SUSPENSION - Terminology

Glossary of terms used in the suspension on the mini. The Mini has consistently more than proven its capability in competition with very limited and cost-effective modifications based on the standard equipment fitted. Having first ensured the bodyshell (in reality little more than a complex bracket to hold suspension and driver securely in place) is well sorted out by removing all cruddy or rotten metalwork and into something like straight, square and strong we, maximising suspension stability and geometry pays dividends in the enjoyment that is driving a Mini. Understanding what the individual ingredients are helps in pursuing what you want from the experience. Smooth Mover Good, reliable, and consistent handling is dependent on a number of factors. At this stage, we’re concerned with clapped out or badly adjusted suspension components. Stiff, seized, partially seized or slack, sloppy, worn out suspension components will cause inconsistent, wayward, confusing and – more important

CAM TIMING - Basic Notes

To avoid lots of swearing and unnecessary damage, check the timing gears slide neatly onto their respective bosses. If tight, first check for any high spots in the gear bores and key-way slots. Clean out using with fine emery cloth, medium Wet 'n' Dry paper, or some such. Remove the Woodruff keys then dress the bosses using abrasive material as mentioned previously. Re-check fitment before re-fitting keys. Check the key-ways and keys too before re-fitting. Get rid of unwanted sticky-out bits on the keys that would inhibit a slide fit. Clean out the key-way and de-burr top edges. I always file a slight 'flat' across them to give plenty of clearance to the gear key slot. If the pulley is a slack fit on the key, turn it anticlockwise before nipping the bolt up. ALWAYS fit it like this. It's imperative to fit cam (and followers in the case of solid wall blocks) following manufacturers instructions precisely using a good quality cam lube.

DIAPHRAGM SPRING - Verto types including injection

The Verto/Valeo type diaphragm included the pressure plate in its assembly, much like a 'normal' car set-up. The spring being of the 'finger' type as opposed to the disc spring used on earlier, three-piece assemblies. There were originally three diaphragm specifications using progressively stronger springs - small-bore, big-bore, and Metro Turbo. Later joined by the type used on the injection cars, though most definitely not interchangeable. Initially, the biggest problem was the Turbo ones were never really available on their own. If you wanted one you had to buy a whole clutch/flywheel assembly - the cost exorbitant. Rover originally believed that if the clutch plate was worn out, then the flywheel and pressure plate would be too. It has only been recent times that the diaphragm/pressure plate has been available on it’s own - but not until after the Turbo unit became unavailable. Even that has changed recently with the cessation of the Turbo diaphragm as a service part.

DIAPHRAGM SPRING - Verto types including injection

The Verto/Valeo type diaphragm included the pressure plate in its assembly, much like a 'normal' car set-up. The spring being of the 'finger' type as opposed to the disc spring used on earlier, three-piece assemblies. There were originally three diaphragm specifications using progressively stronger springs - small-bore, big-bore, and Metro Turbo. Later joined by the type used on the injection cars, though most definitely not interchangeable. Initially, the biggest problem was the Turbo ones were never really available on their own. If you wanted one you had to buy a whole clutch/flywheel assembly - the cost exorbitant. Rover originally believed that if the clutch plate was worn out, then the flywheel and pressure plate would be too. It has only been recent times that the diaphragm/pressure plate has been available on it’s own - but not until after the Turbo unit became unavailable. Even that has changed recently with the cessation of the Turbo diaphragm as a service part.

DIAPHRAGM SPRING - Pre-Verto types

I'm ignoring the old original spring-type jobs here for the same reasons I wouldn't suggest using their flywheels! The first two can be lightened, see accompanying diagram. Limit removal of metal on the rear face to 0.120" to be safe, 0.150" if you're feeling brave/lucky. The third can be further lightened by carrying out the machining operation on the rear face as indicated in the diagram and as per previously stated dimensions. Do not remove any more material than indicated for any of these pressure plates as it will not only reduce their strength, but will also cause over-heating of the clutch. Too little material will not be able to absorb any excessive heat generated during spirited driving! Bear in mind what was said about lightened standard cast iron flywheels - the same applies here. Under no circumstances use lightened standard cast iron pressure plates in ANY competition disciplines. The SG iron items are suitable for full race use despite lightening operations, although f

