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View Full Version : Fitting electric power assist system (EPAS) to RHD drive roadster



Nigel Allen
02-11-2021, 12:58 AM
At the time when I purchased My roadster kit in 2011, power steering wasn't available from FFR for right-hand drive. As such, my kit came supplied with a manual rack. Whilst it worked okay, I was never really happy with it, as steering was quite heavy and sluggish. I could have replaced it with a hydraulic rack option available locally but it was very pricey. Additionally, I would have to fit a pump to the Coyote. I was out to $5k even before hoses and a cooler. Thanks to the feedback on this forum from other members who have fitted EPAS their cars I decided to take the plunge.

I chose the Epowersteering kit as used by others. Ordering it was the easy part, making it fit was a little trickier. As the corpulent Coyote takes up a lot of the real estate in the engine bay and because of the orientation of the electric motor on the EPAS unit, my only choice was to mount the EPAS on the driver side foot box. Fortunately, FFR had sent me two steering shafts assemblies with my kit. This meant I did not have to hack up the original assembly. This gave me the confidence that I could revert back to manual steering if it didn’t work out.

I started by cutting the upper universal joint off of the steering shaft assembly and replaced it with the splined adaptor that was supplied with the power steer kit.

I then fabbed up an angled bracket to mount the EPAS to the foot box. It was a bit of work to get the angles correct but I got there in the end. This bracket was then bolted through to the ~6mm steel plate that normally supports the lower steering shaft bearing. With everything all lined up, I could now rotate the steering wheel and see the output shaft on the EPAS rotate. All nice and smooth without binding. Happy days.

142438
- This is the prototype bracket, a prettier one is on the way:)

By a stroke of luck, I located a lower steering shaft complete with universals that was an exact fit, to connect between the EPAS output and the steering rack. An added bonus was that the universals were more robust than FFR supplied. I had already experienced wear on the original universals that made for slop in the steering. A bit poor for 3,500 miles (I suspect the wear was exacerbated by the extra force I had to apply with manual steer, or maybe just faulty from new. Either way, glad to see it gone).

All that was left to do was to wire it up which was pretty straightforward other than having to extend the cabling from the control box to the potentiometer that controls the level of assistance.

Once everything was buttoned up I took it for a test drive, gingerly at first but then for a good blast on some windy roads in the hills. I have to say that the car is absolutely transformed. I certainly wish I had done this from the get-go. Tracking and overall drivability is now hugely improved. Once I get the caster increased, it should improve the handling further.

It was an expensive exercise getting this kit landed in Australia, with our exchange rate being so poor. I wish to thank everyone that took the time to give feedback on the EPAS systems.
Cheers,

Nigel

frankb
02-11-2021, 08:01 AM
Nice work, Nigel!

Ian G
02-11-2021, 03:30 PM
Thanks for this info Nigel. The older I get, the more I am considering adding PS to my Mk 3. My Flaming River quick ratio rack gets hard to maneuver in tight places. How does the adjustable sensitivity work out?

Nigel Allen
02-12-2021, 06:29 PM
Thanks for this info Nigel. The older I get, the more I am considering adding PS to my Mk 3. My Flaming River quick ratio rack gets hard to maneuver in tight places. How does the adjustable sensitivity work out?

G'day Ian,

The adjustable sensitivity works great IMO. I have the adjustment potentiometer mounted under the dash within easy reach. After a little bit of experimentation I found that I have it set at about 20%. This works nicely for me and everything I have thrown at it so far.
I will give an update in a couple of weeks when I have got some varied driving experience.
The downside I have seen to date is that the feedback from the road is less, however there was way too much feedback with the manual steering. Also the self centring isn't that great compared to my daily driver. This might improve when I add some more caster.

Cheers Nigel