Gear Ratios

[Lee]

OK Guys,

How do you get a taller 6th gear for our gearboxes? I have heard of an RS4 running some Diesel cogs from something to give taller gearing but that might be total BS. Anyone shed any light? Standard 6th on an ABY is 24.7mph/1000rpm on stock rims/tyres. Can this be increased? Sienna mentioned that an RS4 gearbox would fit an S2 engine but how strong are these? What are the gear and diff ratios so I can work out the mph/rpm for comparison?

I guess I have been thinging about transmissions recently! LOL!

Thanks

Lee

[Doug_RS2]

Have you maxed the car out then? What speed? I thought the modded RS4s were getting close to 200mph?

[s2avant]

I've done some investigating on ETKA about gear ratios. I don't know why I felt the urge to trawl through gearbox/engine info on a Sunday morning. It was bad enough when RevoTechnik phoned me on friday afternoon to sort out a final drive for one of their modded Seat Ibizas.

I haven't got a clue how you work out the mph/rpm figures though so you'll have to give me a quick how to guide.

RS2 (CRB gearbox)

6th Gear - 27/37
Final Drive - 37/9

RS4 (FDP. FTU, FZW gearboxes)

6th Gear - 27/37
Final Drive - 37/9

A4 Quattro 2.5 V6 Diesel - AKE engine (ENV. FTM, GBB gearboxes)

6th Gear - 23/41
Final Drive - 35/9

A4 Quattro 1.9 TDi - AVF engine (FTT, FYT, GBC gearboxes)

6 Gear - 24/41
Final Drive - 37/9

A4 Quattro 3.0 V6 - BBJ engine (FRE. GBD gearboxes) & 1.8T petrol - BEX engine (GDZ, HER gearboxes)

6th Gear - 27/37
Final Drive - 35/8

I know you need to have the front and rear diff final drives the same so I am assuming the A4 Quattro 1.9TDi highlighted above is a possibility.

HTH

Ben

[Audi Parts Guru]

Oh the joys of gearbox ratios

[s2avant]

I found a website that calculates MPH/RPM. Going by the figures above, it comes out with 24.7mph/1000rpm on stock wheels(24.9in diameter) for standard RS2/RS4 gear ratios, thus agreeing with Lee's figure.

For the 1.9TDi 6th gear it gives 30.82mph/rpm. Am I correct in assuming that this would give a the theoretical max speed of around 215mph!!

Excuse my limited knowledge of ratios etc but how would a sixth gear like this be in normal driving? Would you need to push 5th gear to the red line before using 6th?

Ben

[S2 Ant]

Sounds good!!!

Need plenty of power to get that kinda speed tho!! along with plenty of room!!!!

[s2avant]

I seem to recall reading somewhere that you would need at least 533bhp at the flywheel to hit 200mph. Can't remember where though.

I have to agree though, 200mph+ would be great. Then I could keep up with the heavily played with import Lotus Carlton round my way. Local legend has it that he has hit 210mph in it. I've not seen him out in it since I got my Avant though I can vouch for the fact that it is ridiculously quick at more normal speeds.

Ben

[s2avant]

This may throw a spanner in the works. I don't know the correct term for the gear in question, VAG call it the change gear 6th gear.

What is the relationship between 'change gear 6th gear' (highlighted blue) on the prop shaft of the gearbox



and 6th gear (highlighted blue) on the output shaft?



The 'change gear six gear' has different ratios on different gearboxes (see below)

RS2 (CRB gearbox)

Change Gear 6th Gear - 27/38
6th Gear - 27/37
Final Drive - 37/9

RS4 (FDP. FTU, FZW gearboxes)

Change Gear 6th Gear - 26/38
6th Gear - 27/37
Final Drive - 37/9

A4 Quattro 1.9 TDi - AVF engine (FTT, FYT, GBC gearboxes)

Change Gear 6th Gear - 24/41
6 Gear - 24/41
Final Drive - 37/9

I don't know how this affects the MPH/RPM ratio. Is this only used as part of the 5/6th synchro to match speeds when changing gear? If so does it need to match the new sixth gear? HELP my brain is starting to hurt

Ben

[Lee]

Are these alternative ratios for 6th? If yes, with my 235/48R18 that should be good for 31.4mph/1000rpm....sweet. How much torque can these 1.9Tdi 'boxes handle?

Cheers, Lee

PS @Ben, good link for the ratio calculator. You can input diameter directly from manufacturer's data too to see the effect of various tyres on final drive speed.

