Juls’s XV-02 pro in depth build - weight bias info page 2.

[Juls1 1661]

Having been a long time fan of the xv-01 the xv-02 was always going to be a must have. It took some time to obtain all the “unnecessary” but obligatory options, but finally I think I’ve got it mostly together so we can get on with the build. I’ll be comparing notes with the xv01 and at the end will put both cars over my 4 corner scales to get some weight bias data and as well as measuring up if this is indeed a upgrade or just a alternate option. Let’s get on with it! 
 

[Juls1 1661]

Section one calls for us to charge a battery, skipping onto part two we open bag A and we are greeted with some nice aluminium servo mounts, alloy blue steering rack mounts and parts to build 2 diffs. 

additionally for part two we need the damper  tower mounts, in this case I’m going with the alloy hop ups. 

in the case of the damper stay mounts tamiya chose instead of screwing into the chassis to use locknuts instead, it’s a little fiddly (tamiya calls for using rubber cement to temporarily hold them in place but that’s not really needed.) but I like the long term reliability. Nothing worse than having to buy a new chassis because half the holes are stripped out. 

Tamiya have gone with full hex hardware for this kit, the screws feel very high quality. 

Tamiya calls for thread lock throughout the kit, I really like using Tamiyas 54032 Anerobic gel, it can reasonably easily be undone, but it’s also easy to use cause it’s not a liquid. 

part 2 completed. 

[toyolien 4680]

Looking forward to this. Nice array of hop ups too. I need to get back on with mine, but and spare time I've had in the last few weeks have been spent decorating my two daughters bedrooms. Last day tomorrow so will get back to the XV-02 then. Have you picked a body yet?

[Juls1 1661]

2 hours ago, toyolien said:

Looking forward to this. Nice array of hop ups too. I need to get back on with mine, but and spare time I've had in the last few weeks have been spent decorating my two daughters bedrooms. Last day tomorrow so will get back to the XV-02 then. Have you picked a body yet?

Body will be EVO 6 or 7, I’ve got both here nib but of course the 6 body is probably worth nearly the cost of the whole kit (although it doesn’t owe me that much.) I’ve also got the genuine tamiya Hyundai body but not sure I could bring myself to drive that as I’ve only got 1. So it’s likely to be the currently disposable evo 7 body. 

[svenb 3778]

Bravo sir on the hop ups

No point going half hearted 

[BruiseWayn 37]

Wow can't wait for your nxt update. I love reading your builds @Juls1

[Juls1 1661]

So onto steps 3 and 4

Step 3 is pretty much the steering turnbuckles, opted for Blue Titanium turnbuckles. 

Beyond that we get onto stage 4, Currently there is no aluminium steering arms, but the TB05 Steering bridge hopup is used. 

Frustratingly the bearings seem to almost just fall out of the steering bridge, and have slop, so i used some blue locktite to fill up the gaps and hold them in. 

Additionally there is alot of slop using normal screws, so i opted for a tapered head, which eliminated the slack on the bolt, however the stock bearing have quite a bit of movement in them, I'm not sure what the go is here with all these sloppy parts. I also did some shimming to try minimize the slop.. probably should have just built it stock and be done with it but you know.. lol

So here that bit is assembled. I was happy with how much slop i removed, but unhappy with the slop in the stock bearing, not sure if a better quality bearing would help. Part of the issue is the steering rack hangs on the screws, I think that exaggerates the feel of the movement. 

Of course my mods didn't get through so easily, the tapered screws just rubbed the top of the chassis where the driveshaft runs in. 

So I added some shims to offset my mod from my parts trays. 

But then the top plate didn't fit and i had to shim that.... yeah should have just put up with the slop lol.. but i got there in the end. Part 4 Done. 

Hopefully Tamiya will release some alloy steering arms that somehow magically tighten everything up.

[Pylon80 2628]

Is the slop you mentioned in the vertical direction? If yes it must be a bit annoying especially for a hop up but might not be noticable at all while driving.

[Juls1 1661]

23 minutes ago, Pylon80 said:

Is the slop you mentioned in the vertical direction? If yes it must be a bit annoying especially for a hop up but might not be noticable at all while driving.

The leftover slop is rotational, probably won’t matter, but if you don’t glue the bearings in the whole plate can slide up and down a few mm. I’d be concerned about the bearing slowly flogging it out worse. But just glueing the bearing in is really probably all that’s needed. I do wonder if I bought a aftermarket bearing maybe it’d fit better. Really tamiya should have made it press fit. Maybe they did and the bearing supplier has missed specification.

