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Aprilia Hints & Tips

Below are some little tips that we know work.

Before you begin to do any work on your Aprilia get a copy of the factory manual for the appropriate series, be warned you're an idiot if you don't, then print out the TAV (diagram) of the part you're working on. An A4 size drawing is much easier to read than the originals, plus you can scribble on them, cover them with grease and dirty finger prints. The LMC publication 'Maintaining An Aprilia' and the Motor Trader 'Servicing The Aprilia' are also very handy, copies of all these can be found on the publications page, so download them now.

Before any attempt is made to disassemble any parts give them a good wash down with kerosene and a stiff fibre brush, we are not doing brain surgery, but keep everything as clean as possible. Another tip; fire up your digital camera/phone thingy and take a zillion photos before, during and after.

Hint No. 1

Gearbox Bearing Location Dowels.

TAV 14a p/no 38-19026 (S2 TAV 24, 238-19026)

Tools & Parts Required.

1. An Aprilia Gearbox

2. Slide hammer

3. Lathe

4. Length of 10mm hex bar

5. 5mm 0.8P die & tap

6. Screwdrivers

The two main shaft and the rear layshaft gearbox bearings are secured in the shell by locating dowels, 3 in S1 boxes and 4 in S2 boxes, the extra is on the other side of the front main shaft bearing. Two common mistakes are one; leave them in place and try and remove the internals. Or two; try and unscrew them. A close look will show they have a slotted end and it's tempting to put a screwdriver in there thinking they unscrew, but they don't. Doing either can lead to damage to the dowels or worse a smashed bearing when you try to remove the internals. (Not my photos!)

To make their removal easier I made up an extension to fit my slide hammer. On your lathe use a length of 10mm hex. Turn a thread on one end to fit the thread in your slide hammer, turn down the other end to an od of 8mm for 30mm and then turn the end down to 5mm and cut a 5mm 0.8P thread, see the photo.

If you don't have access to a lathe or a slide hammer a long 5mm bolt and another method of pulling should get it out!

According to the factory manual the correct valve clearance between the valve and rocker arm for both inlet and exhaust valves is 0.25mm. There is debate as to if they should be set with the engine hot or cold. The 1st series manual says hot while the 2nd series manual says cold. The opinion amongst owners seems divided, personally I set them with the engine cold.

To access the dowels unscrew the outer grub screws, p/nos. 54189 & 54195. Look closely at the dowels and you will see they have an internal 5mm thread, this is what you use to get them out.

The three dowels and grub screws from an S1 gearbox. The longer grub screw, 54195, is from the front of the main shaft. Note the machined end on the dowels that locate in the bearings, their internal threads will most likely be damaged, run a 5mm tap down them to clean them up.

Hint No. 2. (Thanks to Ben Courage)

Engine Valve Clearance The Easy Way. TAV 5a, p/no. 38-2557. (S2 TAV 6, 238-2557)

Whichever you decide on there is a very simple way to get the correct clearance. The thread on the adjuster, 38-2557, has a 1mm pitch, so a quarter of turn equals 0.25mm travel. Undo the lock nut, screw the adjuster in so it just touches the rocker arm then screw it out a quarter of a turn, lock the nut. How simple is that!

Tools & Parts Required.

1. If you have a Lancia tool kit.

     a. Tappet key 38-91526.

     b. Adjusting probe 38-91527.

Or if you're like the rest of us and don't.

1. 11mm spanner

2. Tappet tool to fit adjuster.

Note the machined slots in the bearings. To reassemble use a screwdriver to locate the dowel in those bearing slots, that's what the slot is for, then fit the grub screws with a dab of sealant, making sure they go all the way in.

Hint No. 4.

Don't Be This Stupid!

Tools & Parts Required.

1. Digital camera

2. Disengaged brain

Now there are some days when my brain is simply not engaged.

When I had the rocker cover off doing the valve clearances I thought it would be interesting to start the engine and see the valve gear in action. Easy to do with the odd spark plug extensions I have to fit the ignition leads and fire her up.

All looked fine, for a bit, camshaft rotating, rockers rocking, springs doing their job, lovely. On the second video the camera viewfinder started to get a little fuzzy, closer observation revealed a lens covered with oil, oh dear!

Of course I hadn't counted on the timing chain flinging oil out the on-side at a great rate. Two wash downs with degreaser latter there was still oil dribbling out of various orifices under the bonnet, but hey I now know what goes on in there under the rocker cover...

Before & after, open in full frame for the ultimate oily experience!

Gearbox bearing chart with modern equivalents. The bearings with slots will have to be machined. Thanks to Mark Sellick for compiling this. (click to download pdf)

This is my version of our local Lancia Guru Peter Renou's one person solution to brake bleeding. Note this will only work on Aprilias with Lockheed brakes, later models with Sabif brakes have their own built in system.

You need an air compressor, access to a lathe to turn up one fitting (there might be a standard air connection that could work*), 2 metres of 10mm plastic tube, the correct fittings for your air compressor hose, two small hose clamps for the 10 mm hose and a lid that fits on the brake fluid reservoir, I found one off a paint stripper tin that had the same thread.

To Operate:

Check the fluid level in the brake fluid reservoir, top up if necessary.

Screw the one person brake bleeder lid onto the reservoir, the top of the reservoir must be in good condition to get a good air tight seal.  Connect the air compressor hose.

