Replace Caliper Bolts ?

I'm replacing all 4 rotors on my 99. In this aritical: https://rennlist.com/forums/showthre...eferrerid=6422 It was recomended to replace all the Caliper bolts too. Most of these bolts look like they are in great shape, so I'm hesitating a bit on replacing them. So ... curious what others have done. If you have replaced your rotors, did you replace these bolts too? Thanks in advance!

Here is what I wrote on the same subject in another forum: "In answer to your question, it is not always possible to tell from visual inspection if a bolt needs changing or not. I am a little surprised to hear that Porsche recommend changing them, because other manufacturers don't. One reason would be if the bolt was to be tightened into the plastic range. However, the bolt is M12x1.5x72. Under the conservative and most likely assumption of bolt grade 8.8 and a coefficient of friction of mu=0.125, the recommended torque would be 83 Nm, which is pretty much the 63 ft-lb that xxxxx mentioned. I can therefore only assume that they are concerned about progressive crack growth during cyclic loading, which could occur due to loss of preload (or because someone hasn't tightened them properly in the first place). Anyway, I don't think there is anybody in this forum who can answer this question. Considering the low price of the bolts and the importance of the part in question, I would probably go with Porsche's recommendation. " Incidentally, there are two things that I would question in the posting you quoted: 1) Using a torque wrench to brake loose the old bolts: A torque wrench is a precision instrument and since the required torque to brake loose the bolts is much higher than to tighten them, you risk damanging your torque wrench. Use a breaker bar instead. (Karl probably uses his 400 ft-lb torque wrench, so he's safe. But a less robust wrench could be damaged. ) 2) Using copper anti-seeze compound on the new bolts. UNLESS EXPLICITELY STATED IN THE ORIGINAL FACTORY MANUAL, never do this! The idea is of course to make sure that the bolts will come out after a couple of years. The big problem is that you drastically reduce the friction of the bolt. When specifing the required torque, the manufacturer assumes a certain coefficient of friction, typically lightly oiled with a coefficient of mu=0.125. If you put on copper grease, you massively reduce that coefficient of friction to about mu=0.08. The result is that if you apply the same torque, you over-tighten the bolt by almost 50 per cent! It won't break, but it will lose its elasticity and be much more susceptible to stress fatigue. Incidentally, the same holds true for MOST wheel nuts, some older Porsche wheels being one of the notable exceptions. In fact, don't use copper anti-seeze at all. It the kind of crap we use in Europe because we can't get anything else. You guys have great products like Never-Seez, which is much superior in terms of contact corrosion. Cheers, Uwe

Very helpful! Thanks Uwe!

The actual reason that Porsche wants to have the caliper bolts replaced is that they come with a little capsule of Loctite retaining compound on each bolt which is crushed on insertion and tightening. Porsche wants to make sure that when the bolts are reinstalled that they have a new application of thread retaining compound on them to lock them in place. It is perfectly safe to reuse the bolts as long as they have been cleaned of surface corrosion, inspected for obvious damage, had a new application of a retaining thread compound such as Loctite Titen on them, and they are torqued to the correct specification. While the opinion of UMN certainly has merit, if there was a danger of the bolts cracking, we would probably see a similar remove and replace recommendation for wheel lug bolts as well. While there is nothing wrong with replacing these caliper bolts, because of the fact that they have a retaining compound capsule on them, they are in excess of $8.00 each to get new ones. In my book that is a little pricey to throw away a perfectly good bolt. As always a good visual exam for obvious cracks is in order, but if the bolt looks solid, just give it a new drop of Loctite and reuse it. I have done this for years with out any issues. Lastly: DO NOT APPLY ANTI-SEIZE PASTE TO THESE BOLTS!

Interesting. The caliper bolts I ordered for my car came with no loctite nor did the bolts I removed have any indication of it being used. The workshop manual also make no mention of it.

Porsche state that the caliper fasteners (and some other bolts) have an anti-corrosion coating which will be damaged when removing the bolt. There is no mention of stretch or Loctite.

GMS, thanks, I believe you are correct. I just checked the old bolts from my car. They have a very thin gold colored coating that is easily scraped away to bare shiny metal with a file.

I did more hunting on this. Apparently without the coating the steel bolt would tend to bond with the aluminum in the caliper and wheel carrier. If you find the bolt hard to remove, tap its head with a hammer a couple of times and try again.

The gold coating is alodine which is used for corrosion control. The loctitie capsule is on the end of the bolt and is usually completely obliterated when the bolt is installed. This type of fastener is pretty standard in the automotive and aerospace industries, and usually does not have special mention in shop manuals. Interesting that the replacement bolts you were sold did not have the capsule. How much did you pay for these bolts? If it was less than $5ea., chances are they are standard fasteners, and not the completely correct bolt. Never the less, just put a drop of loctite on them and you will be fine.

