Colotti-Francis Gearbox

[mk1]

I had one of these years ago, beautiful watch like thing it was & reputedly about as reliable as a Chinese Rolex. Very fragile, I never got it working & eventually sold it on to someone else who never got it working either.

[Vegard]

Wouldn't this be perfect on a seriously high spec 970S. No torque means more gears needed

[mk1]

It certainly would,. but I bet you it would still break.

[Vegard]

How could it be so much weaker than an originale 3sync?

Hmm now off to find out if I can use it on a FIA 970S

[mk1]

How could it be so much weaker than an originale 3sync?

Everything is thinner, smaller, weaker & above all it's made in Italy!

[Vegard]

How could it be so much weaker than an originale 3sync?

Everything is thinner, smaller, weaker & above all it's made in Italy!

[ivor badger 2]

Wouldn't this be perfect on a seriously high spec 970S. No torque means more gears needed

That's where they got fitted. Completely unnecessary on a 1275.

[mk1]

The only person I know first hand to use one in anger was Neville Trickett.

He used one on his very well developed 970 circuit racer during the 1965 season. He said that it was nothing but bother & it cost him far more races than all other mechanical failures put together.

[ivor badger 2]

The only person I know first hand to use one in anger was Neville Trickett.

He used one on his very well developed 970 circuit racer during the 1965 season. He said that it was nothing but bother & it cost him far more races than all other mechanical failures put together.

Bill Bor.rowman of Sportstune fame used one to good effect.

[59fan]

Just a quick update on my Colotti in case anyone is interested.

I've done just over a 1000 miles with it this year and all is well so far. Mostly road mileage but i was out on the track at Blyton last year. I built a rudimentary gate to stop me going from 1st to reverse but now I've got used to the box I don't really use it.

Its running with a magic wand and works very well, the gears are very close so you need to be careful but its super precise, it's not a great road box but is fantastic on the track.

The only issue I have had is that it very occasionally pops out of fourth immediately after changing up from 3rd, I've put this down to character.

I'm currently running a 3.7 diff due to the confusion over the ratios highlighted in this topic, I am going to pop a 3.4 in over winter to improve the cruising ability as Blyton is a bit of a trek for me and I need to keep the revs down due to the blower.

Ian

[ianh1968]

That's great that its all going again...

The image below is from the "Ratios" spreadsheet, found on the main MK1 site
Here:
http://mk1-performance-conversions.co.u ... anical.htm

It shows the gearbox speeds for 3.765 and 3.444, assuming:
1) The box has the 2.76 ratio for 1st
2) Direct ratio drop gears, ie 1:1
3) Max revs has been set to 7000 for the intermediate gears and 6500 for 5th
4) Yokohama A008 165/70/10 tyres

Ratios.006.png

You can click it a couple of times to make it bigger,
Click the "Back" button on the browser to return to the post.

Mark F - You are a technical Genius


(The other) Ian

[R&R]

Does anybody remember Roy Marriott from Scunthorpe and his 997 Rally Cooper with Collotti Francis gearbox and ingenious method of separating engine from the box in car. He's told me about it on a few occasions, and I suspect he still has it somewhere. Apparently he made it so he could remove the engine easily without having to remove the flywheel, never understood quite why, but perhaps the Collotti box is the answer!

[618AOG]

Given that the Maxi engine and gearbox will fit into a Mini automatic subframe, and that a working Maxi gearbox is worth all of 75p on a good day, I'd imagine that modifying the Maxi gearbox casing to accept an A Series engine wouldn't be beyond the wit of man. The Maxi E Series engine was very narrow - narrower (length ways) than the B Series because BMC designed it to fit under the bonnet of various cars as a six cylinder. It's also very strong and coped easily with both the 95 bhp Maxi HL and the 150 bhp Lotus Elites that used Maxi internals in their custom made Lotus casings.

The Maxi unit (also used on the 1500 and 1750 Allegro) also housed the engine oil pump, driven from the crank by a quill shaft - this can be binned and an oil pick up pipe made up.
As for modding the casing - clever folk than myself managed to fit Ford Crosslows onto Mini gearboxes. Unlike the 1800/Landcrab unit, the Maxi unit uses the same primary/idler drop gear set up as the Mini. You'd need a post '71 Maxi box with the rod change and not the original cable change nonsense.

Alternatively, by having both units in bits, see if it's all all possible to fit a Maxi gear train into a 4 syncro rod change Mini casing.

[Tonycs]

I had a 5 speed Colotti dog box in my 1071s which I bought the car 6years ago and never realised what the car had until I stripped it down,I did sell the box for good money years back,the previous owner didn't have a clue in history of car it's last mot was in mid 70s and been a garage since it was in a sorry state,but have no idea or history on these gearboxes!

[Spider]

Alternatively, by having both units in bits, see if it's all all possible to fit a Maxi gear train into a 4 syncro rod change Mini casing.

There is a guy in these parts who has done a few just like that.

I looked in to it a few years back and while definitely doable and worthwhile in a Mini, I wanted it for my (big wheel) Moke, given that you're stuck with the 3.9 FD, it would have been a backward step in y case, so i never went any further with it.

I don't know how you'd get on for parts these days?