Category Archives: Suspension

KYB – Inside Suspension

KYB – Inside Suspension

 

Showing how suspension is working inside the car, and which part is doing the hardest work during each manoeuvre.

Types of Coil Spring

Cylindrical

A cylindrical spring normally consists of end coils, transition coils and spring coils. A cylindrical spring can be designed to provide a linear rate, or equally designed to give a progressive spring rate by varying the pitch. One advantage with cylindrical springs is that they can be automatically handled easily during production.

Cylindrical Spring

Cylindrical springs can also, in the axial direction, be bent in shape. This variant can be of interest when the designer needs to compensate for lateral forces influencing the shock absorber.

axial

Conical

The conical spring is normally chosen when there is limited space for the springs in a suspension system. This type has today mostly open ends and sometimes one pig tail end. The spring can be designed with either linear or progressive spring rate. Should the designer wish to achieve a linear rate, this is achieved by changing the pitch in accordance with the spring diameter to hold the spring rate constant throughout the deflection. The designer would increase the pitch as the spring diameter increases.

Conical Spring

Mini-block

A real mini-block spring design has coil diameters adjusted so that most of the coils fit inside each other when the spring is compressed to a short length, hence the name mini-block.

This design solution can reduce the bloc length close to two times the material diameter. The advantage is the very small bloc length of the spring hence space is saved. This can be of value in the rear of a car when, for example, a flat loading area is required.

It is important to note that the fitting of the coils inside each other is controlled by the diameter of the coils, and is not dependant on the type of material used (tapered or parallel).  For this design, tapered material is sometimes used which gives a weight saving benefit, but against this is the increased risk of premature end coil failure:  A more detailed explanation of this is available from our technical brochure.

Mini-bloc springs can be designed to have progressive or linear load and deflection characteristics, and this can be achieved through the use of either tapered or parallel wire.  They often have a linear rate however since the reduced material diameter compensates for the reduction in the springs external diameter.

For this design Kilen always use parallel wire; fulfilling the mini-bloc requirements and achieving the load and deflection characteristics whilst ensuring springs that are not prone to premature end coil failure.

Mini-block Spring
Kilen produce the World’s largest range of coil springs for the automotive aftermarket
The Complete Spring Supplier

What is a judder damper?

As a technology and development partner to the world’s leading vehicle manufacturers, LuK –  a brand of Schaeffler Automotive Aftermarket – is well equipped to provide innovative solutions to the problems encountered by engine designers in the quest for ever lower emission levels and fuel consumption.

One such problem can be a ‘judder’ from the drive train, which is caused by what engineers call ‘excitation’. Whilst not a major functionality issue, excitation can cause vibration and noises that may affect the comfort and drivability of the vehicle.

There are three types of ‘excitation’ that are the root cause of judder: ‘facing excitation’ which exists between two surfaces (such as the drive plate and clutch cover or flywheel), ‘geometrical excitation’ caused by rotational anomalies such as gearbox to flywheel misalignment, and ‘modulation excitation’ which is brought about by relevant movement between components (i.e. excessive crankshaft end float).


Solving the issue

A team of LuK engineers looked long and hard at all of these factors and came up with a solution that honours Schaeffler’s history of creative innovation. They call it the ‘judder damper’, and you will find it incorporated into the design of some the very latest clutch discs when specified by the vehicle manufacturer.

Essentially, the clutch disc has been enhanced by the inclusion of a centrally mounted weighted and sprung damping mechanism which provides an effective barrier that absorbs and eliminates drivetrain vibrations caused by excitation. The ‘judder damper’ system works by adding a mass damper to the drive plate. The increased damper mass rotates due to inertia and changes the force required to turn it via a diaphragm spring and friction ring combination. This effect is entirely independent of any excitation torque and always provides the optimum level of damping required. What’s more, thousands of hours of development and testing have proved the key benefits of the system.

Many vehicles have already been equipped with a judder damper as original fitment and, as you would expect, LuK is ready to deliver this very latest technology direct to the aftermarket as a RepSet® repair solution.

