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Interesting, the steering rack in my 81 hasn't been changed since my father purchased the car in 1991 (or 92). It could very well be the original.
I have records going back to the 90's on my 79, no record of that one being changed either.
5-6 years ago the rack in my 81 started to leak and I emptied the reservoir and re-filled with Lucus power steering sauce, hasn't leaked since.
btw when my rack blew out it didn't just leak, it flooded. I could hardly keep fluid in the system for the 4 mile trip to my shop. I was literally leaving a trail. I tend to think that Lucus sauce wouldn't have done the trick.
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 to support 1,985 lbs on jack stands, or should we really use the actual jack points? I just finished about $2K worth of other work so I can't afford the new rack right now.
Im on my third rack, original came with the car, swapped after 170k miles or so and then the current one. One in the middle which must have only made it 20-30k miles i put down to the bigger front rubber.
THe one the GT is original , other than the hose replacement under the reservoir and getting 3 years of sprints on the track in the queensland heat , I cannot complain about the quality.
Well folks I've been running with my new rebuilt rack (courtesy of Roger), and I must say it is world of improvement over the previous rack. I think maybe that one was always defective. Low-speed turning was very heavy, which I had put down to the fat tires. But my new one steers like a regular car. It even unwinds normally when you let it go, while the previous one didn't really. The previous rack also creaked and groaned like a '68 Nova, and at a certain turning angle it would bind up so bad that the car would grind to a halt at idle in a parking lot. When I first got the car I thought the front tires rubbed because of that, but they don't.
All together this new rack feels like a different car, steering-wise. Even tramlining is less. It's a weird unexpected improvement.
So like had said in the first place, it does seem like a lot of these rebuilt racks are junk.
Im on my third rack, original came with the car, swapped after 170k miles or so and then the current one. One in the middle which must have only made it 20-30k miles i put down to the bigger front rubber.
So you're kind of proving my point as well, thanks.
Still on the original rack at almost 110k. In my deep dark past, I've had the pleasure of dealing with experts in several engineering specialties, one of which is hydraulics. Early words of wisdom from this one said that hydraulics are self-lubricating by nature, and will last forever if kept clean. In car and power-steering terms, this comes down to flushing the system regularly, replacing the fluid and filter regularly, and avoiding contaminants in the fluid. The fluid and filter replacements is on the same every 25k schedule recommended for the automatic transmission. Avoiding contaminants sounds simple, but includes replacing deteriorating hoses that shed particles into the system. Of course regular inspection and replacement of the dust boots on the rack is part of this.
Then take a look at the angles of suspension and steering components. At normal ride height, ideally you'd have the tie rods sticking straight out of the ends of the rack. But, to get the correct Ackerman effect in the geometry, the rack is purposely located forward of that point. If your car is sagged/lowered, more angle is accumulated. The increase in total angle means that there's some radial force added to the ends of the "rack", the actual piston in the hydraulic cylinder with the teeth on it. The ends of that piston are supported in bushings, and therea are seals to keep the oil inside. As those bushings wear from the radial forces, eventually the seals won't be able to seal against the polished piston surface anymore.
Wheel offset, amazingly, has an impact (literally) on cylinder life. The factory wheels have the centerline of the tire just slightly inside the pivot axis of the steering. Besides adding to directional stability, this reduces the effects that tire impacts and braking forces have on those rack bushings and seals. Move the wheels out with more positive offset, and the same increased impacts you feel in the steering wheel are transferred to the rack bushings.
Replacement racks vary in quality of rebuild, but also suffer too often from poor installation prep. The hydraulic system must be flushed until clean --before-- the new rack is installed. This isn't rocket science, but it is pretty messy. Still needs to be done, since the dirt and debris that caused and are the result of the failure of the previous rack all needs to come out. A few pieces of hose and some clean fluid, and a pail to catch the blowdown will net you a significantly longer service life from your replacement rack.
Still on my original rack with over 230,00 miles...now that I have mentioned that. I believe there is a significant Legal definition difference between rebuilt and re-manufactured when it comes to auto parts. Re-manufactured is more thorough and more likely to last longer.
Pretty simple economic equation. For $300-$400 you are going to get a rack disassembled, cleaned, and get the seals replaced.....no more.
As the racks wear, the duration of time they last decreases.....the internal wear of the pieces obviously increases with mileage. If you are lucky enough to get back a rack that had 80,000 miles on it, when it got sent in for a rebuilt exchange, you have a better chance than if you get a rack that had 400,000 miles on it, when it got sent in for a rebuilt exchange.
And if you get really lucky, you get a rack back with the lower effort power steering....like it appears the OP got.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
08-15-2014, 12:56 AM
