Haven't updated the thread for a while. Been too busy doing other things . Some of them to the TT. I did this mod with the power steering pump back in June.
Small upgrade to the car to try and resolve issues with the power steering on track. Getting lots of noise from the power steering I think due to cavitation in the pump and the fluid getting aerated / hot. I have a decent size cooler but with the power steering pump pulley being 20% smaller than the crank pulley the power steering is being spun at 9K RPM when the engine is at 7500 RPM.
Decided to try and install an electric power steering pump, I wanted to keep the existing rack and didn't fancy an electric column assist like the Corsa rack mod.
I found that Porsche cup cars used an electric power steering pump made by TRW that was almost identical to some model Astras. Ford and Volvo also used similar pumps , and of course there are pumps used in the Polo, Fabia , Ibiza and Audi A1.
The Astra, Ford, Volvo and a few other types are all usually used in a fairly dumb manner where the pump just responds to load and cannot actually see any sensors on the car.
The VAG pump is intelligent, it sees the engine RPM, Vechicle speed and steering wheel position over the CAN bus from the ECU, ABS module and steering wheel sensor for the ESP.
It only has 5 wires to connect, ground, 12V battery through 50A fuse, Ignition switched 12V and a CANH , CANL .
The pump doesn't actually start running till the engine is running that's why it needs the RPM signal. The assist is speed dependent as it knows how fast the car is going, and from the signal it gets from the steering wheel ESP sensor it knows when and how fast the steering wheel is being turned.
I bought a cheap used pump off a Skoda Fabia for £40 just to see if I could fit it and make it work. It does fit and I think works pretty well. Had to modify the bracket slightly and fitted the pump in a very similar place to the OE location under the LHS headlight, behind the bumper. It only just fits but I managed to reinstall the wheel arch liner so you can't see it and there is plenty of room so the tyre does not foul the liner.
There are several maps for varying assistance from disabilty mode which is very light through too a light vechicle which is not so much assistance. I have found option 2 or 5 seem to be the best in terms of feel and assistance.
Had to recode the module to 012 for the first three digits to get rid of the air bag fault code and make the pump use the ESP sensor. Last two digits of the code determine the map. There are also other maps not shown on VCDS 7, 8 and 9 all work as well.
Adding the electric pump has added around 0.5Kg weight to the car but moved 5Kg from the RHS of the engine to the gearbox side so slightly improved weight balance. The pump can take upto 65A current if you run it at the rack stops , It is rated to 100Bar (1470 PSI) but typically take around 3A when driving in a straight line and 10-20A if you are moving the steering wheel quickly at speed.
AN6 fittings from Torques on Fleabay, Pump outlet is an M16 I used the original green washer that came with the pump. Used just over 1m of braided teflon pipe. Braided pipe 2500PSI normal working pressure, burst pressure of 10,000 PSI so easily handles the 100Bar from the power steering pump.
Weight of the alternator mount bracket after I cut the surplus off and removed the pump, reservoir and pipe between the pump and reservoir.
Pump fitted under the LHS headlight. You have to remove the bumper and headlight to top up the level. On the stock Fabia, Polo etc you need to remove the battery to top up the fluid. You can see the level on the side of the bottle .
size comparison of pump
Weight of complete mounting bracket, pump and reservoir.
weight of the new pump on it's own
TT has a spare 50A fuse way already.