458 Coil over bottom mount nut stuck

Take spring pressure off

 

Can you post a picture? I think I know what you are talking about but would like to see it before I say more.

 

Sometimes you can apply a little heat to the ring NOT the shock body with just a propane torch

 

You might have inadvertently friction welded the aluminum threads together. This can occur with stainless against stainless threads also sometimes. I had a case once, where I was making a welding cart and I was using a stainless steel nut with a stainless steel bolt to hold a little wheel on. I went to test fit the wheel on and the heat from welding nearby caused the stainless nut and bolt to start to seize up. When I added more pressure to remove things, it seized up worse and then the friction from trying to get the bolt out welded the threads together. I tried everything in the book to get that bolt out, but nothing worked. I ended up having to cut the frame out and re-weld a new leg into the cart and start over.

I've been very careful with stainless to stainless threads ever since.

If you attempted to unthread the seat perch with any sort of pressure on the threads, then you either galled the aluminum (which will mechanically bind the threads - lubrication or not) and/or some level of friction welding took place. Either way, usually the outcome is not a good one.

Adding heat to the situation (especially with aluminum threads) usually is a bad idea. There is a special product for threading aluminum - it's all alum-a-thread or maybe Safety tap; I use it here in my shop when threading or turning aluminum on the lathe. It's pretty slippery stuff. You might try putting some of that into the threads to see if it helps.

If all seems lost, you might want to try using an air hammer on low and see if you can free the nut like that. Sometimes the small repeated blows will break things loose. The other thing is put everything into the freezer for a while, then hit the collar with a tiny bit of heat. Sometimes that will help free things up. When I press on wheel bearings or chainsaw bearings, I usually freeze one side and heat the other to about 175 degrees.

Anyway, good luck over there. Worst case, you'll be shopping for a spare strut on eBay

Ray

 

Go on YouTube and search "friction welding" - just for fun

Ray

 

There are always damaged ones for sale on eBay and/or you can contact a couple of the Ferrari parts recyclers directly.

You should be able to find a damaged shock assembly for around $300 to $500. Then just salvage the lower collar and you'll be back in business.

Ray

 

I am carefully checking this thread and the others about lowering the car on OEM springs, as I am considering doing it myself, so I am trying to learn as much as I can, and gather all the available information and advice in advance.

I would summarize that, in order to prevent nut jamming, the following helps:

· Clean the threads the best possible.

· Soak the ring nuts with the best anti-lock product available (note: the beloved WD40 isn’t particularly aimed at this) and let it sit.

· Lubricate the exposed (lower) portion of the thread, where the nuts will have to go once lowered.

· Release the spring tension with spring compressors before doing the job.

· Rotate the nuts very slowly and make frequent pauses, so that there will be no heat build up; immediately stop and try something else (more lube, backing it up...) if they feel getting harder to move.

Once the nuts are jammed, the “usual” things can be tried:

· Heat on the nuts.

· Freezing the assembly + heat on the nuts.

· Your best unlocking product in liberal amount.

· Longer sitting time once soaked in your best unlocking product in liberal amount.

· Hammer (yes, in the end you will try that, once replacing the shock is the only option left).


When all is lost, before replacing the complete strut, we can also consider to have new collars fabricated, maybe not ajustable (basically a portion of correctly sized pipe): this is still a viable and cheap solution, that will deliver with some luck and some adjustment (shimming/trimming of the fixed collars, adjustment of the working ones). Unfortunately this of course requires removing the shock from the car, but it still saves the strut.
An even luckyer backup solution is having just one nut locked in a position that is at least close to what we wanted: in this case I would consider leaving it as it is, adjusting the others accordingly, and trying to forget about the whole story.

All of this said, I also have to say I am sorry for you, Tim, I share your disappointment, and your experience makes me think twice about proceeding.

Last thing I feel to say is that there must be something wrong with this shocks, as most of the preload-adjustable high-end shocks have aluminum preload rings threaded on aluminum bodies, and they are frequently operated without even releasing the spring tension, and with no issue whatsoever. Take Öhlins as a reference, and check the user’s manual of any of their coilovers…
All of this extreme precautions and extra care we have to take on our cars are undoubtedly due to some defect in the collars/nuts manufacturing: surface treatment? Threads cut? circular tolerance of the collar?...

 

Tim,
after all of this hassle and pain your car looks beautiful, and sure it handles well. Happy about it.
If I will do that, I won't go any lower than that (I am in EU, so my metric plan is 10-15mm!).
Question: did you make a suspension alignment after lowering? I believe the camber change for such a small lowering could be acceptable, if not even an improvement... I think we are talking about a few tenths of degree here...

