Tailshaft to diff - Bolts will not stay tight!

[AndyMack]

Read a few old threads but no answer seems to fit. There seems to be no recess on my diff flange for the nuts to lock into. This is a VN SS with LSD, Auto.

Can someone please recommend a solution. I'm tired of jacking the car up, Locktiting the nuts, and then they come lose a week later. Where can I buy new bolts/nuts or what's a suitable replacement that won't come loose?

Mr welder keeps whispering in my ear but i know that's a bad idea.

 

[wortus]

Can you try some nylock nuts? The factory bolts might be those type that are a bit out of round and self lock. they can wear and no longer work as intended. this happened to the bolts holding my steering rack to the Shaft.

 

[ephect]

If you don't have the lip, try adding spring washes to either side of the bolt shaft and see how that goes. At worst, weld the nut to the flange

 

[top line]

I would say the same, when purchasing bolts I always buy new nuts as well as a rule, if you have done this then I would imagine that what was mentioned about the nylon nuts or spring washes would work. I've had to replace my uni joints earlier this year and could not get the old rusted bolts and nuts of the flange which joined the tailshaft to the diff on my series 1 vn. I had to cut them off with a grinder. But I was about to get 4 new bolts with nuts from my local auto guy that fit, these were self locking and had no problems since.

 

[RebelSS]

Hi,

My suggestion would be to get some hi tensile screws/bolts (that have the three dashes on the hex head) and have them torqued down to correct Nm's. This allows for the thread on the screws/bolts to 'stretch' to the degree that makes the nuts 'lock' on.

But, this is a 'Band-Aid' treatment. You should determine why are they loosening prematurely, perhaps the parts are not 'mated' and/or tensioned correctly in the first place.

Good luck,

RebelSS

 

[Immortality]

Are you still using the original steel lock nuts ?

IF the flange doesn't have a shoulder on it then it would suggest it's not the original unit.

The shoulder stops the nut been able to turn fully but still allow some movement and I would not recommend trying to use the shoulder alone to stop the nut turning, I still use a spanner on the nut to hold it and then turn the bolt to undo - do it up.

The drive shaft flange should self centre on the diff pinion flange, if it's not centred correctly it may cause a vibration which could possibly cause bolts to come loose.

Have you tried your local Holden dealer for replacement bolts,nuts? I believe the same bolts/nuts were used right through to the VX V6 models. Otherwise try a local diff specialist. I use Steelie Gears in Otahuhu. Failing that a local faster supplier, take a sample bolt nut and make sure you tell em you need a high tensile bolt/nut with a lock nut type nut.

 

[strgas]

are the flanges straight or bent ever so slightly put a straight edge across the two flanges . clean both flanges before refitting . unsure any replacement bolts are of the correct type with a shank and then thread , nylock nuts or pinch nuts should hold once torqued correctly .

 

[Jxfwsf]

If they're undoing by them self then they need replacing, they're a locknut from the factory.

If the flat on the flange was missing it shouldn't stop them undoing.... I'd be replacing the flange if it was massacred enough to no longer have all the flats to lock the nuts.

Are you sure the nuts are the correct size?
Are they installed the correct way? Nuts on diff side, bolts on tailshaft side.

 

[greenacc]

A lot of the old British cars used to have these special little stamped washers on the tail shaft uni's. There are 2 holes in each washer with a stem in between to connect two bolts and on the outer end of each hole there was a steel tab. After the 2 bolts had been torqued up you bend the tabs up against a flat side of the nut so neither nut could turn.
Hope that makes sense.

 

[mickm73]

Another reason I have found rotating bolts can come loose is the direction the bolt is facing. Try turning them around, that way they might tighten at speed, rather than loosen.