haplm

What about Front One-Way Set (54517)? Wouldn't it be even better?

What I consider plus is:
- Diff action is canceled under throttle, ie. the car should be more stable under full throttle coming out of a turn
- Front is freewheeling when off throttle, making it easier to turn, especially with little brakes (causing a lot of oversteer)
- Better ability to go through rough terrain

Negatives:
- Rear brakes only
- Only rear wheels are reversing (but I can perfectly live with that)

I have asked people what they think about it during last race, and I've got very mixed responses. As I read it, it changes handling of the car so much, that if you have already practiced your technique with the classic setup, and have good result with it, it might be really hard to change this and take advantage of it. But I'm really tempted to try this...

haplm

And let's come back to our favorite topic - tires :-)

Yesterday's race was a combination of tarmac, gravel and turf. I've been comparing modified Fastrax Rally Blocks (softer Tamiya Rally Blocks), VR Tyres Pins (medium and soft compound), VR Tires Rally Blocks, and HPI Rally tires.

There were 10 stages, doing changes on the car is allowed after every second stage. So I couldn't come back and retest tire that I have already ran. In first two stages, I have suffered from rocks getting into my steering, until I have fixed that problem using duck tape. Since I was running HPI tires first, I have no credible data for them. However, they felt OK on gravel and turf, not so much on tarmac (probably too hard compound).

VR pins (both compounds) have excellent traction on turf. In fact they have so much traction that it is very easy to roll the car because of that. Both compounds also perform well on gravel. Medium compound is not really great on tarmac, soft is OK (but wearing quickly).

VR Rally Blocks - although soft compound, they didn't felt right on tarmac. Good on gravel, OK on turf. I wanted to write them off, unless I found out that I've recorded my best stage time on them.

Modified Fastrax Rally Blocks - the tire is quite soft, providing very good traction on tarmac, good on gravel, OK on turf. However, I have recorded slower stage times on them (not sure why, it could have been the driver :-)).

Resolution is, that unsurprisingly pins are good for turf/gravel, modified Fastrax rally blocks for tarmac/gravel, HPI rally for gravel/turf, VR Rally Blocks tarmac/gravel (but choose soft or ultra-soft compound).

Speaking of Modified Fastrax Rally Block - I did this to it (it makes the tire really soft):


During the race, I have learnt that this is an outdated thing, suppressed by this modification:

To do this, you need scissors, pliers, and couple hours of time...

fyrstormer

iTrader: (1)

The XV-01 doesn't need help oversteering. You can install a spool in the front and still get more steering than you can handle at high speed. On my XV-01TC I had to add a front swaybar in addition to the front spool to keep it from oversteering. Remember, the XV-01's weight balance is very different from most touring cars and that changes all the conventional wisdom about suspension and drivetrain tuning.

You won't be driving the XV-01 through terrain rough enough to need a spool anyway; that only matters on rock crawlers, which often have one or more wheels up in the air for several seconds at a time. The XV-01 is a rally car, and as such it will always be traveling fast enough that a diff with thick oil will provide effectively the same torque split as a spool for the split-second intervals that one wheel is in the air. I have a spool on my FWD XV-01, but only because that car has two drive-wheels instead of four and I was willing to sacrifice all other handling attributes in exchange for maximum forward traction at all times. I could've used a diff filled with 100,000wt oil instead, but I decided to go with the zero-maintenance option.

The rear-only brakes will have a hugely detrimental effect on the car's handling. Consider how squirrelly a RWD buggy is when braking hard, and it has a rear weight bias; the XV-01 has a front weight bias. Rear-only brakes would cause the rear tires to lock and skid basically every time you touch the brakes at all.

4roller

Front spool vs heavy oil:
If anyone wanted try a front spool, I'd suggest first going with some heavy silicone oil up front. I am currently using 60k (60,000) cst. And it pretty much keeps both front tires spinning close to the same rate. Yes there is diff action, but you car will definitely pull in the direction you turn those wheels. No need for a front spool, just get some 100k CST or putty.

One way front diff:
A one way front diff sounds interesting. Freewheeling front wheels, what would that do? No front braking. I think the front end would push a lot, since there would be little front weight shift when you let off the throttle. Does the one way work as a diff still? Not in the same way our current gear diff works (spin one wheel and the other rotates backwards.) I guess it would be like two wheels acting independently, unless there is power coming through the transmission. Strange option for a front mount motor.

