rsgl

My Cayman's steering wheel was shifted off true center in relation to the steering box, by a not-so-swift 'tech' who shall remain nameless, during a wheel alignment.

Can anyone tell me how to determine dead center on the steering rack? This is important because of the variable ratio box Porsche uses.

99firehawk

your going to need a alignement rack

Jim Michaels

I agree with brad. You'll need to get the car back on the alignment machine all set up as for a full alignment. Assuming the car is properly aligned, you may only need to do the last part: centering the steering wheel. Be sure that the toe settings are about even on each side as the steering wheel is centered. At my previous alignment total toe was initially correct, but all toe was on the left side, cocking the steering wheel a bit. It was a quick fix on the Hunter machine.

rsgl

Thanks for your thoughts guys.

The issue here is that the 987/997 steering box has a variable ratio. Therefore, unlike constant ratio rack and pinion boxes, and like the recirculating ball boxes, they have a dead center position. As you go either left or right from dead center the steering gear ratio starts to increase. The car's wheels can be aligned correctly, toe set correctly, and the steering wheel centered when the car goes straight down the road, but the setup can still be wrong if, when going straight, the steering box is not centered. If this is the case the steering effort/ratio as you turn off of center to left will be different than when turning right.

My question, in any case, is, how does one correctly determine when the steering box is on dead center? Is there a mark on the rack or steering column, is there a PWIS readout, what?

Jim Michaels

I saw the thread reporting different steering effort turning right versus left. I admit to ignorance regarding the steering box being on dead center, but I think that's part of the centering process in an alignment. I just went through this yesterday, sitting in the driver's seat while the alignment was done. I could see the steering graphic on the screen. There were three different steps to centering the wheel; turning the steering wheel to the left and centering the wheel position over an arrow shown on the screen, turning the steering wheel to the right and centering it over another arrow, and then turning the wheel straight for the final steering wheel centering over another arrow. Hopefully, centering the steering box happens somewhere in that 3-step process. At any rate, the steering feels the same turning left or right, gently or tight.

99firehawk

Adjusting toe
Preliminary work: Check whether the steering wheel is displaced with respect to the steering gear. To do this, centre the steering gear as described below.
Turn wheels to the straight-ahead position.
Then readjust the front wheel alignment, if necessary, until pin -2- in driver -1- and lug on steering gear housing -4- , line up.

Steering in centre position

No. 3 is the desired breaking point for pins in new steering gears. The (new) pin -2- is inserted into driver -1- and its underside sits in lug -4- . This locks the steering gear in the centre position. After installation of a new steering gear, the lower part of the pin is sheared off at desired breaking point -3- ) by turning the steering wheel. The upper part of the pin -2- remains in the driver.

Steering in centre position

If necessary, reposition the steering wheel. When doing this, seek the best position.

Mark for the centre steering position
Warning

A triggering of the airbag (malfunction in the airbag system) caused by improper work on airbag components cannot be ruled out. In the case of such a malfunction, an unsuitable steering wheel holder could cause injury or damage.
→ Use only steering wheel holders that do not project into the area of the airbag unit!
→ Observe safety regulations when working with airbag vehicles (see in Repair Group 69)!


Clamp steering wheel in centre position with steering wheel holder -A- . Use only steering wheel holders that do not project into the area of the airbag unit -B- . If necessary, shorten guide rod of steering wheel holder at top -arrow- .

Steering wheel holder

Release tie rod locking nut(s) -2- . When undoing or tightening tie rod locking nuts on the square part of the tie rod -3- , with a spanner, apply counter-pressure. Next, adjust toe at the hexagonal part -1- of the tie rod(s). Then tighten tie rod locking nuts -2- with the specified tightening torque.

Adjusting toe

To loosen and tighten the tie rod-lock nut(s), use special tool (socket wrench insert) P 9730 -A- together with a torque wrench -B- . The tightening torque for the tie rod-lock nut(s) of 50 Nm (37 ftlb.), when using a socket wrench insert P 9730, corresponds to a value of approx. 32.5 Nm (24 ftlb.) on the torque wrench.




take it to the dealer

JEC_31

+1 to that - holy cow that's a lot of special toolishness.

rsgl

Thank you Brad, that's what I was after.

I presume you got this from a Porsche manual, and that it was accompanied by a diagram or picture showing what/where 'pin-2', 'driver-1', and 'lug on steering gear housing' are.

I'm guessing they are outside the steering gearbox at the area where the steering shaft enters the steering gearbox? Can you describe them any further?

In any case, you've understood the issue and provided the first hard answer I've found on this. Thanks alot.