PRESSURE PLATE- Pre-Verto & Verto types

There is an astonishing five other types generally available. For high-tech ones see 'Flywheels & Pressure plates - technical advances' part numbers: 22A598, 22G270, C-AHT230, Apart from very first one that should be avoided at all costs (cast in part no.2A3509), there is an astonishing five other types generally available. For high-tech ones see 'Flywheels & Pressure plates - technical advances'. 22A598 - Number cast in. Standard-grade cast iron 22G270 - Number cast in. High-grade cast SG iron as fitted to Coopers and Cooper Ss Quinton Hazel - Triangular in shape, but only standard-grade cast iron. C-AHT230 - Mini Spares high-grade SG cast iron, but cast pre-lightened. Farndon Engineering - Machined from steel billet. The first two can be lightened, see accompanying diagram. Limit removal of metal on the rear face to 0.120" to be safe, 0.150" if you're feeling brave/lucky. The third can be further lightened by carrying out the machining operation on the rear face as indica

CLUTCH PLATES - Verto types, including injection

There is only one original Verto/Valeo clutch plate and is fashioned more like a ‘conventional’ clutch plate - it has a sprung centre section. Four springs around the centre section of the plate take up shock, and supposedly reduce the likelihood of judder. It was an attempt by Rover to improve the clutch take-up and engagement to make is more like a 'modern' car. Except it didn't. The engagement feels wooly at best, and judders horribly at worst. They even went as far as making two plates, one for small-bore, one for big-bore. The difference being the centre spring tensions! From experience, judder is caused by undulating flywheel/pressure plate surfaces, or ‘breakfast cereal packet’ lined non-genuine plates. It's OK, but if any warming up of the engines output is considered, definitely go for the pre Verto plate. This will fit with the Verto set-up and is a cheaper into the bargin. The Metro Turbo had a Verto flywheel type, but the clutch had the more familiar solid centre of the p

GEARBOX - Limited Slip Diffs; necessary parts for installation.

Fitting an LSD isn't as simple as replacing the diff cage unit. In all cases a certain degree of diff housing modifications is needed - material needing to be ground/filed away to provide clearance for larger diff housing cases and crown wheel bolts. Although it has to be said the Quaife diff is supposed to fit without these mods. I've never found that. The design and manufacture of the LSD to facilitate any other function other than that of a standard 'open' diff assembly precludes use of standard CWPs. So one suitable for an LSD is needed. Naturally Mini Spares/Mania supply these in an extensive range of FD ratios. The output shafts are also different. A much thicker spline type is used within the LSD assembly. Consequently a suitable pair of LSD-compatible output shafts are needed. Some folk still insist on running the archaic, power consuming Hardy-Spicer type driveshaft to diff joints - although this is the only real option for rallying unless a change in driveshaft assembly

Primary Gear - Bush Replacement

With the cost of new primary gears spiralling ever upwards, and the availability of good, serviceable used ones, fitting new bushes to existing gears is becoming a more common solution. For some reasons for bush failures and rectification to stop it re-occurring, see article Primary gear - Bush problems. Since there is no useful information given in any of the workshop or DIY manuals on this subject, following is my approach to dealing with the issue. The first thing to get to grips with is which bush is which. This has added an element of confusion to many conversations I have had with folks on this subject, so - the FRONT bush is the one nearest the engine block, the REAR bush is the top-hat one nearest the flywheel. This is because the front of the engine is actually the radiator end - quoted in 'in-line' engine-speak. The REAR bush is the same on all primary gears - be they for small or large bore engines. The FRONT bush is different for each though; the small-bore one is smaller

Idler Gear - Setting End Float

A fairly crucial part of how the idler gear operates is its tolerances and running clearances. part numbers: 22A1545, 22A1546, 22A1547, 22A1548, 22A1549, DAM4822, DAM4823, DAM4824, DAM4825, GUG705563GM, AAU8424, ADU6033, CCN110, 2A3643, 22A152, 53K547, Terminology: DTI - Dial Test Indicator End float is a continual problem as folk either ignore it through ignorance or lack of accessible information on how to do it, or belief special tools are needed. Also, later factory assembled engine units (from about 1992 onwards) were built up using whatever shims and thrust washers were available, since Rover were not making regular orders for all shim/washer sizes due to the forthcoming end of production. Consequently, many units left Rover with incorrect (usually too big) clearances. The idler gear was no exception. Too tight a clearance and the idler gear will either seize solid when it gets hot, or destroy the thrust washer thrust faces in the comparably soft aluminium gearbox and t

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

Gearbox - Up-rating diffs and FDs

There’s a good selection of straight-cut final FDs available. Examine the FD table, and using information from

