PB Mini Mustang Refurb

[Dadio]

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.

Am I right in thinking that the HPI two speed has a pawl that pivots out more like ratchet or a dog clutch ?

[Incredible_Serious]

If you'd like some more comparisons.....

This is Schumacher U1399Q, the 2-speed setup for the Daytona.

Later came U1665X (offroad) / U1666Y (onroad), the 2-speed setup for the later mk.3 Nitro 10 range.

The first version is pretty much a copy of the PB 2-speed, while the second generation has some slight changes...

Alex

[GoMachV]

Am I right in thinking that the HPI two speed has a pawl that pivots out more like ratchet or a dog clutch ?

Yes, a pawl instead of shoes

[Dadio]

The first one is exactly like the PB two speed but fitted with a second one way bearing as I tried but its for a nitro engine that's incapable of running backwards so it could never lock the transmition , the second later one seems to be like the HPI version or probably vice versa .
I love learning all this stuff thanks for sharing it guys , I think the PB version is a more elegant design as it would have a more gradual engagement than the later Schumacher or HPI design , those would both be quite a violent on off switch as the pawl engaged or disengaged . When holding the mustang and revving it up the engagement of second gear is quite sudden but when driven its easy to miss the exact moment of gear change as its fairly smooth , I found so far its easier to hear it change down and certainly you notice the cars attitude in a corner change more than you hear a change of revs .

[coxbros1]

Just read this whole thread....real decent read!

[Dadio]

I had to get a Mini Mustang body to fit over the 2 speed gearbox and i redesigned the gear cover as well to prevent dirt getting in , i was not too bothered about an open spur gear under the Maxima body but the 2 speed setup might suffer more if sand gets in .







Again it was really hard to get good pictures , the orange looks more pink than in real life and the meta flake really sparkles .

[Dadio]

When the new Mini Mustang body arrived I expected to have to swap back to the original undertray that came with the car as it was very different to the one I got with the Maxima so I assumed it was a Mini Mustang one .... But its not , the Mini Mustang body fits perfectly over the undertray for the Maxima , the undertray that came with the car was definitely designed for the PB Mustang group of cars as its fitted around the transmition at the front so I'm guessing its for the Eco version , I think mine was an Eco originally as it had plain plastic bushes at the diff's and I think both the original Mustang and Maxima had propper bearings there so this odd shaped undertray supports that unless anybody knows differently ?

[Dadio]

Today we finally got a good head to head speed run test with my Mini Mustang and my friends CAT , it was interesting , the gearing on the two speed transmition needed a little tuning or rather the ESC settings , maybe both but the upshot was that second gear was not always engaging , when stuck in low gear the Mustang was a little slower but in high gear it was almost equally faster , made for an interesting afternoon , I had the pre tension on the clutch springs a little tight and the punch turned right down on the ESC , I've tweeked both now so next time it should be different one thing that shocked me was that I wore 1/3 of the tread of a set of Hot Shot Oval Block tires ! I don't think I've ever seen a worn out set of Oval Blocks !

[Dadio]

My belt snapped , it was NIB but 30+ year old rubber is never going to be good , so I started looking for a new new one ,firstly I looked at the parts list scan on file here and it says its a 215 tooth belt ..... I counted the teeth on the broken belt .... Five times, my wife counted twice and between us settled on 317 teeth not 215 as suggested , anyway then i measured the length at 646mm , did a little math and its an MXL pitch so I started looking for a 317 tooth MXL belt .........no modern equivalent that I could find so I've ordered a 254MXL that's 318 teeth , my guess is I can more easily take up an extra 2.03 mm than cope with an over tight belt as the next size down is a 252MXL at 315 teeth or 4.06mm shorter , why do manufacturers use such odd sizes for everything rather than fit the design to an off the peg part ? Anyway I'll let you know how it goes .

