XV-01 Pro Rally (re)Build

[Big Jon 684]

 The XV-01 has been my all-time favorite chassis for years now because of its performance, durability, versatility, and overall ability. Because I enjoy it so much, mine gets a lot of use and abuse, and could really use a full on freshening and rebuild. This is my first and only XV, and I'll try to document the modifications as I go.

Here's a few "before" pics, with a Lancia Delta body and Losi Gravel Spec tires. I just finished the body before we got locked down.

 

 

[Big Jon 684]

Some chassis shots....

It began as a Pro kit, back when they were still available. During the kit build, I added all of the carbon reinforced plastics, replaced all of the screws with hex hardware, installed the slipper (mostly to use 48p gears), and opted for the aluminum suspension mounts, so that I wouldn't have to worry about beating it like a stolen go-kart.

[Big Jon 684]

I started with the shocks. They're 55mm TRF shocks that came with the Pro kit, with shafts and pistons from Yeah Racing 60mm Shock Gear units for a 57mm length. This length gives you the maximum amount of down travel without having any steering binding issue at full droop.

This go around, I'm using two-hole tapered pistons and 30wt oil, and will be adding the new reinforced caps and rod ends, 54871, which require oversized balls, 42344.

The new caps require you to ream the aluminum cap retainer to 10mm to pass the mount through the hole. I did not drill the vent in the cap due to the filthy environments that I usually drive in.

I'm hoping that going with the two-hole pistons will give me some additional pack without losing the suppleness of three holes and 40wt, and that the reinforced parts will increase durability and reduce wear. I've broken two or three caps over the years, and have replaced several due to wear. This is an old car, heavily used well outside of it's intended use.

I'm not sure which springs I'm using. I know that the ones with fewer coils are Yeah, but I'm not sure about the rates or anything. They are a little stiffer than stock and seem to be about right. There are a million springs in my box 'o shox, and someday, I'll get a spring tester and sort and label them all. I wish that I'd done a better job with all of the packages!

[Big Jon 684]

Let's start with the rear transmission. The plan is to replace the ball studs with new Tamiya parts, refill the diff with fresh 900cst oil, clean the bearings, etc. I've installed the aluminum pulleys, aluminum diff cover, swaybars, and carbon shock tower over the years.

Unfortunately, I've already run into my first hurdle. The swaybars mount on the left side of the lower transmission housing has broken, and I don't have any spares. The last time I ran the car was a bit exuberant, I guess. I'll have to place an order later this evening.

[Big Jon 684]

After the disappointment of the broken transmission case, I ordered one up (and a few other little goodies) from RCMart. It should arrive in a couple of weeks from Hong Kong. I couldn't find a US shop with one in stock, and Tamiya USA is closed for a while. Ah, well. There's plenty of other stuff to do in the meantime.

The rear suspension needs to be cleaned up, as it's gotten a bind from fine dirt everywhere. The car is shimmed fairly tight, so it does require occasional maintenance to keep it free. It's not "carpet" slop free, but tighter than most so that the adjustments are more effective than a standard "kit" build. It seems like a reasonable trade-off to me.

[78Triumph 2610]

I'll enjoy watching this thread.  I'm a huge XV-01 fan too, and mine is in need of some freshening up as well.  I'm gonna use your thread to get motivated!

[Big Jon 684]

1 hour ago, 78Triumph said:

I'll enjoy watching this thread.  I'm a huge XV-01 fan too, and mine is in need of some freshening up as well.  I'm gonna use your thread to get motivated!

You have any tips as I go, or if you see anything that I'm missing, speak up!

I'm considering grabbing a Long Damper and doing a Hilux Monster Racer truck next. I've got a lot of projects around here, though, and I'd like to get the entire fleet complete this year. Parts availability considered, of course. DB01 parts are scarce on the ground, at least the ones that I need.

[Big Jon 684]

Decided to strip it all the way down, and build up the chassis while I wait for the gearbox housings. It's just plain filthy!

