Technical > Engine and Transmission

Clutch/gearbox choise overpowered G40

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SteilheckG40:
So, here's the story.

Since I bought a Polo MKII, and we don't really know what to do with it, so we decided to prepare a new PY engine for the car witch is a little bit different to what we are used to.


For Worthersée 2013 we are trying to get the max out of a G40 PY engine.

Tough the setup is almost completely worked out on paper we still have some questions I hope you guys can answer.


First problem would be the clutch, what clutches would you recommend? I've seen the Sachs ''racing'' clutches that are claimed to survive a maximum of 300nm torque but my buddy is saying it is probably not enough. Suggestions?

Second unsolved problem is the gearbox, does anybody know howmuch torque/hp the average g40 gearbox can handle without breaking?
Ive heard story's about gearboxes collapsing in Polo's with about 165-180 hp.
Also i am aware of the modification needed on the fifth gear (oil supply), thats something that has to be done for sure.

So,

- What clutch will do the job for us
- On what torque/hp does an average gearbox decide to give up
- What 085 gearbox is the toughest (so we can already start stacking up a huge pile of those fuckers  ;D )

Hope somebody could provide us some answers  :)


Cheers!


 

hayesey:
I don't know how on earth you're going to get more then 300lb/ft from a g40 engine but forget about using the 085 gearbox with that, I dare say it'll just smash itself to pieces every time you put your foot down. 

You can kill the box in a standard g40 with some spirited driving, with about 200bhp, 200lb/ft the gearbox needs to be considered pretty much a consumable item much like tyres or oil filters.  I currently have 4 of them in my garage, some OK, some awaiting rebuild.  The differential needs fairly regular rebuilds too.  It's a gearbox that was originally designed to handle something like 50-60 lb/ft, I doubt when they designed it in the 1970s they ever even thought VW would attach it to an engine with 113bhp, 110lb/ft.

Anyway, I'm interested to see what you have planned that'll produce >300lb/ft that doesn't involve putting a 20VT engine into it :)

hayesey:
just to add, with mine, which is 194bhp, ~180lb/ft, I use a Helix Paddle clutch and it handles the power very well and has lasted a decent amount of time (even though most miles are on track).

POLOMON:
Adding oil to 5th gear, whats this modification ive missed this one? :-(

bobrosco:

--- Quote from: hayesey on November 27, 2012, 02:03:21 pm ---I don't know how on earth you're going to get more then 300lb/ft from a g40 engine but forget about using the 085 gearbox with that, I dare say it'll just smash itself to pieces every time you put your foot down. 

You can kill the box in a standard g40 with some spirited driving, with about 200bhp, 200lb/ft the gearbox needs to be considered pretty much a consumable item much like tyres or oil filters.  I currently have 4 of them in my garage, some OK, some awaiting rebuild.  The differential needs fairly regular rebuilds too.  It's a gearbox that was originally designed to handle something like 50-60 lb/ft, I doubt when they designed it in the 1970s they ever even thought VW would attach it to an engine with 113bhp, 110lb/ft.

Anyway, I'm interested to see what you have planned that'll produce >300lb/ft that doesn't involve putting a 20VT engine into it :)

--- End quote ---
he was talking about NM, you are talking about lb/ft, if im right thats a difference of 106nm(thats a lot)

And polomon the 5th gear on the g40 gearbox dosn't get enough oil sometimes and thats why you can destroy a g40 gearbox by driving fast in 5th gear for a long time. And as a mod some people drill the oil hole bigger so it gets more oil and then it should handle high speed driving a bit longer.(thats what i heard)

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