The one ways I've read about make more sense in mid-motor cars where the rear wheels generally have the motor/tranmission coupled.

Centrifugal momentum of the front wheels would be carried off power. Turning will definitely change. I think it would be fun to try.

gigaplex

iTrader: (2)

You get weight transfer to the front wheels during any kind of deceleration. And since the front wheels would be using all their traction to steer rather than help brake, you actually get more steering. Combined with the increased chance of the back end losing traction, you're going to get oversteer rather than a push.

And yes, a traditional one way will have independent wheel action. Xray did have a fancy multi-diff type thing that could be a spool, a solid one way (no independent wheel action) or a traditional one way. Not all one ways are created equal.

4roller

When it comes to tires, I think everyone else on this thread must has some amazing tires and traction. I don't ever hear about your spinouts

The slicks I sometimes use (hard pillows, with the center raised a little) lose front traction off power (push). A d sometimes spin out with too much power. Slicks are a weird kind of tire because of how much traction you get when you have it, and how little you have when you reach the limit. It makes for a challenge to tune out those undesirable behaviors. But when you get it, it's so good.


haplm's post is great. I love the pictures 🤓

Radials I find work the well for asphalt/tarmac. That little bit of texture always hooks up.

Knobs? I rarely ever put those things on my car. But when I had the rally blocks on, it was controlled power slides everywhere. I've read that sipping (slicing up your knobs) really increases surface area. Super grippy. Mini/micro pins on hard packed were the best tire I found when I used to drive a buggy. They work really great on asphalt too, except they get eaten quick.

I enjoy hearing about traction rolls in your xv-01s. I've never rolled mine because of too much traction. I'd love to have that problem 😂

fyrstormer

iTrader: (1)

You can go either way. If you care about weight, a spool is lighter; if you care about maintenance, a spool needs none; if you care about adjustability, a diff is tuneable. I use spools, ball-diffs, and gear diffs on my various XV-01 builds. My XV-01 R and XV-01 FF work great with front spools, but my other XV-01s also work great with front diffs.

Push means understeer; the front end wouldn't understeer at all with a one-way diff installed -- or at least, no more understeer than the freewheeling front wheels on a RWD car.

You're right, Tamiya's one-way diff doesn't work like a normal diff. The car is only 4WD when accelerating in a straight line. When cornering softly, it is 3-wheel drive (both rear wheels plus the slower-rotating inside-front wheel), and when cornering hard it is 3-wheel drive (both rear wheels plus the outside-front wheel, while the inside-front wheel spins against the pavement). When braking or reversing it's 2-wheel drive. I tried it very briefly and didn't like it, mainly because of the almost complete lack of stopping power with no weight holding the rear wheels to the ground.

If the rear breaks loose and swings out too much in a corner, the front tires will end up losing traction because you won't be able to countersteer enough to keep the car from spinning-out and the front wheels from skidding sideways.

I say again, the XV-01 doesn't need help oversteering. The front tires already have much more traction than the rear tires, on account of the boat anchor sitting on top of the front axle. Other touring cars need to shift weight forward when cornering in order to loosen the rear tires to induce a bit of oversteer; the XV-01 is built with a forward weight bias to begin with. Preventing excess oversteer is the challenge with this chassis.

4roller

Hi all,

4roller here again. After reading a bunch of threads, I've noticed that many of the parts on Tamiya onroad cars are shared between models. I was wondering if there were some cars that share similar parts with the xv-01.

The ones I know about:

Tb03,tb04,Ta05,ta06,ff03,Trf415,416,417,419.

Most of these share suspension parts like reversible arms, toe blocks, uprights, caster blocks, CVD/DCJs drive shafts, kingpins, hinge pins, etc. These are all more similar to the xv-01TC. I know the ff02/3? Uses similar gear boxes, and the ta06 has the same diff and pulleys.

Are there any other models that this car shares main parts with? Why? Because if I find one on eBay that is cheap, I'd like to get it to try TC suspension on this car. And maybe a ball diff? Idk just more play options.

4roller

I just watched a couple of videos of how to balance out your touring car. And I must say, even though I thought my car was pretty dialed, I went through the steps and found lots of unbalanced bits.

