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Hi,

Is there a special tool for dismantling the suspension struts? Something to undo the top nut while a hex key holds the strut itself.

Thanks,

Richard
 

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Yes. It's called an impact wrench, either electric or air powered, and I'm sure you can just rent one to loosen that big nut. Many of us hold the top of the (removed strut) shaft, above the part swept by the seal on full compression (so that you don't potentially damage the part the seal runs on), with a big Vice Grip pliers with sand paper or emery cloth in the jaws.

The impact wrench does a good job of loosening the nut. Forget about the Allen hex tool. Some loosen the top nut of the front strut by using the impact wrench while the strut is still mounted in the car. Then they remove the strut with the nut still on the shaft.

DO NOT take the nut off in either case until the spring is fully compressed by clamps or hydraulic press. Same for reassembly.

The removed rear strut is easy to do, as the very soft rear spring really doesn't need much compressing at all, most just use their hands to compress the spring when taking the nut off after loosening with the impact wrench. Same for reassembly.
 

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I wouldn't! I mean use an impact wrench on a Boge strut. At the bottom of every Boge piston valve, whether a CDS or non-CDS strut, is a delicate set of shims and springs held by a couple of nuts (see photo below). Although the nuts are lock tighted, the jarring movement of an impact wrench can loosen them, contributing to their eventually undoing. It's so easy to undo the top nut with a very primitive but proven method that won't hurt a thing. Clamp a vise grips at the very top of the bare shaft (with a sleeve of reinforced vinyl tubing to prevent scaring on the shaft), then mount a socket and breaker bar on the nut, possibly with an extension to boot, lay the strut on the ground with vise grips held by the ground, then whack the breaker bar with a heavy mallet, the nut will loosen in a second. Then do your normal compression routine, and remove the nut.
 

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Ok, thanks for the comments and warning. My experience, though, is that almost all have done it with the impact wrench way without troubles, and using a special socket to clear the Allen wrench was a dismal failure. There is not an Allen wrench made which will not twist out of shape when the socket on the nut is torqued. I suspect the Allen wrench socket was there only for initial assembly, not for later disassembly.

If the shaft is tightly held by the Vise Grip pliers, it won't rotate when the impact wrench is used and potentially jar/loosen the bottom nuts. Has anyone had those nuts come loose that we know of? I strongly suspect that whacking/impacting the breaker bar is basically the same as using the impact wrench since it takes only several wrench impacts (at the most) on the socket to do the job. Certainly, when I asked car repair places how they did it, impact wrench was always their solution.

My own experience was that when I first tried the method with the breaker bar and whacking it, nothing happened with reasonable "whacking". I felt that the impact wrench successful applied a similar load in comparison, but only a couple of impacts did the job. I used a small 150 ft-lb Harbor Freight electric wrench.

So, anyway, now people have been warned. The method they use is up to them.
 

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My experience was I had to cut the rears apart to get the bits I needed - the base plates and such as the springs and strut were being changed. The fronts an impact. Same deal, changed everything, just needed the plates and upper bearing/mounts. ciao jc
 

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Using "Johnny rat-ta-tat" technique should only be used as the very last resort. The possible damage you do is invisible, you won't see, hear or sense a change in strut performance until much later. Performance will slowly degrade as a loose nut will score (ruin) the inner tube. It's not worth the risk. CCW movement of the impact wrench is exactly the direction that the nut is removed. I mentioned the fragility of the valve mechanism in post #3 but if you have CDS struts there are other parts that can get damaged as well: the solenoid assembly and some of the seals, especially the fitting and o-ring on the side of the bypass tube. When I said I use a "heavy mallet" what I meant was 5 lbs—that nut will not argue. Also lock the vise grips with the most force humanly possible so it doesn't slip or slips very little.
 

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"Also lock the vise grips with the most force humanly possible so it doesn't slip or slips very little"

In that case, the two different methods vary not at all, as since the shaft does not rotate, therefore imparts no loading to the nuts at the other end, the applied torque being reacted by the hand, workbench top, or floor restraining the Vise Grips. And the difference between one, two, or three impacts by the workshop mallet on the cheater bar, and a couple of "Johnny rat-ta-tats" from the impact wrench is insignificant at best. As soon as the impact wrench loosens the nut, most likely on the first "rat", the nut spins freely anyway. Further, the total mass of the two bottom nuts is very light compared to anything else, thus providing very little reactive force, if one was to be developed by not restraining the shaft with Vise Grips.

