Boxster cv axle bolts shearing off, 3rd time now. Help!

[truepro87]

Well, first thanks for reading and hopefully solving my problem. Im a 22 y/o with a 2003 porsche boxster, barely making the payments now, and I have a persistent problem! It has happen three times. I'm driving around, stop at a stop sign then release the clutch into first and BANG! axle pops off the drive flange. I don't ride it hard and i dont drop the clutch hard and for some reason this keeps happening. The first time I just replaced the end cap and bolts on the axle and was driving around for a couple of months when it happened again, then on the first week of October 2009 I had it fixed by a local shop. All they did was exactly what i did the last time and it broke again tonight 10/13/2009. I cant afford this anymore and wanted to hear your opinions on the situation. Im completely clueless and looking for some guidance.

my email

[N41EF]

I was a 19yo with a 1971 Corvette, I feel your pain. I had a constant U-joint problem, replaced them twice, I just wasn't doing it correctly.

What did you tighten the cap screws to? Had they been replaced before? are they the correct part? The torque from the engine goes to the wheel through the friction between the flange and the axel. The cap screws hold the two together, but shouldn't be under axially load.

Tightening them too much will make them fail under tensile load as they are stretched. Too loose and they will fail by shear, they are not designed to take the torque the engine can put out.

Chuck

Well, first thanks for reading and hopefully solving my problem. Im a 22 y/o with a 2003 porsche boxster, barely making the payments now, and I have a persistent problem! It has happen three times. I'm driving around, stop at a stop sign then release the clutch into first and BANG! axle pops off the drive flange. I don't ride it hard and i dont drop the clutch hard and for some reason this keeps happening. The first time I just replaced the end cap and bolts on the axle and was driving around for a couple of months when it happened again, then on the first week of October 2009 I had it fixed by a local shop. All they did was exactly what i did the last time and it broke again tonight 10/13/2009. I cant afford this anymore and wanted to hear your opinions on the situation. Im completely clueless and looking for some guidance.

my email

[truepro87]

well I'm pretty sure I did it correctly since i followed pedrosgarage.com I'm trying to find the cause of this, since it happened before I touched it in the first place, and since I had a professional fix it the last time.

[jjanari]

do you know whether loctite was applied to the bolts prior to install? iirc, that's mentioned in pedro's instructions. I believe I used the blue loctite.

[truepro87]

do you know whether loctite was applied to the bolts prior to install? iirc, that's mentioned in pedro's instructions. I believe I used the blue loctite.

i looked at the broken bolts that i could find and can't tell if the shop used loctite, its just covered with grease.

[jjanari]

did you use loctite when you did the install yourself? (didn't you say you did one of the installs yourself)?

maybe someone else can chime in regarding how critical or not using the loctite is or if it's in the service manual, bentley, etc.

while this may have nothing to do w/your situation, when I installed new boots, I used all new bolts, partly because I stripped several of them trying to remove them. in fact, a couple were on so tight, I resorted to using a torch to break them loose. while replacing the bolts was probably overkill, i read several threads involving situations like yours, i.e. driving and then the axle pops off...

[wvicary]

I use loctite but the threaded area in the axle flange also has to be free of oil/grease. If the bolts are loctited and torqued to the correct spec this fault should never occur.

[truepro87]

I use loctite but the threaded area in the axle flange also has to be free of oil/grease. If the bolts are loctited and torqued to the correct spec this fault should never occur.

are there any other things that could be causing this cause remember, this happened the first t ime without ever being worked on in the first place.

[mikefocke]

How about a theory that the forces are all wrong

because the motor is somehow shifting and the angles are SNAFU? Motor mounts OK?

What is your driving style?

Done anything to the suspension? Wheels?