4.5 Diff head... pulled mounting bolts.

[HellK9]

Although I haven't dropped the diff yet I wondered if anyone had a repair solution for me pulling the threads from the diff mounts.

[tvrolet]

Helicoil. Mine all pulled out (on the Tuscan, but same diff casing). Easy DIY job once the diff is out, and should be stronger than the original.

Get something like a 'recoil' kit and it will come with the correct size drill, tap, coils and tool.

[HellK9]

Mechanic pulling the diff thinks helicoils will pull as well... however I've held hubs together with them before I suspect the torsional load on the diff will be within the realms of being held in place with coils.
Thanks for the reply!!

[pmessling]

Could always go fitted bolts. But you would have to have them made or if you can do turning make them yourself, then the only fasting is the nut but a nylock should hold it all together.

[tvrolet]

Mine held the best part of 500hp after helicoiling. A bit more power now so I'll have to wait and see if it still holds.

Problem with them pulling is when some of the bolts loosen the mounting plate can act as a lever and puts a huge 'pull' on the 'tight' bolts. Once they've pulled the plate will act as a lever again and pull the others out.

Since the mounting plate is on a bush, as the diff wants to 'rotate' and the bolts are loose the mount will twist 'away' from the diff on one side with the flexibility of the bush acting as a pivot. I've found the bolts loosening off a few times before I started to loctite them in, and I actually tore a mount apart too on the car.

So long as the bolts stay tight I don't think there's a problem.

A smarter design would have had the mounting bracket/chassis place the bush immediately above the mounts on the diff so all the forces on the bolts, however tight, would always have been in sheer.

[HellK9]

Sounds a go on the Helicoil. I've noted a small shunt in the rear that was obviously the diff slackening off. I'll have to nordlock it in place this time!

Thankyou Gentlemen.

[Nickccc]

Just to make extra sure use a high strength thread locker when you insert the helicoils into their new threads.

[HellK9]

Nickccc said:

Just to make extra sure use a high strength thread locker when you insert the helicoils into their new threads.

Nordlocks rather than thread locker. I'm a great fan of their mechanical lock. I've never had one fail yet and considerably easier to remove at some later point in time.

[Nickccc]

That's interesting, hadn't seen them before, thanks.
http://youtu.be/mgwmuZuJ02I
I was referring to setting the actual helicoils into the diff not using thread locker on the bolts.