19 replies to this topic

[Chewy LSMM 1275 MAYBE]

Hey all


i want to put S/C drops in my 1275

what do i need from mini spares for this conversion

do they do a 1.1 ratio same as standard

[Ivor Badger]

Hey all


i want to put S/C drops in my 1275

what do i need from mini spares for this conversion

do they do a 1.1 ratio same as standard

Jack Knight did 1:1 and 1:1.04, these used the same bottom gears allowing the overall FD to be altered slightly by changing the primary gear. They also did a 1:1.08 set but these have to be run as a set.

If you are running a road car, I wouldn't bother unless giving up on in car conversation.

[Chewy LSMM 1275 MAYBE]

It is only a single seater when i am doin the track days and hill climbs

do mini spares do a kit

[Guess-Works.com]

Minispares sell them individually, as there are many combinations, but if you ring and ask for a set of SC dropgears ( or transfer gears ) , 1:1 ratio, 1275 then they will supply. Think the combined price is around the £200 mark give or take. My advice is get a 23 tooth primary and Input gear...

PS, it's not an in car change without the use of special tools, so it's likely you're pulling the engine.

[Chewy]

i am dropping the frame out to rebuild the diff - will these gears give the howl when i boot it.

what do i need

primary + input gear and transfer

what will the different teeth do on the gears

[Ethel]

They are just direct replacements, as a set, for the existing gears so any fitting info in your Haynes etc still applies. You'll need to get the primary gear bushing right and, of course, A & A+ are different.

[Guess-Works.com]

You need, Primary, Idler and input..

The idler is a common gear, so is shared for all drop ratios...

The Primaries are available with different tooth counts, as are the input gears..

Usually, 22, 23 or 24 teeth and even some 25's..

Changing which tooth count primary you use with which tooth count input changes the ratio, the idler does not affect the ratio.

The 'best choice' is when considering 1:1, is to run 2 23 tooth gears ( Primary and input ), ie the middle ratio...

And yes, it's the drop gears which produce the whine, more so than the gearbox.

[Pooky]

what do i need from mini spares

Ear plugs?

[Cooperman]

what do i need from mini spares

Ear plugs?

Yes, oh Yes!

I fitted SC drops a couple of years ago when my helical transfer gear finally packed up after 30 rallies.
The SC gears are so noisy I am going to revert to helical ones as I need ear plugs even for short road journeys.
It's fine with crash helmets on, but on the road it's 'orrible'.
The SC CR box is bad enough, but never, ever again SC drop gears.

[mini93]

what do i need from mini spares

Ear plugs?

Yes, oh Yes!

I fitted SC drops a couple of years ago when my helical transfer gear finally packed up after 30 rallies.
The SC gears are so noisy I am going to revert to helical ones as I need ear plugs even for short road journeys.
It's fine with crash helmets on, but on the road it's 'orrible'.
The SC CR box is bad enough, but never, ever again SC drop gears.

thats over reacting, i drove mine through 600 miles newquay and back, but hey i might have less sensative ears than some

[Chewy LSMM 1275 MAYBE]

I am goin to order them from mini spares

engine has got to come out the diff needs a rebuild

[Calver ST]

The issue over noisy drop gears stems from the prolifically available Jack Knight stuff from years ago. JK used to make their gears fast and cheap so they were machined very poorly. The teeth looked like they had been cut with a saw blade rather than a tooth-cutting machine. Not reflected in their sale price of course- being the only real player in the ganme they made fortunes from badly made parts. They also machined in excessive back lash to make sure the gears fitted ALL applications, no matter howm badly bodged. This just made the noise thing worxe.
The MSC/EVO (original and genuine Trannex desugn) drop gears are manufactured using more exacting tolerances and far, far better quality with far les back lash. The result are gears that are MUCH quieter than previously available parts. PLUS they offer somethinmg ike 9 different ratios using a common idler gear. Where JK could only offer a limited 2 ratios with the same idler and drop gear, MSC can offer a minium of 3.

[Cooperman]

Mine are the latest Mini Spares ones and are still very noisy.
I guess having tinnitus makes it so much worse. Now, did I get tinnitus from years of angle grinding, working inside aircraft rivetting as an apprentice, discos ( as a younger guy!), rallying in noisy cars. I guess that's a 'Yes', so beware of all those things, you younger guys.

[Ibexx]

I want to do this conversion in the near future (with the SC box). I've seen two types, normal bearings and roller bearings. Can somebody tell me what's best? Probably the rollers as they are more expensive, but when is this needed?

[Calver ST]

The rollers as opposed to the taper rollers give less trouble in service. As for when they are needed? Great things are claimed from them - stronger than the straight pin/bearings in the casing type. But I have raced on the latter for years and years with no problems as have others I have discussed these issues with - but then I only use the A+ big pin type. I think folk used to have failures with the pre-A+ small diameter pin types because they rarely changed the needle roller bearings - consequently they would collapse after a short time in race use. Plus folk have a bad habit of not setting the end float on the idler correctly. The taper roller bearing was the first on the scene and solved both these problems because there is no shimming required and no needle rollers to change. Folk didn't/don't change the needle rollers because they were/are dificult to do. Espcially the one in the transfer gear casing.