[Juls1 1661]

Onto Stage 6/7 and we build up the diffs

Tamiya Includes gear diffs as standard, these diffs are pulled from the recent TT02SR 

While I'm at it I'll also be building up the optional Centre Differential (not included with the kit) You need the centre diff gear and case, plus a TT02 Oil Differential set to complete this. 

Tamiya includes both 39T and 40T Diff ring gears for a 3% drive bias, you can install the 40T gear in the front for more rear drive bias or in the rear for a more front drive bias (whichever has the 40T will drive slower) Tamiya says in the manual not to use the 40T gear unless you have a slipper or centre diff installed, Tamiya includes 2x 39T and 1 x 40T in the kit. 

The Pinion gears are also different if you opt for the 40T diff gear.

Tamiya is nice to us this time round, they included a relief in the diff casing that makes it easier to install the gear drive pin internally. 

The guide parts on the gear for the gasket improve sealing but also aid assembly by holding the gasket in place. 

The included gears are made of a very very hard white plastic, I'm certain they are more than up to the job, in the TT02 Diff set they included the flourine coated diff cross pins, these are not included with the kit diffs and your expected to use the plastic cross pin but I found it was oversize and caused the diff gears to bind horribly, i had to do alot of work with wet and dry sandpaper to make them work nicely. 

The flourine coated cross pins included in the hopup TT02 Diff kit thats used to make the Centre diff for the XV02 are dramatically superior to the plastic cross pin setup, in my kit, day and night better. I don't know exactly what cross pins these are to buy for the other diffs and Tamiya makes them for TB04, TA06 and TRF419 all with different part numbers. I'm gonna try figure it out, I'm not really happy with my diffs with those plastic cross pins. 

Well all three diffs are together, you can tune these as you prefer, but I found I had so much friction in the system from the plastic cross pins i couldn't possibly run anything firmer than the stock oil, I don't know if these will wear in, but gauging how much work it was to try to sand them down, I very much doubt the material will wear enough to solve that issue. 

[Juls1 1661]

Steps 8 to 9 and 12 to 13 have us build up the lower arms and mounts,  

I'm going with Adjustable mounts front and rear and carbon reinforced arms straight up. 

The Carbon reinforced arms (bottom) are slightly different color to the stock arms, the stock arms actually are not terribly flexy, but the carbon reinforced parts are noticeably stiffer, I weighted the carbon arms compared to the stock plastic arms, the carbon arms save about 1 gram per arm, I hadn't expected much difference but it's nice they are not heavier. Really adding the carbon arms is likely to reduce traction in low grip situations, but will make suspension adjustments a little bit more effective. I don't think you need them.. it's just that you can...

At this point we also need to open bag B. we are greeted with a nice Alloy motor mount, and some nice blue dogbones, all the parts are top notch. 

I think really, for more people these adjustable mounts are probably more trouble than they are worth, just get the regular fixed alloy mounts, the kit includes steel balls as standard (a weak point on the XV01 that had plastic balls). So your set to go in that regard. So when would you want these mounts, well being able to adjust the rear toe is somewhat handy, but you can also adjust your rear anti squat and change the front kickup/caster using these mounts which are all useful when you know what they do and how to use them to tune in the driving character your looking for. Will they add more fun? for most probably not, for techy people there might be a bit of a kick here. 

the mounts are mounted upside down on the car, so you need to really really pay attention when your putting these adjustable mounts together that you don't do it backwards, or even different left to right. There is some included literature in the original manual for the separated mounts and more literature with the single piece mount hop part manuals. 

Once your got your head around it you can assemble the arm mounts to the lower diff casing. 

 

[Juls1 1661]

Steps 11-12 and 14-15 call for us to mount the diffs into the chassis and screw the lower diff covers on. In order to do that you need to make up the pinion portion of the differentials, for me this means building the option hop up universal prop shafts (what to do with the lovely normal blue dogbones!?!? lol).

Usual assembly process for the universal prop shafts, few parts to deal with. Not entirely convinced there is a lot of performance value here over the stock parts.

Although they are pretty blingy.... 

With the prop shafts built we can drop the diffs in. 

[Juls1 1661]

Steps 16-19 calls to install the centre drivetrain and motor, in this case as you saw before i've gone with the optional centre differential instead of the stock fixed arrangement or the slipper clutch. 

The Centre diff installs nicely, just drops right in, the pink sponges eliminate any backlash in the drive system. 

