2wd layout

[sam690]

Has anyone ever thought of creating a mid motor belt driven 2wd buggy?

[roboliver]

i have been working on the idea for a while as the belt drive design i belive will give a wrap up effect i dont think it wil be the way to go i do belive since its such a short distance a chain drive will be a better effect as it will try to sling itself away and i think will give the car a effct as that of putting a brass weight on the slipper

[8rad]

I have a mid motored Topcat in the works. It is going to be absolutely sick. Custom alloy chassis, belt drive, big bore shocks.

I will post some pics in a while.

[dodgydiy]

belt drive used to be ok in a 2wd, it does actually help cushion the kick of the motor. chain drive is awful, had an old rc10 with the mip chain drive, any slack on the chain at all and it just wheelied everywhere, even with a slipper. the kick of the slack being taken up was much too severe then, so i dread to think what it would be like with modern motors

[RLGfx]

been there, done that.... ran it once then headed back up to scotland where we don't play with toys...

Mine is based on a hybrid of the Yokomo MX4 and the Kyosho RB5 (metric cars FTW)

http://oople.com/forums/showthread.php?t=42080

went well, i was rusty as hell driving!

Needs fixing, and more droop at the back and it'd be reet. Planning to get it running again, so I need to get -

new rear shock tower to lower top shock mounting positions (Will be home made so will probably look pish)
new rear belt (old one was from a well used MX4 and was bobbins)
new rear diff pulley (see above, it killed it)
adjust motor mount to give option to run bigger pinions

[HyperDunley]

Back in the day of the Losi JRX2, Losi released a product called Hyperdrive, which didnt really take off in the UK.....

I have done some digging around t'internet and not been able to find much, however I did come across this link:

http://www.rc10talk.com/viewtopic.php?f=35&t=17704

Not massively related to the thread, but interesting anyway (I think so.... )

[roboliver]

i belive you are refering to the losi hydra drive .this was a oil filed slipper type clutch that helped smooth out the delevery of the motor reson why it lost popularity was the added weight ,schumacher also made a similar device in the late 80 early 90's for the cougar and fireblade with the power of the todays brushless motors and batterries i belive this could once again be a usefull tool to aid in mid motor mounted cars

[Highoctane1981]

Originally Posted by roboliver

i belive you are refering to the losi hydra drive .this was a oil filed slipper type clutch that helped smooth out the delevery of the motor reson why it lost popularity was the added weight

The weight would be a good thing in a 22 now.

[RLGfx]

Originally Posted by roboliver

i belive you are refering to the losi hydra drive .this was a oil filed slipper type clutch that helped smooth out the delevery of the motor reson why it lost popularity was the added weight ,schumacher also made a similar device in the late 80 early 90's for the cougar and fireblade with the power of the todays brushless motors and batterries i belive this could once again be a usefull tool to aid in mid motor mounted cars

Nope, he means the HyperDrive, it was a belt drive system that was used in place of the pinion/spur. Hydra Dive was something completely different, and a much later development.

[mr. ed]

I've been trying to put together a mid-moter 2WD with belt drive. And I'm not talking about a belt to the diff; I want to something like the hyperdrive.
adding the belt between the pinion and spur has the same effect as the infamous 4th gear.
The hard part is to combine everything with a decent slipper set-up.

[Mb3195]

We ran a cat XLS with the front diff removed using two belts to drive the rear diff, absolutely awsome on carpet, so fast it regularly beat 4wd even at "open meetings" ................cr4p offroad

motor belt drive would give very limited gear ratios.

[RogerM]

Originally Posted by Mb3195

motor belt drive would give very limited gear ratios.

Would give the same range of ratios so long as you could keep the tooth counts simialr to the geared option. Plenty of fine pitch belt systems out there to allow that.

[Mb3195]

Yep, they work on nitro where the power comes in via a clutch and there is power to spare but fine belts would slip with the punch of an electric motor, you would need to run them very tight but that would sap power.

Also, how would you get the correct final drive ratio?, the pinion pulley would be tiny and the drive pulley huge.

[RogerM]

a 20T pinion to an 80T spur is 4:1 * gearbox internal (say 2.5:1) = 10:1 overall

a 20T pulley to an 80T pulley is 4:1 * gearbox internal (say 2.5:1) = 10:1 overall

There are other ways of keeping the belt in contact than tension .. a bearing on the belt surface mounted such that it didn't touch until the belt start trying to climb the teeth on the pulley but still close enough to prevent the teeth from jumping would work fine.

[mr. ed]

Originally Posted by RogerM

a 20T pinion to an 80T spur is 4:1 * gearbox internal (say 2.5:1) = 10:1 overall

a 20T pulley to an 80T pulley is 4:1 * gearbox internal (say 2.5:1) = 10:1 overall

...

No need for fine pitch belts and keeping the same teethcount either:
a 15 teeh pulley against a 60 teeth pulley gives the same 4/1 ratio

[Mb3195]

Originally Posted by mr. ed

No need for fine pitch belts and keeping the same teethcount either:
a 15 teeh pulley against a 60 teeth pulley gives the same 4/1 ratio

But why would you want a pully drive belt and a gearbox, the other way around would be more efficient

[reflexuk]

Efficiency is no longer the be all and end all it used to be with modern electrics. The problem with a Hyperdrive is the belt wrap around the pinion which is minimal anyway the more teeth the better here if more teeth equals more grip. Really the transmission ought to mimic a 12th car - but with a belt.

Does it matter which way the rotor is spinning in relation to the rear axle?

[RogerM]

Originally Posted by mr. ed

No need for fine pitch belts and keeping the same teethcount either:
a 15 teeh pulley against a 60 teeth pulley gives the same 4/1 ratio

I was just keeping things simple

Benefit to fine pitch belts is that they are a little happier being wrapped around small (pinion sized) pulleys but correct, not essential

[RogerM]

Originally Posted by reflexuk

Efficiency is no longer the be all and end all it used to be with modern electrics. The problem with a Hyperdrive is the belt wrap around the pinion which is minimal anyway the more teeth the better here if more teeth equals more grip. Really the transmission ought to mimic a 12th car - but with a belt.

Does it matter which way the rotor is spinning in relation to the rear axle?

If you mean a direct drive like a 1/12th (just 2 pulleys and 1 belt .. done) then you would need such a large rear pulley to get sensible ratios that the diff height would be huge, not good for many reasons. By using a gear box the diff can be more compact and thus mounted lower which makes loads geometry options possible that simply wouldn't work with a larger diff.

As for does it matter which way the rotor turns relative to the spur/slipper & wheels the simple answer is YES.

Not 100% but in a nut shell if using a traditional 4 gear transmission you will generate more rear traction and the expense of keeping the front end loaded (thus lossing on power steering), if using an 'external idler' set up or the 'hyperdrive' type set up the result is slightly less traction but less front end unloading ( thus more on power steering).

I personally prefer the later, hence why Scorpion runs external idler.

[mr. ed]

I've finally gotten my hyperdrive parts and after some fiddling with different gearboxes found the A&L Lethal Weapon is a near direct fit.
Now I just need to figure out what alse to use with this and we'll see a twin belt (innner and outer) mid motered buggy or truck or SC...