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Why's reverse straight cut?

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Old Oct 19, 2008 | 12:22 AM
  #1  
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Default Why's reverse straight cut?

As above really
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Old Oct 19, 2008 | 12:32 AM
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It's cheap to produce, and seeing as reverse gear is only a very small part of a gearboxes life, the manufacturer can get away with it.

helical gears are actually slightly stronger than straight cut and you always have about 1.5 teeth engaged at the same time, while straight-cut you only have one.
But with straight-cut there's no lateral force generated like the helical gears, so you make more power at the output end of the gearbox.
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Old Oct 19, 2008 | 01:24 AM
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It's so old people know if they are driving backwards or forwards
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Old Oct 19, 2008 | 12:00 PM
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I would beg to differ....

Straight cut gears are stronger, but too noisy for mere mortals to endure !

Adding "dogs" just adds to the fun.

IMHO

DunxC

P.S. Right about the cheapness for reverse gear tho' !
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Old Oct 19, 2008 | 02:12 PM
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I believe straight cut gears are stronger for two reasons - because of the spur engagement there's no lateral force that needs to be restrained by bearings and they're made out of uber strong heat treated stuff. GavinE's right that there is more engagement on a helical one though.

And all boxes have dogs
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Old Oct 19, 2008 | 02:18 PM
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Dog rings are alright for a Sunday afternoon: but Id sooner have synchromesh for the rest of the week.
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Old Oct 19, 2008 | 08:17 PM
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Quote
''Straight-cuts are stronger than helical gears is a myth. Helical cut teeth run quieter as they’re almost constantly engaged, also eliminating shock loads. They’re stronger through better tooth root design and more load-bearing area – the helical angle increasing overall tooth length and surface area by a small but appreciable amount''.

taken from here, however it is referring to Mini's, but surely it's the same principal.
Quit Whining – the truth about straight cut gears
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Old Oct 19, 2008 | 08:25 PM
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would have thought the reason is so you cant select reverse when going forwards or is that the syncromesh,,, been a while since i looked at a box
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Old Oct 19, 2008 | 08:26 PM
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Helical gears are used instead of straight cut gears because theyre quiter. Thats the advantage; the disadvantage is that they absorb more power.
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Old Oct 20, 2008 | 09:07 PM
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Aye, because the force isn't acting in a straight line

Is that screaming an F1 car makes its gears?
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Old Oct 20, 2008 | 09:41 PM
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no its the 19k revs that scream lol
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Old Oct 20, 2008 | 09:44 PM
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Originally Posted by tath
Aye, because the force isn't acting in a straight line

Is that screaming an F1 car makes its gears?
Screaming? You're probably talking about the fact that they rev to crazy rpm.
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Old Oct 20, 2008 | 09:47 PM
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Originally Posted by Tidgy
no its the 19k revs that scream lol
Beat me to it.
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Old Oct 20, 2008 | 10:14 PM
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Originally Posted by TerzoAlan
Beat me to it.
great minds think alike
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Old Oct 20, 2008 | 10:38 PM
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Its some of it: but its drowned out by the unsilenced 10 cylinder engine screaming at 19,000rpm!
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Old Oct 21, 2008 | 12:16 PM
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Someone told me that a lot of the whine isn't just the engine, it's the straight box.
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Old Oct 21, 2008 | 01:51 PM
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The box whill howl like a banshee, but itll be completely drowned out by the engine. Havent you ever heard a Mini with a Jack Knight straight cut box?
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Old Oct 21, 2008 | 03:23 PM
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From: Llandudno
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Not at 19000rpm
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