"A man's gotta know his limitations" - Dirty Harry
Someday I really want a barn with a proper 2-post lift in it. They are the joint.
One of my goals for the 911 is not to take it off of the road for an extended period of time to do work on it. I enjoy driving it too much, and restoration is a slippery slope in ways that are obvious and not so obvious.
Obvious, because there is "while I am here" stuff - tasks you may want to add in to some planned work. But then there is not obvious stuff like "we pulled out the windshield and found rust" or "the oil lines are seized". 35 year old cars will keep you on your toes.
When I got the front suspension back together and got the car aligned, it tracked well and handled great. At the same time, I knew it still needed new front strut inserts and upper strut mounts, and of course there were the semi-crushed rigid oil lines and weeping flexible oil lines. And that sandblasted windshield was not getting any easier to see through.
I found a great local Porsche specialist shop in Milford, CT named Butzigear. I put down a deposit for parts and waited to schedule the work. I can't do the windshield, I just don't have the experience and too much can go wrong, from breaking the glass to having water leaks. The oil lines are expensive and have some complexities to them such as galvanic corrosion (more in a minute). We added on a block of work to install the new strut inserts, upper mounts and all the hardware while it was in with an alignment of course. This will complete the re-build of front suspension. That is a great body of work to have behind us so we can focus on the rear next year.
Having a second set of eyes look at things is also very valuable. Especially when those eyes belong to 25 year master technicians who specialize in these cars & will know what to look for. I'm a shade tree mechanic at the end of the day, not a pro and certainly not a specialist. I am just starting to fumble my way around this car.
Strut Inserts
They started out by removing the front suspension and strut housings. This would make running the new oil lines a little easier perhaps, but since it was also the newest block of work it let them find any issues up front. I had just re-built nearly all of it, so it came apart nicely. What was unexpected is that the stub axles both had some pretty bad wear from a bearing spinning at some point. The wheels spun fine and there was no play, but the axles were shot. And since the stub axles are part of the strut housing, that meant the strut housings were toast. Luckily they were able to source a pair of used Boge strut housings in great condition for the car. (the stock housings on this model) That was a huge help! I had not spotted this wear, nor had other shops - there were no tell-tale signs anything was wrong. The bearings were fine, the assembly worked fine, but it was hiding this. To their credit, they knew where look. I am really glad this was resolved before I did any big track days.
That is all supposed to be shiny and smooth behind the thread, not look like it got welded. This strut housing is toast.
One of the replacement strut housings with a good stub axle. Much, much better.
The new upper mounts went in without an issue. These are the Bilstein "HD" strut inserts. (Green) where the "Sport (Yellow) seem to be preferred in the rear. It's an interesting situation, there is so little weight up front that you need to be careful about not making it too stiff. Our head driving instructor for the CVR PCA has never replaced the front inserts on his '69 911 and said he has something like 300,000 miles on them and they are "finally acting properly". Mine did not allow the car to bounce, and they moved fairly easily. But with 36 years and 121,000miles on them I felt like they must be bad, and the Porsche techs agreed there. The HD inserts make it difficult to push the front down, but do not seem to be overly tight in practice. I have some video of a drive by and the car seems to be moving well (up and down), is not upset by bumps and it certainly handles well.
Oil Lines
With the struts in good shape, they moved on to the oil lines. One of the things I read in my own on-line due diligence (I can't really call it research) was issues with the oil lines seizing to the oil thermostat due to galvanic corrosion. This is when two dissimilar metals are in contact with a few mitigating factors (see link below) The T-stat is located in the passenger side rear wheel well. It is made of aluminum; the lines and fittings are copper (I think!). Suffice it to say it is a bad pairing when it comes to corrosion. Despite me soaking them in penetrating oil for weeks ahead of time, and despite the Porsche master techs using all the usual tricks (heat, etc) they would not budge and the whole assembly had to be cut out. The new lines look like they might be aluminum but I am not sure.
Once removed, the nuts were cut and prised off of the thermostat housing and the threads were cleaned up. Note the soft brass jaws to avoid marring the thermostat housing.
The old hose ends. This would have been a bit on the dramatic side for me having never done this before. The other issue is the thermostat is pretty expensive so you really do not want to damage it.
Here it is back in the car with the new lines:
Cleaned up, remounted and a really nice touch was using a paint pen to mark off the nuts that have been torqued down. Also really handy to help see if anything moves or has been tampered with. It is really a "best practice" and the factory did this in fact. I have purchased some paint pens so I can track my own work this way. (using a different color though)
These are the new flex lines up front going into the oil cooler
And the lines headed back through the wheel well and attaching to the flex lines.
With this work completed, they got the car on the alignment rack to get the front end sorted out. The front is dialed in with -1 deg of negative camber, stock caster and stock toe and with stock toe and 1.5 deg of negative camber in the rear. It tracks very well, no bump steer at all and the handling is lightyears beyond where it was when I purchased it. It's hard to believe it is the same car. It goes through corners with real confidence now.
Up on "the rack".
We delayed the windshield work because I have the last few auto-x's of the year coming up and just since the car is as old as it is, we're exercising caution in case we find rust in the windshield frame. But soon enough we'll go back in for the windshield.
Special thanks to David Esposito @Butzigear for taking the pictures!
The crew:
David Esposito, Luke Armshaw & Hans Probst
References:
Galvanic Corrosion Table: https://structx.com/Material_Properties_001.html
Butzigear: https://butzigear.squarespace.com/
Commentaires