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YOKOMO Touring Car BD-7

Old 01-10-2015, 01:07 PM
  #5206  
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If have some problems with traction rolls running my 2015 on a high grip carpet track.
What can I do against? The car does the rolls at the corner entry

17.5 motor in blinky mode
Tire is Ride REX30 with LRP Carpet 3
HB Mazda 6 MPS
Front motor kit
Attached Thumbnails YOKOMO Touring Car BD-7-bildschirmfoto-2015-01-10-um-22.03.06.jpg  
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Old 01-10-2015, 02:46 PM
  #5207  
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Originally Posted by walzjer
If have some problems with traction rolls running my 2015 on a high grip carpet track.
What can I do against? The car does the rolls at the corner entry

17.5 motor in blinky mode
Tire is Ride REX30 with LRP Carpet 3
HB Mazda 6 MPS
Front motor kit
Maybe add more camber front and rear -2, add 1 mm shim to outside roll center front & rear to create more camber gain arc.
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Old 01-10-2015, 04:35 PM
  #5208  
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Originally Posted by antivert
Maybe add more camber front and rear -2, add 1 mm shim to outside roll center front & rear to create more camber gain arc.
Seems backwards to add camber and increase camber gain to try and stop traction rolling... I haven't personally used those tires, though, so maybe more camber makes them happier?

If anything, why not raise the inner front camber links and take out a bit of camber in the front? Could also glue sidewalls if you aren't already...
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Old 01-11-2015, 01:16 AM
  #5209  
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Yesterday I fight with a Yokomo BD 2015 and had a lot of fun.

He was faster than me, strike next time back

Must say, the yokomo is very good.
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Old 01-11-2015, 05:45 AM
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Originally Posted by walzjer
If have some problems with traction rolls running my 2015 on a high grip carpet track.
What can I do against? The car does the rolls at the corner entry

17.5 motor in blinky mode
Tire is Ride REX30 with LRP Carpet 3
HB Mazda 6 MPS
Front motor kit
Increase droop
Softer springs
Widen the track width
Reduce camber
Raise inner links both front and rear
Use lighter oil
Go in one shock hole
Check your tires to make sure they haven't come unglued
Check and see what insert you're using. To soft of an insert can cause grip roll issues.
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Old 01-11-2015, 03:28 PM
  #5211  
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Hi guys,

Looking to possibly switch to the BD7-15. Having not raced a yokomo for over a decade, I was hoping you could tell me a little about you're experiences with this chassis. Both the good and the "bad"

Does the diff leak?

Does the shocks leak?

What options to get for carpet racing, and so on

Kind Regards
Chris
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Old 01-11-2015, 05:19 PM
  #5212  
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Originally Posted by Lonestar
uh-oh - sanding diff gears... didn't do it Which ones, planetary (the big ones) or satellites? Thanks!
Both.

What I found on all cars (Xray, Tamiya, Yokomo) is that proper gear diff mesh is best achieved when the back of the gears is sanded and shims are used. This is perhaps due to inconsistencies in housing molds or whatnot. Butter smooth may not mean anything though. The gears have rather coarse teeth so profile is crucial. Material used is also important and for my money, the xray plastic is the best here. Metal gears are pointless and heavy (perhaps more durable, but short of running stupid motors in mod, I don't think they bring any advantage over the increase in rotating mass they come with). Then again, running stupid motors in mod is not making the situation any better if the rotating mass is high. On the contrary.
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Old 01-11-2015, 08:53 PM
  #5213  
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First time running the BD7 (2013) on carpet, and boy was it fun to drive. I've only raced it about 3-4 times on asphalt using a 17.5... So, everything on it is still pretty fresh for testing on carpet. A while back I bought the 'Japan National' upgrade package which included the floating servo mount, titanium turnbuckles, carbon arms and hubs <---- old news but, it's worth getting for those who haven't upgraded. The track I was testing in the video is called K-Stadium, located in Kurume, Japan ( google Kurume, K-Stadium). RC legends such as Marc R, Masami, and many other top drivers have raced here. The track uses CRC carpet and has a medium to high traction suface. This is all dependent on how many cars are running that day.

First outing with the BD7 was.... a little big of a headache to be honest. Now, it wasn't the car it's self that was causing the problems. I'll tell you later what it was. Anyway, the car kept grip rolling...I checked my setup, change many settings. Nothing was curing the grip roll. Then my brand new Futaba servo stripped out a gear. The impact was minor at best, I just clipped the inside boards coming off the end of the sweeper. The car was fine, no broken parts, no bent axles, nothing. So, I'll be sending that back to Futaba for replacement. I ended up buying a Sanwa servo as a replacement. Nice, little servo, I think it's an 808? I can't remember, I just asked for a decent servo and that's what they gave me at the hobby shop. Lol.

