57 replies to this topic

[cooperdan]

Hi Guys

Urm this will probably be bit of a hard one to ask of you..but can you give me a rough idea of what a straight cut gearbox sounds like, and of course drop gears sound like please

Would appreciate it

Thanks

Daniel

[MRA]

I would say a cross between a big bee and the radio interference you get from not having suppresion for your radio

However, if that sounds bad then don't worry as plenty of people do like them, me included

Regards Martin

[gregh55]

they sound like this . . .

wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, weeee weee weee wow wow wow, clunk clunk clunk waaahhhhhhhh, we, we, we, weeeee brrrrreeeeeeeee wahhhhhh we we we

heres my mates mini




cheers

[Kam]

Heres straight cut close ratio, not sure if the close ratio 'adds' to the sound, the tech heads will let you know

[MRA]

The ratio changes the pitch of the noise........

The actual noise is caused by oil shear, which is oil under extreme high pressure escaping under extreme high speed. The noise is the oil breaking the sound barrier

[Sprocket]

It sounds much like first and reverse gear, but with more volume

[Sprocket]

The ratio changes the pitch of the noise........

The actual noise is caused by oil shear, which is oil under extreme high pressure escaping under extreme high speed. The noise is the oil breaking the sound barrier

Im not so sure that is the case as straight cut gearing systems that rely on grease, make much the same noise. Take for instance a high end electric raidio controlled car

[mk1leg]

Hi..This is what a just a set of s/c drop gears only sound like as I fitted them to my 1380.........



.....................

[mini13]

So...

does oil not escape from between helical gears under extreme high pressure??

[mk1leg]

well yes but its the way the cogs on a sc/cr gears are cut so when they mesh together that squeezes out the oil @ extreme high pressure...........helis are cut different..........

[pepper20]

It sounds much like first and reverse gear, but with more volume

i believe all cars have a straight cut reverse gear. so jus go to an empty carpark n floor it in reverse (only were its safe tho!!)
might be wrong about this

[liirge]

Mk1leg, what brakes are you running?

Pepper20: yes minis run on a straight cut first gear, which in turn reverse uses as a crash gear, of course they sound different to Drop gears as they are not immersed in oil, the drops tend to be more severe and chatter, they also do that thing when you come off the throttle...Waaaaaaaaaa.wwaa..waaa.waaaa.wwaaaa.wwooouuuuuu......throttle....wwww
oooooooowwwwwwwwwwwww

[samsfern]

I have straight cut drop gears on my 1293 mini, i think and occasionally get told that it sounds like a motorbike, i love the noise, especially at over 6k, things can get a bit loud and annoying on the motorway though, i use ear protectors, lol

how far away is lordswood from ashford, ill come and find you, well after the minis been to the doctor for a new wing, so you can hear for yourself.

Edited by samsernie, 10 January 2010 - 01:41 AM.

[foxfan]

The ratio changes the pitch of the noise........

The actual noise is caused by oil shear, which is oil under extreme high pressure escaping under extreme high speed. The noise is the oil breaking the sound barrier

I have wanted a straight cut box since i first learned about them in the eighties. I know they have benefits bit didn't know about the noise being the oil breaking the sound barrier. wow, ta mate

[ivanhoew]

Hello tmf,

Having just returned from ,cern, in switzerland ,after attending a conference studying sound and transmission sources and solutions in automotive applications ,i have a bit of an insight into the problem of gear noise propagation.
the scientifically verified cause of audable frequency emmision from non helical gear sets , is primarily the ejection of air from the machined faces meeting at high velocity .
the research to find a solution to this has centred around frequency management ,in particular ,changing the frequency from one audable to humans ,to one out of the normal range .
surface treatment of the gear faces to create an occilating contact space has worked in laboratories but has yet to be utilised in general design ,and exciting progress in frequency management through the coating of gears has also born fruit , in the use of colour coating that modify the gear hertz in accordance with the reflective frequency of the colour used, after extensive experimentation.
specifically and most effectively ,painting the driven gears red ,and the drive gears green ,has raised the frequency to inaudable to humans and barely audable to dogs although some dogs do find the sound produced somewhat exciting ..this produced an unfortunate side effect in the test vehicle ,but im certain this can be ironed out ,and did result in the vehicle aquiring a very clean exhaust pipe .
research is continuing into the use of alternate shades ,and we have high hope for a combination of tope and vanilla.

regards
yuri.k hunt
cern research
oxford
uk.