Gearbox - std vs st8 cut
Turbo Mini Forums

Straight cut gears are the way to go for performance.

Less power absorbed through the transmission so more is applied to the tarmac to propel you forward.

I like being propelled forward at great speeds!!

Lots of people think that straight cut gearsets are stronger, this is not always the case. Usually straight cut gearsets are made from a better specification of material to compensate for the smaller surface area of the teeth. If you made straight cut and helical gearsets from the same standard material, then the straight cut ones would fail much sooner.

Where the straight cut gearsets have an advantage is due to the fact that, unlike helical sets, they produce no side loading. Thus they absorb less engine power and reduce wear on bearings. This is true for gearbox sets and transfer gears.

When allied to powerful engines, most helical gearboxes fail due to bearing wear caused by side loading on the gears. This means that the lifespan of the gearbos is much shorter and ultimately the bearings and other components wear so much that the gears can mesh incorrectly and this will cause the gears themselves to fail.

Just my two penneth.

Dave.

Dave is correct.

see you at Oulton DE.

Bearing wear is basically no problem since most of you seem to tear the engine apart every 5000 to 10000 miles or so Just check the box the same time...

I am currently rebuilding a box for a mate. Turns out it has Metro Challenge gear set. JKD has one spare laygear that the box really needs but the gear alone is 235 quid + VAT+ P&P. The first gear would be best replaced as well so we are near the cost of a new box.

I am trying to fix the laygear with an alternative bearing setup, let you know how it works. (The laygear has defective bearing surfaces)

Jukka, just look for a used laygear from a dog box, there exactly the same, thats what I'm using in mine now with now problems. I spoke to jack knight about using it, and they said it wouldn't work, the pitch and teeth count would be different. I checked, the pitch and teeth count is exactly the same.

Team Racing

Basically it is not my box so it?s not my headache ... the problem is that the 1st gear is worn as well so to make the box pristine it needs both laygear and 1st gear. The latter is a bigger problem. If we can fix the laygear he can drive several summers considering the current yearly mileage.

jukka, I'm not great on box's, when you say 1st gear, do you mean the input gear, (the one nearest the flywheel end) if you do, I have a spare one of these

Team Racing

No, that is a 1st motion shaft or input gear or whatever they are called. 1st gear is closest to the double row bearing and pinion.

I'll have a dig and see what else I have

Team Racing