Alternator models with integral diode. (most common)
Disconnect the brown lead and the thin black lead from Regulator box, terminals 51and 67 respectively and tape up (these are the old wires from Dynamo)
The old wires from the Dynamo (at RHS front) need to be taped up and secured out of the way
If your alternator comes with the loom then connect the thicker brown wire to terminal 30 of the regulator box
Connect the thin black/Mauve cable to the terminal 51 to join the green wire or use a connector block.
If your alternator comes without wires then you will need a new length of thick brown wire (35 amp) and connect as above, plus you will need a new thin wire as above, OR you can use the old thin black Dynamo wire if that suits.
Note: When you fit an alternator, the regulator box no longer functions, but just used as a connector point! You can remove the box completely and just use connector blocks if that suits.
Until October 1957
October ’57 until March ’58
March ’58 onwards
|500 sport||21 Hp||25°||51°||64°||12°|
|500 D, 500 SW
Giardiniera And Autobianchi
|500 F and 500L||18 Hp||25°||51°||64°||12°|
For the whole production of the Fiat 500 saloon from 1957 to 1975 the wheel and tyre size remained the same:
125 x 12inch x 3.5inch (125mm tyre width, 12 inch wheel diameter and 3.5 inch rim inside width)
There was as a change in tyre quality from Cross ply to Radial in 1964.
Wheel designs varied across the different model configurations, the most common ones are as below:-
The ‘R’ model (a model that was never imported into the UK by Fiat and was only made in LHD), was fitted with a pressed steel galvanised wheel of a different design. It did not have hub caps, but did have a Fiat logo in the centre of the raised dome. The design looked just like the very early 126 (chrome bumper model) wheel, but was of the standard rim size of 3.5 inch and not the 4.0 inch that the 126 car had.
Notes for interest
- All Fiat 500 models had the wide brake drum stud pattern
- The later model 126 (652cc version) wheel and tyre size is 135 x 12inch x 4inch width. The 126 wheel bolt gap of 98mm, compared with 190mm of the 500. These wheels do NOT fit directly onto the 500
- Many people fit other ‘non-standard’ wheels, often with differing tyre sizes but it should be remembered that in the front wheel arch of a 500 ‘D’, ‘F’ and ‘L’ there is a lip and oversize wheels or tyres can cause the tyre to rub
- 135 x 12 is the most common alternative tyre to the 125 x 12 and is often more readily available and cheaper
Time to fit: 1.5 hours
Hazard warning lights are taken for granted on modern cars but for our little 500’s this was not an option. In these days of increased traffic volumes and speed then some means of visual warning of a breakdown is vital and as our cars are prone to the odd roadside rest then Indicator flashers are a sensible idea.
For those of us who like to keep our cars original then having modern accessories is not always acceptable, but something to increase our safety might be deemed a good idea, especially for those members who do long distance touring.
Another reason not to have a modern extra is appearance and originality, so I hunted around and found a couple of solutions that could be easily fitted and if required hidden from view!
All solutions are essentially the same:
- Switch with the Hazard logo with internal lamp
- 4 wires
There are a number of retro fit kits that can be purchased and designs vary, the one I like best is for a motor cycle (circular switch and remote relay) other “Car” ones usually are bigger with switch and relay on a bracket. Whatever you choose installation is similar and very simple and on a 500 the added advantage is that all the wires to connect to are conveniently behind the dash switches and all come with their own instructions.
(Important – read and use those instructions as they may differ from my notes below)
**First job Disconnect the battery terminals**
- Locate the switch – Fasten to bulkhead near or behind the windscreen washer plunger. (If using the kit without a bracket then make a “small” L bracket to take the switch)
- Feed the wires through to the bonnet via one of the suitable holes nearby. (Don’t forget to fit a rubber grommet into the hole to protect the wires). (If using the kit with remote Relay then fasten this to the bonnet hinge stay unit with a small nut and bolt an ideal location is on the opposite side to the original flasher unit)
- Wiring – Connect the Red wire with the fuse, tap onto the Red +ve wire from the ignition switch
- Connect the Black or Green Yellow wire to a suitable earth point. (The one where the flasher unit is bolted is ideal)
- Connect the 2 Grey or Blue wires onto the cars indicator wires. These are located in the mass of wires coming from the steering column (behind the Speedo in the bonnet) Blue wire is LHS indicator and the Blue/Black wire is RHS indicator. 1 wire to the LHS and 1 wire to the RHS
- Finally Reconnect the battery and click the Hazard switch – all 6 indicators should flash!
A. With a standard 500 engine (if you have a 126 engine, please see section B)
- Remove the end fixing of the inner cable by bending the split pin legs straight and pulling it out. Pliers will be needed. Unless the pin it is perfect, discard it, as it is always best to use a new split pin when re attaching the fixing.
- Inside the car undo the 2 bolts holding down the Starter and Choke lever assembly.
It is often easier to remove the 2 front seats, by holding the forward / back lever up and pushing the seats FORWARD off the runners, then you can easily lift the rubber tunnel cover or carpet.
Lift up the lever assembly and remove the inner cable from the lever; this is secure with a split pin and washer. Make sure you put the pin, split pin and washer in a safe place to reuse, as before best to use a new split pin.
- To remove the starter cable from underneath, first undo the large self-tapping screw holding the outer cable bracket to the body (just behind and below the back of the starter). Then under the centre of the car remove the starter cable from the back of the tunnel by pulling gently. Then pull the cable towards you from the other way, noting the route of the cable to the starter motor. i.e. round the driver’s side of the gearbox.
NOTE:The cable comes complete with outer and inner cables as they do not separate.
