Super Mighty Mini championship to rounds 3 and 4 at Snetterton, Norfolk.

A barmy mid summer-esque May weekend greeted the Super Mighty Mini championship to rounds 3 and 4 at Snetterton, Norfolk. Jokingly nick-named the Far East round by some drivers due to its location, Snetterton is a circuit that as seen some of my better results.

Saturday qualifying saw me achieve a hassle...

GEARBOX - Close-Ratio Conversion Pre-A+ Gearbox

As outlined in the 'Gearbox - standard production gearbox types' article, it is entirely possible to change the common 4-syncro gearboxes to the helical close-ratio set-up as used in the Cooper S, 1275GT, 1300GT, and some early MG Metros providing the right parts can be sourced. And you don't already un-knowingly have the close-ratio kit fitted! Part numbers are detailed at the end.

The other pre-requisite for this conversion is that it can only be applied to the early, pre-A+ type mainshaft gears. That's those that have the square-topped teeth as supposed to the distinctively pointed A+ profile. This is because despite being endowed with A+-type fittings for the mainshaft end and layshaft, the conversion gears have the pre-A+ tooth profile. This is not to say that the conversion cannot be put into an A+ gearbox casing - it can and is detailed in the relevant article.

What is essential to understand is that the pre-A+ second and third mainshaft gears are going to be

GEARBOX - standard production gearbox types

The first Minis rolled off the production line with a three-syncro gearbox, first gear as explained earlier was still a hit and miss affair.

Terminology -
FD - Final Drive

NOTE; A 'high' or 'low' ratio gear is in reference to it's performance, not it's numerical number. To illustrate - a 'high' FD ratio will give 'higher road speed', but will have a numerically low figure. A 'low' FD ratio will give lower road speed, but have a numerically high figure. A by-product of this will be reduced acceleration capability on the 'high' ratio, increased acceleration capability on the 'low' ratio. The main gearbox gears work in the exact same way.

I’m sure we’re all aware of Sir Alec Issigonis’ brilliant solution to the gearbox location in the Mini - just fold it up underneath the engine, simple. Following is a résumé of the production gearboxes to date.

Gearbox - Fomulae for FD/Tyrespeed and Gear Ratio Calculation

Basic rule to remember is ratio is established by dividing tooth count ondriven gear by the tooth count on its driver. To work out overall gearbox ratios you also have to establish the constant ratio.

Terminology -
FD - Final Drive (diff ratio)

Formula : 60,000 FD (Final drive/diff ratio) x wheel rev per mile.

Calculation for establishing vehicle speed for different final drives.
Formula These are for common tyre types, and accurate enough for assessment - a combination of using industry standard for theoretical calculation, actually measured assortment of wheels/tyres, and calculated averages! Applying

Gearbox - Formulae for FD/tyre size/car speed and gear ratio calculation

Calculation for gear ratios and transmitted engine rpm Basic rule to remember is ratio is established by dividing tooth count on driven gear by the tooth count on its driver.

Basic rule to remember is ratio is established by dividing tooth count ondriven gear by the tooth count on its driver. To work out overall gearbox ratios you also have to establish the constant ratio.

Terminology -
FD - Final Drive (diff ratio)

Calculation for establishing vehicle speed for different final drives.
Formula :                               60,000 
                    FD (Final drive/diff ratio) x  wheel rev per mile.

Alex Comis at the Mignty Minis in Croix-En-Ternois, France

There was an international flavour to rounds 2 and 3 of the Mighty Minis Championship as for the first time in 4 years it visited the French track of Croix-En-Ternois.

Just an hours drive South East of Calais, this small circuit consists manly of tight hairpins connected to a fast main straight which makes overtaking notoriously...

Straight Cut Gear Kits

Table of straight cut gear sets.

Mini Spares Evolution Helical Close Ratio Gear Set

Over the last few years we have developed this gear kit to be the ultimate for the rod change gearbox! Although there are many advantages to using a straight cut gears, often their disadvantages outweigh the advantages....

Mighty Minis racing season 2016

Mighty Minis racing season 2016

The images below capture the essence of what this season has been about, and most obvious is the closely matched cars and drivers trying their utmost to do as best they could. This is what Minis racing is all about and long may it continue.

After what can only be considered as a most enjoyable season with great racing and lifelong friendships made and rediscovered, we now look forward to another exciting season with the BARC.

Straight cut gearbox assembly

 

Any straight cut or helical competition gear set needs to be assembled by a trained mechanic and adhere to the following. Never fit lock tabs to the mainshaft and 1st motion shaft.