Stubborn Pinch Bolt
 

I have owned my October 2000 75 V6 from new. The NS front spring broke in February 2012 so I bought a pair of new springs. I replaced the broken NS spring with the intention of replacing the unbroken OS spring when the weather improved. However the second new spring remained in its box in the garage to this day. Last week the OS spring broke. The OS suspension has never been disturbed. A few days ago I applied penetrating oil and engine oil to both ends of the pinch bolt and the bottom of the strut including the slot in the clamp part of the hub. Today I applied more penetrating oil and engine oil then carefully tried to remove the pinch bolt with a 3/4'' drive hex socket and bar. It moved a degree or two in both directions but it was very tight. I repeatedly heated the clamp part of the hub with a heat gun and turned the bolt in both directions. I did this for about an hour at which time the bolt was turning backwards and forwards through about 80 degrees. When it is 80 degrees anticlock from its original position it goes solid again and I am frightened that if I force it the bolt will shear. The bolt is rotating along its length because I can see the threaded tip of the bolt that pokes out of the hub rotating. I have sealed the bottom of the hub slot and filled the slot with penetrating oil and engine oil hoping it will creep down the sides of the bolt. Any suggestions for removing the bolt?

I believe you are talking about the bolt which clamps the bottom of the damper strut into the hub ?
This is what I had to do after I had destroyed the head of the bolt ......
https://www.the75andztclub.co.uk/for...ad.php?t=84261
The problem with mine was not in the threaded end of the bolt but in massive corrosion along the plain shank of the bolt , and the bolt head could not withstand the torque needed to get it turning . I see that yours is turning and therein lies hope ; suggest you carry on soaking and twisting the bolt back and to for a while longer yet before you resort to my last resort !
Good luck :xmas-smiley-008:

Have you tried tapping a cold chisel in the "V" of the pinch section of the hub where the strut sits (ie towards the bolt that you are trying to release)? It can fractionally open up releasing the bolt. By "tapping" I mean a healthy whack on the chisel with a heavy hammer! If the bolt is moving, they usually release. Also you can try popping the nut back on to protect the thread and tap the nut. I always use a new nut and bolt anyway.

As my bolt is now turning through 80 degrees the plain shank cannot be seized and the threaded part cannot be seized. I wonder if my problem is that when the bolt is rotated anticlock by 80 degrees the rusty bit of thread that pokes out of the hub is trying to enter the hub but is tight due to the rust. I tried removing the rust with a scriber but it didn't work very well. This fits with your experience that your threaded part was easy to remove after the bolt was cut because you removed it the other way so the rusty end bit did not have to go through the hub.

I will try the chisel method but there is no nut on the end of the bolt. The bolt screws into threads within the hub. I omitted it from my original post but I did give the bolt head a few sharp taps with a big hammer before I started!

I will keep doing what I was doing. The penetrating oil/engine oil contained in the slot may creep overnight. I like your idea that it will draw in the penetrating oil as it cools. It is much easier to turn the bolt when the hub it hot. As it cools more force is required to move the bolt. I am patient and can devote some time to removing the bolt however progress was steady until I reached 80 degrees then it went solid. As I said in a previous post perhaps this is due to the rust on the tip of the bolt. I have a wire brush that fits an electric drill. I will see if there is enough room to get that onto the tip of the bolt.

try a small wire brush on the thread you can see plus penetrating oil.
As said back and forth is the way to go.

These bolts do indeed get well and truly seized.
One member I think had to remove the strut still attached to the hub, hacksaw through the bolt via the slot and then remove each half of the bolt separately.

I would undo the other side and then do it back up as preventative maintenance

macafee2

Did you heat up the full length of the bolt or just the threaded bit?

Maybe worth a bit of freezer spray onto the rusted end, then heat, maybe crack the rust off? The freezer spray usually has a length of small bore plastic pipe like WD40. Might be cheaper to get from plumbers merchant rather than car shop?

I don't know.

JohnnyBG

Be careful with the spray and protect "rubber" hoses atc. It will make them brittle.