re re bruiser

[JNSD1]

Awesome vid!

[topforcein]

On 03/02/2018 at 3:04 PM, nde63h said:

good idea..^^ looking forwarding to your photos..

Here you go the upfront Servo mod 

[Nitomor]

8 hours ago, nde63h said:

the 5 degree thing (as shown in attached pic) is somewhat mysterious. i don't know why Tamiya suggest us to install the front axle that way.

if you follow the instruction, the angles of the two universal joints connecting the gearbox to the front axle would be different. uneven angular velocity would occur to front axle.

please see this video for explanation

so i decided NOT to follow the manual. i installed mine at 0 degree.

I think you're reading that wrong. The manual is saying to tip the rear of the gearbox output upwards to reduce the strain on the propshaft angle. It doesn't help that the image is rotated unhelpfully 180 degrees of what would be logical, showing the axle from the underside if you look at the orientation of the leaf springs. Initially I read that wrong and had to go back and correct it on my truck. You need to look at that image upside down for it to make sense!!

 

[nde63h]

1 hour ago, topforcein said:

Here you go the upfront Servo mod 

it's beautiful but it doesn't eliminate the bump steer effect..^^

[nde63h]

1 hour ago, Nitomor said:

I think you're reading that wrong. The manual is saying to tip the rear of the gearbox output upwards to reduce the strain on the propshaft angle. It doesn't help that the image is rotated unhelpfully 180 degrees of what would be logical, showing the axle from the underside if you look at the orientation of the leaf springs. Initially I read that wrong and had to go back and correct it on my truck. You need to look at that image upside down for it to make sense!!

 

no it is concerning the front axle. rear axle should have 0 inclination as suggested by the manual which makes sense. please see my drawing..^^'

[Nitomor]

My comments were relating to the front axle. When I said tip the rear of gearbox output upwards (I was referring to the output on the axle) I should have said 'front axle input upwards' it would have been clearer, either way from your drawing above we are on the same page. Surely they are just trying to match the front axle input angle to the gearbox propshaft thrust line to make as straight a line as possible for the propshaft universal joint?

I hear what you are saying about caster, Mercedes usually run a load of positive caster on their cars which is great for self centering. I would have thought on an RC model, reducing the propshaft angles would be more beneficial.

and under full axle compression...

 

[nde63h]

45 minutes ago, Nitomor said:

My comments were relating to the front axle. When I said tip the rear of gearbox output upwards (I was referring to the output on the axle) I should have said 'front axle input upwards' it would have been clearer, either way from your drawing above we are on the same page. Surely they are just trying to match the front axle input angle to the gearbox propshaft thrust line to make as straight a line as possible for the propshaft universal joint?

I hear what you are saying about caster, Mercedes usually run a load of positive caster on their cars which is great for self centering. I would have thought on an RC model, reducing the propshaft angles would be more beneficial.

and under full axle compression...

 

actually it is not a good idea to just minimize the angles of universal joints..^^' universal joint does NOT preserve constant angular velocity from the gearbox when bent. the output shaft would rotate in uneven angular velocity which causes fluctuation. it is a chance to cancel out this adverse effect: mount another universal joint to it, with same bending angle and 90 degrees out of phase.

please see the video i posted on last page. it explains this phenomenon clearly..^^'

[Nitomor]

Interesting video, I couldn’t listen to it from work. 

Thanks, hmmm.

[JNSD1]

You guys must be engineers or VERY enthusiastic students 

Good to clearly see what you talking about, thanks.

You motivated me to clean up my Bruiser build thread with the dead Photobucket links and I transferred them all to Flickr. PITA! 

 

[nde63h]

2 hours ago, JNSD1 said:

You guys must be engineers or VERY enthusiastic students 

Good to clearly see what you talking about, thanks.

You motivated me to clean up my Bruiser build thread with the dead Photobucket links and I transferred them all to Flickr. PITA! 

 

visited your bruiser build thread. you put a lot effort on the body and did an excellent job. i am weak at handling this so i leave mine unpainted..^^' i mainly am interested in the mechanical parts and driving experience of this truck. try take yours outside for a long ride and you would notice the physical characteristics of this truck, e.g. it would have steering bias on inclined road if you set it having positive caster.

the universal joint stuff is important. i strongly recommend all builders take a look into it. universal joints / dog bones do NOT preserve constant angular velocity from the source. that's why i said before that my driving style includes minimizing the steering angle. the more the steering angle, the more the fluctuation it would produce. there are the dog bones in front axle that transmit torque to the wheels.

