Mini
Published: 27th Jun 2011 - 0 Comments - Be the first, contribute now!
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All models, excluding cooper variants, up to 1996
Engine
All Mini units are overhead valve (pushrod), in-line four cylinder BMC A-Series types 848cc, 34bhp 998cc, 38bhp 1098cc, 45bhp 1275cc, 54bhp
Valve Clearances
Inlet and exhaust, 0.012in. (cold). Adjustment is by conventional screw and locknut. Use ‘Rule of 9’; check/adjust valve No. 1 with No. 8 fully open, No. 2 with 7 open, No. 3 with 6 open, and so on (in each case sum of valve numbers is 9).
Cooling System
At all times, use quality anti-freeze mixture containing corrosion inhibitors. Every 3000 miles/annually, inspect radiator, all hoses, water pump and fan. At least every three years, drain system, remove thermostat and reverse-flush prior to re-filling system with fresh anti-freeze solution (observe dilution recommendations of anti-freeze manufacturer that’s printed on container). Capacity, including heater: Approx. 6.25 pints (3.55 litres).
Lubrication
Engine oil: For optimum engine life, ideally change oil and filter at least every 3000 miles or annually (whichever comes first). Regular oil/filter changes are essential as the oil lubricates the transmission as well as the engine. Use premium quality, SAE15W50, 20W50 or 20W60 oil. Please dispose of old oil in environmentally friendly manner – local councils provide waste oil collection points. Drain/refill capacity, approx: Manual models: 8.5 pints (4.83 litres) Automatics: 9 pints (5.11 litres). Note – ‘dry’ capacity, 13 pints (7.39 litres) Running gear: At least every 3000 miles or annually (whichever comes first), re-grease: Sliding joints on inner driveshafts (total of two nipples; early cars only). Steering tie rod ball joints (total of two nipples; early cars only). Upper suspension arm inner pivots (total of two nipples). Steering swivels (one nipple on upper joint, one on lower, on each side; total of four). Rear radius arms (one nipple each side; total of two); remove rubber plugs to access nipples. Handbrake mechanical linkage, cable swivels and cable guide channels at rear of exhaust pipe tunnel (generously apply grease to all). Rear wheel bearings: Every 12,000 miles, re-lubricate bearings with grease specifically stated as being suitable for wheel bearing use. Other aspects: Every 3000 miles, clean/re-grease handbrake operating linkage. Every 3000 miles, lubricate carburettor pivot points/controls, and accelerator pedal pivot. Every 3000 miles, lubricate hinges and lock mechanisms (wipe off excess lubricant). Every 3000 miles, lubricate clutch and brake pedal pivot points. Every 12,000 miles, re-lubricate dynamo rear bearing (with a few drops of engine oil), and - where provision is provided for re-lubrication - water pump (use water pump grease).
Fuel System
Every 3000 miles or annually (whichever comes first), examine all fuel system pipework and check/top up carburettor dashpot with SAE 20 oil. Check filter in electric type fuel pumps, where fitted (early cars). Check for fuel/oil leaks from mechanical pumps (1969 on). After valve clearances and all ignition settings have been checked/set, and with engine fully warmed up, alternately re-adjust carburettor mixture/idle speed settings, to achieve smoothest possible tickover. Aim for idling speed of approximately 500 rpm (650 rpm for automatics), for 850/1000 models; 650-750 rpm for 1100/1275GT versions. (Note: If fuel mixture seems excessively rich after all engine/carburettor adjustments have been made, carburettor needle and jet assembly may be worn. In such cases, replacing ailing needle/jet with new items will improve emissions, fuel consumption and driveability). Clean composite type air filter (early models) or renew paper air filter element every 12,000 miles (or sooner if visibly dirty; check every 6000 miles). Ensure that breather pipework is clean.
