PB Mini Mustang Refurb

[Dadio]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

[Incredible_Serious]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

I should have all of those parts spare... let me have a look.

Alex

[Dadio]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

I should have all of those parts spare... let me have a look.

Alex

You might just become my favourite person

[Incredible_Serious]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

I should have all of those parts spare... let me have a look.

Alex

You might just become my favourite person

That's a dangerous place to be......

[Incredible_Serious]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

How does this look, mate?

Alex

[Dadio]

I'm all ears , whatever you know please tell me , sometimes I forget how much knowledge is here on offer , and anybody with spares for the 2 speed system , I need the clutch shoes , clutch drum and the 54 tooth gear

How does this look, mate?
20191208_211247.jpg



Alex

Looks a bit like Christmas , shoot me a PM with the price I like the price of the middle bit

[Dadio]

I met up with a friend and took the cars to a quiet sandy car park nearby , its the first time I've driven it off road and apart from throwing the belt off the front diff it all went well , reminded us both of my old Hot Shot a bit , that might have been the tires talking though but its really easy to drive and not much slower than my friends brushless , lipo'd CAT ! Mind you he got 30+ min run time and I only got about 6 or 7 min but I took other cars along ....to break , I had a broken Zerda and a broken 3d printed Dogfighter by the time we went home .

[Dadio]

Just found out why the belt came off at the weekend , it seems the 30+ year old belt has failed , outrageous ! May have to demand my money back from eBay I've already got one spares coming , a genuine vintage one that may or may not be much better and a modern one that's 6 mm wide so will need trimming .

[Dadio]

A new belt and spur gear arrived today so I swapped out the belt and WOW what a difference ! I need so much less tension on it , probably because it has teeth on it lol !

[Dadio]

Thanks to Incredible_Serious I now have a fully functioning Two speed transmition , its too dark to test drive tonight but I can hear it change gear wheels off the deck .
One slightly annoying thing that I should have seen coming was that the body won't fit over the two speed assembly , it a Penguin Maxima body , I'm loath to cut it to get clearance ! The reason I should have seen it coming was that I could not fit the gear cover I made for it under the body , i just guessed id made it too big so I took it off but then I couldn't fit the body over the mounting post for the gear cover and that's a stock part so I knew the body was a close fit but even without a gear cover the body won't fit by a mile .
Not sure what to do ......

[Dadio]

I was going to meet up with a friend and take the cars to a local car park to check out the two speed transmition but that's fallen through but I did get the chance to try it in the road outside , I couldn't get it to a top speed cruise as there just wasn't enough space , its for sure the fastest brushed motored buggy I've ever driven , very strange too , there's no breaking at all from the motor so you need to really think ahead as the only quick way to scrub speed is a broadside slide , its almost like a radio controlled ice skater ! I can see from this exactly why people who raced the PB cars favoured the normal single speed setup , previously from what I'd read I had the impression that it was the unpredictable nature of the gear change effecting over/under steer but the complete lack of breaks must have been really hard .
In all honesty I'll probably switch back to single speed eventually after I've had a good chance to fully understand its ways , I'm so glad I'm able to try it and for me its really iconic of the car in my memory and owning a Mini Mustang without it would never have seemed complete or a finished car , it will mean getting a Mini Mustang body for it as well though .......damn

[Dadio]

Just a few pictures of the two speed installed and a little description of its function for those who are curious .


The way it works is with a double pinion on the motor that drives two spur gears , the larger spur for low gear is fitted to a one way roller hub that drives the spindle initially.


behind this there is an expanding clutch similar to the centrifugal clutch on a lawn mower although its not a true centrifugal clutch .

this clutch comprises of two semi circular shoes that are forced outward to engage on the inner surface of a drum to transmit drive , the drum is fitted to the other smaller spur gear for the higher gear , when not driven by the clutch the drum freewheels on the spindle on plain bearings , the clutch shoes rotate with the spindle and are forced outward by ball bearings that sit half in the shoe and half in a groove cut into the edge of a central hub that's locked to the spindle , two springs and screws hold the shoes inward around the hub and help control the rpm that a gear change happens .





As the central hub is spun faster the ball bearings move from the center of the groove toward the edge forcing the shoes apart and locking them onto the inner face of the drum , as i said its not a true centrifugal clutch but one operated by a rising ramp effect that's more torque driven .
Once the clutch engages it locks the smaller spur to the spindle for the higher gear , the larger spur is now over driven and so freewheels on the one way roller bearing that it was driving with initially .

[Dadio]

I had another drive today with the two speed transmition and was thinking about the lack of breaks , I had a thought , what if I replaced the ball races in the clutch drum with a one way bearing , my thinking was that if I fitted it to engage in reverse then it would not only make second gear work for reverse but also give it breaks ..... It didn't work , it was still fine forward but locked up the transmition completely in reverse ..... Oh well

[GoMachV]

That is how HPI designed their two speed, and it works great so long as the car NEVER rolls backwards- under power or not. If you do it will strip the spurs or tear up the oneway as the oneways would be pitted against each other. Its hard to tell in the pic but the "clutch bell" contains the second oneway bearing.

[dinglem]

Thanks for posting all of the above relating to the 2-speed set up guys. Fascinating posts and pictures, and great reading.