So onto installing the motor, I run a Tamiya TBLM-02S 15.5T in my XV01 so decided I'd go this way with my XV02, I have run a 10.5T but found it a bit over the top for scale rallying. These are the only quality sensored motors you can buy these days that don't have venting holes, I've tried running these various vented motors in the past off road and constantly had them filled up with gravel and little pebbles, Not a issue on the TBLM-02S. I've opted at this stage for a 20T flourine coated pinion, it's likely I'll need to gear up further but this is just what I had on hand. Stock pinion is a Aluminium 19T.

I don't love the pinion adjustment access, a ball type hex wrench is probably a necessity a L wrench could make it with alot of fiddling, somehow I managed to guess fit the motor perfectly to the mount before I put it on the car and the mesh was perfect.. I mean that'll never happen ever again right? or maybe thats what Tamiya expects to happen? 

A Cover over the top helps hold the centre drive in place, in addition to the motor mount holding the opposing bearing, It's a snug fit but i doubt it's dust proof, but it'll certainly keep little rocks out of there. 

 

 

[Juls1 1661]

onto Step 20 to 23 we open up bag C, lots of good quality parts inside, including front and rear CV's, adjustable turnbuckles and more. 

Time to install the shock towers, I've gone with the optional carbon towers, these are nice and thick, I reckon probably 1mm thicker than the usual touring car tower, probably the same thickness as on my DB01/02's. Also going with titanium turnbuckles, not because the stock steel adjustable units are not strong... they are just not blue..... 

The manual calls to install alot of the shock hardware, however since I'm not using the stock shocks I've omitted that step for the time being.

Towers installed, the car is starting to take shape. 

[Big Jon 684]

The XV-02 is such a neat update of the XV suspension design. Your build really does it justice, showing how it compares to the OG Pro, and how it has evolved toward the cars rally enthusiasts are actually competing with.  The steering has been better protected , it’s got an obviously durable driveline, and an improved version of the best rally suspension. 
 

I really wish that it was Tamiya’s answer to the old Losi XXX Rally - XV-02 with a direct belt drive! Belt 4WD is my absolute favorite to drive. I can’t wait to drive a good XV-02 to compare to my 01. I think that the suspension improvement alone are going to make it much, much faster, let alone the durability improvements. 
 

What I’m most curious about is torque steer. Tamiya tried to address it with the DB-O2 and TB -04, I’m hoping that they’ve fixed it. I haven’t read about torque steer issues with TC-01 or TB-05; they aren’t usually raced with low winds or low traction, though, and I’ve never driven a properly set up example of either. 
 

Looking forward to seeing your next installment.

[Nicadraus 6198]

On 8/27/2022 at 4:16 PM, Juls1 said:

 

Proper build! Some people don't believe in upgrades/hop ups. But what they don't realize is how important and useful these parts are whether for racing or bashing. 

[Juls1 1661]

getting onto stages 24 to 30, I’ve got a few hopups here, some carbon reinforced front uprights. All the bits to run front double cardan driveshafts and sway bars to round out the suspension. 

For the uninitiated here is the regular cv shaft and the double cardan’s. The double cardan shafts allow for wider angles of movement without chatter, in fact they can operate at their limit without binding. Same can not be said if single cardan shafts. 

I decided to assemble all the shafts even though I don’t plan to run a pair of the stock shafts. 

Which is a good thing I built them all because I forgot to order a 10 x 5 x 3mm bearing so the double cardan driveshaft doesn’t fit…. ******. Anyway I’ll put the stock shafts in and keep building because a pair of those bearings is going to take about 2 weeks to mail order in.. notice in the picture the drive pin hole is currently partially covered by the bearing. One of the bearings needs to be 1mm narrower for double cardan shafts to fit. Tamiya part 42220 or 42379.

When fitting the alloy hex hopup parts I found some backlash between the bearing and hex, so I added a 0.3mm shim. Perfect. 

Onto the rear hubs, I don’t fully understand why tamiya made a totally new part here, not sure what was wrong with the xv01 rear hub. 

All 4 corners ready to go on. 

It’s always nice to have captured hinge pins. And these have carried over with the xv01 arms. 

Starting to take shape now. 

[Juls1 1661]

Now that we’ve got the basic suspension installed we can see what max droop looks like, I’m a bit disappointed that the universals are not 38mm instead of 37mm as it seems this will be the limiting factor for modding to get that long droop look over crests. On bottom out the end of the shaft is probably 5mm away from bottoming out on the inner of the diff cup. 