[nde63h]

drove it approx 10km yesterday. i found the slops between the bearings in front wheel hubs and the knuckle arms were quite obvious which (suspected) made the steering not so precise. 

the battery life was excellent. i strongly recommend the traxxas 7600mah 7.4v 2-cell 25c lipo battery. really impressive. i ran out of energy far more sooner than the truck..

[njmlondon]

7 hours ago, nde63h said:

drove it approx 10km yesterday. i found the slops between the bearings in front wheel hubs and the knuckle arms were quite obvious which (suspected) made the steering not so precise. 

the battery life was excellent. i strongly recommend the traxxas 7600mah 7.4v 2-cell 25c lipo battery. really impressive. i ran out of energy far more sooner than the truck..

You walked 10km and drove your Bruiser the whole way?! Excellent stuff! Any photos / videos?

[nde63h]

3 hours ago, njmlondon said:

You walked 10km and drove your Bruiser the whole way?! Excellent stuff! Any photos / videos?

yes i walked with it..^^ the battery is excellent. here're some photos

[topforcein]

3 hours ago, nde63h said:

yes i walked with it..^^ the battery is excellent. here're some photos

 

 

you may want to remove that pic  

[nde63h]

18 minutes ago, topforcein said:

you may want to remove that pic before the mods see it and have you 

really?.. how to edit it?..@@ i am new in this forum. let me investigate..

there were graffiti on the wall..

[topforcein]

just click on the edit on the bottom left of your post then click on the pic it should highlight blue then just hit the delete button

[nde63h]

1 minute ago, topforcein said:

just click on the edit on the bottom left of your post then click on the pic it should highlight blue then just hit the delete button

it's ok now..^^

[Saito2]

It appears nde63h's axle installation would be advantageous. Not only does it give more straight line stability with the increased caster but (assuming the front transfer case output is also level) should equalize the front output (transfer case) and front input (front axle) u-joints' angles. These angles should be roughly equal (+/- 3 degrees) to prevent binding (and brinelling in full size needle bearing equipped u-joints) due to bad angularity. In full size cars/trucks, some angle HAS to be present in a u-joint driveshaft system to allow for needle bearing processing (rotation/circulation) as well. In other words, its bad to have a u-joint drive shaft run "dead straight" most of the time.

[nde63h]

1 hour ago, Saito2 said:

It appears nde63h's axle installation would be advantageous. Not only does it give more straight line stability with the increased caster but (assuming the front transfer case output is also level) should equalize the front output (transfer case) and front input (front axle) u-joints' angles. These angles should be roughly equal (+/- 3 degrees) to prevent binding (and brinelling in full size needle bearing equipped u-joints) due to bad angularity. In full size cars/trucks, some angle HAS to be present in a u-joint driveshaft system to allow for needle bearing processing (rotation/circulation) as well. In other words, its bad to have a u-joint drive shaft run "dead straight" most of the time.

the front output of transfer case is level. 

so i don't understand why Tamiya suggested us to build the front axle with 5 degree inclination. what's the benefit of following the instruction?

i think you are interested in engineer / mechanics. i have a question and doesn't have definite answer yet:

case 1, always use 1st gear

case 2, always use 2nd gear

which case would cause more wear to the system?

bruiser doesn't have center diff. front wheels need to rotate faster than real wheels when steering. without center diff, front axle can't run faster. tires wear. stress exists in gearbox and corresponding moving parts too (imagine rotating the front wheels while not allowing the real wheels to rotate). in this concern, 2wd is better than 4wd in a vehicle without center diff.

but 2nd gear have lower gear ratio which causes more stress in gearbox than 1st gear.

if the objective is "preventing wear", which gear should i use the most often?

[Saito2]

29 minutes ago, nde63h said:

if the objective is "preventing wear", which gear should i use the most often?

While I think it may depend, to a degree, on the situation, overall, I think 2nd gear would be better at preventing wear.

