WR/WT-01 Expectations..

[Arbedub 25]

Bit of a sanity check being asked here please.. as I'm unsure what direction to take.

I have 4 tamiyas,

1 x TL01b - stock apart from bearings and a HPI firefbolt 15T with a 19t pinion. 

1x WR01 - silver cans, 18t pinion, kimbrough saver, metal bearings

1x WR01 - twin HPI firebolt 15T with 18t pinions, kimbrough saver, shapeways servo mount, metal bearings,  Hitech metal servo

1x WT01 - 3652SD 4100kV with 18t pinions, kimbrough saver, shapeways servo mount, metal bearings, CVA 2's, Tall tower mounts, FTX carnage wheels

 

As a family, we just bash in gravel paths, tarmac, grass fields and forest.

 

The TL01b is so much fun and behaves well.  However, only usable on flat hard surfaces.  Anything that resembles grass = smoke.  I can't easily take this out with the kids as they run the WR01's everywhere.

The WR and WT's however are such a frustration.  We have upgraded the power as capabilities have improved and tightened up the steering, but they now seem to be too unpredictable.

They have too much torque steer on acceleration (from rolling and standstill), they are unstable at medium+ speeds and generally require far too much correction to enjoy them.  They seem incapable of keeping a straight line whatsoever.

 

From the specs you can hopefully see what I've tried so far.  Much patience has been spent fiddling and ensuring the setup is tight, smooth and play is reduced as much as is possible and the power is delivered as equally as possible. The front steering is also configured with negative toe, which has improved things a bit.

I understand though that these models are pretty susceptible to this and that there are cambered uprights to help address this - however they are only an improvement, not a resolution.

Have I got my specs wrong? Am I expecting too much?

 

I'm at a crossroads now.  Am I correct in thinking that something cheap and cheerful (like the brushless ftx carnage) is likely to be just as frustrating and maybe even a step down in quality and durability?

I don't want to spend a fortune, but I do understand that there are hidden costs in upgrades when you should have just bought at the right point in the first place!

 

Thanks for your thoughts - be as harsh as you like..

[wolfdogstinkus 2098]

The HPI motors have timing advanced?

So the forward motor turns faster than the rear/backwards motor fighting against each other. 

Not sure of the specs on the HPI motor but you definitely need 0 timing so that both motors run the same speed.

But with the suspension arms and driveshafts from the tl01 buggy and a longer suspension stroke, they will be a completely different animal.

 

Oh, and add an extra axle.

Now it's a handful.

[Saito2 8749]

I've run twin Firebolts in that chassis as well and I agree, its a wild, oft-times unpredictable ride. It sounds like you've done about all you can except adding the optional C-hubs that add in some caster.

That lack of any caster or kick-up is to blame for the dartiness. On pavement, it was impossible to keep mine going in a straight line.

With those deep dish WR/WT01 wheels hanging way out past the steering center line, scrub radius is pretty bad too.

The two-piece suspension arms are pretty resilient to damage but also very flexible. With the big tires hanging off them, sudden acceleration with higher power probably was causing some twist. 

I given thought to what it might take to seriously improve the platform like bigger wheels with less offset that might bring the wheel center line closer to the steering center line. You'd lose width that way and be looking a longer custom arms to make up for that, much like the Traxxas E-maxx was designed. A custom chassis might allow you to remount the front gearbox at an angle to introduce some kick-up too. In the end, I gave up as it seemed to be forcing a square peg in a round hole. These trucks can be modded and improved to a point but then one reaches the part where its not the right tool for the job.

[Mad Ax 11909]

I think @Saito2 has the right answer here - and you allude to it in your opening post.  A lack of caster angle is the main cause of the unpredictable handling, and you need to fix that.  You mention the caster hubs in your post but don't say if you have them fitted - if not, give them a try.  Hopefully that will tame the chassis and make it nicer to drive.

You could also look for some toe-in rear hubs.  IIRC they are just TL01 rear hubs, and there is a toe-in rear hub option - I use them on my M03 and FF01 race cars, which have the same suspension design.

Also as was pointed out above - double-check the front and rear motors rotate at the same speed.  If they don't, you'll either need to adjust the timing or replace them with zero-timed motors.  I use silvercans and 3S batteries as it's way cheaper than finding good fast zero-timed 2S motors.

A few years back I made a custom chassis for mine, which has a rotated front gearbox mount to give 10 degrees of kickup and caster.  This is a much more extreme way of getting the caster angle right, but you do get kickup as a bonus, which you can't get with a stock chassis.  That should help it soak up the bumps better.  It is, however, a lot of work - mine is made from aluminium and is grossly overweight, so I've had to beef up the shocks and add sway bars to keep it under control - it could do with being rebuild using GRP sheet to cut the weight.  You can read about it here:

 

[Arbedub 25]

thanks for the replies! 