The GT3 bolts I bought are expensive, part number 999-067-047-09, description CHEESE-HD. SC lists for $27.26 each. I got a 19% discount from Suncoast. They came with no loctite capsule, just the bolt, sealed in a appropriately labeled bag.

Looks like you are spot on. I just called someone up at the factory and he said they are coated with microcapsules (the bolts that is, not the people at the factory). I haven't been able to check it myself. New bolts for the standard Carrera are only 2 Euros over here but we pay 25 Euros for a quart of Mobile 1 at the dealer's Cheers Uwe

The coating is the same as used on 964 and 993 cars, all of the coated bolts I have seen have NOT got any micro-encapsulated locking chemical on the threads. We recently replaced most of the right side suspension of a 2001 996, none of the coated bolts were treated with any locking chemical. All bolts were purchased from the local Porsche dealer and were the correct part number. The coated bolts include 964/993 front lower control arm, brake caliper, rear suspension fasteners etc..

Bolt anti-corrosion coating may have changed at some point, current GT3 bolt coating is a light golden color, some older 996 coatings are a much darker reddish color. A loctitie capsule at the end of a GT3 bolt would do no good as the wheel carriers both front and rear are drilled completely through, so a capsule at the end would never be crushed. The GT3 bolts do not have microcapsules either. Just the clean surface of the anti-corrosion coating.

Bump a ancient thread....for some good info

Sweet... good info here.... so no anti-seize, that's good to know.

There is a lot of speculation here. Most if these comments are theoretical and come from people that do their wrenching behind a keyboard.

Quotes source post: 11003613

When it comes to technical matters, doesn't it make sense to put your trust in someone who spends their time at a keyboard, reading and learning about important matters as opposed to someone who is capable of using a wrench or a screwdriver? A child can use a wrench. That doesn't make the child an expert on automotive repair. Don't get me wrong - I believe that people who work on their own cars can offer unique insights based on their experience. However, it doesn't mean that they are experts by any means. It's one source of input that should be considered along with the knowledge offered by research, reading and learning from others.

hahaha you could spend 365 days researching all you want, but when the info your are reading is wrong.. your wrong..plain and simple. Again why a guy that does it himself will always be a lot more informative then some yahoo on a keyboard. And why is a 10 year old thread being brought back to life??

Quotes source post: 11003613

The reasons for replacing or not replacing are both theoretical. Both sides of the issue can point to no problems from their way of doing this as proof their theory is the correct one. My final comment is I would advise one to check with the parts manager or senior tech at a dealership or a trusted/highly regarding indy shop to get the latest info regarding this subject. It could be Porsche has rescinded the recommendation to replace the bolts if the caliper needs to be removed. I haven't bothered to check on this in several years. When it comes time to do my Turbo's brakes and if I decide to do them myself, when I buy parts this is what I will do. Or if in the experience of the of the tech you rely upon for advice/counsel regarding your car's care/servicing is that caliper bolt replacement is unnecessary -- if you feel comfortable listening to your tech and you should otherwise IMHO you are using the wrong tech -- then do what he advises.

Quotes source post: 11003894

This thread was brought back to life because it discusses information that was discussed in a related thread. You made some posts in it, as you may recall. As far as your thoughts on research, it comes down once again to who you trust. Anybody who researches anything in earnest will look at multiple sources of information. I agree that if you only look at one source and that source is wrong, then you will make decisions based on bad information. However, I disagree with your assumption that somebody who works on their car is somehow a credible source of information. Anybody can work on a car or claim that they work on a car. Let's look at you as an example. You claim to be knowledgable because you work on cars. Nobody here really knows that. You could be a certified Porsche mechanic, and you could be a guy who just opens the hood and gives it a try. Nobody here knows you. Based on that, I wouldn't trust your advice over my own research, under any circumstances. Based on your previous posts, any reasonable person would assume that you are clueless, and wouldn't follow your advice. If somebody who does their own work is wrong about something and you take their advice, then you're making a decision based on bad information. Hopefully you understand the point I'm trying to make.

It would help us if you would give your thoughts on the IMSB, CEF's, and MOF issues!

Quotes source post: 11004062

He seems to have thoughts on everything... so he probably will!

please.. you have no idea about it yourselves.. so why would i give you very useful info only you have you say.. "that's not right, my bill said otherwise"?? This thread says.. "use Loctite products" again, anybody with common sense knows this.. not some post jockey that post to see himself talk..

