What is the crownwheel bolt thread?

[Richspec]

As title really, i need to hunt out some cap head bolts online while i'm working away andI've no idea what the thread is apart from its unf.


Ta

Rich

[Spider]

3/8 UNF.

A word of caution though if going to Cap Heads, well 2 actually.

The Profile of the Head is generally taller of a Cap head and the stock one doesn't clear the Bearings by a lot. Perhaps trial fit it all and machine the Heads back a little.

The other point is many of the In-hex Tools for use with a Socket drive are not up to the task of applying full tightening torque through them without self destructing.

[Richspec]

Thanks,
However bearing clearance isnt an issue as it for a lsd where the holes are well outboard of the bearings, i think we have some half inch drive allen sockets so should be ok for that.
Whats the torque setting? I have 45 lbft rattling round my head but cant find a reference for that at the moment.

[Spider]

Just talking stock bolts (haha, pun intended) here;-

Early ones were 60 ft / lbs
Later ones were 48 ft / lbs (from around 74 on)

For the Cap Head to work properly, assuming Grade 10 (Unbrko brand are Grade 10), you'll want a minimum 50 ft / lbs according to Unbrako's Charts, however this will also depend on the depth of thread you have in the LSD assy.

[Spider]

Just one last thing in regards to using Cap Heads on an LSD, trial fit to check clearances from the fastener heads to the case and in particular the diff cap.

[Richspec]

Thanks for the replies, I did a dummy fit last week with the solitary cap head I found and initial judgement was it'll clear the case, just, but the set I have ordered might be different, we'll see

[Spider]

Ah, well, you're all over it then

[CooperTune]

When doing crown wheel onto posi I have found a ARP offers a torque converter bolt kit which is a high quality and has a thin multi point head. Steve (CTR)

[Richspec]

I think i did find Swiftune? selling the same, but wasnt sure that the head would be much less in size (diameter), I did have one caphead to try and although an inch too long it did solve the clearance issues i have.
The bolts came today from Namrick and of the two lengths I ordered the 3/4 inch long is about 3 to 4 mm too long to clear the casing so abit of shortening is required this weekend.

[rich@minispares.com]

the annoying thing about the fancy ones that swifty sells is that they are too long, so you have to fit them, measure them, cut them down and have a load of messing.....


the BTA370 drive flange bolts are the budget alternative, they are a nice bolt and only have a 9/16th head, so a socket fits nice into the lsd cwp