- From the underneath, feed the new cable up the tunnel. From inside attach the end of the inner cable to the Starter lever, ensuring it is securely fasted and that the split pin legs are bent around the pin after the washer. Bolt the starter/choke lever assembly back down.
From underneath again, route the cable towards the starter motor, bolt the outer cable bracket in place and align the end fixing to the starter motor lever and using one of the 3 holes push the split pin through (usually the 2nd hole)
NOTE: Ensure there is a little slack in the inner cable when the split pin is in position. It must NOT be tight! or the dog on the starter motor will catch on the flywheel teeth and damage it!!
Once you are happy that the fixing is in place bend the legs of the pin to a large V. or bend completely round, but that can be difficult in the confined space.
- Check that it works correctly and then reinstate the interior of the car.
B. Special instructions for starter cable when fitting a 126 engine\
For the starter to work properly on a 126 engine, a 126 starter cable must be used! (inner cable length is 1257mm, this is 75mm longer than a 500).Both starter motor end fixings on the inner cable on a 500 and a 126 are the same.
- The route of the cable is different as it has to attach to the bottom of the heater duct
- The attachment of the outer cable is different!!
The end fixing on the outer cable on a 500 is shaped as below, and is connected to the body with a self-tapping screw:
The end fixing on the outer cable on a 126 is just a plain end and attaches to the heater duct by a Plastic or Aluminium end stop.
Most people use a 126 heater duct if they can get one.
If you wish to retain the original 500 heater duct on the car with a 126 engine, then make a small end stop bracket. an example is shown below, this can be pop riveted onto the 500 heater in a suitable position.
The big hole should be the diameter of the outer cable ferrule, the slot to be the size of the inner cable.
Twin-spark ignition is essentially a means of doing away with the distributor cap and the rotor arm.
It should be noted that whilst this is a relatively simple alteration a few points need to be noted to ensure long service.
- IF using the coil off a 126 (or one specified at 1.5 ohms) then the use of the resistor wire (block) is essential.
- IF using a twin coil at around 3 ohms then you Don’t need a resistor wire.
Very useful videos of the coil theory can be found here:
THE CIRCUIT (assuming use of resistor wire)
The circuit wiring for the twin spark ignition system:
- From the Battery
- Through the Ignition switch
- Through the resistive wire
- On to terminal +B on the ignition coil
- Then from terminal –1 on the ignition coil to the distributor body
HOW TO FIT THE IGNITION SYSTEM
- Remove the existing coil, the distributor cap, the rotor arm and existing HT lead set
- IF using a round coil then this will fit the same mounting bolts, if using the square coil then fit as appropriate
- The resistor block needs to be placed in a suitable position, often above and behind the coil. NOTE: On a 126, Fiat fitted it in the bonnet under the opening catch lever!! If you do this then you will have to run the +ve (positive) all the way from the front of the car.
- Connect the old coil +ve wire (Blue) to the resistor and then connect a new wire from the resistor to the +ve terminal on the new coil.
If not using a resistor just connect the blue wire to the +ve terminal in the usual way.
- Connect the old wire (often black) from the distributor body to the –ve (negative) terminal of the new coil
- Connect new HT leads from the coil to the spark plugs
- Note the mechanical points and condenser are still being used.
The contact breaker points should be set at the following settings. Metric 0.47mm to 0.53mm, Imperial 0.018 in to 0.021 in
- Replace the distributor cap with a blank plate that can be purchased OR the existing cap could be used as preferred
There are many spark plug manufactures around and all have different codes for their spark plugs, please see below a list of the most common ones for standard fitment
500 original engine (479cc & 499cc):
Marelli CW 225 N or Marelli 6N; Champion L7 or Champion L 87 Y
NGK BP6HS or NGK BPR6HS; Bosch W7BC or Bosch WR7BC; Unipart GSP541
126 650cc engines
Marelli CW 8 NP; Champion L81 Y
NGK BP7HS; Bosch W5BC
Check the belt tension. When the belt is correctly tensioned it should be possible to depress the belt 10mm at point ‘C’ (centre between the two pulleys) by applying a 10Kg load. (firm push)
If it is more than 10mm the belt could be slipping causing the dynamo or alternator not to work effectively.
If it is too tight, that entire extra load is put onto the bearings, which will gradually ruin the bearings.
To adjust the tension, proceed as follows:
Remove the three 10mm nuts (D).
Withdraw the outer pulley half.
Note. If the belt has any wear or is splitting, fit a new belt
To tighten the belt, remove one or more of the large shim washers.
To slacken the belt, add one or more shim washers.
The shim washers that have been removed should be refitted on the outer side of the pulley. Always fit the thick shim washer under the spring washers and nuts.
Fitting a new belt
- With the front pulley and large shims removed and the back part of the fan pulley in place.
- Put the fan belt over the crankshaft pulley and pull and see whereabouts it is situated on the fan pulley, if it is low down in the pulley, put all the washers between the two pulley half’s. If it is halfway up the pulley, only half the washers are on the inside and the rest outside.
- Once you have determined roughly the amount of washers (you should have one thick, a number of medium thickness and one thin shim washer) On the first setting use the thick shim washer on the inside.
- Fit the “spare” washers out-side the pulley and fit the nuts without spring washers and start to tighten.
- NOW BE CAREFUL YOU WILL TRAP THE BELT AT THE SMALLEST DIAMETER. Turn the engine over by hand and the belt will start to ride out of the small diameter into its correct seating position.
- When the bolts are tight now check the belt tension. If it is too tight, you will have to remove the three nuts and half the pulley, and add a thinner washer between the two pulley half’s and try again. You may have to do it a couple of times before you get it right.
- Once the belt tension is correct take one nut off and fit the spring washer then do the rest one at a time.
- Start the car and run for a couple of minutes. Stop the engine and recheck the belt tension.