'Gearbox - Final dives, standard' and 'Gearbox - Formulae for car speed, etc.'

you can assess which would best suit your usage. Bear in mind that they’re noisy, make sure you select one that’ll fit your diff unit, and also consider that using drop gears will allow fine-tuning of the ratio where necessary. See

'Gearbox - Up-rating drop gears'

Gearbox - Up-rating diffs, FDs and ancillaries.

part numbers: C-BTA166, C-BTA167, DAM6624, BTA101, 2A7062, DAM5071, DAM6027, RPS1418, C-AJJ3385, C-22A1731, ...Read more

Primary Gear – Bush Problems

Although not of immediate interest to many road-runners/street-burners, mainly accorded to the racing scene, it seems to be a perplexing problem to a very large number of folk around the world, and has burned up plenty of telephone time.

part numbers: 13H2934, LUF10005, CE12, 22G109, DAM8889, DAM8887

With the cost of new primary gears spiralling ever upwards, and the availability of good, serviceable used ones, fitting new bushes to existing gears is becoming a more common solution. For some reasons for bush failures and rectification to stop it re-occurring, see article 'Primary gear - Bush problems'. Since there is no useful information given in any of the workshop or DIY manuals on this subject, following is my approach to dealing with the issue.

The first thing to get to grips with is which bush ...

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

Brakes - Rear brake bias adjustment

When altering the front brake set-up away from the standard installation, it invariably alters the amount of rear brake bias needed to re-balance the cars brake balance.

The problems start occurring when folk graft alternative brake set-ups onto the front of their Minis. Be this 7.5" discs onto a previously drum-braked model, or going from current standard disc set-ups to one of the 4-pot varieties. The question then is 'what bore size rear wheel-cylinders do I need?' Unfortunately this isn't straightforward. Actually, that's not strictly true - more on this later. The pressure developed in the lines determines brake effectiveness - aside from disc size, pad type, co-efficient of friction, etc. that is. Understanding this may assist in choosing which way you should go for your particular set-up.

The basic facts you need to remember when dealing with brake pressures is how they are affected by the components you use.

Valve Guides - Materials and Useage

Material choices for guides are down to two distinct types - cast iron and bronze. Yes, cast iron. NOT steel as described in many adverts and by vendors. Never have been, never will be. These are as fitted to the various A-series cylinder heads as standard in all applications. Cast iron is used because it is a very dissimilar metal from any used in valve manufacture - important to eliminate galling that causes seizure of the valves in the guides - is softer, yet resilient enough to wear well. Bronze, on the other hand, is a very general description as there are a variety of 'bronzes' used by various folk. In days gone by, the bronze base type used was 'PB1' (also known as 'Navy Bronze') - a phosphor-bronze alloy that was very orange in colour, and very soft, used primarily in race engines. Unfortunately they wore out very quickly. Silicone-brass content bronze is probably the most popular now - often with a high aluminium or manganese content - is very yellow/gold in colour.

Distributor - Electronic Ignition

Since the A-Series has such an efficient combustion chamber design, the standard points set-up is perfectly capable of providing sufficient sparks for effective combustion when new. And this is the problem. They require regular servicing to maintain maximum performance. This can be a chore, so is generally neglected. And it doesn't take long before deterioration seriously affects performance. Points bounce is also a problem on high-revving race motors.

Deterioration of the points set-up can be caused by several factors - wear and tear on the dizzy spindle bearings creating 'wobble', electrical erosion of the points, and wear of the points cam heal. All have the same effect - dwell angle alteration. This in turn reduces spark effectiveness. The consequences are a loss in power and economy, poor starting performance, and general poor running.

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

Flywheel - Pre-Verto Types

The early spring-type clutch flywheels are of no use except where total originality is required on a concours car. The taper is too small and diaphragm pressure ring non-existent. No use to man nor beast. Part No Applications: C-AEG421, C-AEG420, C-AEG619, C-AEG620, 2A3657, 2A3658, 2A3659, 2A3512 With the exception of the fact the two-piece flywheel is two pieces bolted together - this and the later one-piece cast item can be treated as the same thing. They will universally fit all transverse engine cranks from 1964 onwards, so that should be easy enough. If all you can get is the hulking great 1300 type, then this too is as universal to fit, but I highly recommend you get that extra cast lump machined off of the outer edge as a bare minimum. Further lightening of these cast flywheels is possible by having metal machined off of the diaphragm side, from the outer edge of the diaphragm pressure ring outwards.