15 replies to this topic

[Java_Green]

They state "they have different profiled teeth with a shot peened finish for extra strength giving much more durability and quietness."

Anyone who has tried these and can say something about there "quietness"?

Edited by Java_Green, 27 January 2025 - 10:02 AM.

[stuart bowes]

I'm guessing that was supposed to say 'quietness' i.e less noisy

[Java_Green]

I'm guessing that was supposed to say 'quietness' i.e less noisy

The text was copied from mentioned suppliers webpage. I also guess they mean "quietness". "Less noisy", is also very vague. I think the real question is if it is so quite that you can run without ear protection and not damage your hearing? If you still need to wear ear protection, the gain is next to non-existing.

[DeadSquare]

It is possible to cut quieter gears, but noise usually comes a long way behind strength and is just a by-product of friction.

 

I once cut some for a Military Application, and was provided with a Broach to make their finished profile.

 

Indexing them a second time, doubled the cost, but the teeth did engage very smoothly, which presumably indicated less friction..

[stuart bowes]

I suppose it depends what you were hoping to 'gain' in the first place

 

I've never had them or fitted them or anything I can only go by what I read, which is that the main purpose of s/c drop gears is the ease of changing ratios at short notice (i.e. circuit racing) 

 

other than that, isn't it mostly just for the whiney noise / pub bragging points

 

again only what i've read in passing, they never really interested me enough to do any proper research into it 

Edited by stuart bowes, 27 January 2025 - 10:41 AM.

[Midas Mk1]

Straight cut drops will never be quiet.

[Gaz66]

I've noticed with straight cut drops that they vary with the amount of "topping" the teeth get.
Some are very pointy which I am presuming will whine more?
I saw someone taking orders for some on facebook that looked very "pointy"

[nicklouse]

Sorry but anyone asking about quietness and straight cut anything is not really wanting it for it’s intended purpose.

 

you can make any straight cut gear quieter but making sure the teeth mesh correctly. This involves machining the block or the gearbox case to get the distance between gear center correct.

 

the gasket size can also affect this.

[Spider]

It is because the teeth are straight cut that makes them noisy. Straight Cut Gears, at their very best can only ever achieve a theoretical tooth contact ratio of 1.1:1, meaning that at any one moment, you can - at best, have 1.1 teeth in contact with each other, though these are not achievable in all ratios and become expensive to make to the point where helical gear forms are often cheaper. Typically, most straight cuts have a real world tooth contact ratio of 0.85:1 to 0.94:1 and it's this that makes them noisy, because as each tooth meshes, there's an impact.

 

Helicals are quieter as they generally have a tooth contact ratio greater than 1.2:1.

[Java_Green]

It is because the teeth are straight cut that makes them noisy. Straight Cut Gears, at their very best can only ever achieve a theoretical tooth contact ratio of 1.1:1, meaning that at any one moment, you can - at best, have 1.1 teeth in contact with each other, though these are not achievable in all ratios and become expensive to make to the point where helical gear forms are often cheaper. Typically, most straight cuts have a real world tooth contact ratio of 0.85:1 to 0.94:1 and it's this that makes them noisy, because as each tooth meshes, there's an impact.

Helicals are quieter as they generally have a tooth contact ratio greater than 1.2:1.

Thank you Spider for the information.

I am fully aware of the different tooth engagement numbers for helical as well as straight cut gears and what actually causes the noise. That is why I reacted to the sales pitch used by MS (mentioned earlier). At the same time I know that the tooth profile to some extent effect how much noise that it radiates. Except from that I guess, there could be other parameters which affect.

My original question was if somebody have experienced them and could tell a difference from other straight cut drop gears? Or, maybe could enlighten me about what MS have done.

Edited by Java_Green, 27 January 2025 - 07:22 PM.

[Spider]

 

It is because the teeth are straight cut that makes them noisy. Straight Cut Gears, at their very best can only ever achieve a theoretical tooth contact ratio of 1.1:1, meaning that at any one moment, you can - at best, have 1.1 teeth in contact with each other, though these are not achievable in all ratios and become expensive to make to the point where helical gear forms are often cheaper. Typically, most straight cuts have a real world tooth contact ratio of 0.85:1 to 0.94:1 and it's this that makes them noisy, because as each tooth meshes, there's an impact.

Helicals are quieter as they generally have a tooth contact ratio greater than 1.2:1.

Thank you Spider for the information.

I am fully aware of the different tooth engagement numbers for helical as well as straight cut gears and what actually causes the noise. That is why I reacted to the sales pitch used by MS (mentioned earlier). At the same time I know that the tooth profile to some extent effect how much noise that it radiates. Except from that I guess, there could other parameters which affect.

My original question was if somebody have experienced them and could tell a difference from other straight cut drop gears? Or, maybe could enlighten me about what MS have done.

 

 

OK, sorry there. The point of my post is that straight cuts will always be noisy, some more so than others. Mini Spares may well have come up with a tooth profile that are quieter than other straight cuts.

[Cooperman]

It should not be an issue because SC drop gears are really only for serious competition use where a crash helmet is worn.
What would be the advantage of them in a road car where the need for easy changing of overall final drive ratios doesn’t exist?

[Java_Green]

It should not be an issue because SC drop gears are really only for serious competition use where a crash helmet is worn.
What would be the advantage of them in a road car where the need for easy changing of overall final drive ratios doesn’t exist?

A bit off topic but...

From my point of view there is a purpose in saving those gearbox and clutch housings that are left. The idler gear solution is far from optimal and especially in > 130 lb ft road engines. Scrapped housings is often a part of the outcome.

Edited by Java_Green, 27 January 2025 - 07:39 PM.

[imack]

Minispares evo primary gear on the right, with Minispares pre evo primary from around 2016 on the left.
I was told by Minispares that the evo gears are compatible with their gears from 2016 period. Not really any real visible difference other than the identification grooves. No difference in noise when used with pre evo idler and input gears.

Attached Files

•  Screenshot_20250127_194021_Gallery.jpg   58.3K   3 downloads

[dotmatrix]

From my point of view there is a purpose in saving those gearbox and clutch housings that are left. The idler gear solution is far from optimal and especially in > 130 lb ft road engines. Scrapped housings is often a part of the outcome.

 

 

I bought my set because of wear on the housing with my helical gears.

I have had these new minispares evo drop gears in my hill climb car for a couple of years now. I don't know about how noisy they are compared to other straight cut drop gears, I never hard other sc drops than this set.

but I do know that these drop gears together with no carpets, one box exhaust, semi straight cut final drive gears and high rpm makes it not suitable for driving without a helmet, its too noisy for my ears for longer periods of time on the highway. 

what i'm most excited to find out is how long time they last.