Look at my diff center - what's your vedict ?

[71 Bee Man]

G'day guys,

knowing absolutely nothing about diffs and having to order my parts from your shores, I was hoping you guys might be able to give me your opinion on what i should do with mine.

Apparently I have an 8 3/4 sure grip in my car, with a 3.23 ratio.

Had some problems a while back where there was an ungodly noise on de-celleration, which ended up being a loose pinion nut. Tightened her up and all is good - for the moment at least.

When I thought she was stuffed (before simply tightening the nut) I took the center out and showed it to a diff repairer here in Australia. He took one look at it and said "Mate......before I even touch it you'll need to get a new limited slip center for it - she's stuffed".

OK.........apparently the limited slip center isn't working on my car, and I'm assuming that means that I'm just not getting the traction when I take off....or something like that because the car still drives me around even though my center is apparently stuffed.

Please take a look at the pics I've included - in particular the one showing one of the limited slip pins with it's elongated hole. Can anyone tell me what this means, what it does to the diff, and whether the one on Ebay at this URL :
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&viewitem=&ru=http%3A%2F%2Fsearch.ebay.com%3A80%2F270122525787_W0QQ_trksidZm37QQfromZR40QQfviZ1&item=270122525787
is a suitable replacement that I can just take somewhere and have them install.

Any observations, advice, anything is appreciated. I don't want to buy stuff and then find out it's unsuitable.

Regards,

Peter
Sydney, Australia

[Ghoste]

The e bay one is a straightforward interchange so no worries there.   Can't tell from the pic how worn your limited slip is but it's safe to say that if that hole is pounded out, it's had a hard enough life to wear it down.  That won't prevent you from enjoying normal driving for now though.

[71 Bee Man]

The e bay one is a straightforward interchange so no worries there.   Can't tell from the pic how worn your limited slip is but it's safe to say that if that hole is pounded out, it's had a hard enough life to wear it down.  That won't prevent you from enjoying normal driving for now though.

Thanks very much.

Does it just mean that I'm not getting the "sure grip"action that the center would normally provide ?

If I can put off rebuilding it for a while that'd be great, but when I saw this one on Ebay, for very reasonable postage I might add, I thought maybe I should grab it. There are a couple of places down here that stock the centers, but they cost twice as much as the Ebay one with postage.

Peter

[Chatt69chgr]

That was a real good price on that clutch type suregrip even at their buy it now price.  I don't know what it actually sold for.  Of course, the suregrip you have is the cone type used in 489 cases.  Both types of suregrips interchange from all three cases---------as long as you maintain the correct differential bearings.  To use the Power-lok suregrip in your 489 case, you would need the differential bearings used in the 742 case.  O/W, everything else is straightforward.  Since you have everything apart, you might as well replace bearings and seals in the center section.  A solid spacer with shims is available for the pinion instead of the crush sleeve from RA Tech.  Autozone has Timken bearings.

[71 Bee Man]

That was a real good price on that clutch type suregrip even at their buy it now price.  I don't know what it actually sold for.  Of course, the suregrip you have is the cone type used in 489 cases.  Both types of suregrips interchange from all three cases---------as long as you maintain the correct differential bearings.  To use the Power-lok suregrip in your 489 case, you would need the differential bearings used in the 742 case.  O/W, everything else is straightforward.  Since you have everything apart, you might as well replace bearings and seals in the center section.  A solid spacer with shims is available for the pinion instead of the crush sleeve from RA Tech.  Autozone has Timken bearings.

Thanks for the advice - really appreciated.

Actually, after the diff guy told me I'd need a complete new L.S.D center, I went home and wondered whether the noise may have just been due to the loose nut on the pinion. So I put it back together and "voila".......she's running again.

I'd still like to get the center fixed though. Hence this post. As I said though, I know pretty much nothing about them and wanted to make sure of what i should get.

Peter.
Sydney, Australia.

[Ghoste]

As for your question about the Sure Grip, the answer is not necessarily.  Best guess would be that if the side pinion shaft has pounded a hole like that, the clutching mechanism (be it cones or plates) that provides equal torque to both wheels is likely worn out as well.
Part of me wants to tell you to just jump on the car really hard and see if it lays down one black mark or two but the other part says to advise you to drive it easy until you get a replacement.  And if it were my car, I would replace it.

[oldkimmer]

HEY MAN U R asking for big trouble, cause the more that pin slaps back and forth it will bust off the little retaining pin allowing the big pin to slide out and jam up the gears, which then I dont have to tell u that it comes EXPENSIVE REAL FAST, not to mention dangerous as the rear tires will lock up.................Kim.......

[71 Bee Man]

HEY MAN U R asking for big trouble, cause the more that pin slaps back and forth it will bust off the little retaining pin allowing the big pin to slide out and jam up the gears, which then I dont have to tell u that it comes EXPENSIVE REAL FAST, not to mention dangerous as the rear tires will lock up.................Kim.......

G'day Kim,

that's the kind of stuff I need to hear. Rather than "cheaping"it out and getting by, I think I'd better fix the damn thing. I was just hoping it was something you could leave until you had the money. Ecven though I'm not a real rev-head, I still like to know things work as they're meant to.

I'll start saving.

Peter