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

C-AJJ4029 Vented disc/Caliper conversion kit

For use when converting cars which already have hubs fitted that hold calipers except 997/998 Cooper which will also require larger Constant velocity joints and Timken bearings, If you have brake shoe front drum brakes a kit C-AJJ4029A is available which contains all parts required..

The contents of this kit ...

C-AJJ4023 4 POT ALLOY CALIPER CONVERSION KIT

These calipers are intended for use on 10”wheels with 7.5”diameter solid brake discs.

The kit contains:-

2 calipers, one right and one left hand. Please ensure that they are installed correctly with the bleed screws in the vertical position (i.e. at the top)
4 longer hub fixing bolts(53K1049)
4 bolt washers(21017Z
4 round spacers (AN1380) which go between hub and caliper where the fixing bolts locate. Bolts and spacers not required when fitting to vented discs
1 set of brake pad split pins (GBK1025) BUT NO BRAKE PADS.

C-AJJ4024 Brake Line conversion kit

This pipe kit is for converting Metro 4 pot callipers with dual feed pipes to a single feed as used on minis.

It is necessary however, to check that this is permitted by the legislation in the country in which the vehicle is to used. To ensure maximum...

GEARBOX - Up-Rating Drop Gears

The standard drop gears are fine for practically all road use - almost irrespective of power output. part numbers: DAM9373, C-STR123, C-STR124, C-STR30, C-STR30A, C-STR30T, C-STR30TA, C-STR230, C-STR240, C-STR250 Terminology - Drop Gears - Transfer gears (primary, idler and input gears) Large-bore - Refers to anything based on a 1275-type unit Small-bore - Refers to anything based on 850/998/1098 units Despite what many folk believe - they are more than strong enough, and will perform perfectly well if correctly set up. That means getting the idler and primary gear end floats right, and using new bearings for the idler gear at each re-build. Simply following the methods outlined in the relevant workshop manuals will achieve these simple goals. There are two problems with standard drop gears - the main one is the helical cut of the teeth, the other a very limited selection of ratios. The helical-cut teeth are essentially power absorbing - both from increased metal-to-metal c

Brakes - How They Work

This time we’re going to look at just how brakes do what they do, and ways to improve them. Without a doubt the most important point to get sorted at the outset is just what makes brakes do their thing - FRICTION. The sole purpose of the brake set-up on any vehicle .....

Brakes - Fitting Discs and Required Ancillaries

What you actually need for the disc/drum conversion is pretty straightforward. Disconnect the steering arms, top and bottom swivel-pins, CV joint, and flexible brake pipes at the subframe - that’s it. There are, however, a number of ancillaries to consider.

Basics

Basics Fitting discs designed for the Mini is easy enough. Just make sure you use CV gaiters for the disc-brake set-up - these have a different bellows shape to stop the gaiter rubbing the inside of the hub. The drum type will rub, then split, shedding grease all over the place. Moly grease is mighty mucky stuff to deal with and doesn't assist braking at all! A tip for racers - to stop the gaiters over-expanding when getting very hot and imitating the aforementioned, put either a decent sized split pin or (my favorite) a piece of very small bore pipe - as in the type supplied with WD40 aerosols, etc. - under the retaining strap on the drive shaft. This allows air to escape and return,

Brakes - Fundamental Considerations

When looking to increase their cars performance, most folks immediately turn to considering higher engine power outputs. Because of this pre-occupation brakes tend to slide down the improvements priority list. However, they are far more important - being able to accelerate at warp speed to hyper-space in the twinkling of an eye is all very well, but disastrous if you can’t stop. You will make a very big hole in the scenery, and possibly end up wearing an wooden over-coat. Getting the braking system sorted out can help to make the car quicker, as you will be able to more confidently, therefore maximising speed in any given situation. Being one of those ‘sciences’ used in the automotive industry I hope to shed some light on the subject as it's another of those where many questions from confused and mislead folks that clog up my e-mail board. The advent of the Metro, and the brakes used on it has spawned a lot of activity in this direction. It was soon discovered that they could b

Brakes - Split brake systems and adjustable bias valves

You can only use the MS72 adjustable brake regulator/bias valve with a front/rear split system. Definitely NOT the diagonal split type (for identification see 'Brakes - Rear brake bias adjustment'). These should have been 'X-ed' at birth. Makes the car handle very interestingly when the system only operates the diagonally opposed brakes. Scary stuff. Almost as much fun as when the rears only work on a front/rear split set-up - particularly as the PDWA is built into the master cylinder, and it still has to go through the FAM7821 pressure regulator valve! Damn near no braking on the rear. Either way - split system brakes are grossly inefficient when only using half the system as they are designed to do when a failure in the other half occurs. Quite frightening. To install the MS72 into a front/rear split system, it needs fitting into the rear feed line. Determining which this is can prove difficult if the system has already been tampered with or new replacement components fitted. Nam

Cylinder Head - Unleaded Fuel Use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this. See bottom for useful part numbers. The situation not at all being helped by all sorts of conflicting information from 'leaned' sources, such as lead levels in humans has declined greatly since 1935 - despite the rapidly expanding ownership of petrol-burning vehicles. And benzene and toluene used in unleaded fuels are cancerous. Still, the powers that be are relentlessly forcing through the 'no heavy metals in fuel' bills, not being at all put off by such trivia. Not surprising bearing in mind the complete debacle on the catalytic converter front - the type decided on for world wide and universal use was developed and tested in California!

