‘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. Read more

Whether you’re building a solid road performer or fire-breathing monster, the main goal is to improve air/fuel flow into the engine. The more you can get in, the more power you can get out. Cheapest chunk of power improvement comes from sorting the asthmatic manifolding and exhaust by applying a stage one kit. Then what? Considering the ‘get more in to get more out’ theme, the main restriction - all else being equal - is the valves and their behavior. How big they are, how efficient they are and how long they’re open for determines how much gets in with each gulp each bore/piston makes. Modified cylinder heads are popularly next, although it has to be said that although a well modified cylinder head will improve performance, the gain against cost is nowhere near that given by the ‘stage one’ kit application. A good stage one kit’s improvement verses cost is around £12.50 per 1 hp, a decent modified head typically £30 per 1hp - dependent on application. Hmm. Read more

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. Read more

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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 contact through having a greater tooth engagement area, and from side loads applied by the helical-cut. Read more

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 in diameter as there is no step in the crankshaft where the primary gear runs. Read more

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 is considered (another story!) Read more