What is the Difference between Helical Cut and Straight (Spur) Cut Gears?

Basically, OEM transmissions have Helical cut gears since they are quieter. The quietness is the main advantage but a major disadvantage is under high loads they produce large axial forces. These large axial forces also introduce the bearings and cases to forces that lead to failures.

Spur Straight cut gears allow us to improve the tooth profiles and eliminate the unwelcome forces that are related to helical gears. In turn results in a stronger overall gear. A disadvantage is that spur gears produce a whining sound similar to reverse gear. Having said that our current manufacturing technology allows us to produce quieter spur gears. Some users actually love the whine and complain our straight cut spur gears are not load enough.

The Picture below shows the TOP row with Straight Cut Spur Gears and the BOTTOM Row as Helical Cut Gears.

I have a high powered street car and my only issue is it breaks gears under load, what gear set do you recommend and why?

We specialize in Straight Cut Synchro Mesh replacement Gear Sets that fit into the OEM housing.

If you are happy currently with the way the transmission shifts and have no issues other than gear breakage then all you need is stronger gears. This type of gear set will be more affordable and maintenance free since there is less parts than a dog set and no worry about dog wear.

OEM manual transmissions are fitted with a synchronizes for engagement from the factory. The advantage is they deliver smooth, reliable, and quiet operation, which is paramount for a street driven vehicle. Synchromesh transmissions operate using a collar that applies force to a cone-shaped clutch attached to the gear. The collar allows the shaft speed of the gearset and the input shaft to be matched or synched to the output shaft prior to the collar locking into place and initiating a shift.

In special circumstances such as professional track racing the disadvantage of synchromesh gearboxes in high-performance applications include slow upshifting at very high engine speeds—e.g. 9,000 rpm—and slow downshifting, as well as the need to fully use the clutch.
Below is an assembled shaft showing typical synchromesh components.

Why does it take so long to make a custom ratio gear set?

There is so much involved in the manufacture of a gear train when supplied with a sample transmission. Below is a basic breif list of steps and times,

Strip and assess supplied sample – 1 day

Design, including engineering calculations, FEA, assembly drawing, part drawing – 1 week

shop drawings – 2 days

Machining approximately 30 different components – 3 weeks

Heat Treatment – 1 week

Shot peening, finish Grinding – 1 week

What CURRENCY are the prices in?

All prices on the the site are AUSTRALIAN Dollars (AUD).

Why dont PAR promise a delivery date on out of stock or custom manufactured components?

The reason PAR do not ‘promise’ a delivery date is because there are so many things that could potentially delay the delivery of your custom or out of stock product. And, a lot of these factors are out of our control.

Your order will be given either a manufacture slot or a manufacture week depending on how involved the worx are. All being well, the manufacture will go ahead as expected. However, any significant interruption within the production plant may push your schedualed slot back

What affects delivery date?

There are a number of “Interruptions” within the plant that affect the delivery of your product. These are thing such as;

  • If there are any issues at the factory – for example;
    • The volume and demand of orders,                                                               Priority dealers demanding stock, race teams, warranty       replacements, etc
    • Factory Closures,                                                                                                    Natural disasters suchs fires, extreme weather, etc. Community or shire issues can lead to closure up until matters are settled.
    • Problems with parts,                                                                                               Parts that are purchased in to compliment orders are delayed or on back order.
    • Problems with equipment,                                                                                  Machinery within the plant is very sophisicated and bespoke, hence any technical problems or replacement parts required may come with delays.
    • Material delays,                                                                                                         PAr source and only use certain materials that are world class and will not compromise. Material can experience delays for reasons out of control.



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