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

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

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

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 - Limited Slip Diffs, what's available.

‘Salisbury’ is the word banded about by most un-enlightened folk when discussing LSDs for Minis, mistakenly believing the word covers all Mini orientated LSDs. This is grossly incorrect. Terminology - LSD - Limited Slip Differential The ‘Salisbury’ was designed in the ‘50s at a time when racecars were a good deal less sophisticated than today. Tyres were usually cross-ply with severely limited grip due to poor compounds developed ostensibly for rear-wheel-drive cars; the front wheel drive of the Mini being a rarity. And tracks were more than a little ‘bumpy’. Agriculturally built cars needed an LSD designed along similar lines; enter the Salisbury - effectively developed from a tractor diff. High static pre-loads were more than common to help compensate for severe short-falls in chassis, suspension, and tyre design. To all intents and purposes the diff was practically locked up, making the car a real beast to drive.

Engine transplants - Changing FDs and speedo drive ratios.

What they don’t tell you in the manual! Terminology - FD - Final Drive (diff ratio) What they don’t tell you in the manual! If you’ve decided the FD fitted isn’t what you want, changing the FD is possible without separating the engine from the gearbox. Removing the diff case will allow you access to the diff assembly to change the crown-wheel, and access to the gear-change linkage. Use a manual for crown-wheel replacement. While you’re in there it would be just as well to replace the thrust washers and diff-pin as these are the source of many a gearbox problem. Particularly for up-rated engines where fitment for the competition diff-pin is highly recommended. Once again, follow the manual here. Now the bit they don’t tell you how to do... Rod-change types - Removal of the speedo drive housing gives access to the pinion retaining nut (1.5”AF socket needed and a long bar). To be able to undo the pinion nut (torqued up to 150lb ft !!) you need to engage two gears - 2nd and 4th - t

Engine transplants - Engine to gearbox fitment

Contrary to popular mis-guidance, all BBUs will fit all four-syncro gearboxes. It was only the three-syncro boxes that varied in casting dimensions causing hassles where 1275s were applied to 850/998 gearbox casings.

Terminology -
BBU - Big Bore Unit (1275cc based engines)
SBU - Small Bore Unit (850/998/1098cc based units)
FD - Final Drive

NOTE: This information is largely for transplanting large-bore engine units into small-bore engined Minis. For further information on up-grading transfer (drop) gears, refer to relevant separate article.

Contrary to popular mis-guidance, all BBUs will fit all four-syncro gearboxes. It was only the three-syncro boxes that varied in casting dimensions causing hassles where 1275s were applied to 850/998 gearbox casings.

Engine transplants - Engine to gearbox fitment

Contrary to popular mis-guidance, all BBUs will fit all four-syncro gearboxes. It was only the three-syncro boxes that varied in casting dimensions causing hassles where 1275s were applied to 850/998 gearbox casings.

Terminology -
BBU - Big Bore Unit (1275cc based engines)
SBU - Small Bore Unit (850/998/1098cc based units)
FD - Final Drive

NOTE: This information is largely for transplanting large-bore engine units into small-bore engined Minis. For further information on up-grading transfer (drop) gears, refer to relevant separate article.

Contrary to popular mis-guidance, all BBUs will fit all four-syncro gearboxes. It was only the three-syncro boxes that varied in casting dimensions causing hassles where 1275s were applied to 850/998 gearbox casings.

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. Distilling the myriad of 'the symptoms go like this' descriptions down from various languages it has been put to me in - the end result was always the same. The bushes at one end or other, and sometimes both, had failed in their duties. Incidentally - some of the confusion when trying to sort the problem descriptions was down to misunderstandings about which end of the primary gear is which. To put the record straight, the end nearest the engine is the FRONT end. Consequently the end nearest the flywheel is then the REAR end. The two biggest outstanding symptoms were severe oil leaks onto the flywheel/clutch assembly, and difficulty/impossibility in selecting gears.

Primary Gear - Setting end float

A fairly crucial part of how the primary gear operates is its tolerances and running clearances. 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.

Terminology: DTI - Dial Test Indicator Also, later factory assembled engine units (from about 1992 onwards) were built up using whatever 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 primary gear was no exception. Too much end float and clutch disengagement is adversely affected, the gear floating up and down the crankshaft in unison with the clutch plate. The result is a graunching gear change since the plate isn't clearing the flywheel and pressure plate surfaces fully. Too little end float and the gear is likely to be pinched tight as it

C-AEA3240 - Replacement Fully-floating Primary Gear Bush. For 1275-Type primary ...

This bush is made to fit as many known 1275 primary gears - both helical and straight cut - as possible that use the original 22G109 type bush. There may be some exceptions where the manufacturer uses a slightly shallower bush housing

C-AJJ3385 – Twin Cross-pin diff assembly.

This differential unit incorporates a twin cross-pin assembly and four planet gears. The kit is made to accept standard production crown wheels and standard differential output shafts of your choice

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

5 SPEED GEARBOX DISMANTLING SHEET

Your 5 speed gearbox has a special 5th gear, laygear, and reverse idler shaft assembled with a modified gearbox main case and a different speedo end casting.

These parts must be removed before the main gearbox cluster can be removed. When a clean work area has been prepared, the removal of the 5th gear and laygear is as follows.

1. Remove the new speedo end casting assembly with the two bearings. These are a slide fit in the casting and are not positively retained.

2. Remove taper bearing No LM11749 off the 5th gear shaft along with the needle roller bearing carrier from the bore of the 5th gear, leaving the gear loose on the shaft.

3. Remove diff and housing as per workshop manual, turn the selector rod at base of diff housing area anti clockwise-and with the spool pull out as far as possible...

CMS10 & CMS13 CENTRE MAIN CAPSTRAP

To enable use of these centre main straps, the centre main cap has to be machined flat to the nearest cut, to level the cap between the main cap bolt holes horizontal surfaces. 

To achieve maximum thrust washer location, it is possible to machine the cap down its centre section using a one inch...

C-BTA166 COMPETITION DIFF PIN

Every effort has been made in the production of this pin to ensure its maximum specification with regard to material, heat treatment, and finish ground size.

The planet wheels to be used should be checked on the pin prior to assembly to ensure a reasonable tolerance. If excessive play is evident, select different planet wheels.

Due to excessive manufacturing tolerances, it should not be assumed that new planet wheels will be okay. Selection by trial and fit should be employed. If intended for arduous use Minispares recommend using the Molybdenum coated pin C-BTA164.

Use of high detergent content engine oil will drastically...

Crankshafts Identification

Crankshafts identification can be confusing as many were converted from the main forgings by British Leyland to produce replacements or alternatives from about 1969 on.

This is evident when a crankshaft has the main forging number machined off and a new number stamped or etched over the original numbers. Part numbers were sometimes allocated using the Stamping number, such as 12G1683 on a 12G1505 forging but then superseded by part number 8G2740.

Historical Article - October 1993 - Mini Spares Centre News

Mini Spares Centre News For some reason, discs (brake rotors for the foreigners amongst us!) for the 'S'/early GT have become more and more difficult to come by. Well, actually, that is not totally accurate. I guess that statement should read "decent quality discs". I know there is a supply of, erm, EEC country manufactured discs purporting to be high quality, but they are extortionately expensive, and are only totally (?) effective...