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

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

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 - Pipe End Flares

One day I'm going to have to try and assess just how it is that every now and again I get a 'run' on folks asking me about a specific problem. These problems exist all year round, year in, year out. And said problems crop up throughout the year. But - every now and then there's a blood-rush on a certain issue. Just recently that issue has been brake pipe ends. The bit that seals the pipe off against it's relevant fitting. There are two types of end - male and female. The male end is convex in shape, the female concave. The male end is used where a male pipe union (nut) is used on the brake pipe - that's a nut with an external thread - that will be screwed into a female fitting such as found in a wheel cylinder or master cylinder. The female end is used where a female pipe union (nut) is used on the brake pipe - a nut with an internal thread - and will be mated to a male fitting such as found on rear flexible brake pipes. Under no circumstances should you mix the too up as the brake p

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.

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 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...

Cylinder head - Min Tec head range

I'm often asked about the range of cylinder heads I do for Mini Spares/Mini Mania, so here's the low-down…

Although the following range of heads accommodate specific fitments - like pre-1992 where by-pass hoses and heater take-offs on the clutch end of the head are used and post-1992 where neither of these exist, and on SPi (single point injection) heads where they don't usually have a threaded hole for the temperature sender - in reality it is easy to convert almost any of them to fit any other engine since holes are easily blocked off - or by-pass hoses not used, water pumps blanked off and drilled thermostats fitted (see articles on cooling/engine transplants). A list of which is what and what to do to each to convert is at the end of this article.

For more in-depth descriptions of the head specs, see article 'Cylinder head - About Min Tec Heads' - basically the valve sizes used have been decided on after extensive and in-depth flow test...

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 - Verto type, injection

The advent of ECU-equipped fuel injection saw the need for a trigger system to provide the ECU with information on engine speed and piston position. In their infinite wisdom, Rover decided to fit a reluctor ring into the rear of the already humungous iron flywheel section.

Identical in all aspects to the non-injection flywheel except for this reluctor ring and the raised ridge it is fitted into. It weighs a little more than the non-injection item, but can be fitted to non-injection pre-engaged starter endowed cars should the situation deem it necessary. But ONLY the flywheel - NOT the diaphragm (see 'Pressure plate - Verto types' for further details). Consequently the same in-effective non-cost effective limited lightening can be carried out to the standard item.

Identical in all aspects to the non-injection flywheel except for this reluctor ring and the raised ridge it is fitted into.

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.

C-AEG423 - LIGHTWEIGHT STEEL OUTER FLYWHEEL SECTION, VERTO TYPE

Reduction of rotating mass releases more power to accelerate the car as the engine sees less weight to accelerate. Considering for a Mini that a mere 1lb reduction in the rotating mass of the flywheel causes a loss of accelerative weight to the tune of around 12lb - the benefits of rotating mass reduction are obvious. The C-AEG423 weighs some 4lbs less than the standard item.

To extend it's range of superior quality, light-weight steel flywheels, Mini Spares has produced this component to give the later model, SPi Mini owner the benefits from such weight saving. This component has the flywheel sensor reluctor ring machined into the flywheel itself. However, it is NOT compatible with the standard injection diaphragm/spring.

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

Mini Miglia Season Opener at Rockingham, Corby 18th April 2009

The 2009 series got underway at Rockingham on a cold blustery spring day  that didn’t help much to heat up the tyres not to battle against the strong headwind.

However Andy Hack claimed pole position from Ralph Saunders who managed his fastest time on his first flying lap! Mark Smith lined up behind Andy Hack. Mark Smith looked very quick with what sounded like a very powerful ...

Historical Article - May 1993 - Five Speed Gearbox

FIVE SPEED GEARBOX - DRIVING IMPRESSIONS

Having given the updates in development and supply expectations of our five speed box, it has come into fruition. Customers worldwide have been receiving their long awaited gearboxes. The feedback has been very good. Odd teething problems have occurred, but more due to the "if all else fails, read the instructions" attitude of those suffering the odd problems. The demand is so high for our five speeder that I have had to wait my turn before I could fit one to my MG Metro. Sorry it's not a Mini, but it's my "utility" vehicle.

Well, what can I say? It would be very easy for me to be totally biased towards our own product, spawned by the genius of Dave Hirons, and manufactured by his gear manufacturing company Tran-X, so I will. I couldn't believe how right it felt. T...

Historical Article-February 1995-Nervous Breakdown

Nervous Breakdown Sometime ago in an issue long, long ago in a Calver's Clinic, I did a short piece on vented or grooved discs, with a promise to look at brakes a little closer at a later date.

Historical Article-February 1995-Nervous Breakdown

Nervous Breakdown Sometime ago in an issue long, long ago in a Calver's Clinic, I did a short piece on vented or grooved discs, with a promise to look at brakes a little closer at a later date.