Went back out on the track and the car was still grip rolling. Luckily, my good rc friend came by for practice and checked out my car. First thing he said, "what tires and inserts?". I said, sorex 28R's and Team Bomber Red inserts. His eyes lit up, "no, no, no" he said... "Use Sweep Blue light weight inserts. The inserts you have are ment for outdoors..." The tires I had were perfect, but the inserts were a tad soft and had a larger air gap. He also mentioned to buy serrated wheel nuts, because they are less likely to fall off and requires less torque to keep the wheels on. As I was replacing the wheel nuts, I discovered another problem...after taking the wheels off I had unknowingly damaged the wheel hexes due to over torquing the wheel nuts. Therefore, it was binding the front drive train and causing unwanted friction and probably causing handling problems... I switched out all the damaged hexs to 4.5 mm hexs which included track 0.5 and 1.0 mm width shims. Nice

I was hoping he was right and fingers crossed that was the ticket to getting the car to stop grip rolling. After mounting some new tires and inserts everything was peachy keen. I was able to drive the car hard into the corners and never gripped rolled. You can see in the short video below. In Japan they run 13.5 boosted and was my first time running this setup. I felt really confident with this car and it's setup on carpet. I was driving it as hard as I could, getting it as close as I can to the board and dots. I think with a little tire prep it should be a contender with the rest of the guys at the track.

https://m.youtube.com/watch?v=q6WOwUwUp6k

Last edited by EDWARD2003; 01-11-2015 at 09:10 PM.
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Old 01-11-2015, 10:21 PM
  #5214  
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Newbie mistake with the hexes, but you're wrong about the serrated wheel nuts. These have to be torqued against the wheel they bite into otherwise they don't lock. This can put extra pressure on the hexes. Nylock nuts lock whether they're tight or not. Of course, some people "forget" to change nylock nuts well past their due hence creating problems, but the system itself is sound. Just change the nuts when the nylon washer is knackered. Serrated nuts don't wear but as I explained above they work differently and you can easily pinch your hex and push against the bearing (as you've found) when trying to do them up tight.
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Old 01-11-2015, 11:24 PM
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Originally Posted by niznai
Newbie mistake with the hexes, but you're wrong about the serrated wheel nuts. These have to be torqued against the wheel they bite into otherwise they don't lock. This can put extra pressure on the hexes. Nylock nuts lock whether they're tight or not. Of course, some people "forget" to change nylock nuts well past their due hence creating problems, but the system itself is sound. Just change the nuts when the nylon washer is knackered. Serrated nuts don't wear but as I explained above they work differently and you can easily pinch your hex and push against the bearing (as you've found) when trying to do them up tight.
Tuning Haus offer Nylock serrated whel nuts
Best of both worlds
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Old 01-11-2015, 11:49 PM
  #5216  
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Nope.

I experimented with serrated nuts a long time before they appeared on the R/C scene and found the problem was as explained above. Back then aluminium hexes were not as widespread as today even on top end kits. I started using spacers between the wheel bearings to address the problem and I guess today these are standard because people use serrated nuts. The problem still stands if the wheel hex is not sized correctly such that it doesn't push against the wheel bearing, but then again, some people are so hamfisted they'll crush the hex, bearings, spacers and all. I use a torque wrench to do up my wheel nuts and set the torque to "hand tight" which I found is more than enough to keep your wheels on.

Last edited by niznai; 01-12-2015 at 12:52 AM.
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Old 01-11-2015, 11:54 PM
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Originally Posted by niznai
Nope.

I experimented with serrated nuts a long time before they appeared on the R/C scene and found the problem was as explained above. Back them aluminium hexes were not as widespread as today even on top end kits. I started using spacers between the wheel bearings to address the problem and I guess today these are standard because people use serrated nuts. The problem still stands if the wheel hex is not sized correctly such that it doesn't push against the wheel bearing, but then again, some people are so hamfisted they'll crush the hex, bearings, spacers and all. I use a torque wrench to do up my wheel nuts and set the torque to "hand tight" which I found is more than enough to keep your wheels on.
What is the specific torque in inch lbs you set your torque wrench to
Just out of curiosity
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Old 01-12-2015, 12:22 AM
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Because I am a weakling I tend to over tighten the nuts up, and ran into the issue above
I solved it with Associated TC6 crush tubes

http://www.tqrcracing.com/shop/produ....asp?p_id=3074

I know not as elegant but this way I don't damage the bearings/hexes pins etc

Rears fit on perfectly but fronts need a really small amount taken off with sandpaper to get to the right thickness between the bearings..

Beth.
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Old 01-12-2015, 12:55 AM
  #5219  
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Originally Posted by RedBullFiXX
What is the specific torque in inch lbs you set your torque wrench to
Just out of curiosity
Sorry, I only work in furlongs per fortnight square chain.
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Old 01-12-2015, 01:01 AM
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Originally Posted by evochick
Because I am a weakling I tend to over tighten the nuts up, and ran into the issue above
I solved it with Associated TC6 crush tubes

http://www.tqrcracing.com/shop/produ....asp?p_id=3074

I know not as elegant but this way I don't damage the bearings/hexes pins etc

Rears fit on perfectly but fronts need a really small amount taken off with sandpaper to get to the right thickness between the bearings..

Beth.
Funny. Yokomo cars of yeasteryear used to come with brass crush tubes like that and given their past association with AE I would say the sizes are the same as those you buy.

But you needn't buy those. You can use 5mm dia shims. The idea is that the hex should push against the inner bearing race rather than who knows against what or worse, against the shield. Of course, the bearings need to have a spacers between them, again pushing against the inner race. That way, you know you're not going to crush anything no matter what and even in case of impact you might be able to save the bearings (the outer bearing might suffer though given its inner race takes the hit and the outer race is fixed against the knuckle).
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