Jack McNamara Salisbury Air locker.

[daddylonglegs]

I fitted a Jac Mac Airlocker to a FC101 today, This is the second one I have done,Nice diff but a pig of a job.
First up, it comes assembled with all the bolts high strength loctited and tightened up.What for?
You would have to be extremely lucky to fit the correct value of shims behind each carrier bearing first time. if you are unlucky, and I was twice, despite having a surface plate and height measuring equipment to measure the old carrier, you must completely dismantle the carrier assembly to facilitate removal of the carrier bearings to alter the shim value. They have machined the carrier in such a way that you cannot use a bearing puller unless you pull on the roller cage with the very real risk of damaging some very expensive bearings, so they drilled two 6mm holes through the bearing shoulders on each half of the carrier so you can drift the bearings off after dismantling.
The carrier is very substantial and I can see no reason why they couldn't machine a decent chamfer on each side to allow the use of a bearing puller, I was almost tempted to do it myself, but its not my diff and I may have voided any warranty by doing so.
What I am getting at here, is that this oversight costs heaps in extra labor charges for installation, so if you buy a Salisbury difflock from Jack McNamara, do not even think about fitting it yourself unless you have the correct knowledge, equipment, and the patience of a saint.
If you do take it to a specialist to fit for you, expect to pay for anything up to 8 hours labor to get it right, particularly if pinion bearings need attention too. These comments apply only to the Salisbury diff. Jac Macs Rover type diffs set up quite easily for the UNF diffs, The spot facing for the crownwheel bolts is a bit small for the earlier Series 2a BSF bolts.
there is also a bit of clearance grinding required on the pinion housing.

Bill.

[Woop]

Bill,
years ago when i installed my ARB Airlocker in my Sailsbury in my S3, i bought some new carrier bearings and had an engine shop bore the centers out to be a snug sliding fit on the carrier. Then i sat there for hours getting the contact pattern right as well as the bearing pre-load correct. Even with set-up bearings, it was time consuming! I've not seen the JAC MAC diff, but could you use set-up bearings for this one?

Nick

[daddylonglegs]

Yes Nick, you could use barings as you described, That is what JacMacs themselves do at their shop. If i were specialising in Salisbury diffs I would do that too but I was only doing it as a favor for a friend and sacrificing a new set of bearings was beyond me financially. I may never get to, or want to do another one. The thing is that the installation time could be slashed if McNamara shamfered the carrier so that you could remove the bearings without completely dismantling the carrier each time.
I would hate to be paying some workshop $75 hr to do this for me, and the patience required to do it right would mean that many mechanics would just say, oh thats near enough and your diff would last 10,000km before the bearings and or crownwheel and pinion burn themselves up.

Bill.

[quaddrive]

yes i understand the frustrations of poor design. Came across a Jac Mac locker in a defender rear a while ago and indeed destroyed the bearings before i pulled it down and punched them off.....
also i built front and rear airlockers up for an new F250. Front no worries. Rear. no real chamfer and bearings so tight that I broke our puller trying to remove them. In the end I had to heat them while pulling just to get them off to get their part numbers to get new ones.....
Silly stuff like the fact that it is a dana housing with a ford centre???
Silly poor designs that cost$$$$$$$.
Just my 2 cents.
Giles

[bazzle]

It might be ggod to feed this back to JacMac.. to help them improve product.

[daddylonglegs]

Yes Giles, Dana diffs can be an absolute bitch to pull apart. Even with a proper spreading tool, getting the crownwheel carrier out of the housing can be very difficult. The factory tolerances for bearing fit and preload are all over the place. In spite of the fact ithat I used them front and rear on a couple of my specials ,in my opinion Dana 60's/Salisbury's are a bit overated, and their popular appeal is more a product of US Gee Wiz hype, than any real engineering attributes. Toyota LandCruiser ring and pinions are just as big, the 4 pinion carriers you get when you fit a locker make them as strong as possible. They are considerably lighter than Dana's and have better ground clearance, and can be worked on in the bush without needing special equipment. That is what is known as good, sensible design

Bill.

[daddylonglegs]

Bazzle, McNamara's are primarily differential reconditioners as well as manufacturers. There should not be any need for engineering suggestions from customers, and I am not sure they would even be appreciated.

Bill.

[LOCKEE]

Bill,

appreciate the thought on Jac Macs ability to take customer feedback. 3 Hypoid CWP lasting only 30,000km each before case hardening issues. Must have got Water in it at the same amount of kilometers each time.

Jason