Clutch - Drive Strap Alignment

Drive Strap Alignment If the pressure plate clutch plate friction face needs re-surfacing, get it machined to clean it up. Make sure the engineering company doing the job records the amount taken off as once done, the recorded amount needs removing from the tops of the 'horns' that stick up to ensure proper clamping force is achieved. If this is not done, clutch slip is inevitable. If using a pressure plate of unknown history, it is IMPERATIVE the clutch drive straps are set at the correct height. Many get this wrong and end up with a slipping clutch for some seemingly unfathomable reason. The following should also be carried out if the flywheel has been machined, or of unknown history also: Place the pressure plate 'horns' upper-most on something to hold it off of the work surface but not interfere with clutch plate or flywheel. Place the clutch plate in position, with the protruding primary gear spline boss on the underside facing the work surface Place the flywheel in positi

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

Clutch - Adjustment of operating linkage

This is one of those areas where there is more than one way to skin the cat - depending on who you speak to. This is the method I have used for eternity, which has been totally reliable and never had a problem with.

This only applies to non-Verto type clutches, as the Verto types are not adjustable. You just have to make sure all the operating linkage components are in good order.

First off, ensure your operating linkage is up to scratch. For details on this, see 'Engine transplants - Clutch and flywheel'.

Satisfied all is OK, you can proceed with setting the linkage up.

1 - Remove/disconnect clutch return spring.

2 - Undo throw-out nuts (15/16"AF nuts on outer end of plunger) lock nut and back nuts off away from clutch cover.

Clutch - Drive strap alignment

Drive Strap Alignment If the pressure plate clutch plate friction face needs re-surfacing, get it machined to clean it up. Make sure the engineering company doing the job records the amount taken off as once done, the recorded amount needs removing from the tops of the 'horns' that stick up to ensure proper clamping force is achieved. If this is not done, clutch slip is inevitable. If using a pressure plate of unknown history, it is IMPERATIVE the clutch drive straps are set at the correct height. Many get this wrong and end up with a slipping clutch for some seemingly unfathomable reason. The following should also be carried out if the flywheel has been machined, or of unknown history also: Place the pressure plate 'horns' upper-most on something to hold it off of the work surface but not interfere with clutch plate or flywheel. Place the clutch plate in position, with the protruding primary gear spline boss on the underside facing the work surface Place the flywheel in position.

Clutch plates - Pre-Verto types.

There are generally three types to be concerned with these days - standard pre Verto, fiber rally/race, and sintered race. All at 180mm diameter.

Standard-type plates. The pre Verto plate has a spring-steel centre section to which is riveted the lining. Between the linings are sprung washers. These take up some of the shock impact of engagement and slight surface imperfections of the flywheel and pressure plate surfaces. Providing a genuine Unipart/AP Lockheed one is used, it will cope with most fast road applications without any problems. This includes almost all road-going standard over-bores (+0.020” to +0.060”) and a vast majority of big-bores (1380/1400). That covers up to 110 bhp and/or 90lb ft. - both flywheel measurements of course!! It is the torque that causes more problems than out-right horsepower. It can also be used in the Verto set-up to improve judder/grip/slip problems experienced when using the 'correct' standard plate...

Engine transplants - Clutch and flywheel assemblies

To go in to all the possible permutations would take a few chapters on it’s own. Suffice to say that the Metro had a few weirdo fitments such as cable operation, an in-line ‘damper’ (some got fitted to Minis too - eek),

Terminology -
BBU - Big Bore Units
SBU - Small Bore Units

NOTE: This information is largely concerned with transplanting a large-bore engine into a small-bore engined Mini. For further information on clutch and flywheel assemblies in particular, refer to relevant separate article.

To go in to all the possible permutations would take a few chapters on it’s own. Suffice to say that the Metro had a few weirdo fitments such as cable operation, an in-line ‘damper’ (some got fitted to Minis too - eek), and ‘top-hat’ plunger and rod bearing operation.