I do agree think that caution should be taken using either technique to use the least amount of "impact" loading on the stubborn nut in any case. It will take what it will take, regardless of the source of the impact. In my own case, rebuilding the S struts, the cheater bar method was not sufficient, even using a large shop mallet, hence the HF impact wrench (it's a weak one anyway). The nut popped off as soon as I pulled the trigger.

No problems, though. I do appreciate your concerns, you having had these shocks apart and describing the components. I think we just differ a little on how the required impact for loosening the big nut could be applied. I suspect there is very little difference.
 

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I just realized (perhaps) the root difference of our two points of view. If you are dismantling the struts to replace them, by all means use an impact wrench. Simple and fast. But if you are dismantling for the sake of replacing dust boots, top or bottom bearing, and will be reusing the struts, then I would suggest not using an impact wrench. I am not alone here, Koni and Bilstein specifically state:

"Do not use an impact wrench for installation or removal of the
piston rod lock nut as it may cause damage to the shock
absorber."

"Torque the top nut to 37 foot pounds. Do not use an impact wrench. With an impact wrench, you risk breaking off the upper tip of the rod (it is hollow) and you risk damaging the adjuster tab."

"Tighten the nut on the strut mount with 22mm and 11mm wrenches. (The photograph shows a 13/16 wrench.) DO NOT use an impact wrench to tighten this nut, you can damage the piston rod."

We will alway have to deal with the clowns (bad mechanics, po) that overtorque everything in sight with their new impact wrenches, remember that thread on the drain plug that was over torqued? Gee, I wonder how that happened.

I imagine that one of the reasons that some strut nuts are so difficult to remove is that someone installed them with an impact wrench.

Boge struts and valves are well made, some of the best in the industry, but the valve mechanism is delicate and easy to upset.
 

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I can agree with that.

However, I will offer that Koni, et al, figure that the shaft is NOT being restrained, but allowed to spin free when loosening, ie, as an example, using an impact wrench on the top nut while the strut is still in the car. Yup, that could bring a world of hurt. The shaft MUST be restrained from rotation so that the applied torque impact loading is shunted off the rest of the shaft.

The trick to not doing damage by rotation or loading is to thoroughly restrain the shaft so that no forces/loads are sent down the shaft to the other end, the torque loading being taken out or shunted off by the shaft restraint, hence the maximally tightened and restrained Vise Grips. Beam loading physics.

Also, I CANNOT imagine anyone in their right mind justifying using an impact wrench to tighten the nut, shaft restrained or not. Really big no no in anyone's book.

"I imagine that one of the reasons that some strut nuts are so difficult to remove is that someone installed them with an impact wrench".

Judging by the torque required to loosen these nuts, it would have had to be at the factory, lol, as the S struts I rebuilt I'm sure had not been touched by human hands after leaving the factory, the mileage being very low when I bought the car.

Anyway, good discussion. Thanks.
 

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Thank you Del. I think the problem with our really old cars is that previous mechanics did not use best practices on them. I am trying to solve the clunk problem caused by an overtightened strut nut and there is no way it is at 40 foot pounds. Someone had to have used an impact wrench on them. I tried using a strut tool and allen wrench and all I can say is it got dangerous. :). I plan to do precisely what you propose with the strut off the car to get the nut loosened.
 

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Wow these are tight. I cannot get enough grip with the vise grips to hold the shaft tight enough. Tomorrow I am going to try some wet dry paper to see if I can get more grip.
 

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Once you have strut spring compressor tools safely installed to retain coil spring, wrap piece of plumber's emory cloth roll around upper end of shaft and use curved jawed viscegrip pliers over top of clothand then use air impact gun with 22mm socket to loosen nut.
 

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If the nut is on as tight as you say, you'll not get it off without an impact gun, yes, an air impact at that.
 

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My plan although i actually think the DeWalt electric is a little more powerful than my air impact. Am now equipped with plumbers tape... Think the hardest bit is holding the shaft tight.
 

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You've got to tighten the visegrips as tight as you can. Nothing less will do it. The impact wrench should do the job, however. Wrenching won't come close.
 

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Success... Plumbers emory cloth 2x visegrips at maximum tightness and large channel lock pliers holding the top retaining washer. Then with the impact wrench it came loose.
 

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We knew all along you could do it.
 
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