Lessen's R&D stock car

[Lessen]

Well, to add to my misery at work I did not get that job I was hoping for so I won't get to build this car in one fell swoop of solitude that I was looking forward to. That may be a blessing in disguise because I heard the training isn't until the end of the month which would put any parking lot testing well into November which is probably not a good scenario for R&D to begin with. With that said, I'm gonna set up my pit table and mini photo studio today and start gettin' to it. I woke up in the middle of the night last night so I figured I'd do a little bit of drawing...

 

[Lessen]

Step A-01

Drive Pulley Assemblies

There are two assemblies here. One with two plastic parts and one with one aluminum piece. I noticed the alluminum piece is milled to save some weight. Nice! Look at those itty bitty screws! That's an .05" screwdriver.

Step A-02

Bulkhead Installation

Pretty cut and dry here. First is the rear with the motor mount and below is the front followed by all four pieces mounted.

Step A-03

Top Shaft Assembly

... of course these builds never go 100% smoothly. The crosspin pictured is actually the wrong one. I have the proper pin installed there now, it's just a bit longer. The short one is needed on the other pulley. However, I still couldn't manage to get the e-clip fastened once the shaft was thru the spur gear. I needed to slightly sand the center portion until the clip would fit into the slot in the shaft. Now here's the thing.. This e-clip seems too big. I may have slightly stretched it when I tried to fasten it into a groove that wasn't completley open. I'll have to crimp the clip slightly. If that doesn't help it fit snugly I'll just have to pick up a couple 4mm clips. Problem #2: I'm already short a part. It's an itty bitty metal spacer 4mm x 1.3mm. I'm supposed to have 2 but they only packaged one. I only cut a slit in the bags large enough to slide parts out and I take them out as needed, generally 1 screw at a time. I guess I need to call customer service Monday. yippy...

 

[Lessen]

Skipping ahead...

I'm gonna skip the top shaft assembly for now until I get the proper hardware. I'll do details of that step later.

Step A-04

Differential Assembly

VERY minor difference in these thrust washers. However, they were nice enough to mark which one goes where. The "in" washer should be closer to the inside of the differential.

VERY important to cake the thrust bearing well with white grease. I also put a bit of grease on the thrust washers.

This is as far as the screw assembly goes into the differential tube. At first you might think it should go in further but when it's all said and done it will look the same. Tolerences are VERY close with this build so far.

Clear grease on the diff tube and diff hub.

Shim...

...and diff ring.

I like to plug the diff balls holes with grease before I put the balls in so that they stick. You don't want to lose one of these suckers.

The end opposite the diff screw. Ready for final assembly.

Just one more to go!

 

[neobart]

Wow man. If I ever was to get back in to carpet racing the JRX-S type R would be the one for me. Well that and the fact that I'm a total Losi fanboy.

Looking forward to some more pics of the car.

 

[Lessen]

Rewind... Fast Forward...

Step A-03

Top Shaft Assembly

Ok. Now that I have the proper parts I can go ahead with this. First we have the rear drive pulley with the proper cross-pin. A shot by itself then with the spur follows.

Getting back to my issue with the e-clip. I was correct. Here on the left is the e-clip that came with my kit. On the right is the e-clip that came in the hardware kit I just got. Obviously, they are not the same and the smaller one fits the shaft groove just as expected. Perfecto!

Metal Shim and bearing for installation into bulkhead.

Then of course the same type shim and bearing in reverse order on the other end with cross-pin for the forward drive pulley installed. Final top shaft installation follows.

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Step A-05

Eccentric Bearing

This kit does not have any power robbing tension pulleys. Instead it uses an eccentric bearing to achieve the perfect belt tension between the drive pulleys and their respective differential pulleys.


Ball Bearings installed

Differential installed into eccentric bearing. Don't forget that o-ring!

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Step A-06

Differential Installation

The first thing I overlooked is when I installing the rear drive belt. Originally I completed the top shaft assembly without the belt but as you can see from these pictures the clearances are sort of tight and with the stock spur you cannot get the belt between the spur and the chassis without pinching and possibly damaging the belt. So get the belt around the pulley when you assembly the top shaft, or else you'll be yanking off that little e-clip to remove the spur to get the belt on. Also, the same goes for the diffs. You gotta get those belts around the diff pulley when you install them.

The instruction have the car setup such that the front diff is in the higher position while the rear diff is lower. This is done by rotating the eccentric bearings.

The eight screws that hold the bulkhead clamps already have loctite type of substance on them. I love those kind of details. You cannot see from the pictures but on each of of the car only 1 of the 4 screws has a washer underneath the head. It is purposely placed on the screw that is for/aft on the pulley side of the diff. This is supposed to be the screw you loosen/tighten to make tension adjustments.

Step A-08

Completed Bag A Assembly

NEXT UP... Bag B of course! Forward drivetrain.