Adding up the key features of the Judder Damper

– Elimination of pedal vibration +
– Significant reduction in cabin noise +
– Reduction in vibration levels to the drive train of more than 60%
= Increased driving comfort

Double Clutch Repair Kit for the Renault Vehicles

LuK has developed its latest new repair solution for double clutch systems with the RepSet® 2CT for Renault vehicles fitted with the DC4 six-speed transmission.

The new product will be able to assist independent garages to repair dry double clutch systems on Renault Mégane III and Scénic III models powered by K9K engines. As wear can also be expected in engagement systems, a LuK RepSet® 2CT includes not only guide sleeve, snap rings and fastening screws, but also lever actuators/engagement lever and engagement bearings.

Worn mounting kits – characteristics and visual signs

Have you ever replaced a shock absorber and put the old suspension mounting kit back on? If you were brave enough to admit it, you will be pleased to know you are not the only person!

Just like a shock absorber, a suspension mounting kit is pushed and pulled 1,500 times every mile – over the course of 50,000 miles that means this small but important component has moved 75 million times. Imagine how that amount of work will deteriorate the components in the mounting.

Suspension mounting kits optimise suspension and steering performance by:

a) Acting as a pivot for the steering mechanism, providing a smooth steering response;
b) Reducing squeaks, rattles and vibration noise.
Worn mountings have an adverse effect on ride control and safety. Mount wear depends on the type of travel, driving characteristics and the individual vehicle, however a good guideline is that if the struts are worn out, the mounts will probably be worn out too. Strut mounts should therefore be replaced every time you replace struts.

Characteristics of a worn mounting kit

* Clunking noises
* Vibration
* Loose or stiff steering
* Poor alignment
* Tyre wear
Visual signs of a worn mounting kit

* Cracked and/or sagging rubber
* Corrosio
* Deformed or bent parts
* Pitted rubber

Suspension mounting kits improve vehicle handling, ride control, alignment, braking and steering. They should be replaced every time you replace a vehicle’s shock absorbers.


Garage and sales training

KYB UK – a leading supplier of shock absorbers, coil springs and suspension mounting kits – provides valuable technical training for its garage customers. The company’s training
programme for technicians advises them on what to look out for when checking for worn shock absorbers and springs on a car

Sue Clough, Customer Service Manager, KYB UK, says: “Our training programme helps garages to look for physical signs of wear on shocks and springs, as well as the symptoms they would feel driving a vehicle. Training sessions are normally held at an individual garage customer’s premises or given to a group of garages at a
central location.

“In addition we supply visual aids, including leaflets and point-of-sale material which garages can use to explain to motorists the importance of checking shocks and springs as they are safety critical components. Their replacement also represents a great sales opportunity for our independent garage customers.”

Shock absorber replacement for the Nissan Qashqai

There are 167,000 Nissan Qashqai vehicles on the road in the UK, yet only around 100 per year are having their shock absorbers replaced. This could be because replacing the shock absorbers and coil springs on the front of a Nissan Qashqai (02.07-) requires a number of components to be removed under the bonnet to gain access.

KYB is one of the world’s largest manufacturers of OE shock absorbers, with almost 1 in 4 of all cars leaving production lines worldwide fitted with KYB as standard. The same world class product quality is available to the UK aftermarket, including front and rear shock absorbers for the Nissan Qashqai.

THE ICME RECOMMENDED FITTING TIME FOR THIS REPLACEMENT IS 1.7 HOURS PER SIDE.

1. Remove the tyre.

2. Undo the stabiliser link bar bracket bolt.

3. Release the ABS sensor cable from its clip.

4. Remove the clip from the bracket to release the brake hose cable.

5. Remove the pinch bolt to release the wheel hub.

6. Release the fuel piping to gain access to the top plate.

7. Remove the clip so you have better access to the top nut.

8. There is an additional nut to remove in the recess behind the top mount. Remove both wiper blades then remove the scuttle panel to ensure access to the last nut.

9. Your attention then turns to under the bonnet. Take out the wipers, lift off the rubber bonnet seal and the shock absorber housing and lift out the scuttle panel. Now you can remove the three screws of the upper mount (hold the SA with one hand so that it doesn’t fall). Don’t remove the top nut of the SA at the moment.

