Yokomo BD7 Build Review
Welcome to my build review of the Yokomo BD7 touring car… this is another big review with nearly 80 pictures so please bear with me!
To me the Yokomo range of cars has always been one of the luxury cars that has traditionally been extremely hard to get in the UK and, if you wanted one, you had to go to Hong Kong etc. Coming up through the last number of years of R/C racing here in the UK there have been a number of outstanding drivers including Andy Moore, Olly Jefferies and Chris Grainger to name a few and I remember a number of years back, after a successful 2005 where Chris Grainger secured the BRCA TC Modified Championship there was a collaboration with Chris and Yokomo Japan to create the exclusive MR4TC BD Grainger BRCA Edition.
The kit was an improved and upgraded kit that was effectively a kit produced for racing within the UK. All the changes that Chris made to the stock BD were included. Set-ups from all 7 BRCA National rounds in 2005 were included, along with building tips and modifications that Chris made to make his Yokomo BD a winner.
But even with that special edition and Chris’s success the car and parts were very hard to get in the UK.
This has changed this year with Yokomo having some of the top drivers in the world including Ronald Volker and they have been pushing the car quite successfully through their Facebook page (http://http://www.facebook.com/teamyokomo) and now, in the UK, MB Models is stocking the cars and parts (where I have mentioned optional parts in this review I have included a link directly to the part on MB Models web site.)
So with everything available in the UK I felt that the last stumbling block was gone in that I would have local supply of parts – now was the time to build the new Yokomo BD7.
I had a chat with Michael Ball of MB Models and a small box arrived the next day… note the use of the word small as the box is one of the smallest boxes I have seen a touring car arrive in;
The box comes with the BD7 logo across the front and on the front side there is a picture of Yokomo’s top pilot, Ronald Volker, and Yukijiro Umino is a pretty good driver in his own right. More importantly he is also, I believe, the main designer of the BD7 and was Masami’s mechanic. Some resume! He’s now Ronald Volker’s mechanic.
Although the box is small everything is in there!
And this is what a complete Yokomo BD7 looks like in bits with each bag labelled to coincide with the correct page in the manual;
My kit came with the #B7-203 Aluminum Special Servo Mount in a separate bag – this is a very nice implementation of the floating servo mount that pretty much all the top manufacturers are supplying with the cars. The aim is to help to stop the enemy of the modern touring car – tweak! It does this by allowing you to mount your servo so that it ‘floats’ about 1mm of your chassis and the mount is fastened to the centre line of the chassis by two screws.
So very little of the servo touches the car and there is no connection to the chassis on the outside (more pics of it built and mounted later).
The manual that comes with the car is a standard black and white printed manual that lists the parts being used and the bag they come from on the left of the page. On the right side of the page is the actual instruction which is pretty clear and concise with some notes;
So on with the build…
For those of you that have followed my other review you know that I like the idea of rounding the edges of the chassis slightly for carpet racing so that the chassis will not catch during cornering and if the byproduct of this is a chassis that will not delaminate then it is worth doing.
My method is to use a Dremel with a sanding bit in it. I run this lightly along the sharp edges of the carbon fibre parts on both sides (make sure you do this in a well ventilated area preferably with a face mask as the dust is very dangerous). I then apply a coat of glue round the sanded edges using a cotton bud. Once this dries I apply a second coat and that’s it.
And hopefully you can see in the pictures below the finished article;
A closer view;
I also do the top edges of the front and rear shock towers for no other reason than it looks nice!
Part one of the build has you start to attach the toe blocks (suspension mounts), steering posts and the bulkheads (all shown on one page in the manual);
Yokomo has gone with separate blocks for suspension mounts as can be seen in a bigger format below. Using separate blocks is supposed to give slightly more flex and therefore more grip. These are clearly labeled with the 3.5 blocks for the front and 2.0 for the rear.
The picture does not clearly show it but at the bottom of the mount there is a small piece sticking out that ‘keys’ into the chassis and that alone with two screws make for an accurate and secure attachment to the chassis;
As is expected of a kit of this quality the bulkhead parts are very nicely made and again as you can see in the picture below the small bit on the bottom of the parts that keys into the chassis. Some of the parts are also an odd looking shape but all will become clear…
A closer look at the quality and one of the ‘odd’ looking parts;
The parts all screw nicely onto the chassis and not a hint of tweak anywhere! I attach each part and then check to ensure that the chassis is still flat on a piece of glass and with the Yokomo there were no problems.
You can see in these picture that everything is very symmetrical – the chassis is pretty much identical from side to side with the exception of the cutouts for the motor and battery tape. Looking at these picture you can also see that the steering posts are symmetrical as you would expect but if you look at the points where the top deck will attach you see no screw holes near were the motor will mount and the only other mounting point for the top deck other than at the bulkheads is a piece attached to the motor mount that is right in the centre of the chassis.