​

 

[Racer 1966]

Man building a kit would be awesome! I love all the small parts,my old eyes would have fun with them. Lookin' good so far :thumbup:

 

[Lessen]

Step B-01

LCD Driveshaft Assembly

OK, I think this is a pretty cool concept they have here with this car. Losi calls these LCD's (Losi Constant Velocity Drive). They are actually a dual pivoting CVD.

Here's a short prior to assembly

A little white grease on the joints

Dogbone, coupler and outdrive assembled. Time to secure those crosspins.

Shrink before/after

A little manicure to free up the movement

and an HD video
​

 

[NCNitro]

I love a detailed build thread like this, great job Josh!

 

[Lessen]

Thanks Joe. I'm purposely being almost over-detailed with it. No point in doing it half-ass right?

 

[Lessen]

Sealing..

So be honest. How many veterans are out there thinking "When is this "experienced r/c driver" going to seal his carbon fiber?" I didn't have any thin CA so I've been putting this off until I could make it to the store to get some. Obviously I did the outer perimeter but also the battery opening as well as the other major openings.

 

[Lessen]

Step B-02

Spindle Carrier Assembly

Well I went and did it. In my haste I installed the two bearings into the spindle w/o installing the aluminum spacer in between. Considering how tightly the bearings fit into the spindle I had somewhat of a difficult time getting one of the bearings and thus damaged the metal seal of the bearings. It does not spin smoothly now so it'll need to be replaced. On to the process...

Here's just the spindle with the outer bearings and ball stud installed.

This is the LCD with inner bearing and aluminum spacer. The spacer keeps the bearings a very specific 0.130" apart.

Here we have the LCD installed into the spindle with a shim and crosspin inserted.

The instruction show that it might be necessary to trim the inside edge of the carrier slightly to make a little wiggle room for the extra diameter that the heat shrink around the LCD coupler creates. Before and after...

Steering bushing in the lower end of the carrier

Lower carrier/spindle secure

This is the order of the parts that go along with securing the upper carrier/spindle. The graphite piece is the upper arm swivel. It can be installed thusly or flipped over. This is just another setup option. Very new to me.

Completed Spindle & Carrier

 

[Lessen]

Step B-03

Front arm Assembly

Here I will assemble the Spindle Carrier Assembly to the lower suspension arm with the other components.

Here the hinge pin and e-clips are installed and I'm inserting a grub screw to hold the hinge pin securely.

This is a Locating Pin. There are a number of these in the build. There are two of them in each of the front arms. One is used to set the droop and the other is used to set the up-travel of the suspension.

I'm realizing that due to the small nature of the screws in a 1:10 on-road build the use of a .050" driver is relatively common, at least with this kit. I suggest using an Allen wrench at times when leverage seems to be difficult with a standard driver.

Since I really don't know what kind of droop or up-travel I'll be needing I'm just going to keep these settings flush for the moment.

Here we have the lower suspension arm hinge pin and spacer installed.

Instruction recommend putting a tad bit of white grease inside of the pivot ball to ease installation onto the hinge pin. This DID help. One ball took a little more muscle to slide on than the other but the fit is great.

Now it's time for installation onto the chassis.

Oh yeah, this would be a good time to get a good clean inner shot with the wheel installed.

 

[Lessen]

Step B-04

Front Arm Installation

This is the outer pivot. It's secured by two screws and two more of those locating pins. It took me a minute to figure out the reason for the pins because the two screws themselves will hold the pivot securely to the chassis. I believe the purpose of the pins is to give you a place to insert shims [to alter roll center] without completely removing the screws that secure the pivot to the chassis. The pivot has four places to mount the actual suspension. The outer locations are for the optional short arm suspension arm. I'll be using the inner location for the stock long arm suspension arms. Also, the pivot can be flipped over so you have your choice of either a low or high roll center position for the lower arm. I'll be opting for the higher position as suggested by the setup tips section which will suit my decision to test with caps (rubber tires) instead of foams.

I found this interesting. The inner pivots came with their respective mounting screws installed into them.

Losi is milling weight everywhere they possibly can. Take a look at his pivot. That area is not even large enough to fit a pivot ball into.

I had an issue getting the pivot ball to fit into the pivot block in the proper location. Rather than force it in I opted to investigate. If you look closely at the inside of the block where the two locations meet you'll see a very slight burr from the milling process. A couple gentile swipes with a #11 took care of that.

and there we are...

 

[neobart]

I'm gonna need something to cover my laptop before my excessive drooling ruins it.

 

[Lessen]

Step B-05 thru B-08

This will wrap up the remaining steps of the front suspension assembly

Front Shock Tower Installation

First I will install the upper shock mounts to the front shock tower. I've already CA'd the tower.

Next is the ball link for the upper suspension arm

Two screws and two washers is all it takes to mount the tower to the bulkheads. Eazy peazy!

Upper Arm Installation

Now it's time to do the upper arms. Like many r/c's it's basically a slightly more complicated tie-rod. Instructions say to turn the set screw into the rod end until it bottoms out. With it being another .050" driver, using an Allen wrench will again help here. Then you simply screw that assembly into the upper arm until the measured length is about 1.86".

