Possible solution for those who break gearboxs
Turbo Mini Forums

BTW - I don't understand this? Can you clarify?

no dave i cannot clarify that sentance, but if i was pissed out of my brains in the pub and someone said that to me 20 years ago , i'd have thought , what a really intelligent person, now i would tell them to fook off talking shite,lol.

carl

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Is it not the reason the helical gearset causes such side loads that it is not the gearset that fails but rather the case?

Obviously straight cut gears do not produce these side loads, but do suffer less load spread across the teath.

what is the highest torque output anyone has put through a WELL built helical box, and how did it fail when/ if it did. Or are we getting back to this common misconception thing and no one has actualy tried it. I know robert suffered a failure recently, but i was under the thought that the box had around 4k on it, which is more than i would want with high outputs. Did it use the larger input shaft suport bearing?

I am considering the helical gearset

lol

The helix could be argued as more of a factor if it were 45-degrees, and the tooth was closer to narrow as the tooth was thick - but as it is totally the opposite, it is not the case.

IN my opinion the 3mm larger O/D of the input shaft bearing is totally irelevant.
Also straight cut gears are stronger than helical for whatever reason you care to choose.
Regards
Dave

Edited by danboy on 16th Oct, 2007.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Hmm, this is all pretty interesting stuff. To me especially, as some of you know im buying a house at the mo so i will be forced into using helical if i wanted to get the car on the road in the next 100 years!

Question: If someone were building a helical box from scratch what parts would they use to ensure a decent life running around 130bhp?

If i can get a general concecus ill go away and do it.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

close ratio s box maybe? all the A series boxes have less angle on their teeth than the A+, and the S ratio would be a nice bonus. But to be honest TD is the guy to listen to here!

BIR1 was driven with an S/GT gearbox its entire life in the UK. When I opened the box, the only faulty thing was that the big 1st motion shaft bearing had spun in the casing. Hardly the gears fault. That var had 160Bb, and was abused all the time. A+ sux!

So, to run an A-Series box on an A+ Engine, you would need to change the drops?

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

isnt the gear that breaks most ,the input gear to the layshaft ,a different ratio with straight cut ?? so the small one is bigger so stronger ,i may be drivelling.

Edited by robert on 17th Oct, 2007.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I've got the swifttune dog box in my car. It will be interesting to see what breaks on it, (if it does at all) Nick Swift tells me that one has never been broken before.

Team Racing

Is it possible to Run.

A Gears in an A+ Case, this would be to stop the cracking in the casing due to that extra hole thing.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

i feel a thing that may make a heli box last a bit more is a sprung clutch plate to reduce shock loads . my sublte burn out technique deff didnt help with shock loading the box

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Nice and Blunt! Just what i like!

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

I'll be hinest - I'd always been sceptical of A+ 'breakages' before the amount that i've seen on this site from folks who've exceeded the boundaries of the A+ gearsets.

If i was to build any helical box for a turbo, I'd definately search out a pre A+ set, and would definately get it cryo treated. This is another thing that at first investigation sounds like hype, but results clearly speak for themselves. Brake discs seems to benefit hugely from it incidentally; worth considering if you have problems in that area also.

Hmm, I think ill go down this route, ill have a word with the dad in to see if they do cryo treatment.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

are pre A+ gear sets any good then?

Vegard is the man to clarify that - but the headset gear breakages that seem common on the A+ gears don't seem to occur on the A- stuff.

Of course it 'could' be that the lack of sufficiently large data pool makes it appear the A- stuff is stronger? Maybe? LOL

I suppose the solution is to use clean steel for starters and then get the set machined out of a billet built out of that. So basically the steel is made from chemically pure iron and carbon and then stamped right. I suppose you could then have it nitrided. That would be a good idea.

ST used to make magnesium boxes but they used to tighten up IIRC.

I think clean steel is probably the stuff to use.

One thing I wonder is why double helical gears are not made. Since this would have the benefit of no thrust and a progressive loading of the tooth. CNC would make it well possible.

Bugger off, I'm getting there.

I'm sure i read somewhere that the magnesium cases were the very early ones that were too expensive to make, so i'd guess they were 3 sync.

Double helicals are doable but expensive, All early citroens used to have them, its where the badge came from