Gearbox Limitations.

[Varley]

Been thinking about this for a while, hopefully someone more technically competent than myself may be able to shed some light or at least spark some debate...

Currently running a G40 lader but been thinking about different forced induction. Ideally I would like to keep it supercharged instead of going turbo purely for the fact that I like owning a supercharged car basically.

Problem is, if I were to go eaton, G60 or even a lysholm or something I've been led to believe that the 'snap neck' nature of the power (torque?) delivery would simply rip an 085 'box to shreds given time (especially with my 1473cc) and I want a setup that isn't a ticking time bomb waiting to explode in a shower of cogs and springs!

This leads most of us to the logical conclusion that going turbo makes most sense as the boost builds progressively without overly stressing the 'box. Perfectly sensible conclusion, thoroughly awesome setup but not for me I don't think.

I remember speaking to Steve Pitt a few years back about him potentially doing custom bellhousings or something to be able to fit a stronger box which could take the instant torque of a supercharger running big boost.

Reason for asking now is I really want a quaife diff but am reluctant to splash the cash on an 085 one as I plan to do the induction changes hopefully in the next 12 months and would be a waste of time/effort.

What do people reckon would be the biggest engineering obstacles and what 'box would be the most likely candidate for the conversion or am I just being mad even considering it?

Cheers guys!

[lance]

quaife will build you a fully custom box if you have plenty coin!!!

[Nick_S]

If you are feeling flush, then this 02A gearbox bell housing converted to marry up to the 085 polo gearbox/engine setup.

http://www.sorgmotorsport.de/Kataloge/2008/Aktionen2008/Getriebeumbau%20Golf02A.pdf

You can use a Golf gearbox then, but you might need some custom drive shafts and box engine mount fabricating!

[hayesey]

an eaton gives a more progressive power delivery than a g-lader does so you could possibly argue that they are slightly easier on the box.

One of those 02 adaptor plates would be great but there's rather more to it than simply buying the plate and putting the box on.  I would imagine everything like driveshafts, mounts, speedo drive, clutch cable, gear linkage will need custom making. 

[lance]

what about lado with the massivly impressive one thats in that red mk3 on the mk4 valver motor?

[hayesey]

he uses a super 1600 box or something along those lines.  I seem to recall amounts around £7K mentioned.

[lance]

there ya go them he can buy that ha ha.

[Yoof]

Try £12k retail 

Plus driveshafts
Plus CV joints
Plus Gearkinkage
Plus mounts
Plus box cooler & pump

Paid the cost to be the boss 

[hayesey]

dont think he bought it brand new though did he?

[Yoof]

Yeah but cheaper than RRP

[Dan]

It's possible to have uprated gear cogs made (say for 5th) with an improved tooth form. Would need a group buy of them to make it feasible to have it done.

Diffs are a a bit of weak point, and getting a new / uprated one should help over a standard tired one.

What else have people broken in the gearboxes other than 5th's and diffs ?

[Yoof]

5th gear stripping itsn't a gear form problem, it's oil starvation. Got a design for a spray bar incorporated into a new gearbox end plate, but it's far too much cash to consider making one.

[Varley]

Cheers for the replies guys, sounds like my choices are expensive, b*stard expensive and insane!

As Dan said really, is the idea of big power G's eating boxes more a chinese whispers idea that came from reports of the 5th gear issue, diffs and/or driveshafts than actual examples of boxes letting go purely due to agressive torque delivery?

Obviously not going to go down this route if not necessary, 900 and odd euros just for the adaptor seems crazy!

Hands up who's ever killed an 085 box with big power basically?!

[hayesey]

hmm well I snapped a gemini LSD in half but that's more down to the weak design of that diff casing than anything else. 

[Andy]

I've killed 5th gear twice and done a diff. First failure was a diff, the pinion gears expired - not uncommon on higher mileage cars, but in fairness the 'box had come from an accident damaged G40 that'd been bounced off some kerbs.

Second was a 5th gear, but think that was gear alignment issues from me doing a pikey DIY rebuild of the original 'box in the garden.

Third time round 5th died completely, the box was a replacement healthy one - but leaked oil slightly, so a combination of low oil and the power killed it.

Since running a turbo it's been fine - think the more progressive torque delivery means the 'box has an easier time, and I keep a close eye on oil level.

I know someone else one here making lots of torque still has problems with them though, and Yoof's just taken his 'box off due to some issues.