The front suspension was in decent shape. The only issue that I found was the steel pivot balls were seized on the hingepins. Even the bearings were still good. Protek sealed bearings hold up really well. 

The transmission was in great shape, too. The JConcepts Silent Speed spur has about worn out, sadly, and will be replaced with a new Kimbrough. I think that it's lasted six years! All this time, I thought that it was a 69t, but it's actually a 75t, so sorry about any bad advice I've dispensed.

All of the parts went into two jars; Fabuloso for the plastics, WD-40 for the metal. After a good soak, I'll put the bearings in lacquer thinner, then re-oil.

[Big Jon 684]

With all of the parts clean, it's time to begin with the chassis assembly. This next part addresses the only real weakness this chassis has: rocks getting stuck in the steering, the #1 reason for a DNF in our rally group.

You'll need a set of MST low profile servo mounts.

Drill three holes in the servo compartment with a 1/8" bit and countersink. Measure twice, cut once. I managed to drill the holes in random locations despite careful measurements, so they are oversunk to compensate.

Install the mounts upside down, with the locating lugs facing up. Leave the lower screws until you install the servo.

Of course, you'll need a low profile servo. I'm using a Turnigy TGY-159BL, an aluminum brushless unit, which is the only Turnigy servo I've been happy with, a High Torque servo saver, and a 3Racing horn. Using a servo saver on the XV01 is a must, as it'll break steering parts and knuckles with a solid horn and very rough use.

With the servo mounted upright, stones will no longer get wedged between the front of the electronics box and the servo. Definitely leave the hole in the bottom of the chassis open to allow the debris to pass through.

[Big Jon 684]

The front suspension is next. I'm using the carbon reinforced arms, knuckles, and c-hubs, steel pivot balls, Tamiya 1XJ separate mounts, and Yeah 1XJ one-piece mount. The carbon c-hubs are a DB01 part, and, while not listed as discontinued, are impossible to find now. The Yeah mounts are not quite as nice as the Tamiya ones, but are definitely acceptable. There's just a little more slop, just a pinch. Steel balls are good for longevity, because they don't get pounded out over time like the plastic ones. I haven't tried the low friction resin ones, so I don't know about their durability.

If you are using the front CVs, there's quite a bit of steering throw to be gained. The standard kit uses a screw in this hole as a steering stop, the Pro, because it came with CVs, didn't. If you don't use the stop with dogbones, it will toss bones constantly. You can lay the steering stop back quite a bit and get a few more degrees of steering angle.

Pretty straightforward assembly. The front end uses 1mm spacers under each mount. All of the plastic suspension shims were replaced with shiny blue aluminum, then fine tuned with stainless shims. While the axles were out, I replaced the CV pins and used the spare holes in the stub axles, because the old holes were well worn. The dogbones ends and drive cups were fine. When installing, I made sure that the retaining clips were in the right direction, so that the ends won't snag on debris and throw a pin.

[Seanster43 222]

Nice thread mate, potentially next on my build list between this and an ff chassis.  Amazing how clean the plastics look now! You planning any more mods, seems a good spec as it is👍🏻

[Big Jon 684]

Thanks! Other than the reinforced shock plastics, I didn't have anything else planned. There isn't much left to do until the transmission housings show up next week.

The XV is a really fun chassis. If you build one, you definitely won't regret it, although the FF03 is really interesting looking. I haven't decided what to rebuild next- I've got a wrecked TB05, an RC10CE that's complete, and a few more waiting on some TLC.

[Big Jon 684]

The electronics: a SkyRC Toro TS120 Pro, SkyRC Ares 13.5 Mod motor, SkyRC gyro, Turnigy  TGY-159BL servo, and Futaba R204GF-E antennaless RX.

Using a gyro works very well for rally use; it greatly expands the setup window, so you aren't constantly chasing setup as conditions change during the event. I use between 0-10% gain, usually in the 3-5% range. Higher gain settings deaden the car too much.