Set the air compressor to no more than 9 psi, or the pressure gauge needle just off the stop.

Fit the correct size tube to a brake bleed nipple, with a container to catch the fluid.

Slowly open the nipple and the brake fluid should flow. Wait until there are no air bubbles in the fluid then close the nipple. You need to keep an eye on the fluid level in the reservoir, best to check after you've done each wheel.

Do all four wheels, disconnect the bleeder and double check the pedal for the correct pressure. I bleed the brakes in sequence starting with the one furthest away from the master cylinder, i.e. the left rear.

Works perfectly on my Aprilia, but please triple check the brake system on your car before you drive it.

(click to enlarge image)

Hint No. 5.

One Person Brake Bleeder. (For Lockheed/Marelli brakes)

Tools & Parts Required.

1. Air Compressor

2. 10mm plastic tube - 2M

3. Plastic lid

4. Brass round rod*

5. Lathe*

6. Air compressor fittings

7. 2 small hose clamps

Hint No. 3. (Thanks again to Ben Courage)


If the cylinders are numbered sequentially from the front (the red numbers in the diagram) the firing order is 1-3-4-2, which is the same, as most straight four engines.

In their infinite wisdom when the men from Turin wrote the instruction book they caused confusion in two ways:

    a) They made no. 2 cylinder their reference point, designating it no.1!          

    b) They put the numbers for the firing SEQUENCE on the cylinder head representation in the wiring diagram (see below)

As a result the mark for setting a piston at TDC for valve or ignition timing purposes is labeled 1/3 on the timing window--see photo. When the flywheel tooth with the zero or phi mark (which is hard to see and is usefully highlighted with a blob of tippex or similar) is aligned with this mark it is actually no's 2 and 3 pistons that are at TDC.

So to check or accurately set the timing assuming that the engine runs or has run with the ignition components as they are:

Firstly clean and set the points in the distributor to the correct gap i.e. 0.3 - 0.4mm (12 to 15 'thou). It is best to remove the distributor from the engine to do this because access to the points is otherwise very awkward.  Undo the vertical set-bolt (A) rather than slackening the clamp nut/bolt (B)  at this stage as this means the distributor can be taken out and refitted without altering the timing.

Then crank the engine over by hand until the "zero" flywheel tooth is aligned with the A/A mark (which gives about 11 degrees of static advance). In practice this is most easily done by having the car on level ground, engaging top gear, and pushing the top of the front offside wheel. This way you can turn the engine and watch the flywheel window without mirrors or an assistant!

(I use the starting handle, because the engine turns clockwise the 0 mark is hard to spot, I painted the previous six teeth with red nail polish to make it easier to prevent going past the mark. ngm)

Then with the distributor refitted slacken the clamp bolt (B) just enough to allow the body to be turned and rotate it clockwise until the points are clearly closed. Then rotate it slowly and carefully anti-clockwise until the contact points just begin to open. This is best done using a test lamp (connected between the contact breaker terminal on the coil and any convenient earth), which will light up when the contacts open.

Verify that the setting is correct by cranking the engine by two full turns up to the points opening indicator and then observing the position of the flywheel "zero" tooth relative to the A/A mark.

Then repeat setting process as required.

Finally tighten the clamp bolt (B)

Tools & Parts Required.

1. 10mm ring spanner/socket

2. Pair 7mm spanners (for points)

3. Engine starting handle

4 Test lamp

Although the Aprilia engine is a narrow vee formation for owners familiar with conventional straight fours it is reassuring to know that timing principals are exactly the same. This is because the Lancia crankshaft has offset big-end journals which results in the same 180 degree spacing between the pistons arriving at top dead centre (TDC) as is the case for the straight four.

This timing procedure is fine if the setting is near to correct to start with but if we are dealing with a rebuilt engine or there is any doubt about the correct plug lead connections the following checks may be required.

With the timing set as above establish which of the no's 2 or 3 cylinders is on the firing stroke. This requires removal of the cam cover to see which of them has slack inlet and exhaust tappets. Or it is possible to set say no. 2 (Lancia's no. 1!) on compression without removing the cam cover by taking out its spark plug and feeling for the (lack of) compression on the starting handle.

Once the cylinder on compression has been identified take off the distributor cap again and verify that the HT outlet that the rotor is pointing towards has its plug lead going to that cylinder.

If you are lucky and you are working with no. 2 cylinder the rotor will be pointing to the distributor HT outlet nearest to that cylinder as per the picture in the handbook. However this is dependent on the engine having been assembled with the gear driving the distributor shaft being suitably synchronised. Often this is not the case! This is only a problem in so far as the final arrangement of the HT leads will not look like the picture in the book!

In any case the final stage is to connect the other three leads working in the sequence of the firing order, i.e. clockwise around the distributor outlets and anti-clockwise around the plug connectors on the engine, to achieve the required 1-3-4-2.

What could be simpler!

Distributor bolts - see text

Extract from wiring diagram showing Lancia numbering system!

PDF copy to download.

PDF copy to download.

Hint No. 2:  Engine Valve Clearance The Easy Way.

Hint No. 3:  Ignition Timing.

Hint No. 4.  Don't Be This Stupid!

Contents -

Hint No. 5:  One Person Brake Bleeder.