You make my point once again weldingmachine. As I mentioned in previous posts, I don't know why Porsche recommends replacing the bolts. That's the reason that I follow the recommendation rather than question it or trying to pretend that I know more than the manufacturer. Why do you display such negativity towards everyone on this board? Did somebody here do something to you that made you angry? Do you feel inadequate in some way? Everyone is trying to help, and you're insulting people and trying to pretend that you know everything. Your attitude doesn't make you look knowledgable, it makes you look like a fool. I feel sorry for you because you feel that you have to act this way. I'm finished discussing this with you. To quote Mark Twain: "Never argue with a fool; onlookers may not be able to tell the difference." I'll take that advice.

My favorite: “Never argue with stupid people, they will drag you down to their level and then beat you with experience.” ― Mark Twain

That is a good one!

hahaha.. so calling me names make you better and right.. I see..

weldingmachine...I don't know if you type all of your posts from your phone and don't check to see if spell check replaced words on you or if this is how you really speak but you'll have a lot more credibility if you speak proper English in your posts. Not trying to act like the grammar snob, but if someone puts forth a coherent response like Dennis has at least 3 times now and each time you respond it looks like a second grader typed it, it kind of makes it hard for the rest of the people here to take you seriously or trust your supposed knowledge. Just some food for thought...

how sad is it that a "second grader" can pay cash for the cars that yall so cherish and think so highly of.. and pretty much treat it like a Honda.. Dennis is a nut swinging poster that just repeats whats he reads or heard.. he even admits to not working on anything and doing whatever someone tells him... but because hes just post a lot and been around a while.. hes treat as a expert.. its comical to say the least.. I honesty could care less if someone looks down on me.. its the internet.. land of make believe and fairly tales.. One more food for though.. if im such a "amateur", why am i getting PM;s from people asking what i think on such subjects and what would i do?? hmmm

LOL, there is no way this guy is for real. He either does not even have a 996 (no pics posted) and is some kind of super-troll or he is another member just putting us all on using his alter ego account. Either way hes very entertaining. Doubt he will last much longer.

Quotes source post: 11005073

IMAG0286_zps18a40e54.jpg Your right only about one thing.. i don't have "a" car... haha Your only cool on this site.. your antics would get you in a world of trouble else where.. so enjoy.. better not leave here.. I find it very funny how a person can come here as a new user, disagree with some one based on common sense and be made fun of and called names.. and is not suppose to defend themselves.. Its a real classy site..

Yes WM, I am an online thread posting bot and certainly not even "cool" on this "site" but I hope to be one day. Actually, Im a real person and dont really live here. BTW, your back window is hilarious. You really need to stop taking this forum so serious. Most of the threads have some type of humor in them. Try the emoticons. They seem to help. See, I feel better.

WeldingMachine, I'm surprised KK hasn't made a comment seeing that you don't have any JG DT40 oil on your shelves. That's really a no no and your motor will blow up soon if you don't use it. I suggest kissing and making up with KK as he might be willing to donate his 300 mile old oil to you.

Weldingmachine, don't worry about KK, he isn't like on this site either. I've been wrenching long enough to see someone that knows what theynare talking about. I couldn't care less about spelling or grammar, the information is what matters. You are ok in my book. There are way too many keyboard mechanics on this forum. Wish it was more like the 928 forum. BS hardly ever last more than page over there and people like KK or Macster wouldn't last a day.

Yeh Imre, Im a "keyboard mechanic" . WM hasnt posted squat to prove anything, so I still know nothing about what he can do with a wrench. At least I can back up whatever I say I can do. Not sure what your problem is with me now but thats OK, too. Some people have no sense of humor. I didnt even comment on the caliper bolt nonsense.

Look what i can do with a plasma cutter.. free.. as i had my old exhaust off my 360 and cut it up to use on the P car.. I even post a log of my other street car... not that i think you can read or know what KPA's are.. but there you go.. I tuned it my self.. not to bad for a v8 spining to 7600 huh?? IMAG0189_zps25762378.jpg IMAG0185_zpsb32a0c03.jpg IMAG0184_zpsd8a32be8.jpg NewBitmapImage_zpsf5d94e9b.jpg

Quotes source post: 11006856

Nope, you aren't just tend to BS alot.

For the record, these are the current 996 GT2/GT3 caliper bolts, from Porsche, 999-067-053-09,, torx headed...

Not long ago, I replaced my 996' wheel lock bolts with new OEM wheel bolts. My p-car dealer tech advised "do not put any anti-seize on the bolts for fiirst use as such new bolts come with an anti-seize/corrosion coating. This coating is "consumed" upon first use. On subsequent tightenings, use an aluminum/graphite anti-seize (Permatex brand, silver color) applied sparingly to the first two to three threads." relinuca