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Old 08-10-2011, 12:13 AM   #1
gcb951
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Default Cheese head axle bolt torque spec?

Did I install these wrong? How could I have broken an axle in less than 200 miles of use? I didn't even beat on it. I am at a complete loss here.

What is the torque spec for the cheese head axle bolts?
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Old 08-10-2011, 12:47 AM   #2
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30 ft/lb
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Old 08-10-2011, 11:04 AM   #3
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Yea, I put them in at 30 foot pounds. I think maybe my trans mount needs to be changed.
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Old 08-10-2011, 12:57 PM   #4
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Been thru this; couple thoughts:

- check your flanges to make sure the bolt holes are not run out (due to joint coming loose). if the flange holes are egged, I think this contributes to the bolts loosening.
- ditto for the CV joint holes, they will egg too.
- yes, check the tranny mount
- when installing the bolts, I've had the best luck when I've lubed them lightly with oil and then used a 2 stage torque down with a star pattern
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Old 08-10-2011, 06:44 PM   #5
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Agree with Jeff. Lightly lube the bolt. Lubed threads results in more of the torque transferred to stretch and its a more consistent torque that way. Make sure you are using the right spec bolts, they are high strength 12.9's. Double check for torque.

With the right bolts, the right sequence, I have never seen a problem. You don't need new bolts each time as some believe, but there is no harm, as long as they are the correct grade. I wire mine for security, but its not really necessarry just precautionary.

There should be no lube between flanges. The joint is like a clutch, the bolt torque/stretch puts clamp force on the flanges, and its the friction force that keeps the joint from moving. Dry flanges, lubed bolt threads only.
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Old 08-10-2011, 10:43 PM   #6
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The two statements are not in conflict. TTY does not mean throw the bolts away. Like I said I only wire as a precautionary. I wouldn't waste my time for a street car, nor am I suggesting a need to wirelock. Like I also said, if you want to use new then obviously its OK, I didn't say don't do it, using new bolts for any maintenance is never a bad idea. It can be misleading suggesting its used bolts that may be the problem its not.

If the joint is loosening up, especially in such a short time, somethings not right.

Porsche head studs are TTY, there is no requirement to replace.

The last thing you want to do is start loctiting. You have to make sure the hardened plates are also used.
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Old 08-10-2011, 11:28 PM   #7
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I used new bolts, torqued to spec and still had them come loose in racing applications. I now also wire mine to be on the safe side. However, I just today serviced the halfshafts in my street S2. Reused the bolts, torqued to spec. 30 lbs. I'll let you know if they come loose.
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Old 08-10-2011, 11:47 PM   #8
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Quote:
Originally Posted by robstah View Post
Don't tell people not to get new bolts and THEN mention that you wire yours. The two statements go against each other. Porsche has spec'd these bolts as a TTY, or torque to yield. You torque the bolts until they yield (stretch) and when removed, they need to be replaced. I don't see the big deal anyway since Pelican has them for $0.75 a piece. Cheap insurance if you ask me.
I ordered a set from Pelican and was disappointed they were regular hex bolts and not the triple squares. There was a group buy on Stage 8 locking bolts for this a while back. Maybe someone has a set they will sell and/or Stage 8 may stock them now. I also use a star pattern in multiple stages (triple checking them all once done) and generally have no problems.
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Old 08-11-2011, 12:14 AM   #9
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No were in the manual have I seen that these bolts are TTY and should not be reused. I have always used new bolts since the force on them is high, they are cheap and it seems like a good precaution. Last set I put on were Stage 8 locking bolts which appear to address this issue of backing out but they stilll need to be properly torqued.
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Old 08-11-2011, 01:27 AM   #10
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Personally, I have started to wonder if this problem isn't related to the mileage on some of our cars. If you've had a couple episodes of loose bolts, I think the flanges get egged out and it's harder for the bolts to remain torqued.

Differences by car in the flange condition could help account for the widely varying experiences everyone seems to have on the board. I do like the stage 8 bolts and will likely go that way next time I have an extra $80 burning a hole in my pocket.
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Old 08-11-2011, 03:33 AM   #11
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Everybody I know has had the axle bolts loosen on these cars.

I red locktight them down. And I use high quality grade 12.9, 8 pt bolts at 40lbs tq.

Then I take a Sharpie marker, and mark a line on each bolt so that I can visually see if one has moved

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Old 08-11-2011, 02:08 PM   #12
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i've had these come loose before too and i think locktighting them is the way to go.

****, i got a rebuild kit from pelican and didn't even look at the bolts. i figured for sure they were the triple square... we'll see.
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Old 08-11-2011, 06:58 PM   #13
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If you use loctite, you need to clean the bolts and thread of all grease using Q tips. There are several threads on this subject.
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Old 08-11-2011, 07:45 PM   #14
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Quote:
Originally Posted by Brian Broderick View Post
If you use loctite, you need to clean the bolts and thread of all grease using Q tips. There are several threads on this subject.
This took me over an hour by itself. Had I known how dirty/oily the area was I would have ponied up the $80 for Stage 8 fastners and locks just to save time and for that extra piece of mind.
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Old 08-11-2011, 08:17 PM   #15
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I had this problem on an 89 S-2 that I used to race. The bolts would keep coming loose after (and sometimes during) every run session. I came to the conclusion that when they loosen up, grease gets between the two mating surfaces, so just re-torquing them doesn't last and just makes the problem worse. I found that after cleaning the surfaces carefully and re-assembling them (making sure to keep the surfaces dry) they stayed put. I marked the bolts as Tony suggested and they never moved again. This was my experience. Yes, I re-used the bolts.

With my current Turbo race car, I did this and they have not moved. I check them after every race along with every other nut and bolt.
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Old 08-11-2011, 08:17 PM
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