the grooves would eventually get deep enough to prevent the dog bones from plunging during suspension travel.

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Not XXX-SCT specific, but a very valuable link that helped me dial in my RS. http://www.teamtekin.com/hotwire_RS.html

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To expand on the RS link above. I stepped through the standard timing profiles found in the Hotwire program.

Timing Profile: This slider contains 5 preset Timing Profiles for your ESC. Setting any of the 5 preset profiles will automatically put your ESC into Sensored Only mode. Profiles 1-5 are as such:

TP1: Spec Stock "blink mode" 0*timing boost

TP2: 15* Timing Boost / RPM Range 5443-20,016
TP3: 25* Timing Boost / RPM Range 5443-20,016
TP4: 35* Timing Boost / RPM Range 5443-20,016

TP5: 45* Timing Boost / RPM Range 5443-20,016

I highly recommend starting at TP1 and moving through each one of these profiles to see how they impact the on-track performance. I found a sweet spot for our layout between TP3 and TP4 that allowed me to have a good balance between speed and control on our short straight.

I also spent some time experimenting with the throttle profiles and the expo on the radio. With all these controls you can really taylor the feel of your throttle application which can reduce wheel spin and improve driveability.

I tried adding drag brake to load the front wheels for improved slow speed turning. In general this worked, but I found at higher speeds you can really upset the balance by dropping the throttle. I'd stick to little to no drag brake and practice applying the brake when needed.

Props to Tekin. I sent in a speed control for repair (my fault-user error) with all the correct forms filled out and the required Return Authorization Number and a replacement/repair is already on the way back to me.
http://www.teamtekin.com/service.html

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Since I was working with the RS boost features I wanted to keep an eye on the motor temperature. I had a standard issue Duratrax IR temp. gauge that has a 1:1 optic ratio. I wanted to potentially get the temp while the body was mounted so I picked up a 6:1 ratio gauge from Thermoworks. The ratio means you measure 1 inch area at 6 inch distance from the surface. It also has a laser pointer for improved accuracy.



With the Duratrax gauge you really want to be right on the surface of the motor when taking a reading. This motor is at room temp. btw. At 6 inches away it's simply not accurate.



Just for comparison I used both to measure at room temperature.



And again the surface of a pan on the stove top.



I found at this temperature there was about ~10 deg. difference. At 160 is was more like 5.



The point is that either gauge will work fine and it doesn't take much to remove the body at the end of a run. Per the post from Tekin keep those motor temps below 180 for sure. I shoot for 160 to have some margin and allow me to practice for extended periods.

Originally Posted by TekinTeamMgr

I don't like to see the Redline's get any hotter than 180 after a long 10 minute race.

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I ordered the Losi steering/servo mount kit and since it's not too clear from the Losi website what it contains I thought I'd include a picture here.



The stock SCT arm is 25T teeth and it is the same length as the 25T and 23T arms from this parts tree.

I'm using a Hitec servo so the 24T arm is what I'll install, it's a little bit longer and I'm not sure why that is.

Other parts on the tree include the servo saver arms, servo mounts and some plastic bushings for the bell cranks.

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My experience with tire testing doesn't really apply to the majority of you racers on dirt, but I figured everyone would enjoy pictures of worn out tires to page through.

Unfortunately, I don't get to the track as often as I'd like so I have to experiment during the event days or out in front of my house. Last week I worked with another SCT driver at the track and we compared cars and setup. That driver ended up going back to the stock springs front and rear while I was experimenting with a buggy green front and truck orange rear spring combination. We both thought each other cars turned better, which is funny. After 4 rounds of racing and 3 practice sessions I decided that my car was just too loose in the rear. Comparing all the setups online you find Yellow, Pink, White and a Red rear springs so I think oranges were just too stiff.

Without changing the springs I swapped out orange bar codes, M3 calibers, and D compound HPI Trepadors.

As I expected the soft calibers reached out and grabbed as much of the track as they could. I knew they wouldn't be a long lasting tire so I put them through an all day torture test. I didn't swap them from left to right and I got pretty even wear across the tire patch. I was getting a lot better at the layout and was using a lot of throttle and brake. The majority of the knob was worn away, but I confirmed my static camber is pretty good. I do feel I was losing grip by the end of the mains though.



The front sees a lot less abuse and they managed quite well for the full day of running.



The top guys are on HPIs and I feel these will be my long term go to tire. In D-compound and belted they have a good consistent feel and excellent tire wear. I don't see these changing throughout the day or during a long run. This is a rear with two races, a practice and a bit of outdoor running.



I was testing out in my concrete driveway and decided to use the orange bar codes to see how they would hold up. During my on track trial they seemed to provide less grip than the stock eclipses, but now I think I might have had the wrong spring combination. With the spring back at buggy blue and pink rears these tires did great on the concrete. I ran 2 very long sessions on fairly rough concrete and this is what the look like.



Front tire shows even wear and provided amazing grip, there just isn't much racing in my driveway.



I assumed the rears would have just been shredded given I was testing the brake and boost settings on my RS. I am quite impressed they have any tread at all to be honest.

I don't really think this level of experimentation is necessary as the other SCT driver is doing great on his stock eclipses. I just wanted to see what the potential of these different treads, profiles and compounds might be. From this point on I'll work on my car setup with the HPI tires for a few weeks and build experience in other areas. I can always do a quick tire swap down the road to see if I'm missing out on anything.

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With all the spring swapping I'm trying I wanted to get some consistency in setting the rear ride height so I tried out the Losi off road ride height gauge.