The front seems to suffer the same but to a lesser extent. 

the limit on the front assuming you overcome the short shaft is also the shaft hitting the c hub. Of course this could be grinded away a bit, which has been done on my xv01. 

the steering arms just touch the chassis at the max droop, actually this is not really a issue, and is thousands of times better than the xv01 on this particular issue. On the xv01 you have to remove large amounts of the suspension mount weakening it to get more droop without effecting the steering in the case of the xv02 this can be achieved by raising the ball joint or removing a little bit of the chassis. but I actually think neither is going to be needed. Unless your trying to build a scale crawler of a car that in real life is fully independent suspension.. 

On a separate note, at this point tamiya asks us to fit this adjustable battery mount. The slide all the way in fits my standard length square packs. I’m not sure how and what battery I’ll use here as my preference for direct plug packs I’m not certain is going to work at the moment. We will see. 

[toyolien 4680]

@Juls1 Have you noticed any play from the rear bearing of the center transmission? I've got a millimeter or so of up and down play in the rear facing bearing. The front that is captured by the alu motor mount is fine, but the rear is not. I've tried a high quality stainless bearing which has made a small difference, but not a lot.

It's as though the moulding it too big for the bearing.

 

[Juls1 1661]

4 hours ago, toyolien said:

@Juls1 Have you noticed any play from the rear bearing of the center transmission? I've got a millimeter or so of up and down play in the rear facing bearing. The front that is captured by the alu motor mount is fine, but the rear is not. I've tried a high quality stainless bearing which has made a small difference, but not a lot.

It's as though the moulding it too big for the bearing.

 

@toyolienI just checked mine, yep there is a little play there. it's almost like there should be a bigger bearing but what I'm wondering is how much of that slop is in the bearing. after the steering issue, I'm wondering about the quality of all the bearings included in the kit. If you noted a difference changing the bearing that suggest part of the play is in the bearing. 

I might try making a shim out of thin alloy or something.

[Juls1 1661]

onto the sway bars, the kit uses the XV-01 Sway bar kit but with slight variance in assembly, 

Frustratingly they do not come with 53827 Rod stoppers which are required for assembly. I don't know why.. silly really. 

The kit calls to cut the back out of the supplied ball end, this is kinda dodgy, so i just grabbed a open end turnbuckle end from my parts tray instead. 

Sway bars assembled, I've gone with the hard sway bars initially, but they feel pretty aggressive, I'll wait and see what springs i'm using, If your using the stock kit included springs, they are probably hard enough you'll get away with softer sway bars (or none) but when you go with longer and softer suspension then the sway bars become more necessary. On my Heavily modded XV01 with GF01 alloy dampers and soft springs from a TRF501/201 the car was hopeless without them. 

Sway bars fitted up, it's a fairly tight squeeze actually, so little bit of tweeking needed to keep them clear of the dogbone etc. 

On a side here is the little battery bracket that is on a slide for longer/shorter batterys, There doesn't appear to be anything included to allow you to run a shorty pack. I'll be interested to see what the access is like for different connections, I generally like to use hard case packs with banana plugs built in, but i'm not sure if thats gonna work here. 

[toyolien 4680]

On 9/2/2022 at 4:39 AM, Juls1 said:

@toyolienI just checked mine, yep there is a little play there. it's almost like there should be a bigger bearing but what I'm wondering is how much of that slop is in the bearing. after the steering issue, I'm wondering about the quality of all the bearings included in the kit. If you noted a difference changing the bearing that suggest part of the play is in the bearing. 

I might try making a shim out of thin alloy or something.

Not wanting to hi-jack your thread, but I thought I'd just share my fix. Tonight I cut some little strips of Tamiya's aluminium tape and stuck them on the four locations below. This has removed ALL the play. I'm much happier now. It will also prevent the outer races of the bearings from moving.

 

[Juls1 1661]

3 hours ago, toyolien said:

Not wanting to hi-jack your thread, but I thought I'd just share my fix. Tonight I cut some little strips of Tamiya's aluminium tape and stuck them on the four locations below. This has removed ALL the play. I'm much happier now. It will also prevent the outer races of the bearings from moving.

 

Yeah I had done pretty much exactly that but with some wet and dry sandpaper. I’ve eliminated the slop as you have with the bearings now locked in place, but of course with the center diff, the diff drives have a small amount of movement through the diff case into the differential. I think the stock bearings still have a small amount of slop too. But I can see the outer race is no longer contributing to the movement. 

[NM Frontier 13]

Beautiful build so far, looking forward to seeing the rest of it! I’m taking notes for when mine arrives!

[Juls1 1661]

Have had to have a temp hiatus but will be back into it later this month.