Second drive on a rebuild - KAABOOM!

[smestas]

I was on my second drive after a full rebuild of my motor and about 10 minutes from home after a 1hr drive I hear a deep thud and a KAABOOM!

Within a flash all of the carnage images and post I've read here on the site went flying thru my head. I turned off the motor, pressed in the clutch and managed to limp to the side of the road. After a bit of pannic and a extigushier in my hand I finally saw what happen. The drivers axle had come loose from the tranny flanges and was just hanging there. WTF I torqued all of those allens twice and in the recomended pattern. I had to call the wife to bring my jack and tools and managed to get the c/v reconected and limp home. Funny thing was that all of the bolts were still there and in perfect shape.

Boy was that a nice scare for me!!!! I did a quick search and it seems that this is a common problem. What can I do the second time around to make sure it doesnt happen again?

The Culprit - so much for a perfectly clean motor & tranny


Dented Pipes


Torn Up outer c/v boot

[dickster]

thats tough, at least its not terminal.

how about some thread lock?

[smestas]

Originally posted by dickster
thats tough, at least its not terminal.

Never would I have thought that I'd be happy to see my axle hanging down from my car!

I think loctite would be a good idea. I installed them dry the first time so I'll try anything that helps the second time around.

[geof33]

I'd torque them, stress them, then go back and do it once again. Between the centrifugal force, heat etc, there was probably some expansion which allowed the bolts to loosen.

This is a common problem on downhill bike rigs... So much stress that the crank bolt can't hang. Usually takes three good, stressful rides to get them to stay tight. Thread lock helps. Obviously heat is not an issue on a bike but the idea is the same.

[chrisreale]

happened to me on my 914 the other day. I was only one block away from home, but it scared the hell out of me as well. Those things flopping around down there can really wreck havoc, especially if you are at speed and it knocks the starter off!

[82SC]

scary...are they new CVs? did you have enough grease in them?

I could imagine if the races locked up, it could do something like that....I have a CV shatter on me...scared the crap out of me

MJ

[smestas]

Originally posted by 82SC
scary...are they new CVs? did you have enough grease in them?

They weren't new CV's but I did clean them and repack them with plenty of CV grease, new boots and gaskets upon instalation of the fresh motor.

My first drive was about 20min and my second drive before it abruply ended was about 1hr.

I think I'm going to go with safety wire and some serated washers this time around. Here is a interesting post on the topic I found from a search.

Safety wiring CV joints

[smestas]

Hmmmmmmm..........

I was just looking at this CV diagram and am now realizing that I didn't have any lockwashers or backing plates on my any of my CV hardware!!!! I just reassembled them as they were before I took them off. Once again the fixes of the PO coming back to haunt me.

[smestas]

Are the backing plates only for the inside CVs? Or do both the insides and outsides get them?

[john70t]

I think some ingeneous people on this board have drilled the heads and saftey-wired them for this reason. The red Locktight might cause more problems down the road.

[89911]

I'd avoid loctite if you could. Those bolts have a strong tendancy to strip out the heads with no thread locker to begin with. Make sure they are new if possible and retorque after a week or two to check.

[toolman]

Did the bolts loosen or did the shaft come out of the joint?

[Jim Smolka]

Recommend going with new fastners. The washers in the above drawing are 'ribbed' as to give an extra bite to prevent things from comming loose. Also, a bit of Blue Loctite may be in order.

To help prevent the bolts from stipping out, clean out the hex with brake cleaner and a pick and then use quailty tools such as Snap-On. My personal favorite is the Snap On Allen Sockets with a 3/8" impact. Of course this eats up allen bits, but the Snap On guy replaces them w/o any hassel. If by chance one allen hex is stripped out, an 8mm 12 point allen socket works well. Just pound it into allen bolt with a hammer, then hit it with an impact. Once again, the 12 point bit takes the abuse, but hey it is Snap On.

[gregk1]

This Happend to my 930 mine came off at the stop light, The problem with mine was the gaskets, they squished out the side of the cv joint, and that is what made the bolts loosen up, they have Kind of a tin cup you put on the end of the cvjoint to contain the grease and the gasket I put them on and had no more problem I also use silicone insted of the gasket and have had no problems

[smestas]

Originally posted by toolman
Did the bolts loosen or did the shaft come out of the joint?

The bolts loosened and came out and the whole shaft and inner CV were just hanging down.

[911SCfanatic]

I'd love to hear what John Walker has to say on this one.

[iamchappy]

I had it happen to me last year in my 914, I used red loctite and painted red line on them so I can check to see if they loosen, so far they have stayed tight.

[Early_S_Man]

Simon,

I would recommend the hardened lock plates and Schnorr washers ... then torque to 36 lb-ft! Never had a CV bolt come loose when I use Schnorr washers!

[yelcab1]

I would buy new bolts if the allen heads are buggered up, and use blue loctite. Never had problems with mine that way.

[svandamme]

Originally posted by smestas
Are the backing plates only for the inside CVs? Or do both the insides and outsides get them?

inside and outsides had em on my car

mechanically , there's little difference between the insides and the outsides anyway... if your insides go loose without the washers and backing plates... so can you outsides imho