Setup with Mr.Hudy
Setup with some Aussie

I lossend all the bottom screws. And removed as much "tweak" out to the chassis as I could. The battery box with wires stuffed every which way can really affect your chassis tweak. So I restuffed everything in a manner that had the smallest affect on tweak when the battery tray was screwed down. Flat-ish chassis, good.

I found my rear camber was off by 2 degrees on each side. I used just rims (with no tires) and no shocks. With a flat chassis, I evened out all 4 corners with my gauge.

I found that the rear droop of this car (after bashing for months now, maybe even before) is uneven when droop screws are pulled all the way out. So I used droop screws to even that out.

I found my front sway bars were not set up evenly, preventing one side from full extension. I also evened out max travel with droop screws.

With that all done I put the shocks on with the collars all the way up. Then adjussted left/right preload on the front/rear.

All this took about 30mins. And now I know my cars suspension is nice and neutral. Wow.

I will test drive tomorrow. But I already know it's going to be boat loads better than it already was.

Papi

Only FF04 shares same gearbox, oter cars are different. Differential from TA06 fits, I think that newer RWD buggies share differetial too.

front caster block is taken from DB01, I think that rear block is compatible too.
CVA dampers are shared through all tamiya models.
Front wheel shafts are same as ones for reversible suspension, but rear is specific only for XV01.

and as you said, you an fit reversible suspesion from any Tamiya, Suspesion blocks have same mounting holes.

That's all I can think of, apart from bearings, ball connectors and swingshafts

fyrstormer

iTrader: (1)

Sounds right to me.

To be clear, only the rear differential from the TA-06 is the same. The front differential is different.

4roller

I don't know why I am so obsessed with TA, TB, and TRF short reversible suspension. I spent a couple of hours scouring eBay for parts only to conclude it would cost me like 100$+ to convert to TC suspension. Where as the current suspension is awesome.

Anyway, I drove the car today after the re-balancing. Holy crap. Neutral AF. Its never been so predictable. I Love it.

Papi

over 100$? you can buy whole kit for 50$
http://www.rcmart.com/tamiya-54083-s...th=595_744_720

add swing shaft and supension mounts (plastic from TB are good enough) and you are somewhere at 70$

I personally think that reversible arms are better even in offroad use, as they are much longer.. But you have to cut them a little

4roller

Oh I saw that which made me pretty excited.

I'd have to add swing shafts. I'd want the aluminum toe blocks after about 5 minutes of piecing it together, I just know myself. The cost would be closer to $100.

These are carbon reinforced, so that's nice. In the picture, it doesn't show the front turn buckles. But it says front and rear uprights in the description.

I have many questions, I didn't really want to bother people without doing a ton of research, but since we are on the topic.


1. Would the stock longer (inner) hinge pins work with these arms?

2. Would I need 44mm swing shafts all around?

3. Would the xv-01 sway bar set still work with these arms?

4. When you say cut, what, where and how much, for what reason?

5. Toe blocks, which ones if I wanted 3 degrees in the back, and I don't know in the front?

6. Am I missing anything else that I'd need to purchase separately to get this car switched over to TC suspension?

Papi, your reply has made the consumer in me want again. I hate you. 😫 🤣

Papi

1. Stock hinge pins won't work, as they're shorter. You need 46mm hinge pins for reversible suspension arms.

2. If you use 1A suspension mounts, yes. (that'ts setting of XV-01TC) If you already have 42mm, you can use 1XD mounts, which are narrower. Also if you have stock XV, you can use front wheel axle and 42mm dogbones.. Personally I prefer dogbones on rear axle, as they don't rattle that much at higher suspension

3. Tamiya site says, that standard XV01 swaybars don't work with TC. I can't say, I don't have them

4. once I get home, I can make photo of my TB03 with suspension modded for 25-30mm. Basicaly you need to get rid of downstops (bad, if you want to ride tarmac afterwards) and you need to make space for C-hub inside of front arm.

5. Tamiya's suspension mounts are in line, differed by letters, from 1XD (narrowest) through 1X, 1A (middle) to 1F (widest). One letter apart means 0,5° difference in rear toe. So for 3° you will need for example 1XB front and 1D rear.
Separate suspension blocks serve as 2 blocks at once, when you flip them you'll get same block with X (A-XA, B-XB etc). I hope I described it well

6. I hope it's all, but I forget about hingepins, so I might be wrong

Now you can hate me even more

When I think about it 70$ is still pretty expensive, I never thought that conversion costs so much