Isphius

My Feedback: (1)

anyone here own the 1/12th scale hummer? i am thinking about getting one to drive around my house and back yard and stuff. And does anyone have some specs on it like top speed, suspension travel and stuff like that?

Karl the Mechan

Five of my mates has one, and I'm next in line.
Actually, the Hummer is discontinued but a lot of shops still have them in stock.
Either in kit form nr. 58154 or XB (tamiya-speak for RTR) nr. 57714. Those two look the same but a lot of things are different. Both sets need a few upgrades to become worthy offroad perfomers, but properly set up they're marvellous. We mostly do trial-competitions. Going slow in difficult terrain. Crossing rivers, stuff like that.

Now to your other questions:
Top speed: Same answer as any other RC car: Depending on what equipment you stuff in it, it can be made to go as fast or slow as you wish. Personally I dont give a toss. We're trialling!

Suspension travel: Depends on how you build/assemble the dampers.
The XB has pre-assembled non-oil-filled "friction-dampers" which need to be replaced by an expensive oil-damper kit, which you assemble as you please.
The kit comes with plastic oil-filled dampers which you assemble as you please.


XB or kit?
Both are based on the ageing TA01 chassis.
The kit has one ball-diff. That will cost extra on the XB.
The kit has oil-filled dampers. That will cost extra on the XB.
The XB has a pre-painted body. It's beautiful and saves you a lot of work.
The XB has a better centre-section of the chassis, with a dust-cover. The kit centre-section is an open bathtub which fills with dirt. Cannot be purchased separately.
The XB comes with a Futaba radio and TWO servos. When you've fitted an ESC (which you must, it's absolutely undriveable with the MSC), you've got a spare steering servo. Nice!

I'd go for the XB.

Interceptor1

I just recently bought the XB Humvee, my first "real" R/C. It's a nice package in terms of looks and realism. Now keep in mind, I have nothing to compare this too since this is my first, but I wasn't born yesterday either .... the Humvee appears to handle well on and off road. The radio system is quite responsive, even with the MSC, but I hear the an ESC would result in better driving. I ordered a set of sealed Duratrax ball bearings and Tamiya's TRF Damper set for improved performance and suspension. This will complete my setup for some good old fun in the backyard or a nice dirt and gravel trail.

The XB Humvee is not a monster truck, so don't expect it to perform as such - since the ground clearance is low, climbing over "unrealistic" extra large obstacles in a real Humvee would not be practical, which is fine since the car was built close to scale for realism which is the REAL cool factor here.

This is a very, very fun car to drive as it is. My 6 y.o. daughter and I have a blast with it everytime. Once I hop it up, it should be set the way I want. I highly recommend the XB Humvee.

Karl the Mechan

...About the handling... this car is NOT for street racing. Because if you try to corner at high speed, it will flip over. Kind'a top heavy, you see. And we're not talking wreckless driving at top speed, the car flips over at milder cornering too. But then again, it's an off-roader.

Personally I think it's a bit too high geared for the ultimate crawling. The chassis design is showing its age, but all in all it's a nice car.


Oh, and Interceptor1 ? Do get an ESC. The car will be TRANSFORMED! And it's important for a car intended for slow driving, to get a high freuency ESC. 1Khz is not enough, the motor goes frying hot. It runs a lot cooler with 2,3Khz.
Having a field trip with several Hummers with different setups, and all driving the same path, allows us to directly compare what works and what doesn't.

Interceptor1

Thanks Karl for the advice. Now you've got my interest peaked...

What ESC would you recommend for the Humvee and what else do I need for the unit? How much will it all cost?

Karl the Mechan

A few guidelines to upgrades we found to work well

ESC: Two of our Hummers use Carson Speed 20. I've also seen them labelled Mtronics. http://www.mtroniks.net/nav.htm
The other brands are Hitech and GM. These are 1Khz ESCs. After a run, the motors were so hot that tiny raindrops falling on it went "Hisssss". Youp: boiling!
The Carson is a 2,3Khz unit, and after a run we were able to put our fingers on the motor. Warm, yes, but not frying hot.
The guy who USED to drive with a GM ESC had an accident. He was going over a crest, and as the car vanished over the top we heard a splash... We went to see, and youp! There it was, standing in water up to the windshield. And YES it went completely dead. The receiver & servo was salvaged and returned to life after a drie-up but the ESC never recovered.
The Carson is waterproof. And the ad's not lying either, we've tested!

