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Discussion Starter #1
My S3 Spider developed a noticeable vibration between 40 and 45 mph this autumn, and so after the driving season I put it up on stands and found that the center support bearing on the driveshaft seems to be toast. The shaft flops around from side to side quite easily. I'm trying to remove the front shaft but the bolts connecting the flanges of the front and rear driveshafts (just aft of the center bearing) will not budge. Other than a bit of surface rust, the nuts and bolts are in very clean condition, not corroded or rusty. As the nuts on this flange connection seem to fit tight against the shoulder of the flange, and as such seem to be locked in place, not able to rotate because they would jam against the flange if they did, I am trying to turn the bolts out. Are the nuts supposed to fit so snug against the flange, or did a PO install larger bolts during a previous repair? The nuts and bolts are both 13mm hex. Is there a recommendation as to the best way to loosen these bolts? A favorite penetrating oil? I'm afraid I'm going to break each bolt if I try to torque them even more. Any ideas?
 

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I think (as in I am not sure so wait for confirmation from someone who knows) that those bolts are an odd size - like 9mm. If so, be very wary about breaking them as that is a very unusual size - something not easily sourced.

As for penetrating oils, I use PB Blaster - I can easily find it on the shelf of local auto parts stores. Kroil also has a good reputation but may need to be mail-ordered. I have read that a 50/50 mix of acetone and automatic transmission fluid beats them all. WD-40 is nearly useless for this purpose. Supposedly the WD stands for Water Displacement - formulas 1 through 39 did not work very well I guess... Whichever you choose, I suggest applying it daily for a few days in a row and then trying to undo the bolts. If they turn even a little, re-apply and wait a few minutes then proceed. With this method I have 95% - 99% success. If there is any evidence that red Loctite was used then heat is needed to soften the bond. They don't need to be glowing red - just 'too hot touch' is enough.
 

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Those bolts will test you....physically and mentally. Not sure of the thread size, but the nut and bolt head are 13mm. S3 used a shoulder bolt and nylock nut. No room for a socket or box wrench. I have ground down a box wrench to fit. A good fitting open end wrench sometimes works. Once I drove a blade screwdriver between the nut and the flange to hold the nut. Soak liberally with PB blaster. Heat will help but you will ruin the nylock. This would have been a good place for hex head bolt or a smaller head nut, kinda like the old Chevy manifold. bolts. Grind off as a last resort and replace the bolts and nuts.
Cheers, Jon
 

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buy a 13mm snap on combination wrench and grind down the box end until it fits onto the nut (or bolt head). You will take off maybe 2 mm all around and the box end will still be plenty strong. Use the PB blaster for a few days and then the box end to loosen. If the side on the U-joint starts turning, use a open end snap on on that side.
 

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I have done 100+ removals Snap-on makes it a snap
 

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Discussion Starter #6
Thanks for all the great advice. This forum and its participants are invaluable! It seems like PB Blaster is in my future. However I don't think I'd ever get a box wrench around the nut - there's maybe 2mm between a hex side and the flange. Perhaps an open end on the nut, but I've already partially rounded one nut with that method so I think I'll concentrate on the bolts, which I can get a box wrench around. I'll update in a few days....
 

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Eric has been on a crusade against WD40 for longer than I can remember. As a penetrating oil it is very similar to PB Blaster.
April 2007 "Machinist's Workshop" magazine comparison
test
**
*They arranged a subjective test of all the popular penetrants with
the control being the torque required to remove the nut from a
"scientifically rusted" environment.*
**

Penetrating oil ..... Average load

None ..................... 516 pounds
WD-40 .................. 238 pounds
PB Blaster ............. 214 pounds
Liquid Wrench ..... 127 pounds
Kano Kroil ............ 106 pounds
ATF-Acetone mix....53 pounds

The ATF-Acetone mix was a "home brew" mix of 50% acetone - 50% automatic transmission fluid.
*Note the "home brew" was better than any commercial product in this one
particular test. Our local machinist group mixed up a batch and we all now
use it with equally good results. Note also that "Liquid Wrench" is about
as good as "Kroil" for about 20% of the price. *

As for wrenches I too have a modified box end which I use with a Proto open ended wrench. It has thicker jaws than my other wrenches and is less likely to round the nuts.
 

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Snap on 13mm 3/8 drive socket and a Snap On 8 inch wobble extension and a 3/8 impact gun. Undo the driveshaft at the rear then hold it up against the body then the socket will slide on to the nut. Sometimes you might have to tap it on. Then use the impact gun to get it off. Works every time.

@ARwrench Snap On hasn't made that wrench for at least 20 plus years. That was their air cooled Volkswagen wrench. You could almost get the engine out and apart with just both ends of that wrench.
 

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Pure acetone. Nail polish is mostly water with only a bit of acetone so it does not dry out your skin like straight acetone. The stuff evaporates quickly and easily so a mix with trans fluid must be stored in a tightly sealed container.
 

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that snap on wrench is a dandy for removing exhaust mani nuts , especially on 3 and 4. I have two of them and would like to buy a third !
 

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Hopefully, some previous owner or mechanic has not used Loctite on your propshaft flange bolts. First thing to do is source a pair of long-handled, 13mm open/box combo wrenches. I found a pair made by "Gear Wrench" on eBay for a very reasonable price. Second step, as others have suggested, apply a decent rust penetrant to the bolts/nuts and let that soak in overnight. The next day, add some heat to the bolts and nuts with a butane torch. Then, attach the wrenches to both sides of one of the nut/bolts in such a way that you can squeeze the wrench handles together like a pair of scissors or pliers. You should be able to create enough leverage to free the bolts up in that manner. If the heat has compromised the locking nuts, or if you have to grind or cut them off, remember to source and purchase only the proper size and temper of replacements.
1605986
1605988
 

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Also use a high quality wrench, not a no name Chinese wrench! Cheaper wrenches give and will round off the the heads. Good luck
 

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Discussion Starter #16
Thanks for all the help (nice photos Edward!) I've got PB Blaster soaking the nuts and bolts now, and will repeat that for a couple more days while I source another 13mm wrench (I've only got one). Hopefully that will do it with the need for heat, as I'd like to save the bolts. We'll see......
 

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Update - that PB Blaster stuff is remarkable. I followed Eric's advice and applied it for three consecutive days, and today three of the four bolts loosened with minimal effort. The fourth bolt took more work - a few well placed strikes with a ball peen hammer and it loosened as well. When reinstalling, do these bolts need to be torqued to a certain spec, or is it by 'mechanics intuition'? The giubo bolts were VERY easy to remove, in fact one of them was loose already. I'm thinking I'll replace the giubo while I have it out. It looks in good shape over all, but upon close inspection there are a few small fissures in the rubber. I've read enough horror stories about what happens when the blow, and with 86K on the car, I don't know if it is the original one or not. I'll be bringing the shaft and center bearing stuff to a shop since I don't have the tools to pull the flange and bearing.
 

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fledermaus said:
Update - that PB Blaster stuff is remarkable. I followed Eric's advice and applied it for three consecutive days, and today three of the four bolts loosened with minimal effort.
alfaparticle said:
Eric has been on a crusade against WD40 for longer than I can remember. As a penetrating oil it is very similar to PB Blaster.
Perhaps you should have tried WD40 on that fourth bolt... :)
 
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