Engine transplants - Clutch and flywheel assemblies

To go in to all the possible permutations would take a few chapters on it’s own. Suffice to say that the Metro had a few weirdo fitments such as cable operation, an in-line ‘damper’ (some got fitted to Minis too - eek),

Terminology -
BBU - Big Bore Units
SBU - Small Bore Units

NOTE: This information is largely concerned with transplanting a large-bore engine into a small-bore engined Mini. For further information on clutch and flywheel assemblies in particular, refer to relevant separate article.

To go in to all the possible permutations would take a few chapters on it’s own. Suffice to say that the Metro had a few weirdo fitments such as cable operation, an in-line ‘damper’ (some got fitted to Minis too - eek), and ‘top-hat’ plunger and rod bearing operation.

Flywheel & Clutch - General information

If there's one subject that gets washed over when transplants or modifications are discussed its the flywheel and clutch assembly. There also seems to be a widely held belief that up-rating an engine from anything other than standard automatically requires a 'competition clutch'.

This, as with many other subjects concerning the Mini, is a myth. May be it's because the prospective transplantee needs not only a bigger/more powerful engine to amaze folk with in the bar stool bullsh*t stakes, but also anything that can be dubbed with the word 'competition'. 'Up-rated', after all, is a fairly tame word.

Although many have written much about how to modify engines, some suspension, and even on bodywork, very little has been written about the flywheel and clutch. Bit strange as it's an essential part of transferring engine power to the wheels! So let us delve into the myths and legends concerning this enigma of power transfer.

ORIGINAL SPECIFICATION MINI BRAKE AND CLUTCH MASTER CYLINDERS

These Brake and Clutch Master Cylinders are manufactured to OEM specification

GMC171 Original Brake Master Cylinder Mini

GMC172 Brake Master Cylinder Mini Cooper S

AAU4969 Clutch Master Cylinder

These Brake and Clutch Master Cylinders are manufactured to OEM specification Part Number and as such are homologated for use on original specification vehicles using DOT 4 or DOT 5 Hydraulic Fluid as specified...

Verto Clutches - Alternatives and differences.

This article has been written owing to the increasing amount of people who ring Mini Spares stating that their 1275cc Injection type Mini will not start after fitting a new clutch...

Verto to Pre Verto,Clutch swap

TEST If converting from A plus verto type clutch to the original Diaphragm type these are the major components you will require:

All the major extra parts required to convert from Verto Clutch to Diaphragm type parts (in brackets indicate alternatives)

6 x GHF323 shakeproof washer 3/8” UNF
2 x GFK5240 bolt remote housing short 1” UNC
1 x 88G508 flywheel keyway – pre verto (EN24T)
6 x 2A3658 clutch flywheel strap
1 x 2A3601 clutch return spring anchor
1 x CLZ628 clutch arm pin – bottom
1 x CLZ518 clevis pin for clutch arm at the top
1 x 22A747 flywheel bolt pre verto
3 x 2A3657 clutch bolt long cover to pressure
3 x (C-2A3657 ) clutch bolt long cover to pressure

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

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

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 - Final Drives, standard

FDs are ultimately responsible for the way your Mini goes after engine, gearbox, and under carriage tweaking has been applied. part numbers: DAM3647, 22G443, 22G101, 22G340, 22G338, DAM4131, 22A399, DAM4162, 22G940, 22A399, DAM2677, DAM2679, 22A411, 22A413, DAM2808, DAM6327, DAM2808, TCC10001, Terminology - FD - Final Drive/diff ratio The aforementioned and the degree to which it has been done will affect the decision as to what FD is required. They’re also responsible for much discussion between many tuning freaks, and confusion to the less informed. There’s nothing weird or scientific about it. Maximum acceleration requires a low final drive, top speed a high one. And these two terms confuse most. The confusion being the LOWER number denotes a HIGHER gear. Likewise the higher number denotes a lower gear. Likewise the higher number denotes a lower gear. Largely because the lower the ratio, the slower you go and vice versa.