Houston, We May Have a Problem

[stoo23]

When last at HSC, I took the opportunity to purchase a couple of 'Retro' Class motors, one of which, was a 'New' Plafit Cheetah II motor.

At the Time, James suggested that he Only had "these New Cheetah's",..which apart from all the other 'nomenclature' on the packaging, included what appeared to be a Later Stamped 'D',.. BUT,..the biggest and most noticeable difference, is in the Can and the shape of the Hole, which would appear to be similar to the recently released 'Fox IV' motor.

Being somewhat circumspect, regarding the ongoing performance similarity of apparently, 'cosmetically 'Updated' motors, I became even More concerned, when I noticed the Motor I had purchased as a 'Cheetah II', was Actually 'Marked' on the Can as a "CHEETAH IV" !!
I decided a quick 'Performance check' was warranted.

As I had 2 x New 'Older Style' Plafit Cheetah II's to compare with I headed off to the track to do a Back to Back test.

First up, I gave ALL 3 motors Exactly the Same 'Run-In' process and Time on the Power Supply, Prior to track testing and instantly Noted that the Older motors were producing a slightly higher 'pitch' / Rpm at the same Voltage,.. never a particularly Good Sign,..

At Raceworld, with the Same car, Tyres, gear Ratio (9:28), etc, etc and an appropriate Retro Voltage, the New Motor, was Extremely dis-appointing, appearing to have Very Little 'Urge' as such and seemed Generally Slow.

The BEST the New motor could Produce, was a 5.385.

Time to 'compare',... I installed one of the Other New True Cheetah II's and Instantly Noticed it had More 'Urge' at take off and produced Consistent laps in the Low 5.0's !!
I then replaced it with the Other older True Cheetah II and found it Also performed the same,.. Also producing a String of Low 5.0 second laps.

After once again installing the Cheetah IV motor,..we were Back up to the High 5.3's !!
Not Good !!,..

Because of the Obvious 'Differences' between the Two motors I went 'Searching'.
Perhaps Typically, it was / is almost impossible to actually Find Any Plafit 'specific' information !!!

You know, if one could Not actually Hold in one's hand Any product from this company, one Could be forgiven for believing it actually Doesn't Exist !!

BUT,.. the Only 'references' I could find regarding this New 'Cheetah IV', was on a couple of Euro' Slot Shop sites, where BOTH the Cheetah II AND Cheetah IV were listed, With the relevant Spec's being 'listed' as;

Cheetah II; 35,000 rpm at 12v
Cheetah IV; 33,500 rpm at 12v

Whilst Not even considering the fact that a Motor that is Obviously considerably 'Different' (and MARKED as such),.. would / could be 'Supplied' as a Cheetah II, it is a somewhat Problematic situation for the performance equivalence etc, that has been enjoyed previously within the Retro classes.

I don't know about how the Rest of the Retro racers would 'feel' about this,.. but am Pretty Sure,..No One would Want to have a Slower Motor !!!!

I must admit, it also made me wonder just How the upcoming APC would deal with this 'change',.. only to find that the classes that Previously ran Cheetah II motors, such as Plafit F1 and JGT, apparently No longer do and Now run a Fox IV motor and am now unsure whether Cheetah II's are used at All in the APC classes.

Anyway,.. just thought I should 'Put this out there', for all those interested / concerned regarding the Performance of these New Motors.
Maybe get one from James and do your Own testing.

I intend to head to HSC and do further testing,.. but from what was evidenced by myself and Cody yesterday, leaves me somewhat concerned, as unlike the Fox IV replacement for the Fox II, It does Not feel like This New Cheetah IV motor has More Torque or Brakes.

With some fairly serious and important Retro races coming up,.. perhaps we should all be rather careful with the Older Cheetah II's we currently have !!

Obviously,..Some discussion should occur regarding this 'Unfortunate' change, so as Not to inadvertently dis-advantage anyone.

I will 'post' any further testing 'Outcomes' etc, ASAP.

[dtslot]

Hi all, Darryl here, at the JULY retro race at HSC, I turned up with the usual 2 cars for each class ,and lack of prep found all of my cars running poorly. Bought 2 of the new cheetah 11 ? and without a run in got 5.3 in f1 and 5.2 in coupes. I was happy with that, so I bought 2 more motors that night. Next round same motors saw 5.2 s f1 and 5.1 s coupes and thats as good as it gets for me....so I bought 2 more motors to share the wear. So what I've got goes as well as as any of the older originals,,,,,and I think most of us have had the one off "gun motor" from time to time. After a good clean up my original motors are running well also so I do have a few to choose from , lucky me.