Cylinder Head - Unleaded Fuel Use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this. See bottom for useful part numbers. The situation not at all being helped by all sorts of conflicting information from 'leaned' sources, such as lead levels in humans has declined greatly since 1935 - despite the rapidly expanding ownership of petrol-burning vehicles. And benzene and toluene used in unleaded fuels are cancerous. Still, the powers that be are relentlessly forcing through the 'no heavy metals in fuel' bills, not being at all put off by such trivia. Not surprising bearing in mind the complete debacle on the catalytic converter front - the type decided on for world wide and universal use was developed and tested in California!

Engine - Identification Data Updated

If you have the engine tag still attached to the engine - just in front/below the thermostat housing - or perhaps the original engine number in the log book then the following should help you determine which engine you have. For Metro units, see 'Engine - Metro identification data'. Original engine identification numbers 850cc 8A Austin up to 25000 8MB Morris up to 25000 8AM Austin & Morris 25000 onwards 8AH Austin & Morris Automatic 8AJ Austin & Morris closed circuit breathing 8AK Austin & Morris automatic with closed circuit breathing 8WR Wolseley Hornet & Riley Elf 8AC Moke 85H/101 All variants 1969 onwards Note: third suffix letter denotes compression type, L = Low, H = High, e.g. 8AM/U/H101 denotes high compression. 998cc 9WR Wolseley Hornet & Riley Elf Mk2, pre closed circuit breathing 9AD Austin, Wolseley Hornet & Riley Elf Mk2 with remote type gearbox and closed

Engine - 998 Tuning, Bolt-ons

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. See bottom for useful part numbers Terminology: MSC/MM - Mini Spares Centre/Mini Mania ID - Inside Diameter OD - Outside Diameter BBU - Big Bore Unit (refers to all 1275cc-based units) SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998) BHP - Brake Horse Power LCB - Long Centre Branch Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay. The single biggest restriction on any standard Mini is the 'breathing apparatus' - anything that is connected to the induction and exhaust systems. The standard exhaust being the biggest culprit - it is desperately restrictive in the name of noise suppression and cheapness of manufacture. Oddly enough it also increases fuel consumption when tested over a better designed, fre

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.

Air filtration - K&N Air cleaner test.

In the forefront of Mini tuning, improving the over-all breathing capability of the very asthmatic A-series the air filter set-up is one that sees priority attention. All the widely available (and widely varying) stage one tuning kits include at the very least a replacement - and hopefully - high-flow air filter element to fit into the standard plastic case,

In the past few years (well, must be nearly 6 years by now!) since I got involved with writing for the specialist Mini Magazines I have been continually fighting with the problem of limited space. This has limited what I have been able to cover, both in subjects and in details. Up until recently (say the past year or so) I have been covering fairly broad topics in a fairly broad terms and detail. Basically trying to cover perhaps the most popular areas dabbled in by the Mini owning masses.

Cylinder Head - Unleaded fuel use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this.

Cylinder Head - Unleaded fuel use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this.

Engine - 998 tuning, bolt-ons (stage one)

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay.

Terminology:
MSC/MM - Mini Spares Centre/Mini Mania
BBU - Big Bore Unit (refers to all 1275cc-based units)
SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998)
BHP - Brake Horse Power
CR - Compression Ratio

To improve engine out-put, you need to increase the engine's 'breathing' ability. The stage one kit deals with all the easily bolted-on external parts, and represents the best increase for investment. From here on in the power increases will cost commensurately more money.

Engine - Identification data

If you have the engine tag still attached to the engine - just in front/below the thermostat housing - or perhaps the original engine number in the log book then the following should help you determine which engine you have. For Metro units, see 'Engine - Metro identification data'. Original engine identification numbers 850cc 8A Austin up to 25000 8MB Morris up to 25000 8AM Austin & Morris 25000 onwards 8AH Austin & Morris Automatic 8AJ Austin & Morris closed circuit breathing 8AK Austin & Morris automatic with closed circuit breathing 8WR Wolseley Hornet & Riley Elf 8AC Moke 85H/101 All variants 1969 onwards Note: third suffix letter denotes compression type, L = Low, H = High, e.g. 8AM/U/H101 denotes high compression.

Engine transplants - Ancillary parts

Engine mountings are a whizz to fit as the Mini ones fit straight onto any of the other units. Just remove the Metro/AA/1300GT ones and swop the mounts over from the Mini unit. If they’re split, fit new ones, they’re cheap.

Terminology -
BBU - Big Bore Unit
SBU - Small Bore Unit

NOTE: This information covers transplanting large-bore engine units into small-bore engined Minis. For further information for exact differences between pre-A+ and A+ units, see relevant separate article.

Engine mountings and steady bars.
Engine mountings are a whizz to fit as the Mini ones fit straight onto any of the other units. Just remove the Metro/AA/1300GT ones and swop the mounts over from the Mini unit. If they’re split, fit new ones, they’re cheap. If using the AA/1300GT unit - it's advisable to cut off the 'wings' on the front plate that carried the engine mounts on the radiator end.