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Picture of diff bolt - stretched??
mad dad - 13/10/06 at 05:14 PM

I think this maybe why my diff bolts loosen off??? they appear to be stretched??? I am thinking of replacing with 1 long bolt/stud top and bottom rather than 4 seperate bolts, new nylocs, loctite and anything else that will lock them up!!! might even go for Nordlock washers they really do lock up..... any thoughts on this 2 versus 4 fixings as best method??? Rescued attachment P1010007.JPG
Rescued attachment P1010007.JPG

DIY Si - 13/10/06 at 05:37 PM

You've over tightened it and started to flatten the thread. Keep going and the thread parts company with the rest of the bolt. I'd suggest using 8.8 grade bolts, new washers and nylocs from a reputable source. Most stud is just mild steel and not rated at all. so proper bolts should be better.

rusty nuts - 13/10/06 at 05:47 PM

Get hold of a pair of Sierra diff mounting bolts , use new nylocks . Problem solved . Using bolts like that is asking for trouble

mad dad - 13/10/06 at 05:53 PM

not my doing one of the things you find when you buy a built one!! are the Sierra ones the longs ones that go through the whole diff??? M12 x 210mm?? Thanks

andrews_45 - 13/10/06 at 05:55 PM

This is why you have a torque figure. The torque used to tighten the fixture acts as the primary locking feature, any things like nylon inserts, crimps, tabwashers, spring washers and such are only secondary locking features.

That bolt is no good, get a complete set and replace the lot. chances are they will all be stretched... oh, and torque them to the correct figure, no need to swing of em

mad dad - 13/10/06 at 06:08 PM

Can you let me know the torque figure please as i assume its not FT.........

indykid - 13/10/06 at 06:25 PM

quote:
Originally posted by DIY Si
I'd suggest using 8.8 grade bolts, new washers and nylocs from a reputable source. Most stud is just mild steel and not rated at all. so proper bolts should be better.


but that's a socket cap bolt! chances are it's 12.9, so surely better than 8.8.

my diff's been in with 2 individual socket caps in the top mounts for 2000 miles and when the bolts came out, they were exactly as they went in, albeit rusty as the first ones were only japanned.

that one looks more like it's been fretting than stretched. was it even tight in the first place?

if it's in an indy, a full length bolt won't go in without fouling on the diff box anyway iirc.

tom

MkIndy7 - 13/10/06 at 08:13 PM

quote:
Originally posted by indykid

if it's in an indy, a full length bolt won't go in without fouling on the diff box anyway iirc.

tom


Pretty sure we've got a full length bolt in.... they were a special order and a pig to get hold of tho!

mookaloid - 13/10/06 at 11:06 PM

I suspect that the bolt head will have been eating into the alloy casting which is why they keep slackening off.

The diff was designed for one through bolt from one side right through to the other. This will bear on the steel mounting plates not on the ally casting.

Get some through bolts from Ford - as mentioned in my earlier posting when you asked this before

I am assuming that there is enough clearance to fit the proper bolts in a MAC#1 there is in an Indy.

Hellfire - 14/10/06 at 08:08 AM

Yep, the full length bolt does go through without too much fuss.

Phil

Johnmor - 14/10/06 at 09:27 AM

I take these are the bolts that attach the drive shaft to the diff flange?

If so these are 50mm M8socket cap bolt of 12.9 grade use nothing less!!

You can buy new at any suppliers. These are very strong bolts and its unlikly you would stretch them.

The bolt that locates the diff to the chassis is around 200mm long and is M12 min 8.8 grade, dont over tighten , use knew nylock nut .

gazza285 - 14/10/06 at 01:43 PM

It's not stretched, its just where the diff has been moving around and flattened the threads. Best advise is still get the correct full width bolts.

MikeRJ - 14/10/06 at 06:46 PM

quote:
Originally posted by Johnmor
I take these are the bolts that attach the drive shaft to the diff flange?


No, these are attaching the diff housing to the chassis, in place of the normal long bolts.

mad dad - 14/10/06 at 11:15 PM

You're right Mike RJ and i have bought 2 new long ones today and 4 of the others to sort the problem out so will try and fix tomorrow - not sure if the longs one will go in but will have a go as i think they may be better than the 4 seperate ones???? Thanks for all the comments..

rusty nuts - 14/10/06 at 11:42 PM

I f you can't get the long ones in try putting the 4 short ones in so that the nut is against the diff. ie on the inside, should spread the load better.