[Graham]

I have done alot of enquiring about what gearboxes will go onto the S2 and this is the reply i got from the specialist who was linked from this site who done a write up about the different o1e gearboxes:
From: Elijahallen92@aol.com
Subject: [s-cars] DSY 6 speed trans install
Date: Tue, 17 Dec 2002 20:46:50 EST

Hi all,
I finally got all the little things out of the way while I had the tranny out and started the install of my new DSY trans today. Well, I was told this would be a bolt in procedure but its not.

The cooler lines were not a big deal, I just bought the stuff from Aeroquip and it worked fine but the bell housing on the DSY is very different and I had to take a saw-zawl to it to let it fit around the RPM sensor (I think that is what it was) on the back of the AAN 5 cylinder engine. There are also two dowels that align the trans to the block and one of them does not fit and there is no way to make it work because the hole that the bolt goes through and the widened area for the dowel are offset from each other, also the bell housing on the DSY is too thin to drill the hole even if you could get the right offset. Only four of the bolts from the old trans fit, so I have to find different sizes to bolt it up. Also one of the bolts is larger than the original and to make it work I have to drill a larger hole in the block.

Elijah


--------------------------------------

Elijah mentions cooler lines. The DSY transmission has a built in oil pump, to pump gearbox oil through an external cooler. You can either rig up a direct connection between the oil pump output and the return fitting as Elijah has done, or you can mount and plumb an external oil cooler up front where it will do some good.

Something not mentioned in Elijah's email, the DSY center section does not have the mounting bosses in the casting that are needed for the ProConTen guide bracket. This means that you will have to do without the ProConTen seat belt tightening feature.

Here's a picture of the ProConTen bracket, and if you click on the center section description at the bottom, you will see 211 C center sections without the boss and a 211 B center section with the mounting boss.

As you can figure from his next email, he has installed a lightweight flywheel and centerforce clutch at the same time as he installed the DSY 6 speed transmission.

--------------------------------------




From: Elijahallen92@aol.com
Subject: Re: [s-cars] DSY Trans Code
Date: Wed, 18 Dec 2002 20:48:41 EST

S-heads,
I spent the day working out the kinks with the new DSY tranny and finally finished the job. Everything seems to be working and feels tight. The lightweight flywheel lets the engine rev faster and catch up quicker on downshifts and the centerforce clutch grabs very nice. It is all actually much more smooth and quiet than I expected. As far as faster, maybe a little in first and second due to the flywheel but not much. Fourth and fifth now have more pull all the way through the revs. Sixth gear I was told was the same as the old fifth but it is not, the rpms are about 400rpm lower at 70mph than they were with the old trans. All in all I am very happy with the new setup and can't wait to get it on the track for some real testing.



For those of you waiting on DSY trannys or thinking of buying one there are a few things that you will have to do to make it fit.

First get out the saw-zawl and cut a notch in the bell housing to fit around the RPM sensor. You will also have to pull the alignment peg/dowel from the drivers side of the block. I talked to Dave Jones who has installed a few of these and he says he just uses the one dowel so that's what I did and it seems to be fine.

You will have to cut a couple of the bolts heads on one side to let them sit right on the bell housing and some of the bolts are different lengths for the DSY.

Other than that the tranny seems to fit and work very well. I will post more as I drive it and get a better feel for it.

[Graham]

And here is the procon 10 write up

The boss used to bolt on the ProConTen guide is located just
between the word Procon and the "10", sort of under the letters
"on" of Procon. You will note that this boss is not present
on the 01E 301 211 C housing to the left.


The bump in the casting that accomodates the wider 1st gear is somewhat
larger on the 211 C casting. You can see this bump clearly on both housings

[s2avant]

Would it feasible just to change the 6th gear instead of changing to a new box? I know there is the hassle of removing and dismantling the box but is it a straight swap cog for cog?

I would have thought fitting a TDi box into an S2 would give some bizarre ratios on the other five gears. Years ago at the dealer where I used to work VW supplied a 1.8T box labelled as a 1.9TDi box. It got fitted in the diesel and it was virtually undriveable. Would the same not be correct if a TDi box was fitted to a petrol engine?

I still don't understand the relationship between the 'change gear sixth gear' and the 6th gear cog. Can anyone explain it?

Ben

[S2 Ant]

Would certainly make the car work a lot harder, but then if its high powered as most on here are now then i should think it would be driveable you just wouldnt go so fast and would drink more juice when pulling away / accelerating.


You'd only ideally want 6th gear, i know of some other people that have done similiar in Golf's.

I wouldnt have thought the whole box would be a good idea

[Audi Parts Guru]

All this talk of gearboxes is making me wanna go and find one to build again

[Greg_S]

talking of ratios my boss at work gave me a calculator that he made on excel for calculating what gear ratio's to go for so you get the spacing right and see what theoretical max speed in gears etc is. Will post it up on the forum later this week.

Greg