10. Remove the strut assembly and dismantle with a spring compressor.

11. Use an Allen key on the top of the strut to remove the top mount.

12. When you re-assemble the unit, the protection kit needs to be firmly located underneath the top mount to secure it.

13. Assemble the new KYB shock absorber, coil spring, protection kit and top mount in the compressor with the gate closed. Ensure that you never use mole grips to steady the piston rod whilst assembling the unit – the grip can damage the smooth chrome coating on the piston rod which will result in it not having perfect contact with the oil seal, causing premature leaking.

14. If the spring, when removed, was seated on a cushion then this should be replaced. Twist the spring so it lines up correctly in the spring seat.

15. The assembled suspension unit can now be offered up under the wheel arch and fixed in position from the top first. All of the other components should then be reattached in reverse order and tightened to the correct torque.

DON’T FORGET TO WEAR PROTECTION!
A shock absorber replacement isn’t complete without a new protection kit. These kits are a critical element for shock absorber performance, offering a host of benefits that includes:

  • Protecting the piston rod from damage and rust
  • Protecting the sealing joint to avoid oil leakages
  • Reducing the risks of damaging other suspension components
  • Shows your customer (the motorist) that the job has been done properly

How to solve a cam sensor fault on a Vauxhall Astra

Andy Horwat, of Engine Tuning & Diagnostics in Swindon, investigates a cam sensor fault on a Vauxhall Astra 1.6, 56 plate.

An interesting case study recently came my way from a local garage. The car in question – a Vauxhall Astra 1.6 on a 56 plate – had been to another garage and was suffering from a cam sensor fault. It was explained to me that the sensor had been changed twice already but the problem still persisted.

There was a lack of power to the engine and the engine management light was on too, so I took the vehicle for a test drive to gather some more information.

The symptoms I discovered included a severe lack of power and hesitation and the garage owner (who was also an ex-Vauxhall mechanic) pointed out that the sensors were ‘aftermarket’ parts which were found to be incorrect.

Scoping the problem

cam sensor faultMy next course of action was to test the vehicle using my trusty PicoScope, and also to carry out some other tests. From this I found that the cam and crank signal appeared with clean lines, however I wasn’t certain at this point that all was as it should be so I carried out a further visual inspection.

It appeared that the cam timing was correct, but after an hour of conducting checks my attention was drawn to the cam sensor itself. I conversed with my friend who was aware of these Eco-Tec engines, which are known to have variables to them. He spoke with the dealer who agreed and a replacement was ordered and fitted. The fault was then cleared and I took it for a test drive.

I noticed that there was an improvement to the performance but the engine was still lacking in power, so the car came back into the workshop for further investigation. The coil spark was as it should be, while the fuel pressure and flow and mass air flow meter was also checked – no issues.

cam sensor faultA fuel pressure check resulted in 50 PSI snap excel, with no drop in numbers there. It is important to carry this test out in that order as a faulty fuel pump may produce the right pressure at idle but, when put under load, there could be an extensive drop in pressure (as much as 10 PSI or more).

Now I needed to reconsider the symptoms: the drivability had improved but it wasn’t a complete fix as only the engine performance had improved. Over the years many Astra’s like this have come into my workshop so I know what to expect in terms of performance.

Testing the injectors

cam sensor faultFor my next test I tried an ‘injector balance test’. The tool I used was an injector actuating tool, which has three settings (10- 30-100 millisecond) and for this test you need to connect the fuel pressure gauge, disconnect the harness for all the injectors and connect the actuating tool.

On this occasion I used the scan tool to prime the pump, although recycling the ignition key will do. The test showed injector #1 dropped in pressure by 10 PSI, which is my benchmark. Injector #2 was 10 PSI, injector #3 showed a drop of 9 PSI and injector # 4 showed a drop of 6 PSI. It was here that I found the cause of the problem.

“A quality scope is a must have tool as it helped to verify cam and crank correlation and that the cam signals were incorrect.”

This test supports the drivability problem, which is due to uneven fuel delivery, as it should be even across all cylinders with the manufacturer stating that a difference of 1.5 pounds is acceptable. In this case injector #4 was definitely faulty while #3 was on its way out. I recommended replacing both #3 and #4 to the customer, who agreed. The injectors were subsequently replaced and the performance of the vehicle was restored.