Motor: Well, the Tamiya 540 Sport Tuned does give long run times. And has more power than the stock silver-can. Enough to make the car jump!

Alloy motor mount: 53142. Recommended. The plastic motor mound may deform when hot, resulting in a wrong pinion clearence. Then the gears wear out quickly, or even strip instantly.
Also, a "clip-on" heatsink for the motor is a good thing. Tamiya's has the fins in the wrong direction, Use a Carson or the one from Team Orion.

Dampers/springs:
Oil-filled dampers of course, and soft long springs. As in, try to avoid short soft springs which need spacers.

Ball-bearings: A must on every car. On this one, I'd actually fork out the extra cash for the Tamiya Super Sealed bearings.

Diff: The kit comes with one ball-diff which is supposed to go in the back. A sort of "limited-slip-differential". The XB comes with open gear-diffs front and rear.
When assebling their kits, three of the guys placed the ball-diff up front. And glue-gunned the gear-diff. (grease all internals first, then you'll be able to easily remove the blob of glue if you wish)
So they've got a front limited-slip differential and a rear non-slip-differential.

Suspension: According to the kit instructions, the tie-rod-balls are supposed to go ON TOP of the front upright. But this gives a tremendous bump-steer. Screwing the ball in from UNDER the front upright cured this. Because now the tie-rod is in PARALLELL with the wishbones.

Alloy upgrade suspension parts: Dont bother. This is not a fast road car where absolute precision is needed. Use your money elsewhere on the car.

Prices? Havent got the foggiest, I live on another continent and we pay much more for everything than you do.


As previously mentioned, I'm next in line for Hummer ownership. But I really dont like the TA01 chassis, Tamiya has made lots of better chassies. I'm in the process of making a hybride but havent collected all the parts yet. I will take some time... (and money) More later.

Karl the Mechan

Another important effect of higher frequency ESCs is smoother power-delivery. Gives better traction on loose sand and such. Where the Hitech and GM equipped cars got stuck, the Carson ESC car drove straight through. And stopped, and drove off again. The 1Khz ESCs would make the cars dig themselves down. To abrupt power-delivery.

Same cars, same motors, same tyres, same batteries, different ESC. We even tried swapping drivers. Same results.

vorta

i also got a tamiya humvee xb with the DF-01 chassis and have replace the MSC with a M-Troniks M.sonik 3 Eco-20 ESC and karl the mechan is correct the car is transformed, this ESC is in the 2.3Khz range and handles motors down to 20 turns which is perfect for the standard motor(27turns). the manufacturor of the esc is http://www.mtroniks.net/nav.htm but i got mine from http://www.modelsportuk.com/ the advantages of this esc are the higher Khz rating, they are waterproof, your motor will run cooler, power take up is smoother and once you pull your MSC out you get a spare servo which will do if your steering servo goes bang.

tomustang90

I was looking at a xb tamiya humvee based on the df-01 chassie last night at the hobby shop and I could hardly take my eyes off it! The body and tires are perfect scale but it didn't look like the perfect off roader. It looked real! Thomas

Karl the Mechan

Oh, but you just need to modify it a bit. :-)

hsw21

Hi Karl..
I tried to put the ball joint under to make tie rod pararel to the suspension arm to eliminate the bump-steer effect, but it seems like it doesn't give me full positon when I turn the wheels to the right and left. Any solution? (beside trimming some of the chasis).
Thank you

hsw21

dado099

No, the only solution is to trim the edge of the chassis.

Anyway I want to ask to all Hummer owners (also Manta Ray) if they can check the rear axle toe-in and report me the results.

