waitwhat

iTrader: (4)

I don't need anyone to convince me of anything. I let the lap timer determine what I run. You can think one thing feels better or faster, but the lap times are absolute. I've lost track of the number of times a change felt faster only to find the lap times are slower.

You don't care about lap times so whatever you perceive is all that matters for you. Most people on this forum race, so how the car handles when you are trying to drive it as quickly as possible matters to them.

fyrstormer

iTrader: (1)

Do you even read other people's posts before replying? This was already mentioned multiple times.

waitwhat

iTrader: (4)

Yes, you mentioned the complexity, I wanted to show everyone what it looks like.

Sir 51D3WAYS

I still think this idea is worth a punt, especially the second pic with more planet gears to distribute the load. Definitely not the one off the 3000gt vr4 though, anything with a viscous coupling is far too complex for rc.....

Your idea of underdriving would sort of work as well, but the center diff would be working overtime, causing it to overheat and degrade the fluids rapidly. You may have to up the oil wt.

Sir 51D3WAYS

I still think it can be done. RC-Monster.com's problem was they tried to make everything fit in the existing space of the center diff. I reckon this caused all kinds of compromises.....

Horatio

I'm quite certain that a spur can be attached to a diff case, sandwiching a pair of slipper pads/thrust rings using an appropriately sized ring nut for torque adjustment. This wouldn't nesscessitate a new diff design as such - the diff could still be an open gear diff or Torsen - just the way the spur mates to the diff case. The ring nut would allow the out drive to pass through it. Bosh. One centre diff with a slipper on it.

Sir 51D3WAYS

Yes, I was suggesting something similar, but what would the slipper nut thread on to? The outdrive itself? It would need to be seriously lengthened and require a thrust bearing to stop it screwing/unscrewing itself. See ball diff for details. Or a projection from the case itself which is threaded? You're still going to require a lengthened outdrive, as it needs to accommodate the length of the slipper assembly. Possibly a third bearing in the middle to support this beastly creation where said lengthened outdrive exits the diff....

But certainly not impossible!

Horatio

Yeah, I was thinking a threaded portion around the outdrive. I know that space is at a premium on a 1/10th buggy, but I'm sure it could be done without making the diff too clumpy and over-weight. If the bearing carrier and thrust race could be designed to be wide yet shallow, I'm sure it could be made to fit whilst still allowing access to the slipper clutch nut.

There's a lot of people out there that love electric model racing cars. Having a slipper on a centre diff is merely an engineering problem awaiting a design solution.

Sir 51D3WAYS

^You know, I've been thinking of making a torsen diff for R/C. Problem is, I don't have the time, money or machine resources for it. Strangely, I believe small enough worms can be purchased off the shelf.....

Horatio

I remember looking at the Fioroni Torsens back in the day and admiring the engineering. Lots of racers raved about the benefits of them, but complained how expensive they were. Fioroni and Hobao are the only makers of them that I know of. Despite the success of the Hyper 7/8/8.5 sales-wise, they were never really revered as a top racing buggy. Torsens change the way power gets to the ground so much, it requires a different driving style and setup of the chassis. But they're still getting more power to the ground. If harnessed correctly, they have to be faster.

Sir 51D3WAYS

Cutting worms and worm wheels, especially at our scale, requires specialized machinery and tooling. Also it requires very hard steels(high tooling wear) or a subsequent hardening process(industrial ovens).

Horatio

I think anyone entertaining the idea of making prototype Torsen diffs would be wise to contact the manufacturer Fioroni for information on the tool-up, seeing as they did a fine job of making them a few years back. It doesn't look like they're making them anymore though, thus they might be happy to pass on the right tools at the right price.

Jammin sold an upgrade diff too -


This type of design could be scaled down from 1/8th to 1/10th scale and used on the front diff of 1/10th 4WD buggies. If a slipper could be mated to one, then a centre Torsen could become a reality for 1/10th scale also. Due to the way Torsens don't diff out like open diffs, they would be far too punishing to the rest of the drive line without the slipper.

Sir 51D3WAYS

I believe the Jammin one is very similar to/the same as the Hobao one, seeing as they were both distributed under OFNA. You are right about Torsens being potentially brutal on the drivetrain, unless you go all hardened steel drivetrain and gear diffs. Which makes things very noisy.

In theory, if you got the helix angles right, you would have virtually limitless grip, atleast in stock buggy (13.5/17.5). Cornering speeds would become almost completely dependant on anti-roll bars/anti-squat/anti-dive.

Contacting fioroni might be a way, but as I said earlier, I don't have the resources. When I finally do, it'll probably 3d printed (as a proof of concept/prototype).

rcgod

iTrader: (33)

Horatio

The short answer is no. The long answer is that as the load increases in the diff, the diff will still operate like an open diff. The free-ness of the diff will be determined by things like the roundness of the balls, the smoothness of the diff rings and the tension of the diff screw.

If the load increases past the point where the balls are able to roll between the diff rings and start to skid/slip, the ball diff is no longer acting as a differential. The more it skids, the less it acts like a diff.

Imagine your tyres aren't glued onto the rims. If the wheels are spinning inside of them, your tyres aren't acting much like tyres any more. It's just the same with your diff. If your diff slips, it's rebuild time.