We then carried out a further test drive to confirm that the repairs made were correct. This is a typical example of an Eco-Tec engine with multiple problems – cam sensor failures are all too common and it is clearly something that caught the previous two garages out. There are at least three variants to this engine or system design and they share similar problems. The original cam sensor had probably failed and a replacement aftermarket part – which was not compatible with the system – only made matters worse.

cam sensor faultIt’s important that the test drive, symptoms, information and a correct procedure are put into place. In my opinion, a scan tool wouldn’t have proved very helpful in this particular case; in fact using trouble codes to ‘diagnose’ the problem is what caused the previous garages to run into trouble in the first place.

For this reason I believe a quality scope (in my case, the Pico 4000) is a must-have tool as it helped to verify cam and crank correlation and that the cam signals weren’t correct. The other key here was the correct information from the supplier.

The injector actuating tool also proved invaluable, as it took me ten minutes to check all four injectors and to conclude my repair.

Helping to prevent drive train noises

In the UK Schaeffler is renowned for its leading LuK clutch, INA tensioner and FAG wheel bearing brands, and the company always goes the extra mile to provide even better products for its customers. This was demonstrated by the efforts it made when building a new acoustic testing facility at its Technical Development Centre in Herzogenaurach, Germany.

A room within a room
A special feature of the facility is a ‘room-in-room concept’, where an entire room is spring-mounted inside a larger room so that it moves independently and can be completely isolated as it is decoupled from the oscillation of the rest of the building. Special bricks were imported from Sweden as the interior rooms had to be of particularly high density (at least 2,400 kg/m³). Unsurprisingly, it has been named ‘the wobble room’ by staff!

The company’s engineers in the Competence Acoustics Centre (part of the Technical Development team) investigate the origins of irritating noise using the latest state-of-the-art analytical methods to discover how noise is generated and what can be done to eliminate it at the beginning of development. As such, typical tasks include investigations of airborne sound and vibration behaviour in the vehicle drive train, as well as in the chassis and its components, such as ball screw drives and roll stabilisers.

In addition, engineers also examine plain bearings and rolling bearings of all types and designs that are used in applications such as production machinery, wind turbines, hydroelectric power plants, railway, medical technology and household applications.

Vehicle test stand: here vehicles up to the size of a delivery van can be examined from a noise technical point of view.

Hi-tech equipment
Equipped with state-of-the-art measurement and computer technology, three test rooms and the so-called ‘wobble room’ have been installed in a 180 square metre area.

CTO Prof. Dr. Peter Gutzmer said: “This is an audible and tangible further extension of expertise at Schaeffler. With the new Herzogenaurach acoustic centre, we have created ideal conditions to further optimise the globally networked development activities at Schaeffler and adapt to customer needs even better than before.”

Especially in the field of drive technology, customers are paying more and more attention to low friction coupled with the quiet operation of the individual system components, and this is also true for bearings in electric motors and devices for the home and office environments.

Acoustic issues from all areas of automotive and industrial engineering can also be addressed quickly and competently.

Dr. Arbogast Grunau, Senior Vice President Corporate R&D Competence and Service, said: “The expertise concentrated here is the result of long-standing experience in product and system development and it is continuously being developed further.

“We use our network of competence to spread our knowledge and experience throughout the world, with training and seminars being an important medium. In this way we make an important contribution to Schaeffler’s global alignment, true to our motto ‘Together we move the world’ – here with a particular focus on noise optimisation.”

Examination of airborne sound and vibration behaviour of car wheel bearings in an anechoic room

Reducing outside noise
The test rooms include a large acoustic vehicle test bay, a room for fatigue tests and one with extensive adaptation options. The ‘room-in-room concept’ covers 30-50 square metres of floor space with the largest room weighing more than 130 tons.

The interior ceilings and walls of the test rooms are lined with up to 35cm thick acoustic broadband compact absorbers to meet the sensitive metrological requirements of the acoustic staff.

Dr. Alfred Pecher, Manager, Testing Competence Centre Acoustics, said: “This constructional measure means it has also been possible to reduce noise intruding into the test rooms from outside – such as the sounds of trucks passing by – to a minimum, and to obtain technically accurate measurements.”

 Even large-size bearings weighing several tons can get inside the acoustic centre by means of a crane system, designed specifically for this purpose. They can also be examined there.