NuttsnBolts

First night racing the Yokomo! I got my delivery of electronics and oil for the shock and diff yesterday and spent the whole Friday wiring up and trimming back cables so they fit nicely. The car was all finished about 45 minutes before we started racing, but due to a problem with the PC we had some extra time so I was able to fine tune the machine with different oil changes and gearing.

All in all I managed to finish the night in 4th position out of about 21 racers while still getting used to the car compared to the tank of a machine that I was driving before. Will say that the car was very responsive with it turning where I wanted it to turn (something I wasn't used to as I used to have to brake and flick the back out to get around tight corners) and it just felt planted to the track. Did make a few mistakes when I got eager with a dome or two, but nothing that set me back majorly. All in all it's a positive experience.

Also using a Hobbywing 3.1 Stock Spec with a Turnigy Trackstar 21.5.

rc_square24

iTrader: (9)

I'm building my kit now and the bearings for the gear diff are very tight on the housing, usually I prefer to have them just slide on slightly snug in this area but just wondering if you guys have made it any looser or just built it stock. There's also some 2mm of side to side play when the unit sits on the bulkheads so I'd like to shim it up as well.

Lonestar

iTrader: (14)

Guys, me again

Does anyone know the dimensions of the steering assembly bearings (those in the two arms, plus the center link ones)... I'd like to already change them, they're full of slop, but as they were sold pressed in the part already I don't have their size...

thanks!
Paul

mikeygar

iTrader: (14)

Thanks RedBullFiXX! Very mild difference, but good to know that we can get that little bit extra toe by facing the dots backwards

RedBullFiXX

iTrader: (34)

Yes, doubt it matters much
Just make sure both are one way or the other, which should work out always with kit parts

Only time it could be an issue is if a replacement part is installed in the opposite orientation

Stuff Of Legend

iTrader: (1)

Hello

I am about to buy one of these cars (1-2 weeks) coming from nitro 1/8th background witch has lost its challenge

I started reading from (BD7 2013) page 60 , now at (BD7 2014 release) page 83 of 139. RCTech set to max post per page.

So far these are the parts i see needed to build a flawless BD7 2015.
#ORG05 kyosho o-rings DIFF
#8HD Black Bladders SHOCKS
#7HG Blue o-rings SHOCKS
#S2W or S2B o-ring Collers thin/thick SHOCKS
#A3605B to A3630B 0.5 to 3.0mm ROLL CENTER SHIMS guess
# Roche or 3Racing DOUBLE JOINT DRIVE SHAFTS Leaning towards cost of 3Racing djs
#I have an idea on parts to get hubs/arms/pins/belts/gears.

These are the questions i have so far.
1. So far i have seen nothing about (shimming Steering slop/ Wheel base slop), fitment is that good?.

2. Witch shims do i need for the entire build? Also (I have never built a diff only seen youtube videos)
http://www.rc-mushroom.com/advanced_...+shim&x=39&y=0

http://rcmarket.com.hk/advanced_sear...o+shim&x=0&y=0

3. Blue o-rings with thick or thin o-ring collers?

4. BD5 anti-roll bars work on BD7? more bars in BD5 kit more roll options.

5.See everyone taking about Roche, when i go on there website i see Radtec RC same thing?
http://www.roche.hk/shopping/index.p...roduct_id=1195

Thanks
dre

RedBullFiXX

iTrader: (34)

2015 diff, comes with proper parts, no upgrades necessary, have had zero issues with it

2- blue orings per shock, thin collars, yes

NuttsnBolts

If you don't mind, can you post up a few pictures showing what the issue is? When I built mine my diff dropped in perfectly and as I mentioned above, I was playing around with diffs during my race meet. Something to check, but have you got all your bulkheads in the correct positions and when you have the X support (B7-302C15) attached to the car, does that sit in it's place properly.

Besides that I can't think of what else it could be with my knowledge as the diff should be a set size from manufacture.
Those bearing shouldn't really be popped out as they are only sold that way. If you need new bearing you just need to buy the corresponding replacement part. Sadly every car over had has been like that. Would shimming the area help?

Lonestar

iTrader: (14)

I wish suspension marks the slope is radial not axial so shimming will not help unfortunately I mean there must be a way to push them out! Thx Paul

Lonestar

iTrader: (14)

by the way I checked my rear blocks and the dots are facing frontward on both sides so the asymetry comes from somewhere else...

RedBullFiXX

iTrader: (34)

Bent suspension mount screws, pins ?

NuttsnBolts

@Stuff of Legend

Yokomo DCJ are built nicely as they have a windows to allow for cleaning where as some of the other brands are fully enclosed and get gritty. Personally I like to used the Spec R brand universals on the rear as they have a flat band around the unit to hold the pin in where as many other brands use a wire. Just a personal preference, so take that as advice not a suggestion.

3mm shims in 0.1, 0.2, 0.3 thicknesses are your friend. They don't have to be yokomo.
Shimming the steering can help with some of that sloppy movement. Slop is good in moderation. Too much and things will break/wear and the car will handle funny, while too little and things may bind up. My spur and pulley gears has slop due to the brand spur because with certain components and shims in place, the unit was seizing up and locking the car.

Like what RedBull mentioned, the diff is pre built, but you should look into pulling it apart and sanding down the gears' back facings to help reduce resistance. When you open your diff you'll see all your components inside. Pulling off the large gear (easiest to look at) and you'll notice on the back there are two dimples from the mould injections. What I do is lightly rub these marks off with some wet and dry (800grit) set flat on a ceramic tile. Do this for all the gears and then get a really fine rat tail file and rub the inside of the centre holes just to take off any small imperfections that you may not see. The diff should go together nicely and contain very little resistance when in use.

Theres a video here to help show what I mean: Pro Tips 2011 with Jilles Groskamp - Part 3 of 3: http://youtu.be/m_DhcfcO8dI

Lonestar

iTrader: (14)

yes I'm going to tear it all down to find out which part is to blame

rc_square24

iTrader: (9)

Thanks, I've double checked the bulkheads and cross brace and they look fine.

What I mean is the fitment of the 10x15 bearings that goes onto either side of the gear diff housing in the first picture below. When I installed mine its pretty much a pressed fit and I can't remove it without using a tool to jack it out (carefully and evenly). What I decided to do was wrap a piece of 600 sandpaper around the rim where the bearings sit and lightly spin it to sand it down while constantly checking the bearing fitment until it fits with a touch of snugness.

Then when I drop the diff into the aluminum bulkheads, there was a bit of side play and I ended up shimming it with a 0.2 and 0.3 washer leaving some slight play so things don't bind. I'd like to note that the diff opening on the chassis plate doesn't leave much tolerance for side movement of the diff and the belt flange of the diff housing may scratch the chassis if the play is not taken care of.

tiny tom

Only 2hrs into the build, and running the forward motor upgrade. The problem is I can't run it with belt tensioner on it? Anyone come cross this?