It is a nice unit with spring loaded knob that holds the setting. The knob doesn't lock down like the RPM camber gauge so it will move if you push on it.
I figured with the shape I could reach under and pick off the height of the bottom of the chassis near the pivot block.



Unlike a touring car that you can use a wedge and the straight edge of the chassis to read off a repeatable height this is more of an estimate. Given the t-plate has ribs and there isn't much access it is difficult to get a consistent measurement. Combine that with the fact you can run different diameter tires and the setup sheets can be misleading.



I think it is more common just to eye ball the rear height using the dog bone or arm inclinations. Somewhere between flat drive shafts and flat arms is a good start. In these shots with barcodes the gauge read 26mm with flat dog bones. Just be consistent in your notes so you know how to get back to where you were. I am looking forward to getting threaded shock bodies at some point as moving the clamp collars can be frustrating.

[dirtracer20]

i have the same ride height gauge yet to use it though,it will be eaiser to check the rear on mine reason being my t plate is graphite smooth

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I honestly never thought I'd be buying oil in 1/2 rating viscosity. I was running as high as 80 and 90 in my ballasted Slash, but when I put 45 in the XXX-SCT I could really tell the difference. Fact is the jump from 35 to 40 was noticeable. So here is my new tuning lot.



I like the little certificate that came in each package, even signed by the vice president of the engineering department. Notice that only 1 bottle has color, most of the other multiples of 5 are all sorts of colors.

I am 57 piston up front and 55 in the rear, for reference.

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I just got back of a good evening of running at The TRACK in MD. I went out with blue fronts and pink rears at 32.5 oil on HPI tires. Another Losi driver qualified first and I was second. We run 10 min. A-mains so it really makes for a nice driving session. In the end the other Losi got tied up in some traffic and I managed to squeak out a win. http://www.rctech.net/forum/8776202-post19101.html

I helped out another new Losi driver who was learning the ropes of the plywood track. Luckily I was able to loan him a few parts when the boards got the best of his ride.

In general we are still struggling with low speed turning on this unique surface. It feels like I'm just coasting through the turns and can't seem to figure out how to make the truck transition faster in the chicanes. I tried limiting the down travel of the rear shocks, but I think that just increased inside wheel slip rather than limiting roll. I went back to 4 internal spacers in the front as well. I even went to far as to experiment with 4 oz of weight in various places and ran the last two races with 2 oz under the front battery pad.

I also feel I'm not geting much of the 13.5 power to the ground, if anything I'm just spinning the wheels most of the time upsetting the rear end. It might be time to go back to the 17.5 or really work with the current limiter on the RS.

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I received great service this week from Stormer Hobbies and Tekin.

As you know I got some mis-matched tires and Stormer quickly sent me a new pair no questions asked.

After following all the proper service procedures my brand new Tekin RS arrived in around a weeks time, and at no charge!

I will certainly continue to purchase from these two companies.

[simoniz]

Great thread bud.

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Our track got a new layout and I'm going for some practice tomorrow.



It's pretty clear there is no place to let the 13.5 really roar so I'm going back to the 17.5 LRP. I removed the transmission and flipped the diff over after packing it with Losi black grease. My drive train was making some noise and I suspect the diff out drives. I don't have replacement parts so we will see how this will work. The rest of the trans internals look in good shape. I like clean wiring and the LRP terminals work well.



I also replaced the metal servo arm with the appropriate stock configuration arm with a 24T spline for the Hitec servo. I was running 2 oz under the front battery pad so I went ahead and shoe goo'd 1 oz under the servo arm. I wish I could say I honestly believe it helps. From here on out, small changes and a lot of practice.



I also removed the rear internal shock spacers and went up in oil to 37.5 front and 35 rear as I need to settle down the roll motions more.

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After a full day of testing I can't say enough about the VLA rear hubs.
Since there is a lot of confusion about these I thought it appropriate to add some pictures here.



You can see from a rear view that there are 2 holes in which the outer hinge pin can fit. The hubs do not move in and out, only the pin does. VLA means variable length arm so you essentially are changing the length of the arm by moving the pin.



In this view the carrier is narrower than the stock piece and it comes with two spacers. Put them both in front and you increase the wheelbase, both in the rear and you reduce it. One on each side and you are maintaining the stock setting. I highly encourage you to try this feature, it completely changed my truck, when nothing else seemed to.



This is just another view. I swapped out springs so much I put a longer bolt and securing nut on the lower shock mount. It is all about not having failures while you run.

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Some setup sheets say no limiter and the lower shock eye 2 turns out. What on earth does that mean you ask?



You simply grab the shock shaft and unscrew the lower shock mount out 2 turns on its threads. The lower one is set this way.

This basically extends the rebound position, or droop of the rear suspension, which can help the inside wheel stay in contact with the ground in a turn.



The lower shock inserts have a bleed channel that allows the excess oil and hopefully air escape during the shock building process. Hold the shock bodies upside down and fill them so a few threads are covered. Once you build a few and see how much oil comes out you will get the hang of it. Carefully thread the lower cartridge in so as to not cross thread it.



Rather than spinning the insert, hold it channel side up and rotate the body. You can see the oil with air bubbles flow out as you screw it together. Just before it is secure push the shock rod in and the remaining oil displaced by the rod will be pushed out. Experiment with when you lock it down and how far you push the rod in. If you lock it down with the rod fully extended it simply will not move since the oil is incompressible.



7/16" wrench fits the hex pretty well, not to tight because the plastic threads will strip and you'll need one of these.