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So...school me on how to evaluate Boge front shocks. These were installed in 1999, at 150,000 miles. So, they are 17 years old and have 18,000 miles on them. Since I am going to rebuild the front end when I do the MM/OPG, I plan on taking Stan's advice and servicing the front shocks. Now, since I am in that far, I want to know how to decide if the shocks are still good, or should be replaced. Yes, I know its only money, and around $260 for a pair. However, if they don't need to be replaced...
Anyway, please offer me some guidance, advice, and the occasional insult. I will appreciate it.
You have gas pressure Boge shocks. You can inspect for oil leaks and condition of the plastic dust cover and washer in situ. If you also see the bump stop flopping down on the washer, then it is worn and due for replacement. If it is still firmly on the shaft, hidden up inside the dust cover, it is likely in good shape. That's about all you can do in situ.
If you remove and disassemble the coilover, you can observe that the shock compression and rebound action is smooth with resistance both ways and the shock shaft returns to it's fully extended position. At 18K miles I'm not sure there is any reason to go through this if the plastic bits look fine and the shaft is clean with no oil leaking at the base and you don't see the bump stop flopping down around the bottom of the shaft.
Now, you have had a impressive amount of corrosion and, um, dirt coating every part you've removed so far, so you be the judge as to whether that extends to your coilovers. If so, they deserve removal and disassembly for cleaning and inspection.
Hello Bill! Thanks for your advice. That makes sense. I have looked again at each of the front shocks. The white plastic washer is still there at the top of each shock body. I do not see evidence of oil leakage. I do not see the bumpers flopping around at the bottom of the shaft. So, I am going to say the initial inspection of these shocks is OK.
Now, having said that...
The white plastic washers are no longer white, and one of them is missing a small piece of the edge. The receipts from the PO show purchase of the shocks from Vertex. However, there is no receipt for purchase of dust covers, bumpers, white washers, etc... To my understanding, the new shocks do not come with any of that. So, I have decent newer shocks with original parts.
Yes, Bill, to put it politely, the Red Witch is dirty. When I rebuild the front end, I am going to disassemble the spring/shock assemblies for cleaning and inspecting. My machinist has the correct fixture for disassembling struts. I will replace all the above mentioned parts and reevaluate the shocks at this point. And clean. Alot...
Got a little cleaning done over the past couple of nights. Spindles from the car, and good used rotor shields from 928 Intl.
They have soaked for a day in the heated parts washer, then been scrubbed in the same. Rinsed in hot water. Scrubbed them with mineral spirits and a toothbrush. Final rinse with contact cleaner.
All are in good condition. I have to sand the seal surfaces on the spindles, as per WallyP. I plan on running scotchbrite through the joint tapered holes to clean them.
Regarding the shocks: if it hasn't been mentioned already, the condition of the adjusting collars is important if you think you'll want to adjust ride height. Mine are frozen on tight, as is common; the bash plates I installed are getting bashed regularly.
Hi Adk46! I have thought about that. My intent is to disassemble EVERYTHING. Including and especially the threaded adjusters. If need be, I will get good used replacments from 928 Intl. I am beginning to think about just replacing the shocks as well. They are probably fine. However, they are 17 years old. Since I intend to replace just about everything else in the front end, I may replace the shocks as well. For peace of mind if nothing else.
Correct my line of thinking, if necessary. The Red Witch has 168,*** miles on her. By nature of needing to replace the upper ball joints, I am replacing the upper control arms. By my way of thinking, the bushings in the lower control arms must be tired, based upon age and mileage.
I have resigned myself to mortgaging my soul to pay for rebuilding the front end. I want to do it once and be good for 30-some-odd years. To my way of thinking, the lower control arms should also be replaced at the same time as the upper ones.
Am I thinking correctly? I had hoped to be able to just drive my 928 and do little things as I go. But, it is turning out differently. So be it. I am tackling this head on and want to be done with it. Finish the repairs and be good for a number of years.
In case you haven't picked up on this yet, I'm of the "do it once, do it right, do it like you mean it!" camp. On the front end/suspension/steering, any single parts replacement triggers a cascade/ avalanche of other WYAIT things that age at the same rate.
Most 928 owners are in denial about suspension wear issues. Most cars that have past 75k and for sure all that have exceeded 100k deserve serious attention. Ball-joints, rubber bushings, tie rods and ends, steering rack and rack mounting bushings are worn, hardened or torn by 100k and all these years. It's a huge epiphany for most folks when they drive a car with full suspension restoration. "So -that's- what it's supposed to drive like!" It will be a different car when you are done, trust me.
Hello dr bob, that is what I am realizing. My only hiccup is the steering rack. However, 928 Intl sells rebuilt units for $395, so I will probably go that route. In for a penny, in for a pound.
I have already made the decision to go seriously into debt to make this car right. My intent is to drive the wheels off of it. To do that, the front end needs to be right and tight.
I asked about the lower control arms just to make sure there wasn't some kind of long-life Porsche magic involved that I was missing.
Before you bring up the rear suspension, I am well aware of it. However, there is a limit to how far seriously in debt I can go. Pay that down, then refurbish the rear end.
Hello GT6ixer! Thanks for the heads-up! That looks like a screaming deal. However, the Red Witch is a 1986.5. She already has the S-4 brakes and suspension. Only thing I can use from that listing is the lower control arms.
Hey: I got similar results by sending my calipers to North Dakota to be rebuilt and refinished. Unfortunately it took 6 MONTHS and a return trip after that to correct incorrect seals initially installed. They did not look much better outside than yours, however the inside of the calipers was " factory" so it was probably worth it. Cost me about $ 700.00 for the refinish / rebuild, but I could NOT have done as good a job.
Is the rack worn or leaking? They last a long time if ride height is maintained and fluid is changed regularly. Mounting bushings get oil-rotted but can be easily replaced. Check radial play at rack ends in the tube, decide from there.
Jerryjohn: Thanks for the suggestion. However, six months is a little much. That, and as of right now, none of the sixteen caliper piston seals are leaking. I am going to draw the line here. In the future, if I need to rebuild the calipers, I will do so. Meaning, I will jump off that bridge when I come to it.
dr bob: That is a very good point, and one I have been waffling back and forth on. As of right now, the rack does not leak. The rack mounting bushings were replaced 17 years/18,000 miles ago. I have been pumped out and refilled the PS reservoir with fresh Dexron III several times over the past few months. I think it is all good for the moment. I AM replacing the damaged rack boots this go around. I will inspect the rack ends for radial play when I do the boots, and go from there.
Seth, take a good look at the aluminum universal joint that connects the steering to the rack. They are exposed to road grit and can be either sloppy or be bound up in one direction. The power steering will still overcome the binding, so it isn't noticeable unless you are looking for it.
08-14-2016, 12:21 PM
