How to Checking, Adjusting And Refitting Drive Belts

How to Checking, Adjusting And Refitting Drive Belts

Here you can get How to Checking, Adjusting And Refitting Drive Belts.

Modern vehicles rely heavily on the utilization of the drive belt. The drive belt powers the alternator, air condition, power steering, and in some cases, the pump. Proper operation of the drive belt is vital in maintenance of the vehicle.

As the drive belt ages, the strain from powering items like the power steering pump and therefore the alternator can cause the belt to stretch. When the belt stretches, it can begin to slip, if left unattended. Not all kinds of drive belt systems are often adjusted. Cars equipped with an automatic belt tensioner adjust themselves over time and don’t require adjustment.

Belt types

  • V-type – Sits in the deep v-shaped groove of the pulley wheel, contacting the edges of the groove
  • Serpentine – Flat with variety of grooves running lengthwise which run in reverse of the grooves on the outer edge of the pulley wheel. The grooves increase the contact surface area to prevent the belt from slipping because it rotates.

Checking the belt tension

Use a ruler to find the midway point on the belt’s longest run between pulleys. Hold the belt between finger and thumb at now and move it from side to side. If it moves quite 1/2 in. (13 mm) it’s too slack – any less movement and it’s too tight. Check the precise deflection recommended within the car handbook.

Adjusting the drive belt

A drive belt is typically tightened or slackened by means of an adjustable pivot where the generator is mounted on the engine. The generator itself is formed to pivot on the two bolts holding it, in order that it can swing out and away from the engine. But its movement is governed and may be restrained by a slotted metal strap bolted to the free side of the generator. Belt adjustment is made by slackening off the pivot bolts, then those on the slotted strap, in order that the generator is free to move.

To tighten the belt, use a strong piece of wood to pull the generator away from the engine – a hammer handle will do – while you test the belt tension with the other hand. When the tension is correct hold the generator firmly therein position and tighten the adjusting strap bolts. Re-check the strain and, if it’s still correct, tighten the pivot bolts. To slacken the belt, loosen the pivot bolts in order that the generator is simply movable by hand. Move the generator towards the engine a touch at a time while feeling the strain on the belt together with your other hand.

When the tension is correct, tighten the adjusting strap bolts and therefore the pivot bolt. Some cars have an idler-wheel pulley which presses on the belt. If yours does, turn the screw adjuster to move the wheel and alter the belt tension. this is often simpler than moving the generator.

Adjusting a split-pulley belt

Take off the front half of the pulley and remove or add to the shims between the two halves, so narrowing or widening the V between them. As the V narrows, the belt is forced beyond the centre, up the shoulders of the pulley, and becomes tighter, as it widens, the belt runs closer to the centre and slackens.
Take care to not trap the belt between the two halves of the pulley when tightening them again after adjustment.

Tighten the nut a touch , turn the engine over one-third of a revolution, then tighten a touch more, then on until the halves are firmly clamped together. Finally, turn the engine over one more time and re-check the belt tension.

Replacing a drive belt

Garages and shops selling fan or drive belts have a list of the correct types for many popular cars. Buy one of the right size and quality. Belts for alternators are usually made from stronger material than dynamo belts. they’re also usually more expensive – but if you employ a cheaper dynamo belt to drive an alternator it’ll probably wear out quickly and maybe suddenly.

If the right belt for your car isn’t on the garage list ask your local dealer for advice, or take the old belt with you for comparison. Even then, confirm the new belt is of an equivalent specification because the old one, or better. Fitting a replacement drive belt is typically simple if the pulleys are at the front of the car. But it are often harder if the engine is mounted across the car, as on the Mini – because the fan is shroud ed or the belt is otherwise harder to urge at. On some cars you want to remove the shroud surrounding the cooling fan, or a minimum of a part of it.

To take off the old belt, slacken the adjustment bolts on the generator mounting and push the generator in towards the engine as far because it will go. You should now be ready to pull the belt off the topmost pulley – usually that on the water pump. Unhook the belt from the generator and crankshaft pulleys and lift over the fan. On cars with a shrouded fan, it’s usually possible to feed the belt over the blades one at a time, between blade and shroud.

Put on the new belt by an equivalent methods, but in reverse order. Often, however, the belt has got to be ‘wound’ over the top pulley. To do this, feed it over the fan and on to the lower pulleys, ensuring it’s properly located within the V of the pulleys. Now stretch it as far as possible over the highest one, and wind it on by slowly turning the fan and at the same time pressing it against the pulley rim together with your thumb. lookout to not trap your fingers between the belt and pulley.

If your car has an electrical or viscous-coupled fan (See How an engine cooling system works ), you’ll need to turn the engine to wind on the belt, because the fan pulley won’t turn the crankshaft pulley and therefore the belt doesn’t wind on. Normally the engine are often turned by employing a spanner on the crankshaft pulley. Do not use a screwdriver or similar tool to lever the belt over the pulley. If the belt is just too tight to be fitted by the winding method, it’s too small anyway, and you want to get one among the right size.

Remove the old belt on a shim-adjusted pulley within the same way as that used for adjustments. Use all the spacer shims between the pulley discs when fitting a replacement belt, then remove as many shims as necessary to get the right belt tension.


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