A slightly clearer picture showing the ? shaped part at the front of the motor mount that the top deck will eventually attach to;
Next up is the solid axle assembly. This comes with the blue alloy axle and some nice strong looking drive cups;
…And goes together very nicely. Note the the small indentations in the belt tension adjustment cams… more on this later;
The centre gear assembly parts are shown below and again nice blue alloy and an included 116T spur gear which will be perfect for the 10.5T racing that I am currently doing.
The other thing to note is the additional instruction sheet that was in the bag with the centre gear parts – this notes the inclusion and assembly instructions for installing three bearings.
The completed assembly;
Next up is the gear diff and no this is not an after build picture – this is how it comes in the packet – all built up.
The Yokomo diffs have a very good reputation and certainly build up well – I’m not a fan of cross head screws but they work well and that’s just a personal thing.
There are instructions in the manual for the build and maintenance tips. I stripped it down anyway and applied a small amount of grease on the cups but no real need to.
Just a matter of filling the gear diff… the kit comes with 700wt oil in a small bottle but most of the guys seemed to use 1000wt or 2000wt oil in the setup sheets that I sourced online (see links at the bottom of this article). I went with 1000wt as this is what I had run in previous cars at our track.
When you have completed all these steps this is what you end up with ready to go into the car;
The bulkhead caps are very nice and again very clearly marked so you can’t go wrong. The interesting part of this picture are the parts to the top left of the picture;
Looking more closely you will see that these parts are four tiny springs and ball bearings;
This is definitely not something that I have ever seen in a car before and may be a bit difficult to explain… there are holes in the bottom of the bulkheads that are attached to the chassis. One of the small springs is dropped into the hole with a ball bearing put on top. Hopefully you can see what I mean in the picture below;
If you remember I mentioned the small indentations in the belt tension adjustment cams shown below again. When the front and rear diff are slotted into place the small indentation line up with the ball bearing on top of the spring. When the top bulkhead caps are tightened down the ball bearing is in the indentation and it stops the cams from rotating. Loosen of the bulkhead caps slightly and you can rotate the cam on the ball bearing to tighten or loosen the belt tension. A really neat idea.
Take care when putting the rear diff and front spool in place as the Yokomo, as per more top of the range cars, allows the diffs to sit high or low depending on the orientation of the adjusting cams.
Everything attached to the car;
The picture below shows how the centre gear layshaft is attached and as I said before this is not attached to the top deck.
And a view of the front spool in place with the bulkhead cap in place.
A side on picture of the rear diff in place – you can see the white lines on the bottom bulkhead and the cutouts on the belt cam that you can use to click it forward or backwards to tighten or loosen the belts once you have loosened the top bulkhead cap slightly;
The steering on the BD7 is the dual bellcrank steering which is now included on the Tamiya, Xray etc. and is supposed to give a smoother, more linear steering feel.
One of the things that I don’t enjoy when build cars is building turnbuckles but the ones that come with the BD7 go together easily due to the slightly softer plastic that the ball cups are made from. The actual turnbuckles are steel and can be replaced with a full titanium turnbuckle set, part number B7-TBS (link to MB Models) to reduce weight but I have stayed with the kit ones for now. Also included in a nice turnbuckle tool.
The steering is supplied with the bearing in place and is full blue alloy;
The built steering with the centre post that connects between the steering and the top deck;
During the build I put the centre post in place but in the end I removed it before racing and put two button head screws some 0.2mm shims in its place. This gives the car a bit more flex and seems to work well on carpet.
Top view of the steering in place;
As I said at the top of the post my car came with the optional float servo mount included. Yokomo also include 3 different types of servo horn for Futaba, Hitec and Sanwa/KO/JR etc. and they also supply two sizes of each in 17mm and 20mm variants. The manual does not give any reason for using one size or the other so I went with the 17mm variant.
I really like how the floating mount builds up and it feels very solid;
Once fitted you can see daylight under the servo – hence the floating servo! As part of the build the servo horn is attached one notch to the left as shown in the picture below – this is all noted in the manual.
With the steering and bulkheads all in place at this stage it is now time to put on the top deck. Before attaching the top deck the front belt tensioner needs to be put in place. This is another blue alloy piece with two bearings and a screw – as noted in the manual don’t crank down on the screw too hard or you will possibly bind the bearings. Again, as per the other alloy this keys to the top deck and a small screw holds it in place.
Top deck in place… I like the fact that there are four screws into each bulkhead front/rear and then the only other two screws are right on the centre line of the chassis. And as I mentioned above I ended up removing the steering centre post that attaches to the top deck.