Yep, the HPI motors were chosen specifically for their cheap cost, speed and zero timings.  The brushless motor was an experiment..   

I do not have the steering hubs with the extra caster angle, and given the responses, I don't think they will transform the handling as much as I'd like without additional major surgery (nice jobs too @Mad Ax and @wolfdogstinkus). 

I don't have the time or tools unfortunately, so the best way to manage the handling is therefore to reduce the power and get back to basics instead.  

[wolfdogstinkus 2098]

A little tweak here, modification there, that's how it starts, soon you'll be calculating gear ratios and looking for parts on the internet until 2am. Lol

[dannymulder 1142]

I Never had any problems with my Wt-01, not with torque steer or keeping it in a straight line, mine had alloy rear hubs with toe in maybe that helped and alloy chubs with bearings in it, and made a servo mount between the 2 chassis halves so that it has no flex any more and used the big kimbrough servo saver and thicker steering rods.

How long are the shocks you are use, if they are to long 100mm or longer, that wil not help with stability, the arms of my truck are almost in a straight line and the shocks set up to just bottom out.

I Had a 3800kv hobbywing motor in it with high speed gears with a 24 tooth pinion.

It was one of my favorite cars to drive, sold it becaus I broke a lot of gear cases.

If you are looking for a good 2 wheel drive monster truck, look at the HPI jumpshot brushless version very good car and they sell them cheap for €200 RTR, I have that car now instead of the wt-01, way more durable than the wt-01 and drives a lot better also.

[Saito2 8749]

1 hour ago, dannymulder said:

sold it becaus I broke a lot of gear cases.

I'm glad I'm not the only one. People always spoke of the gear train's durability (which is true) but never about the gear cases. Mine always broke and split at the mounts. Eventually I had to drill them out and run threaded rod all the way through to clamp them to the chassis.

[alvinlwh 8245]

15 hours ago, Arbedub said:

brushless ftx carnage

I have the Bugsta which is effectively a Carnage with a different body. I got the brushed version but ripped out the 550 and threw in a 3660 3300kv with 3S and upgraded almost every thing possible, at think at the moment only the rear suspension arms and uprights are not upgraded. (I can dig it out of the box if you want a picture)

I drive on similar conditions as yoy and it is fun bashing. It is quite a brutal thing and had ripped itself apart more than once already although the first time was at a skate park and most cars will get damaged there.

Now it was cheap, very cheap to aquire, which may have lowered my expectations, but it is great fun drive car.

[Badcrumble 4432]

I would have a look at a brace for the steering servo too - the steering is floppy enough before stress is put upon the two little servo mounts.

[Arbedub 25]

well, after a skill issue at the skate park, and a few snapped gearbox and body mounts, as well as bent gpm shock towers and hinge pins later .. the hand has been forced.  

 

I've got a Rival MT10 on order which I can keep at 2s, and if the kids are still into it I can get a kraton 4s or 6s for myself.

These seem to be bigger nowadays though for 1:10, I wasn't prepared for the space they will need!

I still have the 2 WR-01's and a TL-01b, but they will be passed on to others wanting to get into RC.

Thanks for peoples comments and input!

[Kowalski86 5263]

4 hours ago, Arbedub said:

well, after a skill issue at the skate park, and a few snapped gearbox and body mounts, as well as bent gpm shock towers and hinge pins later .. the hand has been forced. 

Yea...I dunno when the whole "send it at the skate park" trend began, but RCs and landing on concrete from great heights don't mix, even if it's an Arrma or a Traxxas.

Edit: Fixed my typo!

[JimBear 1538]

@Kowalski86 Perhaps you meant "skate park"? But maybe that's a new trend ... hopped-up crawlers going cannonball in the greenery.

[ad456 593]

MT10 is a sound buy for a skatepark, it’s a death trap for most RCs. My bones are way too old to still be skating so do love taking my ECX Torment down to our local park for a bash, great fun but a very divisive part of the hobby for some

[Arbedub 25]

Hah, believe me, nothing was being “sent” here.  A combination of concrete and 30 year old plastic meant that it was inevitable really I suppose.  

Lessons were learned though, and hopefully the message of mechanical sympathy made it through to younger minds…(yeh right).  

The MT10 will be remaining on 2S for the foreseeable though.  

 

[Kowalski86 5263]

29 minutes ago, Arbedub said:

Hah, believe me, nothing was being “sent” here.  A combination of concrete and 30 year old plastic meant that it was inevitable really I suppose. 

30 Year old ABS/PC plastic at that, once it gets old enough that stuff can fall apart even when it's sitting on your shelf!

[ad456 593]

1 hour ago, Arbedub said:

A combination of concrete and 30 year old plastic

Exactly why I leave my skateboard at home these days, my joints don’t hold up well either