On pavement, 1st gear (4wd) would create the most amount on strain on the drive system. In fact (due to the lack of a center diff. you noted), I would only use 4wd on slippery or off road conditions. Full size trucks and Jeeps owner's manuals caution against using 4wd on dry pavement for the exact reasons you listed. Now, for center diff equipped cars (AWD) this isn't an issue but for "locked in" 4wd mechanics like the Bruiser, it proves to be a problem.

In full size applications, using the numerically lower gear all the time would "lug" the internal combustion engine driving it upon take off. This creates a great deal of engine wear and can, in time, be just as bad a over-revving. But internal combustion engines develop power over a comparatively narrow rpm band. With an electric motor, this isn't a problem so you are only left with the concern of gearbox strength.  

2nd gear is numerically lower which does cause more stress in the gearbox but I feel in normal, (non-over stressed situations) the wear factor would be negligible, especially compared to all stress caused be leaving it in 4wd.

[nde63h]

10 hours ago, Saito2 said:

While I think it may depend, to a degree, on the situation, overall, I think 2nd gear would be better at preventing wear.

On pavement, 1st gear (4wd) would create the most amount on strain on the drive system. In fact (due to the lack of a center diff. you noted), I would only use 4wd on slippery or off road conditions. Full size trucks and Jeeps owner's manuals caution against using 4wd on dry pavement for the exact reasons you listed. Now, for center diff equipped cars (AWD) this isn't an issue but for "locked in" 4wd mechanics like the Bruiser, it proves to be a problem.

In full size applications, using the numerically lower gear all the time would "lug" the internal combustion engine driving it upon take off. This creates a great deal of engine wear and can, in time, be just as bad a over-revving. But internal combustion engines develop power over a comparatively narrow rpm band. With an electric motor, this isn't a problem so you are only left with the concern of gearbox strength.  

2nd gear is numerically lower which does cause more stress in the gearbox but I feel in normal, (non-over stressed situations) the wear factor would be negligible, especially compared to all stress caused be leaving it in 4wd.

thanks for your info. i know what i should do now..^^

[WillyChang]

15 hours ago, nde63h said:

if the objective is "preventing wear", which gear should i use the most often?

top gear!

its straight thru with no reduction, RWD with front drive disengaged. Only gears in action would be pinion/spur and the rear axle.

Scary fast on the 750-powered oldies.

rere Bruiser still has oneway drive in the front hubs don't it? 

[nde63h]

5 hours ago, WillyChang said:

top gear!

its straight thru with no reduction, RWD with front drive disengaged. Only gears in action would be pinion/spur and the rear axle.

Scary fast on the 750-powered oldies.

rere Bruiser still has oneway drive in the front hubs don't it? 

the rere bruiser doesn't have front one way, sadly. 

i tested it today. i used 2nd gear most of the time. the playing time was 4 hours. it seems the 2wd 2nd gear didn't consume more energy than the 4wd 1st gear.

the handling was more comfortable / responsive as expected. i only needed to pull a little bit of the throttle most of the time and the speed was enough.

i drove it on pavements which were high traction environments. 

let's see some pic. unfortunately google didn't record my path correctly so the 33.7km is not trustworthy..

google thought i could walk on water. anyway the battery ran out after 4 hours of playing. it's excellent. photos cont'd..

let's look inside. the esc, traxxas xl5, doesn't have a separate on/off switch so the radio box cover can't be installed otherwise it would be very inconvenient (each time you need to unscrew the cover in order to press the button on the esc). the antenna of receiver is planted on the esc. the position luckily match that on the body.

next time if i run it on the beach, it would be the 4wd time..

[WillyChang]

Oh yeah, new Bruiser now has diffs in its axles  

[nde63h]

2 hours ago, WillyChang said:

Oh yeah, new Bruiser now has diffs in its axles  

yes it has in front and rear axles but not in the center (i know it is difficult to design a gearbox that can shift between 2wd and 4wd while still having center diff).

btw, my receiver have tsm (traxxas stability management). it will try to correct your car's steering in the case of losing control / traction. i found it not so useful in high traction + low speed scenarios. it introduced some unexpected movements. for example if you drive along a path which is inclined sideway, say, left side higher than right side, with your steering wheel neutral, the tsm would think you are sliding to the right and "correct" the car by steering to the right which makes the situation worse.