The front and rear shock towers are next to go on along with the turnbuckles that attach to the bulkheads (and later to the hubs front and rear);
There rear shock tower in place;
And the front;
With the centre line of the car in place the manual moves on to the front and rear hub carrier assemblies… here are the parts that make up this part of the build;
It is worth noting that in some setup sheets (most notably the carpet setup sheets) the team drivers replace the slightly softer kit plastic parts with the graphite equivalent. This includes the front and rear hubs although the kit hub carriers are used. I duly replaced mine with the graphite version as my first run would be on carpet (part no.s BD-415RG for the rear hubs and BD-415SG for the fronts).
And yes, another place where Yokomo supply parts already built in the shape of the driveshafts. These from in two sizes so be careful when doing the build; the front are the 45.5mm version and the rear 44.0. They are nicely marked as you can see below. They seemed to be well built but I took mine apart again and greased them with a little black grease before building them up and ensuring the grub screw was threadlocked.
The finished front and rear assemblies;
My desk was starting to look a bit crowded now with all the parts to complete the front and rear but this includes the parts for the roll bar roll car connectors;
The suspension mounts are nicely marked up with the 43.5mm (marked F3.3) used at the front and the 46.4mm used at the rear;
The kit blocks are;
FF – BD-301FF Aluminum front/front suspension mount 43.5mm
FR – B7-30135 Aluminum split suspension mount 43.5mm
RF – B7-30120 Aluminum split suspension mount 42.0mm
RR – BD-301RR1 Aluminum rear/rear suspension mount 46.4mm
So you get 0 degrees toe out at the pin in the front and 3 degrees toe at the rear;
It is worth getting the 44.2mm front suspension mount as some setup sheets use this to get 0.5 degrees toe out at the pin for more steering. This is part no. BD-301FF3.
As mentioned before the carpet setup sheet replaces the kit plastics with the graphite versions so I did the same for my car;
And the completed assemblies along with the hinge pins and spacers all ready to attach to the car;
Note when attaching the roll bar holders to the arms don’t tighten them down too tightly as they will bind.
A closer look at the front assembly;
And it in place on the car;
Steering turnbuckle attached… getting close to completion!
The rear assembly in place;
From the rear;
Getting close to completing the build now with just the shocks roll bars and front bumper to go…
Here I have laid out all the parts that make up the shocks and that includes some 400cst oil along with pink (front) and blue (rear) springs. The pistons that come with the kit are three 1.0mm hole pistons – some drivers have been drilling the holes out to 1.1mm but I elected to leave them 1.0mm for the first run. Some drivers have also been replacing the light blue diaphragm/badder with the thicker black one (YS-8HD) but again I have done my initial build with the kit ones.
The only other addition that I made to the shock build was a 0.1mm shim between one of the E-rings on the shock shaft and the piston just to take any movement from the piston (stops the piston spinning around on the shock shaft). And finally I decided not to put the sponge in on top of the diaphragm/badder to make it easier to get less rebound.
The shocks that come with the BD7 have a great reputation and certainly the quality of the parts and the fact that you get alloy spring cups when most other manufacturers provide plastic is a plus;
And the shocks fully built are very nice indeed;
The front shocks with the Pink spring in place (in hole three initially);
On the rear I put put the shocks in hole two initially;
The kit comes with a 1.2mm anti-roll bar for the rear and a 1.3mm roll bar for the front;
These go together like the anti-roll bars for other cars on the market and then Yokomo also supply some nice stopper in blue alloy which you can see fitted in the picture below;
These fit over the roll bar and stop it from moving from side to side.
And a picture of the rear roll bar from above;
Finally the front anti-roll bar in place;
The final stage of the build before fitting wheels and electrics is the front bumper and body posts;
There are foam inserts that can be taken out once the bumper is in place… I haven’t decided whether I prefer them in or out but have taken them out for this picture;
And the rear body posts in place;
Before I finish the review some pictures of the completed car complete with my electrics installed and ready to go.
Complete with my electrics of choice; KO PDS-2413ICS servo, LRP Flow Works speed controller and Reedy 10.5 motor;
The car really does look good;
And that’s it – we have come to the end of another build review… I have to say that the Yokomo BD7 goes together very well and quality wise it is definitely up there with the Tamiya and Xray cars. It goes together with no tweak issues whatsoever. The only things that I would like are some Yokomo decals to decorate the body shell (there are none in the box) and also a setup sheet so show the settings that the manual builds to.
Very minor things and as you can probably tell from this review the BD7 was a joy to build and is definitely highly recommended.
I would like to thank Michael Ball of MB Models for sorting the kit for me and helping me to get up and running.
For further information it is well worth joining the Yokomo team page on Facebook and for setups and general information PetitRC provides a lot of good information. Forum wise RCTech also has a lot of good information on the BD7.
The official Yokomo page on Facebook;
Yokomo setups and manuals etc. on PetitRC;
The Yokomo BD7 on RCTech;
As a final note – I have now run the BD7 indoors on carpet and I have to say that it is very good indeed… I will be putting together another blog post along with my current setup and will try and get that up on the site soon.