MR4BC Gearing

[Chrislong]

Im using a 12x2 in an MR4-BC on 84 spur, main belt slightly tight as its a new car but everything is free considering.

Which pinion should this be on? looking for decent pickup without over revving the poor thing.

Also, what is the internal gear ratio of the MR4BC?

Chris

[sosidge]

Internal ratio is 2.2:1.

[Chrislong]

Ok, I think I should mention which motor I am intending to use, its a new Reedy PT 12x2 - apparently high revving beasty but I never tried one yet.

Any ideas on ideal overall ratio? which pinion?

Cheers for the final drive, sosidge. ;D
Is the formula spur/pinion x 2.2?

If so 84x18 = 10.267 and sounds about right for a high revving 12x2? or am I wrong?

Chris

Chris

[Doomanic]

I would say that sounds a little low.
I ran 19/84 in an MR4MT with a Peak Carrera 11 double.
Good as the new Reedys may be, I doubt you will need to gear them that low.

[darryl]

hi chris
if you notice mate there is already a thread on mr4 bc gearing in this yokomo section,on sunday at teeside iam going to start on a 21t pinion and an 84 t spur ,that is using a 11*2 ,as i have noticed that a 17/18/19t pinions leave the motor extremely hot
cheers
darryl

[BC Rog]

On a BRM 12x2 off-road I'd run

26/78 for a long track

25/78 for a short track

Indoors, 25/78 works nicely but you must not jam the throttle or you'll cook it!!

On a Reedy Ti I would be 1 tooth lower against an 81 spur.

Hope that helps

Rog

[sosidge]

Last time I ran the BC at Teesside I used 19/84, with a 12 single, but that was on a club layout without much of a straight. They tend to stretch it a bit onto the touring track for the big meetings, so a couple of teeth bigger should be in order.