CHEERS DARRYL

[stoo23]

Hi Darryl,
So the 'New Cheetah II's you have purchased Recently, are they Marked on the Motor as Cheetah II's, or as Cheetah IV's ??

[dtslot]

STOO, Just checked and they are marked 1V. Also hooked up to 12 v and the sound pitch sounds about the same... comparing 2 x new motors to 4 x older ones ,, but there again I am a bit deaf and certainly blind. Still have some not out of packet yet.

Darryl

[Mark Fox]

Hi Gents

Very interesting discussion - it would seem that Stoo will need to test at HSC as the requirements of the King track will, in my opinion, tell you nothing about overall performance around HSC.

It's promising that Darryl has consistent times with the 'old' and the 'new' - if they are indeed any different.

Maybe a really accurate electronic analysis - resistance of arm, current draw, tacho reading etc over a reasonable sample size will help determine if there are any differences.

On the subject of times at HSC I consider that in the 5.0's is a really good motor whilst in the 5.1's is not at all shabby (for Can Am and Coupes) - depends a bit on the conditions as well of course.

Look forward to more feed-back on this.

[stoo23]

Hey, thanks for your 'Input' Darryl !!
That is certainly 'encouraging' to hear.

I was Not aware that James had the New motors back then, I must have purchased some of the last 'batch' of Older motors around the same time ??
I must admit, I Too have a whole 'Pile' of Older Cheetah II's, Many of which are probably/possibly,.. 'Pearlers' !!,.. ,..well I Hope some of them are !!,..

Hey,.. I Know what you mean Mark, regarding the 'King' track but it was really only because of 'proximity' and a very 'direct' and simple way of comparing a 'few' Apples, from the Same Box, as it were.

Perhaps,.. (as would seem to have been rather 'typical' of My luck with Motor purchases of late), the Cheetah IV I tried, may Not really have been a very good one !!,.. lol

Hopefully, I will have the TEKIN Motor checker up and running in the Next few days, so may be able to provide a more definitive comparison.

But,..atleast,..from what Darryl has 'suggested',.. May NOT be such a Big problem, Performance Wise,... On Track as such

[stoo23]

Hi all.

Happened to pass by HSC the other day whilst traveling home and mentioned all of this to James.

Whilst obviously Aware of the different 'appearance' of these New Cheetah's, he had NOT Noticed that the motors 'in the Bag', were Actually 'Marked' differently and as it transpires, (after apparently having contacted Werner at ACE Hobbies), either was He !!

It would appear this New 'style' of motor, (similar in style of construction to the New FOX IV), will eventually Replace the 'Older' style Cheetah II but was not expected to 'arrive' as such until later.

As had been 'noted' on closer inspection and Also similarly to the New Fox motor, the Commutator appears to be slightly different, as is the Brush 'Gear' and 'Material', so perhaps Also like the Fox IV, may take Longer to 'Run In/Seat well' as such.

The overall 'Specifications' of the Motors Are different and once again, like the new Fox motor whilst having slightly Lower 'Quoted' RPM, apparently, has slightly more Torque ! so perhaps some experimentation with Gear Ratios may result in suitably appropriate On Track Performance !!??

Whilst there Are apparently Still some New Cheetah II's about, James Does have a Whole 'Bunch' of the Newer Motors, so 'Supply' should Not be a Problem, if they Prove to be at Worst, similar,.. if Not,....... Better,..

CHEETAH II
8631 - 35,000RPM at 12V, 147gm-cm torque.

cheetah2.JPG (21.76 KiB) Viewed 10016 times

CHEETAH IV
8631D - 33,500RPM at 12V, 185gm-cm torque.

cheetah4.JPG (84.08 KiB) Viewed 10016 times

[Mark Fox]

Well what a huge pain in the Proverbial.

Hopefully the 'new' motors will be ok against the 'older' - however they are at this point illegal of course as they are NOT Cheetah IIs

Unfortunately I will not make the next Retro round as I will be at a wedding (yes it seems people still do that).

[jcol56]

The Cheetah II motor has been discontinued, is no longer available from the Australian Distributor and is not being produced by Plafit. It has been replaced by the Cheetah IV motor, which is the new spec motor for Aussie Retro on the Hornsby Slot Car road course. It is OK if people still have Cheetah II's to run those as well as the IV's for the time being (until they run out). Interesting to note the Cheetah IV has considerably more torque than the II, but down on a few RPM's and harder motor brushes. It has been recommended that a shorter gear ratio be used to fully maximize the additional available torque.
James C.