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Straight cut gears etc


thminiman

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Basically, for a mini you are looking at two types of straight cuts:

Standard syncro - drives like your standard box, except makes a lot more noise, doesnt last anywhere near as long, and puts more power to the ground.

Straight cut dog box - uses dog clutches instead of sychros (think motorbike), what guys above are talking about. clutchless shifts etc, basically race only.

If i were you and want the noise either get a straight cut drop gear set. Or a straight cut cam drive (i think MED engineering in the UK do them).

All of them are pretty silly for fast road car really. Wouldnt you rather spend the money on the engine to make it quick? By the sounds of it your motor isnt that worked?

Or if it were me, i's spend it on some force racing 3 peice 10x7's and some yoko ao32r's :)

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Wow I reckon $1100 for a straight cut box that is stronger and has that mean sound is an insane steal! I'd deffinately do something like that if I had the option and I wasn't sure my gearbox was up to the task. People regularly spend more than a grand modifying toyota boxes and bellhousings and shit just to have a slightly stonger box and thats not as cool as a straight cut standard one.

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ok, thanks volodokovich, that makes things make a bit more sense, so, new prices.

close ratio, straight cut, 4 synchro box = 1100 bucks nz

close ratio, straight cut, 3 syncro = 1500

'dog box' as above, clutch type gears = 2400 bucks (4spd)

above are just gear sets

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Yuh I know. Was just saying how big the prices range etc. @ $6000 I would never ever consider it. At $1100 I would.

yuh, but as said above, lowest price one = lasts least time and is weaker,

mid one around 2g = probably best bet, but drivabilty somewhat goes out the window

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For the ping and power I'd stay bevel cut. bevel cut gears try to turn while under load, thus, wear the bearings more. stock boxes last forever, even mini one, long as servicing is regular due to them runnng on 20w50 shared with the engine........

straight cut crash box would pwn my face though, but you'll have a cunt of a time learning to use it if you've no experience with fully non-synchro boxes.... first shiz i drove properly were non synchro, and hugely heavy clutches hah....

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In short, helical gears operate quieter than straight cut. Straight cut will 'whine' the faster they go but offer both A. More directional application of force allowing for less power loss. and B. Higher acceptable loads until failure. Basically making the transmission stronger and more efficient. However though, like noted before, car manufacturers don't use straight cut due to the imense noise the transmission will produce.

Actually that is a common misconception, straight-cut gears aren't stronger than helical-cut. Helical gears are generally stronger, due to more surface area being in contact on the mated gear faces. They do have a lower efficiency though, hence why they are popular in motorsport, but even then they aren't everywhere you'd think they'd be.

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Actually that is a common misconception, straight-cut gears aren't stronger than helical-cut. Helical gears are generally stronger, due to more surface area being in contact on the mated gear faces. They do have a lower efficiency though, hence why they are popular in motorsport, but even then they aren't everywhere you'd think they'd be.

Was fully going to post that up helical gears = more teeth contact area. Only reason some straight cut sets are tougher is because they have larger gear sets + made of better material

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Actually that is a common misconception, straight-cut gears aren't stronger than helical-cut. Helical gears are generally stronger, due to more surface area being in contact on the mated gear faces. They do have a lower efficiency though, hence why they are popular in motorsport, but even then they aren't everywhere you'd think they'd be.

Was fully going to post that up helical gears = more teeth contact area. Only reason some straight cut sets are tougher is because they have larger gear sets + made of better material

Yup, truth is there's so many variables involved in determining the strength of a gearbox or gearset that there is no hard and fast rule like 'straight-cut is stronger/weaker than helical'. And while you can make a straight-cut gearset with less, larger and so stronger teeth, you can do the same with helical-cut gears, which is exactly what Quaiffe did when developing their gearset for the GTIR (which I used to own).

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screw streetable if we wanted streetable cars wed all just nana spec 3e powered ee82 corollas wouldnt we. straight cut is stronger then standard boxes because the gears arent trying to push apart from each other under load. when they try to push each other apart they have less surface area touching and hence forth go bang. just do it. dog box ftw

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