Building a Yokomo Mr4-bx
 

I currently race 1/12th Oval and me and a few friends are looking at changing to join the merry band of 1/10th Off Road racers. :)

We have visited a local off road club and we are thinking about each buying bx's
I have only ever built 1/12th Mardave cars and they are pretty basic so i`m just after a guide to what tools to get to make the build easier.

What size allen keys, thread lock etc

and if there are anything I should do different to the manual.

Any help would be appreciated. thanks

As far as tools go: 1.5mm hex driver, 2mm hex driver, 5.5mm nut driver, 7mm nut driver and a small and large phillips screwdriver. The rest you should already have. Use the red loctite on the universal joint set screws and blue loctite on anything that goes into aluminum. That's about it mate.
Take a look at Jimmy's Review here.
You'll want the buggy's even more.........:)

I can't honestly remember what the BX comes with in terms of tools. possibly basic allen keys but dont quote me on that, I don't even remember if it comes with a turnbuckle wrench ?!


Most of the screws are 2mm hex head screws as far as I remember, so a decent quality driver with a decent lenth to it - so you can easily reach stuff like the motor screws.

You'll definately need some threadlock since there is a lot of alloy on there, the rear UJ drive shafts in particular need a proper degreasing and threadlocking. I use the Tamiya stuff myself.

The car comes with plenty of grease but the shock oil and springs will need changing probably to suit your track

^ He said it far better than I could :D

I have no red loctite so relied on brute force and good cleaning!

Thanks for your help guys :)

Yes i`ve read Jimmy's great review and found it very informative.
I`m sure I will be referring to it frequently.

It only takes 20mins to build the cars I currently race so obviously these are gonna be a bit different.

We are gonna build these over xmas and race at January, currently the best price we can find if we buy 3 at the same time is £350 each.

If anyone knows of any better deals please let me know.

wings n wheels the place to buy everything:D

If you are clubbing together to buy 3, then I think you'd get a decent discount at least, surely ?! Definately should in my book.

Contact Apexmodels, they do them for £359 each, i bet buying 3 they would better £350.

give mb models a call and speak to bally he will sort you out for sure

check out www.mbmodels.net for his number

Craig

Craig, you have a PM

Cheers Brett

You too Brett:p

We have ordered 3 x Bx`s just waiting for them to arrive.

Then its gonna be a rush for each of us to build them 1st and get them on the track. :)

Great stuff mate! Really nice to build, one of the best I've ever built.

If you need them, I do window & border masks for the car since it doesn't come with any. I'd ask miself if that was ok to advertise, but I'd probably say yes.:jimmeh

Jimmy's masks are the best!!!!!!! You gotta order some NOW!!!:D

hi what size turnbuckle wrench do i need? i measure the buckle it measures 4.4mm so that would mean i need a 5mm wrench?

I would try to get a Lunsford turnbuckle wrench. Try are small and just the right size.

We have built the 3 Bx`s now. Found it an enjoyable build and I have never built anything like this before.
Shame there were a couple of small parts missing from 2 out of the 3 kits.

We are now trying to kit out the electrics.
Ordered some world cells from DR Voodoo
Got a Quantum 2 ESC
Looking for a KO servo ( not sure which one to go for ? )
The club we will start racing at, only run 27Turn motors on polished floor ( not sure which sort to go for ? )

Never raced anything like this before, built the car totally as per instructions. How should I set diffs / slipper clutch before testing ?

Many thanks for the decals Jimmy,

I`m very impressed by them and a fast turn around what more can I ask.

Our cars have now been well and truly OOpled :D

The three yoks have been finished, and have been racing for a couple of weeks now.

Well you want the slipper to slip before the diff's. I would run the front diff tighter than the rear for more steering or get the one way. With a 27 turn motor the diff's should last a long time...

Umm... With a tighter front diff won't we get lees steering?

Well yes and no. A tighter front diff will give you less off power turn in but more on power steering going in or coming out of a corner.

Could you explain why?

Go to this link and start at page 35 and read about set up. It will apply to the BX as well........
http://www.teamlosi.com/ProdInfo/Fil...ompleteMan.pdf

Also look here: http://www.jconcepts.net/BJ4%20World...al.pdf#page=29

Well, I'm not able to open de JConcepts file. Regarding the Losi's one, it says the same as you posted.

I don't preted to be wiser than anyone, but I'd why to understand why this happen. COuld someone explain why this happen, please?

Entering a turn: A tighter front diff will give less and thus the tires will not roll as easily off power. Just like in a real car, if your front tires lock up you can't steer even if they are turned all the way. The same principle applies. The tighter the front diff, the more the tires try to "lock up" off power. This results in less off power steering.

Exiting a turn: By the same principle, a tighter front diff will slip less on power, resulting in more power transferred to the tires and (assuming there's adequate traction) the front tires will pull the car through the corner on power.

This is why a one-way gives you greater on and off power steering. It free-wheels off power and it's like a fully locked diff on power.

Hope I didn't confuse you further.:wtf:

Great reply. I could not have done it in that few words but you said it all........:)

Hi guys, it's always a pleasure to talk with you!

I undersand what you said, however, I have some doubts:

Exiting turns: As far as a tighter diff will make both wheels spin at more simillar velocities, the inner wheel should push the car out of the turn.

I'm just wondering about it, I'm not talkng about traction and grip, but turning radius.

I'll try to show it in other words: Asumming that diff doesn't "unload" under aceleration, a softer one will allow tigjter turning radius. Does this make sense?

Well try it both ways and let us no how it went.;)