Help: More steering rack issues - flexing rack rod ?!?
 

I had the S4 back on a Hunter DPH 400 rack today for a fine tune up following an alignment two weeks ago: the steering did not have a good on - center feel: We found that the toe-in had apparently shifted at the right front, so it was reset to spec. After checking everything else, including rolling the car back and forth a couple of times to confirm settings on all four wheels - we went underneath to examine my handiwork on the rack spacers I posted on yesterday. They were installed because "something" felt loose, so in looking, we pressed against the inside front of the right side wheel - and the toe settings went all to hell !!! :eek:
We pulled the rack boots back - and rechecked inner & outer rod ends: all were perfectly tight, and the rack is solid to the crossmember - but the right rack end was flexing !!! - in a horizontal plane. ie- push the inside front of the right wheel outwards as gyroscopic forces would do at speed, and the rack shaft flexed forward enough to create a negative 'toe-out' condition.
This is very similar, although less extreme, to the condition gruffalo has been posting about https://rennlist.com/forums/928-forum/203707-sorting-out-instability.html.

So what's up? This is a rebuilt rack: is there a bushing missing in the rack end?? I am/was under the impression that the rack ends could not flex - and that is at a straight ahead position. In a left turn, the right end of the rack is fully extended, and even more susceptible to bending. With my faith in the rack stability crumbling, I am looking for answers.....

Has anyone any experience or insight into this issue?

we live parallell lives,

mine is exactly the same, even the recent rebuild. it must be due to the rebuilder using the wrong bushings or some other mistake.

when reading the WSM there is a lot of side notes regarding parts compatability, so I guess there is some potential for getting it wrong.

I'm considering having some bushings made, machined from nylon/polyurethane perhaps? Maybe I can slide/hammer them on from the end with the rack in the car.

The WSM does not describe the rack internals, so I'm in total darkness as of now.

mm

Where are you guys getting the racks rebuilt?

https://rennlist.com/forums/showthre...=steering+rack

Gruffalo and all,

Go to the above pic. The bushing that holds the rack is #24 which fits into #25. Has to be replaced from the inside.

I have found that the "bargin" priced rebuit racks are really more like a reseal then a total overhaul.I've been through the loose end bushing on a bunch of racks for my own car.I had an extended warrenty company that shipped in a rack from a supplier that specialized in forgien cars.Shipped me 4 different racks...all loose at the rack end bushings. POS.Fought with them for a week to get a factory rebuilt unit from Porsche that is rebuilt by ZF.Much much better.Still in the car 7 years latter.

Glen, Thanks for the link to the pic - attached: Looking back through the archives, it was also a link to the valued contributions of our sadly departed friend, Erik of Denmark.
Yes, #'s 24 & 25 appear to be bushings - also, #'s 23 and 7 appear to be centering spacers.
Following up on the racks warranty, I had two return calls today from the rebuilding company - very friendly, but equally confused as to why the rack rod deflection witnessed either could or would occur. They committed to further investigate and reply..... but want to assure the rack is functioning correctly. We shall see.