[Coelacanth]

I had to get a Mini Mustang body to fit over the 2 speed gearbox and i redesigned the gear cover as well to prevent dirt getting in , i was not too bothered about an open spur gear under the Maxima body but the 2 speed setup might suffer more if sand gets in .

Again it was really hard to get good pictures , the orange looks more pink than in real life and the meta flake really sparkles .

I really dig your paint job, very nice color choices. You're right, metal flakes don't picture very well unless in bright sunlight. The only things that brings down the looks are the wheels...not because they're Tamiya, but just that bland off-beige color takes away from the overall appearance. Maybe if they were dyed black? Can you even dye Tamiya wheels? I imagine they might be ABS plastic rather than nylon. Beautiful body and car, regardless!

[Dadio]

I've managed to get a set of stock wheels now , still running Tamiya boots though just because i used to love the Pin Spike tire back in the day .

[Coelacanth]

Now you're talkin'! That's looking awesome. I like pin spikes too, I put those on the Marui Shogun I'm working on, but I don't think mine are Tamiya...the spikes are staggered instead of lined in rows. I honestly can't remember who makes them.

[winner_evo]

Hello mate,

The 2 speed isn't in the main PB manual but a printed supplement is included. If you don't have it, here's a copy of it explaining set up and brakes.







I haven't got my car running fully yet so I haven't tried any of the 2 speed settings.

[Dadio]

Thank you very much , I've seen the exploded view before but never the instructions after reading its clear I've been adjusting it to change gear much later than it should , i had it adjusted to come in when first gear virtually topped out but it should come in after just 2 meters or so .
Its really odd to see the mixture of imperial and metric components they used as well , very much of its time , i learnt both in school as well and i always think its odd how i measure things , if its very small its in mm up to maybe 20mm then its feet and inches up to about 2 feet , after that its meters but i skip kilometres and go to miles after that , all makes sense to me .

[Dadio]

Thought I'd resurrect this thread to share a few bits I've been working on . Firstly the belt , i broke my original 30+ year old belt so i started on an odyssey voyage to find a modern replacement , firstly trying a belt off Ebay that was listed as suitable for the PB Mini Mustang and Maxima , the stock belt is an MXL pitch with 317 teeth and about 4.8 mm wide , these are just not made any more , you can get 315 or 318 teeth both in 6 mm wide , the Ebay belt was 315 teeth and 6 mm wide , 6 mm wide belts wont fit in the pulleys ! so i thought I'd cut 1 mm off , bit fiddly but i did it and fitted it , the tensioner was hard on its limit from the start and the belt lasted for only about 20 feet ! so a bit disappointed i started searching and found a supplier of the 318 tooth belts , ordered 2 as they cost fairly little , anyway they arrived and once again were 6 mm wide so i started to look at what i could do to make it fit , the diff pulleys have a convenient design that has a side disk that holds in the planetary gears and is also the belt guide fence .

So looking at the transmission case there was no width restriction at the diffs so i designed a spacer to go between the pulley and the guide fence .

this spacer is only 0.8 mm thick but the belt fits perfectly after its fitted .
Next was the drive pulley for the belt and again the guide fences are just a little to close for ac 6 mm belt so i designed two new fences , the original ones are just press fitted and lock into a groove , they take a bit of prying off but they are made of the soft plastic that's used all over these cars so there was little fear of braking them , it took a few attempts to get the fit tight enough but still easy enough to fit .

You'll notice if you look closely that one has a cut out for the set screw as once made wider the fence would cover it .
The only other thing needed was to remove a little material from the transmission case just above the battery hole , there's just a small belt guide there that needs widening by 0.5 mm either side .
Now i can use modern easily found belts YAY !
Next i finally found a front bumper mount , its a little rough but usable so i needed a new bumper to suit so i modelled this one up , its not a direct copy as i don't have one and its narrower than stock but racers generally cut them down anyway .





All the above parts were printed in CF Nylon , I'm going to model up the bumper mount itself when i can find the time .