worf928

I had the same issue as Earl when I put a rebuilt rack into my '91GT. I was pi$$ed mightily by the change in steering sensitivity. I have *heard* that the issue is that the US rebuilders cannot get new internal bushings for the racks from ZF. I don't know if that's truth or fiction. But, I do know that the next time I will either do Earl's bushing fix or - more likely - send the rebuilt racks back as unfit for duty until I get one that does not exhibit the initial front-back movement of the shafts to steering input.

Earl Gillstrom

Garth, All the racks that I have checked have slop on the drivers side. The drivers side is the only place that I have used the bushings. Maybe your rack has some abnormal problem? I am probably the wrong person to answer the question due to low sampling numbers. I have three racks in storage and will try to sample.
Brendan, I thought about making the bushings available but, the installation method is so non professional, and the liability, and the cost, so I thought it better to keep it secret, but maybe I will rethink the problems. I also wondered if the stabilization would reduce the leaking wear problem, but at the time, the one non leaking rack I had is the one that I just replaced due to leaks on the drivers side, where I put the bushing. Probably not a good sample since it was a rebuilt "A" rack. I still can't believe that Porsche would use such a POS steering rack. The '88 rack that I just rebuilt and installed in my '91 GT had no leaks and is "C" level and never rebuilt, so we will see. This rack was used for DE and had an occasional loss of power in high speed tight turns. I will probably never stress it that hard.

BC

Porsche has done alot of suprisingly weak things over the years. Check the 996TT thread about X51 transmissions, etc, or the one about 996 engine problems.


This rack can be strengthened.

Bill Ball

Earl & Dave's comments are very interesting. My original rack at 155K miles does not leak, BUT I can force the shaft fore and aft in the rack housing by pushing hard on the tire. Aha! Same as you report in rebuilt racks. The rack's mounting bushings are good, but the car has more tramlining than I have felt in other 928s. Thanks for the bushing idea, Earl!

Garth S

Try that when on an alignment rack! The toe setting can easily be forced positive from a correct slight negative setting if these internal rack supports are worn/missing. When driving, centrifugal force will then clearly result in +ve toe on that side .... and squat all for directional stability: in my case, the car was constantly drifting right ...
After reinstalling my rebuilt original rack, we could never get the alignment stable. Having installed spacer 'bushings' on the rack to lock it down, etc., nothing worked: then, leaning on the wheel in frustration when on the Hunter DP400 rack, the toe-in jumped into the red zone ... eureka

Must find some delrin ... perhaps nylatron, as it is perhaps even better at self lubricating.

AO

Down at Frenzy 9 last October, someone (I forget who) mentioned that they got a rebuilt rack from AutoZone. I don't recall the price, but they said it came with a Lifetime warranty! Might be worth checking out.

Bill Ball

I've always wondered why mine seems to align OK, but I get weirdo wear of the front tires (one wears inside, the other outside) and tramlining. And I drive this thing 170?

worf928

I would have set fire to and melted-down the rebuilt rack I got rather than install it - except I had a track day only a few hours away. I suspected that the steering would be vague and was right. These rebuilt racks result in an "American-like" vague on-center feel. But, I haven't noticed poor tire wear.

I suspect that 928 community immortality will be the reward for a easy fix to this. Garth??

Garth S

I just ordered more Duct tape and JB Weld .... lemme 'tink

An ideal approach would be the ability to source the internal bushings from ZF to supplement the reseal kit available: it appears that they do not distribute these items, reserving them for their exclusive remanufacturing service ( as distinct from ' reseal = rebuild'). I suspect that they may have a reservation releasing these items, for the home rebuilder is unlikely to either measure or correct any wear on the main shaft. That would be allowed for in a remanufacturing operation, if required. (Through a Canadian ZF rep, I've tracked down the ZF tech guru in Chicago - but haven't yet made contact to verify this).
Griffiths also have the reputation of remanufacturing racks to as new condition vs a simple reseal. In either case, it does appear that an as new rack can be had from either of the two - just lay out the cash. Perhaps these are the racks offered by our major suppliers ...???
For the DIY approach, Earl has succeeded in doing what Gruffalo & I had only planned. Think I'll ask my friendly machinist to drill some delrin or nylatron ....
Time for action, as opportunities for immortality don't appear every day ...

Bill Ball

I need to find a friendly machinist.

worf928

No. Yes.

As in the rack I got and didn't burn was from a well-known rebuilder recommended by a well-known supplier. It was the supplier that mentioned the internal ZF bushing deal.

If one was to source a real ZF-rebuilt rack at a cost of a zillion dollars would that rack also be junk?

EDIT: one other thing I didn't mention before: Before I put the junk rack into my '91 I compared the fore/aft (as opposed to axial) movement of the shafts of both racks. The leaking one from my '91 exhibited no fore/aft movement. The rebuilt one exhibited fore/aft movement on both shafts. So, someone got a really good rack from the rebuilder when mine was recycled...

crackerfeet

Hey Guys,
You have all given me a great deal of information and i very much appreciate it!
Just one more question. Has anyone used the solid replacement bushings available from one of the big 3 instead of the rubber ones that are OEM?

Andrew,
Look here http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

GRTWHT

Hi guys, I know this post is old but I'm kind of new to the list for my 928. It's interesting, this movement in our racks. I got under my car last night (engine oil and filter change) and moved the left wheel back and forth at the 9oclock and 3 oclock positions and it moves quite a bit (rack has no leaks).
Driving the car now for about 11 months, you dont seem to notice anything wrong till you are over 100mph when the car starts to tram track slightly. I dont like it at all, feels loose.
So are people still doing this mod to the rack with the fitting of some sort of bushing/guide at the end of the racks. I liked the idea and think it would work a treat. I'm willing to make some up and fit them in as soon as i can.
Cheers,
Glenn '81 9-2-8

worf928

If you are moving the wheels/tires then you may be seeing tie rod joint, upper or lower ball joint wear too. So, you need a way to isolate the rack.

In order to determine if your rack's pistons have the front/back movement that *I* described, the best way (if the rack is installed in the car) is to have someone in the driver's seat move the steering wheel while you observe the rack's pistons. And you'll need to slip the boots off the rack towards the wheels to see the pistons clearly.

Note that some folks in this thread write about movement of the entire rack. That's usually caused by wear in the bushings that hold the rack to the cross member. (And that's not the front/back piston movement I complained about.)

The type of slop I described results in a steering "dead spot" at all speeds. Is that how you would describe your car's behavior?

BTW, there is another mongo-sized steering rack thread that contains a lot of posts and pictures from one of the rebuilders:

https://rennlist.com/forums/928-forum/295812-hey-nice-rack-but-what-am-i-missing.html

ceedee

i talked to angel about that subject. he bought a kit. but he said that it is way too much pain in the ...
any grain in that rack will prematurely screw up the gaskets. also, if the actual rack is worn you're screwed, too.
he also thinks it's better to buy a professionally rebuild one with life time warrantie