 

Phenomenon is known as galling. Good explanation here:

https://www.boltdepot.com/fastener-information/materials-and-grades/thread-galling.aspx

 

Thanks Tim, this is what I thought.
I think the camber change can be hardly noticed (if not better), and it has a negligible effect on tires wear...
Enjoy in good health, in the meantime I will order the smallest spring compressors possible (I have the one with two hooks at the ends, I will look for single hooks) and then maybe try...

 

Thanks, I will consider that.
What what did you do, in the end, with the locked nut?

 

Ah, OK, got it, thanks.

 

This job is very simple if approached correctly:

1. Remove the strut
2. Clean threads
3. Fully compress spring
4. Loosen jam nut

Once you do that, you should be able to adjust the seat perch with nothing more than your fingers. The only time you need the leverage of spanners is for breaking the jam nut free and also for holding everything in place while snugging the jam nut back into place. Otherwise, everything should turn relatively easily and freely. Cleaning the threads out with compressed air and/or a little used toothbrush works great. There really isn't a lot of need to soak the threads or use a lot of lubricants. A tiny bit of WD40 works great. Even just a drop or two of sewing machine oil works plenty well.

The big pitfall is thinking you can somehow safely do this job while the struts are on the car. I initially thought I could do it using this approach also. But it quickly becomes apparent that this method is full of problems (mostly access and clearance problems). Removing the strut is a bit of a hassle, as you have to remove the fender liner and also the liner up top (as I remember). You also have to loosen part of the windshield wiper motor & arm stuff and push it out of the way. However, in the big scheme of things, it's not all that bad. Once you have room to work, the strut comes off the car with only 3 bolts - it's actually a bit shocking how easy it is to pop off the car. Once it's off, working on the bench, while holding the strut in a bench vise, is relatively straightforward.

If someone out there is able to fully compress the springs while on the car, then great. Personally, I would like to see what spring compressor is being used, as I wasn't able to accomplish it myself. It's been a while since I did this job, but as I remember it, there is so much in the way, it's nearly impossible to clamp onto enough coils to remove all the tension from the spring - and as this thread illustrates, even a very small amount of load from the spring can result in damage to the relatively delicate aluminum threads.

Anyway, I'll say this: I bet Tim Gould Sr. will be a pro at doing this job in the future

Ray

 

I have seen it happen numerous times. Usually happens when someone tries to adjust the spring perch with the spring not compressed, but also sometimes with the spring compressed. The aluminum spring perch galls on the threaded aluminum sleeve installed on the shock body. Once this happens you are done, there is no moving the perch, as it is basically welded to the sleeve.

I do everything that Ray Johns recommends (though I use a new brass or stainless steel brush to clean the threads), but I also recommend using a good penetrating lubricant (not WD40) like Wurth HHS plus or K on the threads.

Not a very good design, as instead of cutting the threads into the shock body, Boge used a threaded sleeve that spins on the the shock body. You can't replace the sleeve unless you remove the top of the shock, which may or may not be possible.

The only fix is to replace the shock.

Brian Brown
San Francisco Motorsports

 

Brian,
I think the sleeve is sustained by a clip (that stands the spring load), so I believe that, once the spring is packed by the compressors, you can move the sleeve just a bit up, so to free the clip and snap it out of its groove, and then pull the sleeve out of the shock from the bottom. In case the lower end eye is too big to slide the collar over it, you can trim the end eye just a bit to make the collar slide, if it's not a big deal...
Or, you still have a couple of chances: you can slide the sleeve down as much as possible onto the end eye and cut a ring out of it to shorten it from the bottom, so that the spring nut will take the axial position you wanted to reach by "un-doing" it onto the sleeve (once it and the clip are replaced in their original position), or even you could split it into 2 halves with a grinder (but you have to be VERY careful not to damage the shock body), and fabricate a new fixed collar made by cutting in 2 a piece of pipe, and then keep it in place by an adequate number of steel clamps, or by welding a couple of eyes where fixing bolts will go and keep the 2 halves together.
What do you think?

 

edit: you don't even need to do that, you could just slide it as low as possible onto the lower end eye, and progressively cut away rings of it until it's all done.

 

I think you are dreaming

You know when I was much younger, I used to try to repair dents in my Datsun with Bondo and sanding and all that. I used to think that the guy who do this for a living must get really good at it - having to perfectly follow all the contours of the body lines, etc.

My next door neighbor owned a body shop for many years, which repaired all sorts of exotic cars. One day I was hanging out with him and I asked him about doing Bondo work and how the heck do they get it so perfect when the cars have so many angles and all. You know what he said? He said, "No, no, we don't mess around with body filler; usually we just order a brand new body panel from the factory and install it, then spray it". He continued, "If we had to spend countless hours sanding body filler by hand on every car, we'd probably end up going out of business."

Wait.. what? My whole life has been a life...

Same deal here. Just get a new shock and bolt it on.

Ray