57 replies to this topic

[cooperdan]

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.

Its about 15-20mile's matey...

Thanks for alot of these replys..so ive listened to all these videos, Im getting the impression that they are good fun and great noise at low speed (around town etc) But going on motorways is a no no as they tend to take there tole on the ears...

Is there anyone to get a good cruisning speed with not this hi pitch on motorway?

[Guess-Works.com]

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.

Hmmm.... think we have a few more days before it's 1st April....

[adam_93rio]

can we stop making threads about straight cut boxes please, every time i cant resist to go on youtube and then i just want one

[Pauly]

Im fitting s/c drops to mine with a standard rebuilt helical box, ive been told that if your cars a weekend warrior then go for them, but if you use it everyday they can get irrateing. If you like the noise then the s/c/c/r box will give you the noise but not so loud, its the drop gears that creates most of the noise.

Sound great though .

Edited by Pauly, 10 January 2010 - 11:08 AM.

[Prawn]

personally, I wouldn't own a mini without a straight cut box! it's half the attraction for me, the noise is literally addictive, I need my weekly fix of SC whine to be happy!

[cooperdan]

Im fitting s/c drops to mine with a standard rebuilt helical box, ive been told that if your cars a weekend warrior then go for them, but if you use it everyday they can get irrateing. If you like the noise then the s/c/c/r box will give you the noise but not so loud, its the drop gears that creates most of the noise.

Sound great though .

So pauly your saying a sccr box will give you a whine, but the benifit is that you can use it on motorways or just everyday use and not have to worry about the noise that it generates?

the reason im asking guys is because im having a engine built and iuts got to handle a fare amount of torque and bhp thats why, I need it to be strong box, but i need it to be everyday managable..But i dont want a loud box constantly

Edited by cooperdan, 10 January 2010 - 11:15 AM.

[Pauly]

Im fitting s/c drops to mine with a standard rebuilt helical box, ive been told that if your cars a weekend warrior then go for them, but if you use it everyday they can get irrateing. If you like the noise then the s/c/c/r box will give you the noise but not so loud, its the drop gears that creates most of the noise.

Sound great though .

So pauly your saying a sccr box will give you a whine, but the benifit is that you can use it on motorways or just everyday use and not have to worry about the noise that it generates?

Ive not run a s/c/c/r box myself but have heard they dont whine as much as the drop gears (probably due to the bath of oil the gears sit in dampens the noise).

Ive been in a mini with both drops and box and the noise, even though gorgeous could probably get on your wick after a while, but mine are going in my weekend car so I dont care .

[samsfern]

ive been told once or twice by different people that straight cut gears minimize sideloading and friction, but arent as strong as helical gears, am i right in saying this?

[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

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

Have you tried removing all traces of grease and then see (hear) what noise you get ?

[MRA]

ive been told once or twice by different people that straight cut gears minimize sideloading and friction, but arent as strong as helical gears, am i right in saying this?

That is correct, as the angle is zero it induces zero side load.......... this is turn reduces the friction by the simple fact that all (or most) energies are used in turning and not in forcing the gears sideways.

The straight cut gear is weaker by design as it has less tooth root, however if better materials are used then they can in turn be a lot stronger than those they replace

[Sprocket]

You are saying that even in an application such as a 1:18 scale radio controlled car with most of the parts made from plastic, that there are forces great enough to force out the lubricant at super sonic speeds?

Bo!!ox!!!

There is something else going on, and I think it is more complex that you would like to believe

Edited by Sprocket, 10 January 2010 - 01:04 PM.

[John H]

LOL @ ivanhoew

[1275 SPRITE]

I've got S/C drops on my 1293, and the sound is so addictive it makes me want to floor it every where I go

[samsfern]

i have that problem, lol, im not an attention seeker though ...

[MRA]

You are saying that even in an application such as a 1:18 scale radio controlled car with most of the parts made from plastic, that there are forces great enough to force out the lubricant at super sonic speeds?

Bo!!ox!!!

There is something else going on, and I think it is more complex that you would like to believe

Maybe it could be another source for the noise you hear..... such as wind shear within the motor and or gearbox............

Obviously you have never really thought why oil within a unit with straight cut gears should run hotter than for a unit with helical cut gears when the engines are identical..........

Of course if you have more power the oil will often run hotter, but ignore that fact and compare two units with the SAME IDENTICAL engine and the oil within the unit with SCCR gears does run hotter.

PS, I am all for complex solutions they add interest........... have you got any to suggest ? How about surface finish of the gears ?? What about putting a Db meter in a mini with SCCR's and normal engine and one with a dry sump to see if there is a difference.....

Either way I don't mind being wrong, I prefer to be right, however I really would like some positive and constructive replies to aid the fellow Mini fans here on this forum

My information comes from several sources.............. including David Vizard.

If I am wrong then prove it, but don't get all bent out of shape, lifes too short