This because my just bought hummer has about 1-2 mm. rear toe-in. I checked that this was due to the incorrect alignement of rear arms (they are not 90 degrees) and there is no way to adjust.

Can you help ?

Thanks

vorta

my tamiya hummer on a DF-01 chassis also has this 2mm rear toe in and is also non adjustable, i have wider than standard wheels and tyres on my hummer and then you really notice the toe in angle!

dado099

So, as I supposed, it's a standard feature of this chassis.

Do you wonder why there's this feature, or is it a bug ?

Bye

vorta

i would doubt it is an oversight, probably a cunning plan to sell rear tyres which last longer than front ones, but don't last as long if the tracking is not parallel. Hmmmmmmmmmm i wonder??

Isphius

My Feedback: (1)

well, I know the toe in on the rear makes it more stable at high speeds while turning. Its because more weight is on one tire, which sort of counter steers the truck if it leans too far. Tow out can also work as 4 wheel steering this way. The effect is barley noticable though, so i wouldnt worry about it.

Karl the Mechan

It's because the Hummer and the Manta Ray share components with the TA01 and TA02 road-going chassies. TA01 and TA02's need this feature to maintain stability at high speeds. Not making a special zero-toe-in upright for the Hummer means less develope- and production-cost for Tamiya.

The only drawback is slightly more drag, and therefore less top speed. Tyre-wear isn't an issue on a Hummer. I've never seen one with worn out rubber. They stay mainly off-tarmac, and don't run fast... :-)

vorta

i agree, i use mine all off road and for trials, slow speed and rough ground = little tyre wear. i still have my original wheels and tyre as new and the super grippers i'm using now are showing little wear, the fronts wear more but i expected as much.

hsw21

Hi Guys....
I went to the park to drive my hummer on some loose dirt. I was so dissapointed with it, because it seems that the car can not handle the terrain at all, It kept slipping here and there.
I didnt expect it to be fast, but at least I expect it to crawl good.
But before I give it the final judgement, Im asking you guys, whats wrong? Is there anything I can do to make it better (or maybe best)?
FYI, my hummer is all standard from the box. (but i use ESC).
Thank you Guys...

vorta

hsw21, what esc are u using? i was advised to get a 2.3Mhz one as power take up was better.
fitted with a Mtronics Eco20 mine crawls just fine and takes off from a standing start to top speed excellently, the only other thing i'm considering is a better limited slip diff for when i get a pair of wheels off the ground and no drive.
check out http://www.mtroniks.net/carfr.htm and see where your nearest stockist is.

Karl the Mechan

Well then, that depends what you do to it :-)

- The XB-Hummer has a gear-diff front and rear. Lock the rear diff ! This can be done in two ways:
1: Buy a set of spare gears (G-PARTS) for an XC-chassis car (58132 Pajero), use only the DIFF-LOCK on the parts-sprue, and toss the gears.
2: (the economy version) Fill the rear diff with some two-component goo (urethane-glue, perhaps), wait till it cures and reinsert the diff.

- The kit-Hummer has one gear-diff (which is supposed to be placed up front) and one BALL-DIFF (for the rear).
Swap them! Put the ball-diff in the front, and use one of the above mentioned methods for the (now) rear gear-diff.

hsw21

What is the difference between the "gear diff" and the "ball diff" ?
I mean the function.

HSW

dado099

Try ball differential for manta ray (Tamiya item 53070) they should do the job....

dado099

Or try to use heavy silicon oil (50.000 grade) in the free xb differentials....

Karl the Mechan

That happens to be EXACTLY the same component which is included in the kit-tamiya.
And like I stated in the above post, it just isn't quite enough to make the Hummer a true crawler.

This, combined with the steep price of a ball diff, is the reason I don't recommend it. For XB-Hummers, that is. The kit-Hummer already has this ball-diff, so stuff it in the front.

Locking the rear diff is WAY more effective. And half the price, if you buy XC G-parts. And gratis if you fill the diff with goo!




Oh, and hsw21 ??
You might compare a ball-diff to a Limited Slip Differential.