AEB Engine & 6 speed box

[B5NUT]

Does any know if a 6 speed box could be fitted to an 1996 1.8T with the AEB engine, the current box is a 5 speed CTE box?

Was looking to see if there is a direct replacement as I don't want to start chopping up mounts or have to much mucking around with the wiring or ECU.

 

[aragorn]

The only vehicles fitted with 6 speed FWD boxes tend to be newer diesels, meaning the ratios arent ideal. The main difference you'll find though, is that they use the V6 style subframe mounting, so you either need to get a V6 subframe or weld bits onto yours. You'll also have to find matching driveshafts, as usually they will have big inners and big outers, and your 1.8T will be on medium inners and small outers, meaning you'll probably need to change the uprights for big bearing versions and use the shafts from the donor car.

Its doable with all bolt on parts, but its certainly not a drop-in conversion.

Theres no wiring involved at all, just mechanicals.

 

[B5NUT]

That's just too much work, thanks for the information.

 

[Geeman]

It's something I'm thinking about for the future, but the ratio-thing is concerning me though.

 

[aragorn]

If you compare the 1.8T ratios with those in say an S4, you find that 6th gear is a little longer than the existing 5th gear, and the rest of the range means they're all compressed nicely giving a closer gearset for 1-5.

The TDi boxes end up with 1-5 roughly the same as your existing gears, and 6th is much longer still.

 

[Geeman]

So... you'd only use the 6th gear for motorway runs... which is what I was really after. :icon_thumright:

 

[B5NUT]

So... you'd only use the 6th gear for motorway runs... which is what I was really after. :icon_thumright:

That's what I'm after, at 70MPH the car is doing around 3K RPM , would have liked to drop that with a 6 speed box, but it's just too much work to retrofit the box.

 

[aragorn]

The problem is though, while it sounds nice, its a low compression turbocharged engine, not a TDi or a big torquey V6.

Sitting at 70mph at 2000rpm might sound great, but the engine is running much less efficiently down there, compared with 3k when the turbos fully available, and it also has no power.

Stick the car in 5th gear at 2000rpm and plant the boot to the floor and notice what happens. Absolutley nothing. Instead of making motorway driving more pleasant, your just going to be left with a gutless engine and constantly having to downshift into 5th, with little improvement (or possibly even a drop) in fuel economy, because the engine relies on the turbo to raise its dynamic compression ratio to burn fuel efficiently.

Perhaps the 190bhp B6 FWD A4's would have a more suited box?