Wolfrace Sonic differential problem
Discussion
Right, on the General Gassing forum yesterday somebody asked about the craziest car and I thought about the Wolfrace Sonic. This monster had two rover V8 engines each driving a separate differential that were linked to the rear axle.
Anyway, my point was that the way they were linked doesn't make sense thinking about it today.
The two differentials sat next to each other and were linked by a univeral joint on their inboard halfshafts. Surely, this would negate the operation of the diffs in that, assuming the engines are doing the same revs, when the outer wheel on a corner speeds up, the other halfshaft on that diff slows down which would speed up the other wheel
Sorry if I didn't explain this very well but if I can find any pictures of the setup I'll try to post them.
Does anybody remember the car and/or have any views on how the hell they got it too go round corners.
Anyway, my point was that the way they were linked doesn't make sense thinking about it today.
The two differentials sat next to each other and were linked by a univeral joint on their inboard halfshafts. Surely, this would negate the operation of the diffs in that, assuming the engines are doing the same revs, when the outer wheel on a corner speeds up, the other halfshaft on that diff slows down which would speed up the other wheel
Sorry if I didn't explain this very well but if I can find any pictures of the setup I'll try to post them. Does anybody remember the car and/or have any views on how the hell they got it too go round corners.
wildoliver said:
the engines are allegedly comp controlled to rotate at the same speed (sounds like a nightmare waiting to happen) so the only time the wheels want to travel at a different speed is cornering. but all that will happen is it will act a bit like a locked diff under those circumstances where both wheels go at the same speed so its a bit tail happy.
If i had time i'd be very tempted to try it!
If i had time i'd be very tempted to try it!
That's what I figured, that it would be the same as a solid rear axle. Perhaps that's why it had to have four wheels at the front, just to make the bloody thing go round corners
jwb said:
As Nick Butler built it I guess it would work (I havnt sat down and thought about it yet) as he knows what he is doing.
It had 4 wheels at the front because it was a rolling advert for the Wolfrace Sonic wheels!
John
It had 4 wheels at the front because it was a rolling advert for the Wolfrace Sonic wheels!
John
I did know that it was an advert for Capri 2.8i and XR2 wheels, yes.
but if there was no diff between the two diffs then engine management would be the only way it could work.jwb said:
As Nick Butler built it I guess it would work (I havnt sat down and thought about it yet) as he knows what he is doing.
It had 4 wheels at the front because it was a rolling advert for the Wolfrace Sonic wheels!
John
It had 4 wheels at the front because it was a rolling advert for the Wolfrace Sonic wheels!
John
The problem is that if those two differentials are linked by their inboard half shafts there seems to be a problem. With a normal diff, if the driveshaft is stationary and one wheel is turned the other will turn in the opposite direction. With two diffs and the driveshafts again being stationary the wheels go in the same direction
and even worse, if the engines are running together the only thing that would turn is the middle half shaft If anybody has any knowledge of Sonic please could they help a poor soul understand
jwb said:
I have been thinking.........
With an open diff torque takes the easiest path. So if the outer wheels are on good tarmac then, as you say, the inner sides of the diffs will just spin and you go nowhere. As one diff is spinning its inner shaft then this means the other diff has a very easy job as the inner side is already spinning, and vice a versa.
But if one diff is locked......
John
With an open diff torque takes the easiest path. So if the outer wheels are on good tarmac then, as you say, the inner sides of the diffs will just spin and you go nowhere. As one diff is spinning its inner shaft then this means the other diff has a very easy job as the inner side is already spinning, and vice a versa.
But if one diff is locked......
John
Exactly, one would have to be solid but then that would load more work on that lead to one engine providing torque for both rear wheels whereas the other engine would only provide torque for one. Interesting to say the least
Thanks for the link to Nick's site, this should be interesting. jwb said:
There is one person who will surely know........www.nickbutler.telinco.co.uk/
Ask the man, I sure he will explain.
His site has some other interesting projects.
John
Ask the man, I sure he will explain.
His site has some other interesting projects.
John
Edited by jwb on Sunday 3rd September 15:00
great idea John. Asked the man and got his reply today. What an honour to actually get a response from the man himself
And he also provided a lot of other detail on the electronics etc. here's his email:- Nick Butler said:
Dear Chris, The twin engined idea was not my original idea. Bob Riesner
built a car in (I think) the 70's called The Invader and it had twin side by
side Pontiac engines driving into twin Jag diffs. I don't know how he
handled the problem you describe but this is how I did it: One diff was a
standard limited slip (Power Lock) diff. The other diff was a standard non
limited slip diff inside which I welded up the crown gear to the planet
gears thereby locking the diff completely but still allowing drive from the
pinion shaft/gearbox/engine into the diff. The diffs were connected together
as you quite rightly observe with a central shaft (a very short Jag "half
shaft" ) and that was it. I had the two Borg Warner gearboxes modified by
Borg Warner themselves so that one box (the master) sent it's shift signals
(hydraulic) to the other box (the slave box) This way both boxes shifted
together. The engines were controlled by a "drive by wire" computer which I
had specially made so that the computer looked at the R.P.M. of both engines
via proximity sensors on the flywheels and controlled the throttle opening
via stepper motors. The system was a closed loop layout so that the computer
adjusted the R.P.M. of each engine continuously in response to the throttle
pedal position. So there was no physical link between the throttle pedal and
the engines at all. The gearshift was all electric with just an array of
buttons on the drivers console. The whole start up routine of starting one
engine, stabilising the tickover then starting the other engine and
stabilizing it's tick over then harmonizing both engines together was all
controlled by a central computer console that you could raise and lower
electrically at will. The car was fabulous to drive and had unbelievable
road holding with those 6 wheels. It was a great project which I managed to
sell to Wolfrace Wheels on the basis of a scale model which I made of the
car. Barry Treacey loved the idea and said he would pay for me to build it
if I added two more wheels to the car - the model only had four wheels. The
rest as they say is history. Let me know if you need more info.
Best wishes,
Nick Butler.
Edited by mondeohdear on Thursday 7th September 08:11
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