Q. Where can I buy Classic Hewland transmissions and parts?
To ensure the continued provision of world-class services for its full historic range of transmissions, Hewland Classic Limited commenced trading in August, 2014. This new company now handles all support for pre 1990 H-gate transmissions, including the celebrated FT, DG MK5/MK8, LD and VG variants. Owned and run by Peter Smith of PDS Racing through a long-term licensing partnership, Hewland Classic will provide experienced, helpful support on the same level as Hewland Engineering’s more modern offerings.
For all parts orders, transmissions and support, Hewland Classic can be contacted here:
Q. What oil should I use for my Hewland Transmission?
Hewland Engineering Ltd is frequently asked to recommend oil types or brands for its transmission systems.
Hewland do not currently recommend a specific brand of gearbox oil. However, we would always offer the following advice to get the most from your transmission:
Fit a temperature sensor from your data acquisition system into either the gearbox sump area, or into the oil pipeline on a pumped oil system. Monitor the oil temperature and note the pattern of temperature increase and the top temperature achieved. Please note that it usually takes at least 15 minutes of running to reach a level maximum temperature. The ambient temperature and the loads through the gearbox will affect temperature, i.e. a cold wet day will produce cooler gearbox temperatures.
There are two reasons for logging oil temperature:
1. An above normal temperature indicates a gearbox fault (usually bearing or tooth failure etc.). This can detect a big failure before it is catastrophic.
2. When you have established a pattern of gearbox temperature for your vehicle, you can then try different oil quantities and then different oil types. As a broad guide, the oil quantity and type that runs coolest tends to be the most efficient at lubricating and minimising power loss.
Payment can be made by BACS, debit card or credit card. Please note that all credit card transactions are subject to a 3% surcharge (4% for American Express).
Q. Which gearbox is suitable for my race car project?
Hewland provide a wide range of ‘off-the-shelf’ transmission solutions, all of which can be reviewed here. If you are after something more specialist, Hewlands experience with advanced, bespoke transmissions could be a significant asset – so please call today to speak to a member of our experienced Commercial Team.
Q. I am considering a Hewland gearbox for my street car. Have you got one to suit and is this a good idea?
Hewland specialise in motorsport and bespoke transmission applications, achieving maximum possible performance. As a result, many of the comforts of modern, OEM transmissions are not necessary or viable.
However, Hewland have developed helical ‘soft engagement’ transmission options, offering the benefits of a sequential transmission whilst providing a less aggressive shift pattern and reduced noise for limited road use. If this sounds like it may be of interest to you, please get in touch with our Commercial Team today.
Lifing figures vary according to application, conditions and maintenance schedule. However, we have built our business on a philosophy of quality right across our range, and believe Hewland products to offer the best cost-per-mile value of any major transmissions supplier.
Q. What is the best method of shifting for my gearbox?
For successful gear shifting, remember that it is critical to ensure that all mechanical elements between the drivers hand and the dog faces are in good order and properly set. This includes the gear linkage in the chassis.
Successful up-shifting (defined as fast and non dog-damaging) will be achieved by fully moving the dog ring as rapidly as possible from one gear to the next, preferably with the engine's driving load removed until the shift is completed. (The opposite is true of a synchromesh gearbox as used in passenger cars, where slow movement helps). It should be remembered that it is not possible to damage the dogs when fully engaged (in gear). The damage can only take place when initiating contact during a shift (the `danger zone`). Therefore this period must be made as short as possible. If a driver moves the gear lever slowly, or if the linkage is not rigid and effective, dog wear will occur. We always recommend lightweight yet solid rod linkage, as opposed to cables.
We list below the different methods of up-shifting that are used in racing most commonly. These are in order of shift method preference.
The movement of the dog ring is powered and the engine is cut / re-instated in a co-ordinated manner. Gear-shifts take milliseconds. This system produces zero dog wear when set up well, and highlights the advantages of minimising gear shift time.
Manual with Engine Cut:
This system is almost as good as an automated one as long as the driver pulls the lever very quickly. A `cheat` version of this is to shift on the engine rev limiter, which can work well. With this system it is especially important to move the lever as fast as possible. Otherwise the engine will be reinstated during partial dog engagement, causing damage. The damage can usually be felt by the driver.
With no assistance from the engine management, the driver must lift off the throttle sufficiently to allow the dog ring to be pulled out of engagement. He should then stay off the throttle long enough to allow the dog ring to engage with the next gear. In practice, the driver can move the gear lever faster than he can move his foot off and back on to the throttle. Therefore the effective method is to apply load to the gear lever with your hand and then lift the throttle foot off and back on to the pedal as fast as physically possible. In lifting your foot, the loaded gear lever will almost involuntarily flick to the next gear before the foot is re-applied to the throttle.
Another method is to load the gear lever with your hand, stay flat on the throttle and dab the clutch to release the dog ring. The overall effect on the gear shift is similar to the above method, but clutch wear may become a big issue.
The worst method (most destructive and definitely slowest) is to attempt to change gear in a `passenger car / synchromesh` way, i.e. lifting off the throttle, dipping the clutch, moving the gear lever, letting the clutch up and re-instating the throttle. The method causes unnecessary clutch wear, does absolutely nothing to help come out of gear and usually causes dog wear whilst engaging the next gear.
This wear is due to several reasons. Firstly, it is impossible for a driver to co-ordinate the complicated sequence of all five physical movements accurately. Consequently the engagement dogs often find themselves engaging whilst the throttle is applied. The lever is usually pulled more slowly as it was not pre-loaded, lengthening the `danger zone`.
Similar rules apply regarding speed of shift, with the unloading of the dogs obviously performed in the opposite manner. Whilst braking, the dogs must be unloaded by either touching the throttle pedal or by dipping the clutch. However, one sharp dab of clutch or throttle is appropriate per shift. Continued pressure on either will cause dog damage for different reasons. `Blipping the throttle` just before engagement is advisable if the rev drops between gears are over 1300 rpm, as this will aid engagement and stabilise the car.
For ease of downshifting, make the downshifts as late as possible in your braking zone (i.e. at lower road speed), because the rev drops between each gear are then lower. So many drivers make the mistake of downshifting as soon as they begin braking, causing gearbox wear, engine damage and `disruption` to the driving wheels.
For any further advice or questions, please contact our Commercial Team, who will be happy to advise.