[StuBeeDoo]

Can someone tell me, please, the difference between SCX's RK-41 motors and the RK-42 version?  My go-to site for motor specs (Slot Car News) doesn't list the RK-42.  For clarity, the RK-41 is fitted in the MGA, and the RK-42 is in various cars - including the Audi A5 DTM and Mercedes AMG C-coupe DTM.

I suspect the -42 is a higher-revving motor, but I'd like to get an idea of how much faster.

Thanks in advance

[Kevan]

A quick google for SCX RK41 brings up an Alixpress page where they're 4 quid each but those two motor types are slightly different sizes.

The RK is 34.5mm long whilst the RX is 38.1mm long

There's some motor data here after a quick google http://auslot.com/forums/index.php?/topi...2b-motors/

[StuBeeDoo]

Thanks for that ^^^ link, Kevan.  

I know that the RK- is slightly shorter than the RX-, my concern is the (potential) speed difference between the 41 and 42 both in the RK type.

[Graham]

Thanks for that ^^^ link, Kevan.  

I know that the RK- is slightly shorter than the RX-, my concern is the (potential) speed difference between the 41 and 42 both in the RK type.

I think you will find the motors were made slightly differently with time, the more recent versions were made more cheaply to save costs. Certainly the fixing of the brushes on the older motors was more robust than the more recent ones.

[Kevan]

One of the big differences will be the gearing each one can handle.  The old RX motors are quite happy to pull 2:1 gearing to get you up to top speed (eventually).  If you want a quick RX motor look for the ones with a 'B' at the end

I've only used one RK and thought it was slow...but smooth.

[Mr.M]

I think the difference between 41 & 42 motors is not in performance, but fitment, whether RK or RX. 41 is for solid chassis, 42 is for podded.

[StuBeeDoo]

I think the difference between 41 & 42 motors is not in performance, but fitment, whether RK or RX. 41 is for solid chassis, 42 is for podded.

Thank you Mr.M! 

I was coming to that conclusion myself, having looked at my stock of RX- motors and pictures of RK- motors on the 'net.

[StuBeeDoo]

Sorry for bringing this subject up again...........

I now know that "long can" motors (such as the NSR Baby King) can be used to replace the RK- series.  

But does anyone know of a long shaft version, other than the Avant Slot AS20107 "Hunter", which could be used to replace the RK-91 in the SCX Fiesta WRC and DS3 WRC and still keep the 4WD?