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What sort of BHP figures are safe with our gearboxes? I'm currentl running 450bhp and considering more and am concerned that I could end up just making my car unreliable where everything keeps braking! The car will now only be used for weekend fixes and trackdays as I have a new company car so mileage won't be anything like it's been over the last 2 years (79k!) but I want this to be the last time any major financial investment is required (as does the wife ), as this year I want to start lightening it.
So how does the standard box perform with over 500bhp? Is it just asking for trouble and a RS4 gearbox, or is 500 still safe? Advice/experience as always, cheers

It is not power but torque that kills boxes. You cannot get much over 500ft-lb on stock rods on an s4 so you are not into the gearbox breaking torque levels from just flooring it. Used RS4 boxes are usally trouble as they usually have had a lot of abuse from just having more power put through it longer than s4 boxes.

The best thing to do is source a good used box as a spare - then if something goes wrong you can swap it over. It is always that case that when you are desperate for one, you will have to pay over the odds.

It doesn't take much to go wrong with a box and you have a £1k+ bill just to repair the box. The last 3 used RS4 boxes we have fitted, without being checked, have all had issues.

Lightening - I got a nice black carbon bonnet lying around that would look realy nice on your S4!

That crazy polish s4 was using quite a few standard parts but not sure about gearbox it dont say
http://www.audiworld.com/news/06/audi-9 ... n-poland1/

Doug_S2 wrote:I got a nice black carbon bonnet lying around that would look realy nice on your S4!

You're going to get me divorced! Interested though....

andybnwc wrote:That crazy polish s4 was using quite a few standard parts but not sure about gearbox it dont say
http://www.audiworld.com/news/06/audi-9 ... n-poland1/

yea it does... stock..

thats crazy must be pretty strong then i seen it launch at really high revs !

600bhp dialynx tt uses s4 gearbox /running gear no drama's

i could post a few pics of polish ozz's destroyed boxes i have found...

we too had the same issue with oem boxes and shafts... for satans child
which is why we have now changed all our plans again..

i now am running a jerico 5 speed air shift gearbox ... which will cope easily with 2000hp..

mind you it has cost £10,000 in all with the clutch..+£2,500 for the titanium bellhousing

thats the way to go boys...

At the risk of wandering slightly off topic... has anyone read part II of that article on Arek's monster S4?

I just did and nearly choked when i read the following bit... bearing in mind they're claiming 800 ish Bhp without the NOS... "Arek grabs the stock brakes which do a respectable job of slowing the significantly lightened car down"

I'm sorry.... STOCK BRAKES !?!?!?! surely not !!?

No bends on a drag strip, it only has to stop once. The stock brakes probably don't do bad with a lightened car.

rs5steve wrote:600bhp dialynx tt uses s4 gearbox /running gear no drama's

does it actually ever get used though?i've always been interested in this car and have seen it at many shows.never ever seen it run

i think if you're using your S4 as a fast road car you should be ok at circa 500bhp but start giving it full bore launches and you could be asking for trouble! IIrc Bretts broken a couple!

i used to launch mine at 5,500rpm all day long with 0.4 second delay on a 100 shot of nos and all on a standard clutch i done this for the whole of 2003 and i never even had the clutch slip ...?

i know some of you have seen me run cj,mr biggs,weiner,
some of you might think im full of it ..

but i think most of it is pure luck... then maybe the driver..?

but i know a few chaps running big hp and doing ok on stock running gear

it also helps if you have the gearbox with the wider 1st gear and bigger output shaft like i have....

which is going cheap still........

again...

sorry i mean input shaft...