MR4BC Special - wheels n spares

[AndyG]

Thinking of buying the above.

Anybody got an opinion on the availability of spares at the moment?

Also, are the wheel fittings compatible with anything like Losi etc?

Just wondering what it would be like aover a race season you see.

Cheers

Andy G

[Doomanic]

Spares are not a problem if you use a shop which supports off road. ;)

Wheels are specific to the SP model. >:(

[AndyG]

I'll cut to the chase.

Do you have plenty of wheels in stock?

Being a Losi driver, I know that occasionaly,even with Losi, there can be some grief getting hold of parts.

Could only imagine it would be a tad worse with the Yoke?

AG

[Doomanic]

I don't hold as many Yoke wheels as Losi wheels for one simple reason;

At this point in time the vast majority of BCs are driven by factory drivers.
In the west mids there is only one!
As driver support for the car grows, so will my stock levels.
There is currently no problem with stock from CML.

[mike.stening]

the standard BC wheels with hubs will fit too and also push the track out wider then the Special or MX4. Keil do some nice dished wheels for the old style hubs as do Fastrax (i think) so plenty of options there.

[BC Rog]

The standard BC wheels and hubs are good for increasing track width but aren't too clever from a mud or strength point of view! Paul W' did some beautiful hubs for the front of my car that push the SP wheels out to max width (with Losi tyres on ... they are the widest so I made sure they would fit in the box!!). Not sure if he could make some more as they where a bitch for him to make ..... might be some left though!!

Rog

[mike.stening]

never had a problem strength wise with the BC wheels but they do like to hold the mud, the fastrax dished wheels are stiffer and from what i have been told the Keil ones are very good and a little wider than the standard ones and the fastrax dished. not sure of the benifits of the narrower Special hubs.

[BC Rog]

If your going for the special there is little point in spending the money to run the heavier, weaker wheel...!!!!!!!

You can get away without the wide hubs at the front, I think I'm the only person still running them. They do make the car feel a fair bit less nervious though so in my book they are worth the effort.

Rog

[BC Rog]

Also another point ......

Since the majority of BC's around the tracks at bigger meetings will be SPs then there is more chance of people stocking the SP wheel than the standard ones .....

Don't know what Doom thinks of this, 1 car ... 2 wheel types .... >:(

I know SP wheels have not been a problem to get ....

Rog

[mike.stening]

well replacing the 10 or so pairs of MX4 wheels i have to BC ones is a bit much for us unsponsored types, about 8quid a pair, so to replace what i currently have would be about £160!!!!!! and thats not including tyres!, yeah i would like to go onto the SP ones if they are stiffer and lighter but that also means buying the new style hubs.
unfortunately i'm a bit stuck in that respect, but i dont race on dirt very much so shouldnt be a problem and the wheels havent broke or got clogged all season.
and as for the keil wheels, if cml can get them in this country no doubt they can be ordered through a local stockist we know and trust. :P ::)

[BC Rog]

Mike, I agree that if you have lots of existing wheels new ones would be silly! I was aiming the posts at the newbie how is probably st
arting with no Yoko bits!!!

By the way, how reliable is you slipper? I've heard lots of bad things about them!!

Rog

[mike.stening]

well i took it out cos no one was using them and found it a little too snappy, also rear belts are hard to come by in my neck of the woods and decided to put it back in. now i know about the possible setup problems that can occur and set mine up with some thread lock on the locking ring thread (dont get any in the bearings mind) and tightened it by hand so i could just about turn it when held with a cloth (stops teeth biting into your pinkies) and i mean only just then let it set over night and ran it all day at a refgional on a 10x1 Kr and a 10x3 Peak, very grippy dry track and had no problems with the slipper un doing itself, now i know i havent really got it setup to slip as such but it does give on very hard acceleration and adds a bit of give to the drive train especially as i am running the center and front one-ways, car felt very good but i would imagine it would feel better with the Ass' shocks on but i am struggling tio get hold of the right springs round here.
was hoping to run it at the f3/f4/f5 finals this weekend but the missus is working the night before so not really got a chance now :-[ . also unfortunately due to the top deck of the BC you cant use the MX4 rear bulkhead cap which would have ment being able to adjust the slipper in the car, as mine stands now you HAVE to take it out which is a bit of a pain but i'm getting quicker at it.
my opinion is its worth a try and my one is getting a bit old, could do with new pads but not sure if you can get them any more.
that any use?

[Doomanic]

The F3's aren't this weekend, they are on the weekend of 20/21 September.

[mike.stening]

ah, must have missheard mr brooke then. might be able to make it then, which would be nice. ;D
cheers doom

[JV]

[Considering buying an MR4-BC1S]

Yokomo's wheel hubs seem quite non-standard.

It looks (from the instructions) like hex adaptors (from something like) an XXX-4 could be used. Is that what folks are doing in order to use non-Yokomo wheels ?

What exact components have you used ?

If I want to have a few different wheel/tyre sets to choose from, is there any reason I would want to stay with Yokomo wheels ?

John.

[Doomanic]

I don't know of anyone using wheels other than the Yokomo Precision Dished Wheels.
They are good quality and no messing is needed to get the off-set right.

[BC Rog]

I must admit to thinking about making wheel adapters .....

... in my case it was to fit Yokomo wheels to the B4!!! Lighter, and easier to do than going the other way around!!

TO be fair, Doom's point is spot on ... why change???

Rog

[JV]

[Some possibly dumb questions from me here]

Doomaniac writes:
> They are good quality and no messing is needed to get the off-set right.

Offset. Good point. What is the offset with the dished wheels ? Close to zero ?