Brakes
At least every 3000 miles or annually, whichever comes first, examine front brake pads and discs (where fitted), or front brake shoes, cylinders and drums (remove drums for proper inspection), also rear shoes, cylinders and drums (remove drums for detailed inspection). Check also brake pipes, flexible hoses and master cylinder. Make a point of closely inspecting the fixed brake pipes in the vicinity of the rear sub-frame (partially hidden and can corrode unseen!). Renew any ailing components AT ONCE. AVOID INHALING DUST FROM PADS/SHOES AS IT MAY CONTAIN ASBESTOS. Adjust brake shoe to drum clearance as required (rotate adjusters on backplates), then check handbrake operation and re-adjust cable length if necessary (at handbrake lever trunnion). Ensure handbrake cable quadrants are free to move; free off/re-lubricate as required. At least every two years, change brake fluid
Ignition
Firing order: 1-3-4-2 (No. 1 cylinder at thermostat, left hand- end of engine) Spark plugs: Champion N5 (early cars) or N9Y (later examples) or equivalent. Gap 0.025in. Check/clean every 6,000 miles or annually (whichever comes first); renew regardless every 12,000 miles. Contact points: Gap 0.014 to 0.016in. corresponding with dwell angle reading of 60 +/- 3 degrees (Lucas 25D4 distributor), or 51 +/- 5 degrees (later examples; Lucas 45D4 distributor with fixed contacts), or 57 +/- 5 degrees (later examples; Lucas 45D4 distributor with sliding contacts), or 57 +/- 2 degrees 30 minutes (Ducellier distributor). In each case, check/clean points every 3000 miles or annually (whichever comes first); renew regardless every 6,000 miles. Distributor cap, rotor arm and high tension leads: Every 3000 miles, clean and check condition, ensuring that all connections are sound. Distributor - mechanical aspects: Every 3000 miles, remove rotor arm and apply a few drops of engine oil to moving contact pivot, distributor shaft/cam bearing and mechanical advance mechanism (via holes in distributor’s baseplate). SPARINGLY apply grease to distributor’s cam. Timing: Note! Settings varied according to specific version and age of vehicle. A huge variety of distributor specifications were used; please consult manufacturer’s literature relevant to your car for recommended settings. As examples, the following figures represent a guide for pre-1970 models, and should be regarded as starting points. Note that many Minis have had replacement distributors installed over the years. 848cc, static setting: Lucas DM2 distributor (early cars), 3 degrees before top dead centre (BTDC); refer to timing marks on flywheel. Lucas 25D4 distributor, TDC for manual models; 3 degrees BTDC for automatics (strobe setting, 3 degrees BTDC at 600 rpm for manual versions; 6 degrees BTDC at 600 rpm for automatics). 998cc, static setting: Lucas 25D4 distributor, 5 degrees BTDC for manual models; 4 degrees BTDC for automatics (strobe setting, 7.5 degrees BTDC at 600 rpm for manual versions; 6 degrees BTDC for automatics). 1275GT, static setting: 2 degrees BTDC (strobe setting, 5 degrees BTDC at 600rpm).
Sundry Items
Every 3000 miles, or annually (whichever comes first)... Check clearance between clutch lever and adjuster bolt on clutch casing; rotate bolt to give gap of 0.020in. (0.51mm). Examine steering rack gaiters for splits/leaks. Check security of steering column clamp bolt. Examine fan belt and re-tension if necessary (3/4 in. deflection at centre of belt run between crankshaft and dynamo pulleys, or 1/2 in. at centre of run between crankshaft and alternator pulleys). Scrutinise clutch operating system hydraulics for deterioration/leaks. Check cleanliness/security of all electrical connections; inspect wiring for damage. Assess condition/security of all running gear components and suspension mounting bushes. Inspect underbody for damage and rectify paint blemishes. Check driveshaft joints for wear/damage (listen for ‘knock on lock’ – with windows open, drive in circle to left on full lock, then to right, again on full lock; clicking indicates worn joints. Inspect gaiters for cracks too. Examine exhaust system. Every 12,000 miles, fit new oil filler cap/filter assembly. Every 12,000 miles (later models with closed circuit breathing systems), dismantle, clean and re-assemble breather valve assembly. Every 12,000 miles (early cars only), inspect ‘rubber’ spider couplings at inner ends of driveshafts. Every 12,000 miles, check hub bearings for wear.
Best Mods
- The car which really started the tuning and accessory industry in the 60s, it’s really a case of what can’t you do to a Mini! That said on a classic worth preserving, don’t spoil its character or value. Sourcing period tuning equipment is probably a better, perhaps dearer alternative or looking to John Cooper Works if you want to keep a classical theme going.
