does anyone have photos of one of Fred's diffs disassembled? I want to see what's in it - IE what happened to the cross pin? how are the spider gears held in place?

here's one assembled (thanks Mick)

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did I tell you that I won a trophy?

ah... here are instructions on how to install the MiniMania one - should be similar, but Fred's seems to have one big spring, which still makes me wonder where the cross pin is


http://www.minimania.com/ArticleV.cfm?DisplayType=Technical%20Information&DisplayID=1468&SCatagory=GEARBOXES%20%20%20%20%20%20

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did I tell you that I won a trophy?

looking at it i would say it has a VERY strong spring in it and under extreame pressure it would allow the diff to "slip" but under mild pressure the spring would overcome the pressure of the different wheel speeds when turning and lock so to speak.

i do not see a pin in there either

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100% Pure A Series Turbo
Morris - The Original RedBull Racing

The spring that can be seen is not in the middle, perhaps there are 2 springs (as opposed to 4 in the phantom) and the pin runs between the 2 springs.

Cheers
Steve

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1964 998cc Cooper
1971 Mini K x 2
1972 Clubman GT

I've just looked at the pics again and if you look properly the pin can be seen in pics 2 and 3.

Cheers
Steve

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1964 998cc Cooper
1971 Mini K x 2
1972 Clubman GT

I think you may be right..... I saw that and thought the plates might have been V shaped in the middle, but its probably a reflection

you're right about the way it works Grant... I'd assume you'd want the springs to be as strong as possible, because any regular slip would grind the plates against the output shaft gears and make a mess in your gearbox quite quickly

no doubt Fred has done a lot of R&D with it - I'd love to see one pulled apart after a few years of work

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did I tell you that I won a trophy?

When I sent it to Fred to have it done, I also send a brand new pin, so it had better be in there

Fred said that mine was on the limits of wear in the sun gears and hemisphere for the machining that he does. I am guessing that the distance between the driveshaft gear faces determines the compressed length of the spring and he needs to machine it flat or some such.

The springs in that Minimania one look like valve springs, and even though there are four of them, I reckon the ones in Fred's diff are exerting a lot more force.

When I got it back from Fred, I stuck it in the vice and tried to turn it with the torque wrench to see what torque it took to make the plates move relative to the hemishpere. I failed to move it even with a four foot long bar on the socket.

It works really well on the track, and from what MrBob used to say on the dirt as well.

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Do these things put much swarf in the oil?
Unkind people have termed the MiniMania Phantom Grip one `a lathe in your diff/gearbox'...

Which wouldn't necessarilly be all bad, but the engine's oil pump sucks its oil from there..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

These diffs are referred to as "cone" diffs, the diff hemisphere and crown wheel are machined where the original bushes run to accept a tapered bronze? "cone" that is pressed onto the output shafts. Under pressure from the middle spring and drive, the cones grab on the tapers and lock-up creating a "limited slip" arrangement. As I understand it, the spring in the middle is a recent development, the much earlier ones didn't have the spring in the middle.
I bought a LSD "cone" diff in the early '80's in Brisbane that did not have the spring in the middle. I had it converted later to accept the spring thing.
It worked quite OK and I do not believe it acted as a "lathe" in the sump to answer Kevin's question. I sold this diff to Ozmotorsport a few years ago now.

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Steve

I don't think the phantom grip works quite that way, it just jams the side gears into the stock hemisphere. So I've been told.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I guess there's a reason why it's called the phantom grip then . . . . .

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Steve

that's certainly the way it looks - hence I'd like to see one disassembled after a few years.

As Mick found, I'd expect it to be almost completely locked

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did I tell you that I won a trophy?

no swarf at all in my oil so far. when i changed it after running in, there was the usual. but after 2 hours on the track at Wakefield, the oil is crystal clear.

Because Fred machines the hemisphere or drive gears to accept the cone (not sure which, maybe both), as i said you cannot use a diff that has too much wear, even if it had the washers in there originally. The instructions for that Minimania one do not indicate any machining of the diff or drive gears, and there is no cone inserted......

GR says that Fred's diffs are good, which is what swayed me to get one rather than saving 3 times the money for a Quaife or Salsibury (second hand at that!). For $450 delivered (supplied my own used diff) I don't think you can get a better budget option.

cheers

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

So when one of these locks, does it lock suddenly? And pull the wheel out of your hands or is it more a gradual thing?

Cheers,
Alex

no they`re quite a nice diff to drive, very forgiving & don`t thrash your arms

They`re pretty long lasting too, i`ve known people still have these diffs after many many years of use

i use one myself in my street/club car

Freddy is not silly, he knows his stuff

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.