Snap the rod end to the respective ball end on the tower.

A hinge pin and two e-clips will secure the upper arm assembly to the upper arm swivel. Don't forget that grub screw!

Steering Tie Rod Installation

This is pretty straightforward. Two rod ends and a turnbuckle. Overall length of 1.55".

And that be it!

Next up: Rear drivetrain and suspension!


Oh. Before I move on I do want to point out one area of dissapointment. Although, the fit of 99% of this is very nice so far I'm a bit dissapointed in the amount of for/aft play in the lower suspension arm. Even with the included shims there is still about .015-.020" (~.5mm) of play. I expected much closer tolerances than that out of a competition level kit. Sorry Losi, that's a small thumbs down for precision. Aside from that, the rest of the suspension parts fits perfectly, tight tolerances and smooth movement. Big thumbs up there. However, I will purchase some shims to lessen the play along the lower hinge pins.

 

[Racer 1966]

about .015-.120" (~.5mm)

I think that should be .015-.020" If anyone needs to know how to build one of these,you've got it coved! I used to build plastic model kits but this is way cooler :thumbup:

 

[Lessen]

You're absolutely right Randy. Thanks for the heads up. I've corrected the typo. I should have more updates before the day is done.

 

[Lessen]

Step C-01 & C-02

RCD Driveshaft Assembly

The rear driveshafts are a more common design and most anybody who has build an MIP CVD should be pretty familiar with this part.

Here are all of the parts for the driveshaft itself and the rear hub assembly

First, a little bit of Loctite for the grub screw that will fasten the pin into the joint.

Here the CVD is greased and assembled. I'm just tightening the pre-threaded grub screw.

Next up is the inner hub bearing and spacer.

I'll finish off the assembly by inserting the above into the hub and installing the rear bearing, shim, crosspin and hex (not pictured).

Rear Arm Assembly

Here I'll start off by installing the two locating pins into the rear arm. As with the front I'm keeping the underside flush for now.

I'm going to share a helpful tip I figured out concerning how to get and e-clip fastened onto a hingepin whilst lessening the chances of it flying across the room. First thing to do is get the groove lined up properly. I like to have the groove level with the surrounding surface, this way I know as long as the clip is lying flush with the surface then it is perfectly perpendicular with the hinge pin. Then I simply lay the clip next to the pin and push it close so that it begine to engage. Lastly I like to use something flat like the back end of my reverse tweezers to "pull" the clip toward me. Be sure to keep your thumb right up in front of the pin just in case you slip and the clip misses. My thumb is low just for the sake of photography. The feel of the process is very akin to peeling an apple and quite natural.

NO!

YES!

Just like the front suspension I've put a little dap of white grease into the pivot balls. There is only one spacer here and it's placed behind the lower arm in stock form.

Time for installation onto the chassis.

 

[Lessen]

Step C-04 thru C-06

I'm going to skim the next couple steps because they are very repetitive of steps I've already covered at the front end of the car. Aside from the shapes of things the process is the same.

Rear Arm Installation

Rear Shock Tower Installation

One thing I will take a moment to point out is the rear shock tower offers two positions for each of the body posts. Seeing this I took a minute to line up the body over the chassis to get a general idea of where the rear tower lines up with the body. Doing so showed me that the outer post mount location may possibly interfere or come very close to the rear window rail on the body. I decided to use the inner location at the left to avoid this.

Completed Bag C

Next up?... Shock Assembly!

 

[Lessen]

Step D-01

Shock Body Assembly

Ahhh. I always enjoy this part of a kit build. Mostly because just about every shock I've built from a kit is different in some way from the others. Let's get started...

First a complete layout of all the parts involved with the actual shock body.

I REALLY like this part. No wrapping pliers with a towel and no special plastic jawed pliers needed. Here's Losi has provided a screw that has no othe purpose than to aid in tapping the shock shaft into the rod end. After the two pieces are assembled you remove the screw. The instruction stated to screw the shaft into the end until the flat part of the shaft just reaches the face of the rod end then to turn the shaft 2.5 more turns. I did this and took a measurement and it is right about 1.40". I brought the other 3 shocks shaft assemblies to this same measurement.

A little shock oil on the end of the shaft before sliding on parts.

Here we have the bottom cap, bushing and inner o-ring on the shaft. There is also the o-ring on the body that seals the bottom cap. (note: There is also an option to which yo can use two small o-rings to seal the shaft. Losi provides the extra o-rings if you choose to use this method, however you must cut the bushing in order to do it. I chose not to for now. I'm not sure what the advantage/disadvantage is.)

A little bit of Locitite ont the shaft screw AFTER tapping thru the piston.

Piston installed.

The machining of the threads on the adjustment nutand shock body are beautiful. As you can see there is a groove inside the nut for an o-ring to be inserted. This o-ring will help the adjustment from turning due to vibrations. Without the o-ring the adjustment nut can be spun completely on or off of the shock body threads with one flick of the finger.. very very nice.

Pop on the shock ball and I'm ready to fill and cap.