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help about the nut on the back diff?

Posted: Wed May 23, 2007 10:49 pm
by tazzazuk
putting a new seal in rite now it is so stiff it feels like u r going to lift the car up when trying to undo the 28mm nut is it left hand or right hand? thinking about jacking the bar up?

Posted: Thu May 24, 2007 12:19 am
by nicbeer
big breaker bar or rattle gun.

it b tight.

pinion nut

Posted: Thu May 24, 2007 12:25 am
by want33s
http://www.suzukiinfo.com/
Section 16-6. Fig. 16-12.

Posted: Thu May 24, 2007 8:13 pm
by NIK
Its a biatch without the proper tools. I ran a chain off a bolt through the flange to the chassis and a BIG breaker bar. Dont forget the nut is dented in on one side to stop it coming loose I use a chisel to open this up.
Nik

Posted: Fri May 25, 2007 11:01 am
by Gwagensteve
I have a concern here and I don't have a FSM in front of me so I am not sure, but here goes. Let me know if this in incorrect though:

Preload on the pinion/bearings is set by the crush sleeve, which is set when the pinion flange is tightened.

A common cause of failure of suzuki diffs is due to lots of thrust in the pinion, which is due to the crush sleeve collapsing under excessive load.

If you undo the pinion flange and pull the seal, I think that technically the bearing as to come out and a new crush sleeve installed, or factory preload might not be achieved when the pinion flange nut is re tightened.

Failure to acheieve this preload might result in sleeve collapse and subequent R&P destruction.

The FSM normally explains what can be replaced on an item without disassembly (the sierra FSM does for the transfer as an example)

Please correct me if I am wrong, but I am pretty sure you can't just pull the flange and whip a new seal in.

(unless you go to a solid spacer like a nissan, which I will be doing when I rebuild my diffs)

Steve.

Posted: Fri May 25, 2007 1:08 pm
by Guy
Gwagensteve wrote:I have a concern here and I don't have a FSM in front of me so I am not sure, but here goes. Let me know if this in incorrect though:

Preload on the pinion/bearings is set by the crush sleeve, which is set when the pinion flange is tightened.

A common cause of failure of suzuki diffs is due to lots of thrust in the pinion, which is due to the crush sleeve collapsing under excessive load.

If you undo the pinion flange and pull the seal, I think that technically the bearing as to come out and a new crush sleeve installed, or factory preload might not be achieved when the pinion flange nut is re tightened.

Failure to acheieve this preload might result in sleeve collapse and subequent R&P destruction.

The FSM normally explains what can be replaced on an item without disassembly (the sierra FSM does for the transfer as an example)

Please correct me if I am wrong, but I am pretty sure you can't just pull the flange and whip a new seal in.

(unless you go to a solid spacer like a nissan, which I will be doing when I rebuild my diffs)

Steve.
You dont have to replace the crush sleave, but you do need to ensure you so the nut back up with a decent torque wrench. From memory the torque setting is something like 10 to 15 inch pounds.

Posted: Fri May 25, 2007 1:38 pm
by Gwagensteve
Doesn't sound right to me -
15inch/lb = 1.694772 Nm

The transfer case flange nuts are 108Nm

I have discussed this with a guru in such matters (GMH metallurgical backgound) and he commented that it might be possible to get correct preload on an already crushed sleeve, but that if the crush sleeve was already marginal for the job (as I believe sierra ones to be) then it will flog out quickly.

Steve.

Posted: Fri May 25, 2007 3:21 pm
by Guy
Gwagensteve wrote:Doesn't sound right to me -
15inch/lb = 1.694772 Nm

The transfer case flange nuts are 108Nm

I have discussed this with a guru in such matters (GMH metallurgical backgound) and he commented that it might be possible to get correct preload on an already crushed sleeve, but that if the crush sleeve was already marginal for the job (as I believe sierra ones to be) then it will flog out quickly.

Steve.
I last did this 5 or 6 years ago ... so the memory may be fuzzy .. but I did have to buy a new much smaller torque wrench to do it ..

Posted: Fri May 25, 2007 3:23 pm
by Gwagensteve
I will check the FSM tomorrow.

pinion nut

Posted: Fri May 25, 2007 3:24 pm
by want33s
Steve, I beleive your friend is right. If the sleeve is in good condition, it can be re-used.
It is standard practise to fit a non crushable sleeves in high performance diffs. My XA ute with 9" has one as does my wifes HR ute (9" also).

Re: pinion nut

Posted: Fri May 25, 2007 4:15 pm
by Gwagensteve
want33s wrote:Steve, I beleive your friend is right. If the sleeve is in good condition, it can be re-used.
It is standard practise to fit a non crushable sleeves in high performance diffs. My XA ute with 9" has one as does my wifes HR ute (9" also).
This is certainly the case for non crushable sleeves which are set up with shims, but the sierra sleeve is designed to deform under load applied by tensioning the pinion flange nut thereby setting the preload correctly.

However, this is the source of A) my scepticism that 15 inch pounds as correct as it couldn't compress the sleeve and set preload and

B) that once compressed correct preload cannot be achieved again because the sleeve has laready deformed.

I might be wrong and will check the FSM tomorrow, but in either case, I have seen far too many sierras with loose pinions, indicating that under high load the thrust of the pinion compresses this sleeve more and leads to short pinion bearing life, or removal and replacement of the seal, on subsequent retorquing, results in inadequate preload and subsequent thrust.

Sierra pinion seals cop a hiding in mud and I would love to be able to replace a seal without stuffing the crush sleeve.

The FSM will tell all....


Steve.

Steve.

pinion nut

Posted: Fri May 25, 2007 6:26 pm
by want33s
The 15 ft/ lbs mentioned is the resistance the pinion has to turning, NOT the tension on the pinion nut. I looked in the FSM and there is a pic showing a special torque wrench pulling the pinion. I cropped and saved it but for some reason Photobucket won't display it.
Edit: I just had another look and it looks more like a fishing scale with a hook on each end.

pinion nut

Posted: Fri May 25, 2007 6:45 pm
by want33s
Image