Driveshaft Bolts Sheared

[jaylward]

My "new" Can Am is testing my patience. Went out for a little spin yesterday and 2 bolts sheared from one of the driveshafts. It looks like all the bolts had worked their way loose over time and it was not something I spotted.

Anyway ... I have got new bolts on order and will make a start on drilling out the sheared ones ready for them. My transmission is a Porsche 930 (turbo) gearbox and the helpful AA guy said "is that a VAG Group tranny cos they all do that"! Has anyone else experienced this and, apart from preventative maintenance, what can I do to stop it happening again?

Cheers

[F.C.]

jaylward said:

My "new" Can Am is testing my patience. Went out for a little spin yesterday and 2 bolts sheared from one of the driveshafts. It looks like all the bolts had worked their way loose over time and it was not something I spotted.

Anyway ... I have got new bolts on order and will make a start on drilling out the sheared ones ready for them. My transmission is a Porsche 930 (turbo) gearbox and the helpful AA guy said "is that a VAG Group tranny cos they all do that"! Has anyone else experienced this and, apart from preventative maintenance, what can I do to stop it happening again?

Cheers

When I got my car the previous owner said to keep an eye on the drive shaft bolts but I haven't needed to touch them other than when I had the LSD bias changed to suit the mid engine layout.

Paint stripe each bolt once torqued down, that way a quick look will tell you if any bolts have moved.

A more permanent solution would be to lock-wire the bolts but you will need pre-drilled heads (or drill them yourself).

[Racingroj]

When we were racing we had the motto 'if it moves lock wire it' . A small pillar drill, lock wire pliers and a roll of lock wire will sort things. On the drive shaft bolts you lock wire from one bolt to the next.

[Storer]

You could also use thread lock liquid.

Use a torque wrench too.

Marking Plastic does make the checking easy as I can confirm.


Paul

[jaylward]

Thanks for the tips guys. Much appreciated.

[deadscoob]

Mark as FC said - easiest is to get a tube of torque seal and mark a stripe across each bolt

[PhillipM]

I have this issue a lot with 930CV bolts - mainly from the massive shock loading - no matter how tight they were torqued or what loctite was used (even cleaning them with acetone and scotchbrite first to help it key) they would come loose as the joints flexed. I was under the car re-torquing them after every single stage.
Stuck Nord-Lock washers under them and haven't had to touch them since.

I don't bother with lockwire as although it stops them coming out it doesn't stop the loss of preload which means they eventually shear or distort the holes and threads in the gearbox cups under the shock loads instead.

Edited by PhillipM on Saturday 18th June 23:20

[F.C.]

PhillipM said:

I have this issue a lot with 930CV bolts - mainly from the massive shock loading - no matter how tight they were torqued or what loctite was used (even cleaning them with acetone and scotchbrite first to help it key) they would come loose as the joints flexed. I was under the car re-torquing them after every single stage.
Stuck Nord-Lock washers under them and haven't had to touch them since.

I don't bother with lockwire as although it stops them coming out it doesn't stop the loss of preload which means they eventually shear or distort the holes and threads in the gearbox cups under the shock loads instead.

Edited by PhillipM on Saturday 18th June 23:20

Yes +1 forgot about them, also known as ring-lock washers.

[jaylward]

Nord lock washers it is. Perfect simple solution. Thanks

[Rscocca]

for a visual quick inspection I put Torque seal on every bolt. If the seal brakes it moved.

[Storer]

Rscocca said:

for a visual quick inspection I put Torque seal on every bolt. If the seal brakes it moved.

Microlight?

[Corsair613]

I utilized a very similar single-sided pushrod arrangement on my RV-8's tailwheel. I couldn't stand the "slop" in the stock chains.

Ken

[845ste]

I wrench the bolts.
I solved it by making the steel bolts C-45 and secured with Loctite.
never had problems