The TS120 is a great speedo, and available for well less than $100. I don't use a fan for reliability reasons, and have never had the slightest issue with heat, even with high boost settings and hot Texas asphalt. It has all of the features you expect from a true mod racing ESC, too, so it's easily tuned for power and personal preference. Mine has 20° ramping, 15° turbo on a .5 second delay, and 30° on the can. Great horsepower, low heat.

The motor was disassembled and given a thorough delousing. Always surprising how much filth hides in a motor.

As for the RX, it's the smallest S-FHSS receiver, and lacks an antenna to make for a neater install. No idea about the range- I can't tell which way the car is going before it runs out of range.

[Big Jon 684]

The parts from RCMart showed up Saturday, so I restarted the build.

On to the diffs! I'd used the Tamiya aluminum diff covers (54602) at some point in the past, so there was absolutely zero leakage to report.

After replacing the o-rings with Tamiya red diff o-rings and a thorough cleaning of the cases, internal gears, and covers, the diffs were reassembled with 120k oil for the front and 1k for the rear. You'll notice that there are stock plastic gears inside. They are the original gears, with no signs of wear of any sort. A lot of guys use the optional steel gearset, but as the stockers have never failed, and are lighter and smoother, they aren't going anywhere. Of course, the o-rings and gaskets got a liberal smear of Associated Green Slime to prevent leaks and lubricate the outdrives.

Previously, there was 60k front/900 rear, but I wanted to see if I could get more drive out of the corners without making the car too free on exit, so we'll see how the heavier oil works out. 

[Big Jon 684]

The front transmission is next. As usual for a Tamiya kit, it's very straightforward, with one small but important exception. When you're building the layshaft, replace the NN4 spacers with SSD aluminum spacers, SSD00151, and 4mm shims as needed reduce play. The NN4 that's next to the pin on the shaft gets dented over time, allowing excessive play and causing the pin to spin in the back of the BG1 idler, which causes a loss of front drive.

We're using the optional slipper set here, which I believe is a valuable addition if you plan to drive hard or have good power. It allows the use of easy to get Associated-style slipper spurs. The BG3 spacer is fine here, just make sure that you removed the nub and sand it smooth. Shim according, of course. When I'm building transmissions, I shim each shaft for minimal play before final assembly. I've got one of those daily pillboxes filled with 3,4, and 5mm shims from 3Racing, and usually order another assortment or two with my RCMart orders so I don't worry about running out.

Buttoned everything up with an aluminum pulley 54450 for a little bling and longevity. The plastic pulleys were showing some wear when they were replaced, although the belt never skipped. Pro and Long Damper kits came with a sweet blue motor mount.

The slipper does require careful assembly. The spring and guide spacers must be installed correctly, or the clutch will loosen as soon as you pull trigger. Don't tighten the nut onto the screw, or you'll bend it- tighten the screw into the nut. We're using a 69t Kimbrough spur and Avid slipper pads.Nice blurry pic, but you can see the correct orientation of the spring guide where it contacts the inner race of the bearing.

[Big Jon 684]

The front transmission is next. As usual for a Tamiya kit, it's very straightforward, with one small but important exception. When you're building the layshaft, replace the NN4 spacers with SSD aluminum spacers, SSD00151, and 4mm shims as needed reduce play. The NN4 that's next to the pin on the shaft gets dented over time, allowing excessive play and causing the pin to spin in the back of the BG1 idler, which causes a loss of front drive.

We're using the optional slipper set here, which I believe is a valuable addition if you plan to drive hard or have good power. It allows the use of easy to get Associated-style slipper spurs. The BG3 spacer is fine here, just make sure that you removed the nub and sand it smooth. Shim according, of course. When I'm building transmissions, I shim each shaft for minimal play before final assembly. I've got one of those daily pillboxes filled with 3,4, and 5mm shims from 3Racing, and usually order another assortment or two with my RCMart orders so I don't worry about running out.

Buttoned everything up with an aluminum pulley 54450 for a little bling and longevity. The plastic pulleys were showing some wear when they were replaced, although the belt never skipped. Pro and Long Damper kits came with a sweet blue motor mount.

