safulop

Over the years I have put 3 rebuilt steering racks into my Porsches (I had a 944, and now my S4), but I have never known one to last more than 30,000 miles.

I even had one replaced under warranty after just 2 years. Now I am replacing one installed by the PO about 8 years ago--has 30,000 miles on it.

Are these things ever any good, or should we really use new ones? I just finished about $2K worth of other work so I can't afford the new rack right now.

Feedback?

-Sean

Bilal928S4

Who's rack's are you using? It all depends on the rebuilder.
We had a tech session by Colin on rebuilding a rack up in Calgary. It did not seem like a very difficult job, but was fiddley and time consuming. Also depends on what cores you are working with.

safulop

I'm not always sure; the dead one in my S4 now I *thought* was installed by Greg Brown's shop back in 2006. PO did it.

Previously I had a Mayval brand rack for my 944 that blew up after 2 years, it came with a 3-year warranty so I got a free replacement.

Now I have one supplied by Roger Tyson so I figure he thinks it is not half bad. The problem failure is always the seals blowing out on the ends, from what I've seen.

Lizard928

The design of the seals is poor for high pressure IMHO.
But I would suspect they should last more than 30k miles..... I know I've had more than that out on racks I've done.
I've been considering putting together better style seals for the ends, but time is in uber short supply these days....

Randy V

Paging GB...

Mrmerlin

since your noting more failures than most others do.
I would suggest that the nut behind the wheel is to blame for poor rack performance.

The usual culprit is holding the rack at full lock turn when making tight turns.

This makes maximum pressure against the seals while the rack is extended to its full moving range.
This combined with worn rack inner bushings will let the rack move away from the seal to begin this leaking .

The end seals begin to leak then the bellows fill up and then system runs low on fluid then the pump runs dry and is damaged.

OR the system has a leak and isnt repaired in a timely fashion,
then pump damage occurs then the debris get into the rack and damage the seals.

OR the bellows are dry rotted and have cracks that let in dirt ,
this scores the rack and make it impossible for the seals to work properly.


NOTE the thing to train yourself to do is to turn to full lock, then back off an inch, and hold this till you need to turn the wheels straight.

NOTE using this procedure will not influence the turning radius/.

NOTE when leaks occur replace the reservoir and the curved line , as there is a filter inside it thats important for proper function.

NOTE when draining the rack from the banjo bolts always use fresh sealing washers,
you will need 4 of them,
the proper fluid is Dextron 3 or 4

NOTE use a quality rebuilt rack, Roger has them and so does 928 INTL.


With proper care you will find that the rack will last many many thousands of miles

GregBBRD

In 2006, we either were using rebuilt racks from 928 International or genuine ZF rebuilt racks. I did no racks, in house, back then.....so totally dependent on the quality of whatever those two companies provided.

I do rebuild racks now....but only virgin racks from the cars that have the "higher assist" power steering. (Basically the airbag cars.) I only do these, because it is "hit and miss" getting a proper "higher assist" rack back from one of the rebuilders, plus getting a rack that has the proper clocking for the airbag requirements.

From what I can tell, both companies pretty much replace only the rubber seals and O-rings. I'd guess that ZF must have some of the original parts, for when severe wear occurs on the internal pistons and bores....but all I've ever seen is used pieces re-assembled with new O-rings and seals.....so they might just have a huge "core" bank to draw pieces from.

Pretty easy to tell the two company's work apart. If 928 International's rebuilder did it, the large nuts that secure the aluminum end pieces into the steel central tube will have been loosened and tightened with a hammer and a punch. ZF uses the correct tooling (as do I.)

The rebuilt kits that are available from various suppliers contain only O-rings and seals, with a couple of the Teflon internal pieces that are impossible to remove without destroying them. None of the other wear pieces (like the Teflon wear guide on the left end of the rack) are supplied. I have to make some of these pieces myself, when they need to be replaced.

New rack?

Does such a thing actually exist, these days?

The Forgotten On

deleted.

GregBBRD

As usual, very wise advice and insight. Stan knows his 928's!

I had a customer that had to make a really tight turn to get into his garage. He ripped the pulleys off of the pumps. Several of them. I had to get some grade 12.9 bolts and make a custom locating dowel to fix that issue. Then he started killing racks. We must have put 4 racks into his car....each one of which would leak before the warranty period was over....of course. He finally modified how he got into his garage (took two swipes at it, instead on one really tight turn.) No further problems.

dr bob

Sean,

IIRC the rebuilt rack in your car was likely installed by Jules Hauer in Van Nuys. He was the PO's go-to guy on most non-serious repairs. Unless it was done as part of a PPI/post-purchase repair episode by Greg. You should have the info in your docs package.

---

Beyond Stan's escellent advice, folk should remember that the reservoir/filter is a service part. Fluid gets swapped at the same interval as the auto trans (25k), fluid gets flushed/replaced and a new reservoir/filter is installed. You usually discover the hardened/crispy/split hoses at the same time. Regardless, regularly flushing all the wear bits and other crud out does a great job of keeping the rack seals intact. Most hydraulic systems will last forever with regular cleaning/flushing and a good supply of clean cool fluid while in service.

safulop

OK wow, maybe I've been holding steering wheel on the lock? I honestly don't know. Come to think of it there is a really tight radius for my spot at the office. . . could be. I never recognized this as a major problem behavior.

My shop quoted me $1900 for a ZF rack from their supplier; with a price so high I assumed it was brand new. I got one of Roger's for a whole lot less.

Thanks for the advice; maybe this new one will last a bit longer now that I've learned a few tips.

-Sean

safulop

BTW the thing that finally killed the current rack was a wicked sweeper I took on a local highway while joyriding. By the time I got back home the fluid was all gone, it had been solid tight with no leaks before that.

Randy V

Sorry, G.

ROG100

I agree with GB - new racks do not exist as far as I know.
The $1600+ ZF racks are rebuilds and not new. Porsche only has rebuilds and they do not differentiate between any year racks.

I used rebuilds from 928 Int. up until about a year ago and now work with a local rebuilder. More about logistics than anything else as I had no issues with Mark's rebuilt racks at all.

geschwindig

HAHAHAHAHAHAHA!

Randy V
Rennlist Perfect Punctuation Police Emeritus