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MG MGF Technical - EPAS tech.question...
the "Green Frog" is now on the roads again after its winter sleep. There is one unsolved question I have regarding the EPAS that I think someone can answer: How "stiff" is the EPAS unit to move (rotate) when it is removed from the rest of the steering ? Is there a rather high turning force needed ? The question is raised because when my car is on stands (all wheels in the air) and no ignition on (battery removed) the steering wheel is really stiff and some initial force is indeed needed! So far in my findings it is not related so much to the rest of the system as steering rack,balljoints etc. but seems more to be in the electrical clutch/motor system of the EPAS system itself. Hope I have given an understandable description... Anyone with a EPAS system laying around to test?
I have a spare EPAS system in my garage - (now in bits after some dismantling to see how it works!).
The force required to turn the EPAS motor is quite a lot.
But when my car has been jacked up it is not difficult to turn the wheels, either the motor is declutched or the leverage through the rack assists.
Hope this helps,
thanks for the info. The reason for asking is that compared to an old Porsche also on stands, (this car has rack and pinion steering too)that one is so very easy to turn the wheel on with one finger as for the "F" there is considerably force needed!
|Carl, as far as I know the power-steering is electrical, so if you have the battery disconnected it gets no power and steering is unpowered and maybe stiffer than with power.|
Also as far as I know it is connected to the speedo, but don't know the how exactly.
|The EPAS has a cluch, and should be compleatly disconnected if unpowered:|
Maybe you have a sticking cluch?
Yes Will, aware about all that and the clutch is free because no detected movement in the electric motor. Just that somewhere there is much more tension than on an "ordinary" non-EPAS steering. It is to such a degree that when moving the steeringwheel just slightly the torosional movement (that is transfered to the potentiometers) can clearly be seen. In other words : The steeringwheel can be slightly moved in either direction but the lower part of the steering rack doesent move until the end stop position of the potentiometers are being engaged. This situation does of course not happen when power is on and EPAS functions as intended. Then the electric motor will come in play and ease up the steering.
Not the easiest thing to describe in a clear way but hope You got it !
"The steeringwheel can be slightly moved in either direction but the lower part of the steering rack doesent move until the end stop position of the potentiometers are being engaged" - do you mean the top of the column turns , but the bootom of the steering column where it attaches to the cv elbow around the carpet does not turn?
If so this would imply to me that you have a fault within the steering column. It is in 2 parts, upper and lower, and these are held together by small plastic pins which would break in the event of an accident - a collapsing column.
A new column is very expensive, but they are easy to remove/fit. Too see if the tension is in the column or the rack, take off the cv elbow on the lower end of the column, this way the column can be turned without moving the rack.
Thanks for the info Jason, will check that during the week end.
|> fault within the steering column. It is in 2 parts, upper and lower, and these are held together by small plastic pins |
do you mean inside the sliding bearing are this pins ?
Location inside the lower shaft where it's attached to the *cross bearing*
On the left here.
Hi Dieter !
The source - as allways ! Thanks for the photos. Do You still have that unit or is it transfered to a new owner ? If You still have it in the garage please test in the week-end with a poly-grip how "stiff" it is to turn at the steering wheel end ! IMO there is a lot of drag (at least on mine) in the clutch/gears when the system is at rest. Very noticible as said when the car is on stands and I want to move the steering-wheel. Could be that I have a faulty/sticky one - but the EPAS works at least as intended when driving and has never blown any fuses etc.
|Hi Carl i can assure you that your EPAS is Ok they are a very very reliable component and there is nothing wrong with it! your problem was probably caused by the fact you had your car up on axle stands and the steering rack rods would be at such a angle that turning the steering wheel would have to overcome this.|
The EPAS column is an all in one construction and is not adjustable or serviceable other than replacing the complete unit itself. the EPAS motor and clutch only operates when steering assistance is required and once the vehicle speed reaches 50 kph [signal from insrument pack EPAS1 - signal from road speed transducer EPAS 2] no assistance whatsoever comes from the EPAS it just becomes a conventional steering column. Hope this helps
Thanks a lot for the info- we "F" owners seems to worry may bee too much about all those small things that pop up... ;) Weather is nice over here but oooh so cold with stubborn northerly winds for over a week now.
|If rgvn is right then you could test this by driving onto a few sheets of paper (under each wheel) then the stearing should turn easily.|
|My comment: "fault within the steering column. It is in 2 parts, upper and lower, and these are held together by small plastic pins" |
and the response:"The EPAS column is an all in one construction and is not adjustable or serviceable other than replacing the complete unit itself."
I agree that the column is not serviceable or adjustable according to Rover, but I know of two columns which have been serviced and adjusted by non Rover tecnicians. In one case the torque sensor and motor were replaced, and the torque sensor was adjusted.
The column is not in one part, the shaft inside the outer casing is in 2 parts, as said these are held together by plastic pins which allow the column to collaspse in the event of a collision. These 2 parts are not replaceabel seperately as the pins must be broken to remove them from the outer casing, but they are definitley not a single piece.
This thread was discussed between 02/04/2003 and 07/04/2003
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