The slipper does require careful assembly. The spring and guide spacers must be installed correctly, or the clutch will loosen as soon as you pull trigger. Don't tighten the nut onto the screw, or you'll bend it- tighten the screw into the nut. We're using a 69t Kimbrough spur and Avid slipper pads.Nice blurry pic, but you can see the correct orientation of the spring guide where it contacts the inner race of the bearing.

[Big Jon 684]

Front and rear transmissions assembled and ready to install. I didn't bother taking pictures of the rear, because it's by the book with the exception of the SSD spacers. You can see the Tamiya graphite shock towers in the pics.

Screwed onto the chassis with the original heavy duty belt. I bought a spare when I bought the kit and it's still in the package. There's no need to worry about belt life on an XV01. When you get swaybars, don't forget to get a set of swaybars stoppers at the same time. They're the blue collars that center the swaybars. I'm using the heavy front bar and the medium rear.

You can see a few little things in these pictures. All of the plastic suspension spacers were replaced with aluminum and shimmed to reduce slop. The turnbuckles are spring steel from Hobbywing, and got a buff to remove surface rust, then clear coated to prevent rust later. I've used these a few times and been very satisfied. These have been on the car forever. At 99 cents a pair, they're a screaming deal. All of the balls were replaced with new Tamiya hard steel parts (the original blue aluminum balls didn't last very long in dirty conditions); the cups are Tamiya Low Friction Adjusters with foam dust seals. The 1mm blue spacers on the shock mounts were necessary with the oversize shock mounting balls. A set of 6mm aluminum Yeah hexes replaced the well worn stock plastic hexes.

[mtbkym01 4008]

Nice job, I'm ordering the LD chassis very soon (along with @KalEl63, we're planning twin builds, like 2 team cars), can you provide a part number for the sway bar stoppers?

[Big Jon 684]

The stoppers are 53827, you'll need one package per car.

[KalEl63 695]

Are these the shims you use extra with the replaced nn4 part

 3RAC-SW04/V2 From RCMart 

[Big Jon 684]

8 hours ago, KalEl63 said:

Are these the shims you use extra with the replaced nn4 part

 3RAC-SW04/V2 From RCMart 

Those are the ones!

[Big Jon 684]

Moving along, I grabbed a new front bumper from the parts bin. The only way to get body mounts is to get the whole tree, which includes the bumper and spur gear cover, so I've got a million spare bumpers around here. Because I'm using the very short Lancia Delta body, there isn't room to use a foam bumper. Those are Tamiya carbon fiber bumper supports and CRC 3" body mounts. The body mounts are attached with 3x20mm set screws. Using mounts on the bumper instead of the shock tower keeps the bodies from cracking at the front wheel wells, and, on longer bodies, keeps the frontend from digging in in rough terrain or jump landings.

[Big Jon 684]

Here's the back of the car, assembled and ready to go. Nothing special back here, just low friction adjusters, hard steel balls, carbon reinforced plastics.

Now that the chassis is finished, it's time to cram in the electronics. While the radio box is a bit cramped, with a little planning, there's plenty of room. The ESC goes up front (the manual shows it going in the rear) followed by the RX, with the gyro tucked in the back corner. A 30mm fan fits right in the lid, and there was a Yeah fan NIP in the parts bin, so...

A 300mm sensor wire is the one you'll need, and you'll have to open the wire hole on the lid a little to allow three wires and a sensor cable to pass through.

A 2mm spacer was installed on the servo horn, with another on top of the bellcrank to keep the steering link flat. I used those little foam dust seals on all of the balls to help things last.

[Big Jon 684]

The 69t spur and 30t pinion give us a 5.98 FDR, which should be about right with the 13.5.

Got the radio set back up, then broke out the setup station and adjusted the toe and camber.

Assuming that it doesn't rain tomorrow, I'll get some nice outdoor poser pics, then commence to get it ready for another rebuild. 

If there's anything that I skipped over, or if anyone has any questions, let me know!

[ThunderDragonCy 7886]

@Big Jon Interesting read. Thanks! Do you have a link to those CRC body mounts? I am interested in them for my touring cars.