Treating Gearbox Cogs

[Neal H]

Hi Guy,

A bit of a general question for your technical expertise regarding gearboxes. I have a rare 6 speed box for my four cylinder VW, now, on examination, the internals are standard VW parts and I am not 100% confident these will be resilient enough to run with a full race spec GC engine. My question to you is, is there any proven method to increase the strength of these internals? I really dont want to change to a cable change box because of the additional weight and the poor shift quality.

Thanks again in advance for your help,

Neal.

[Guy Croft]

Yes. Shot-peening is commonly used on at-risk parts like gears. However it must be executed by a firm with proven expertise with steel gears and the right equipment to do it otherwise they're going to do more harm than good. They would have to be prepared to show you a properly drafted shot-peeing regime before you place the order and tender a certificate of conformity after it's done.

I suggest a comprehensive internet search for such a specialist.

GC

[tmvolumex]

I would also take a look at cryogenic processing of your gears. There is a fair amount of info on the web, no point in posting it here.
Search: cryogenic processing of gears and cryogenic processing of steels.
It improves the entire gear not just the surface.
tmvolumex

[Neal H]

I have done some web research into cryogenic processing and in theory I can understand the benefits of doing this with the whole gearbox, especially bearing in mind the slightly fragile nature of the box and it's internals. By the look of what is written on the websites I have visited, this is a fairly new technology and I was curious to see if anyone has had any real-life experience of this process and it's results?

Any feedback much appreciated,

N.

[Guy Croft]

My advice is to email someone like this and settle for shot peening.

http://www.sandwell-uk.com/shotpeen.html

Cryogenics on gears etc already heat treated? Without phoning my consulting metallurgist first I'd be very nervous about that!

Some of the shot peening specialists in the UK are huge affairs, try Sandwell. They do at least advertise as specialising in motorsport rather than turbine blades..

GC

[Neal H]

Thanks Guy. Between £7 and £10 per gear, and £75 for REM finishing so the whole box should be around £200 all in. To me that sounds like good value considering how much a gearbox rebuild would cost in the event of failure.