- Bear in mind that although the shape of the original remained oh so similar, right up to the ‘MK7’, parts swapping isn’t as straightforward as it appears. Bear this in mind if you have a scrapper to source bits from.
- Unless you’re a purist, the 1275 engine is the best all rounder as even in standard tune it gives good gutsy pep and can be taken out to 1400cc plus up to 100bhp for lusty, reliable road use. The later 1980 Metro-derived A Plus engine with its stiffer block and better valves and rocker assemblies (both known weak points) can be substituted although the earlier water punps won’t fit.
- A cheap tune, if you can find one, is to use the unit from the original MG Metro (or a post ‘96 Cooper block). With its ‘Cooper S’ like cam timing but on a single carb, the MG engine gives similar pace without the hang ups or expense. The higher tuned Turbo engine can be squeezed under the bonnet.
- Essentially, the way to improve a Mini’s handling hasn’t changed too greatly over time even if the aftermarket names have! But if you go for modern ‘coil-over’ damper units on ‘dry’ Minis, remember to remove the standardrubber cone or the car’s ride will be intolerable!
- Although discs have been fitted to Minis right from the Cooper of 1961, the larger type fitted from 1984 cars are vastly superior to earlier types although it does require the larger 12inch wheels to be fitted as a consequence if you run on the old 10inch affairs.
- You can fit complete Metro assemblies along with their calipers although you need to modify the pipework between the caliper and main one. Mini hubs need to be retained or the geometry will be adversely upset.
- Vented discs can be bought off the shelf or sourced from later post ‘84 Metros although require some machining to fit without fouling. Aftermarket ones are a straight bolt on. KAD is probably the best expert in this field as it offers a wide range of sizes and types to suit all needs.
- As you know, five-speed transmissions were only available on competition cars due to their cost and noise. After 1996, an especially tall 2.76:1 final drive was fitted to the Cooper models, although this was really only feasible due to retuning the engine to lower the torque curve. If you are tempted to use this gearing some engine tuning may be needed or the car will probably feel woefully sluggish.
Top Tips
- All Minis are prone to corrosion to some degree. The most important parts of the bodywork to inspect are the panels in front of the doors as they tend to rot and are difficult to repair as this is where the wings attach to the A-post and scuttle.
- Check the front subframe mountings on the floorpan, as this is a stress point that frequently gives problems.
- Each year it’s also worth removing the rear seat and looking at the floorpan. Removing the rear side interior trim may reveal a prime view of the road, as the wheelarches and sills rot readily.
- The engine’s stabiliser mounting bar bushes decay after a while, not least of all because they tend to get soaked in oil leaking from the engine. Try rocking the block – worn bushes will be obvious from the excessive play. It’s worth investing in some uprated (polyurethane) items for a fiver.
- The A-Series engine isn’t very good at retaining its oil, due to seepage from the timing chain, sump and rocker cover so don’t expect a leak-free unit. .The big problem with the Mini’s transmission is that it shares its oil with the engine, which is a lot to ask of any lubricant. So have it changed every 6000 miles – although many reckon 3000-mile oil swaps are a better idea.
- The Mini’s steering should be light and responsive. MkII Minis were fitted with a modified steering rack to reduce the turning circle from 32 feet to 28 feet – the two racks are interchangeable. Rattles are normally due to a worn top bush.
- Check the ride height on a Hydrolastic; if listing it’s probably because the unit needs pumping up, and replacement parts are hard to source and expensive. An alternative is to convert to rubber-cone, although this is quite involved and not especially cheap – not least of all because it means changing the subframe.
- If the car is fitted with rubber-cone suspension you can check if the knuckle joint between the cone and arm has worn on any of the car’s four corners by trying to put your hand between the top of the tyre and the wheelarch. If you can’t you can expect to pay £40 per corner to get it fixed. It’s pretty easy enough to do yourself – unless you don’t have the special tool that is required to do it.
- The boot-mounted battery means a long main power cable and this can lead to poor starting if it becomes aged and connections deteriorate. Check for both plus see that the battery box is clean, free from acid attack.
- If aftermarket wheels were fitted before you purchased the car then it’s worth checking the width of them. Anything over six inches wide will put an undue strain on the bearings, and will probably foul the bodywork into the bargain.
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