Won't the offset change with the the camber and the toe-in ?
Does anyome have a good way of measuring (or calculating) the offset ?

I guess I'd want to shim the driveshafts in the steering blocks/hub carriers to control the float.

B C Rog writes:
> why change?

Well if the geometry is good with the dished wheels, maybe you're right.

I was thinking that with locking hex adaptors, I'd have:
- More choice of wheels.
- The possibility of swapping wheels with other buggies.
- A way of adjusting the offset

Regards,

John.

[DA_cookie_monstA]

Off set is the relation between the centre line of the wheel and axle, or something like that, and does not change with suspension travel or camber.

To use someone elses wheels, where the offest on the wheel could be different will alter it, or different thickness hexes.

[Chrislong]

What wheels are available on hex's for off road nowadays?

I think Schumachers offset would send the width beyond regs, and Kyosho new wheels not available.... (don't know what will be on the new Kyosho 4wd tho')

[JV]

A_cookie_monstA writes:
> Off set is the relation between the centre line of the wheel and axle,
> or something like that,

OK. my understanding is that what is generally meant by steering offset is the distance
(on the ground) between the line of thrust of the wheel and the axis of the kingpins.

So it tells you something about the torque which is trying to steer the wheel, for a given accelerating or braking force (at that wheel). The perpendicular distance between the kingpin axis and the line of thrust would be a slightly more useful thing to know, but it doesn't seem to have a name.

If the axis of the kingpins passes through the line of thrust - for example the kingpin axis passes through the centre of the contact patch - the offset will be zero, and the thrust or braking won't try to turn the wheel from side to side.

> and does not change with suspension travel or camber.

Suppose we have a front wheel with zero caster and no suspension at all (to make life simpler), and the kingpin axis is in the centre plane of the wheel and passing through the axis of rotation of the wheel.

If the wheel has zero camber, the offset will be zero, and thrust/braking forces won't try to steer the wheel. If we now tilt the hub carrier so that the wheel has negative camber, the axis of the kingpins will move outside the contact patch, giving a negative offset (unless the tyre width is tiny, like a setup wheel). If your tyre has a very square profile, the contact patch will move inwards, while the point where the steering axis hits the ground moves outwards.

John.

[Doomanic]

Sorry, I should have specified wheel offset, not steering offset.

[DA_cookie_monstA]

On the front wheel, the relationship between the wheel offset and the kingpin is static, othwise this would mean that the wheel actually moves inwards and outwards on the axle.

All the off set is, is the relationship of the wheel to the axle, if you fit wheels with a different offset, then the change is constant, in as much as, no matter what csator/camber/steering angle, it will remain the same.

I didn't say it would have an effect on the handling though, far from it.

And Doom, as the post is to do with wheels on the BC (or any other car for that matter) I assumed we were talking about wheel offset too, nothing else.

[BC Rog]

JV,

PM me you phone number ... I think we need a little chat as you seem to have been reading a few of those books writen by people that couldn't make a "push-cart" ..... trust me there are pelnty of those in print!!!!!!!!

I have had some drive adapters made for the BC to push the front out to max width (2.5mm wider per side). My motives for doing this was simple, improved stability.

The effect is to widen the track between the centre of contact patches, this will discourage the car from unweighting the inner wheel in corners mainly by vertue of having to do more work on the outer wheel to get the car to roll enough to transfer weight of the inner wheel.

There are several other side effects.

The car will track straighter as with a 4WD car the effects from the contact patch serves to try and drag the steering into toe-in (assuming that you aren't trying to run sill amounts of toe out in the first place). By pushing the wheel out you are moving the centre of contact patch (towards) outboard relative to the KPI (king pin inclanation angle) incidence with the plane on which the centre of contact patch is acting.

Still with me?

This in effect will serve to limit the effects of the drive through the contact patch (due to an increased leverage) and thus prevent the car from behaving differently on, off and during changes to throttle.

So we have more stabilty from the wider effective track, more from the effects of the contact patch so something has to give right???

Yes, of course. In this case it is two fold. 1) The servo has to work a bit harder (a HiTec 5925 is never work that hard to notice trust me ...) and 2) the car will be a little more sensitive to steering inputs around the mid position than the extremes of lock.

Personally I think that this is a good thing, as anybody that has driven one of my cars will tell, because I run massive amounts of lock but drive with only small amounts of stick for most of the lap and only use the full amount in the tightest turn on the track.

If I could get the same thing in my head for the other thumb then I might be higher up the finals :D

With the Yokomo they seem to have made a genuine mistake somewhere. The MX4 had the geometry of the wheel adapters and drive hubs spot on, and that car was at max width.

Yokomo seem to have made the BC to a price (was a basic £100 kit to start with don't forget) and so only fit one thickness of drive adapter, the MX4 was different front to rear (10mm on the front, 7.5mm rear I beleive). My only reasoning for the drop in drive adapter thickness was an issue with some of the wide american tyres making the car over width (I can't run cut and shut Pro-lines on the front with the wide adapters). and wanting the front and rear the same to keep costs down.

Incidently, the rear is spot on as the wheels are slightly different offset, trust me ... I put them on a CMM to get the measurements (shut it Doom ... I like my old parker).

For a while I ran Pred wheels via home made adapters which could be shimed to any place I wanted so I have tried what you propsed. After much testing I had the +2.5mm adapters made for the front and keep the standard blue one on the back.

Paul Worsley made them for me but I'm guessing he won't do any more as they were a bitch and he actually lost money on every pair (based on his usual hourly rate). They are superbly made though ...

Hope that helps mate ...

Rog

(Senior design development engineer for the largest automotive component manufacturer in the world)