swaping flanges

[andyrew]

hey guys.

ive got a large flange and small flange diff. any words of wisdom for swapping the flanges over? they are both sammy ones. but the one from my sammi is duff. the replacement is from a later spanish sammi and has the smaller prop flange. i seem to remember something about counting turns??

help mucho apreciated

[twiss]

I know the flanges are a pain to get off in the first place!!!
To put it back on you really should use a diff backlash setting tool.
You can count the turns and guess it but it might not last very long!

[ScottieJ]

Just drill new holes in the diff flange in between the existing ones, use your prop as a template and it'll mean you don't need to take anything off.

Twiss for flange swaps you don't need any special tools all you really need is a new crush collar, then you need to torque the pinion bolt up, none of the diff settings will be Changed as long sec that is done

[andyrew]

the flange is quite a bit smaller than the old one. i think drilling holes would leave it a bit to close to the edges.

ill post a photo later.

[twiss]

Ahhh the bearing pre-load is what I meant... it says it should be set correctly in the service manual

[ScottieJ]

It doesn't matter if the holes are close to the edges, people do it all the time for toyota props and I've even seen them with the holes overlapping the edges with no problems.

[ScottieJ]

Ahhh the bearing pre-load is what I meant... it says it should be set correctly in the service manual

and that is the purpose of the crush collar, once the pinion nut is correctly torqued, it will be at the correct preload

[andyrew]

good to know. ill be doing some drilling then.

thanks guys.

[twiss]

What I have to say is... the service manual states that you the nut should be done up to the correct level by measuring the pinion preload, while you are tightening the nut.
It states that you should tighten the nut, measure the preload, tighten, measure, etc... until it is correct.

I'm not trying to take the P or anything but it would be a real shame to put fix it then have it break again.

Otherwise where have you found the torque figure for flange nut? Its not in the service manual...

Note:
Bevel pinion bearing preload is adjusted by tightening bevel pinion nut to crush spacer.
Therefore, be sure to use a new spacer for adjustment and tighten pinion nut step by step and check for starting torque (preload) as often as tightening to prevent over crushing of the spacer.
If exceeds specification given below during adjustment, replace spacer and and repeat preload adjustment procedure.

if it was the haynes book of lies then I would take that with a pinch of salt... but the service book rarely seems to put a foot wrong from my experience with it

If its overtight the preload will be incorrect and the diff wont last

[ScottieJ]

Twiss not trying to argue as what you have said above is correct

However the problem with the above procedure is that you need to completely strip the carrier from the diff in order to set it up like that. You cannot really accurately measure the bearing preload using the technique in the service manual with the carrier fitted as there is such a small amount of backlash. Who wants to completely strip a diff just to swap a flange?

I've successfully done it before by replacing the crush collar and seal then tightening it to the point there is no end play, it takes a lot of force to get the crush collar to start crushing but once it starts you need to be careful to not tighten it too far, technically there isn't a correct torque but around 55-65lbs/ft should be ok at a guess once the crush collar has started to go and there is no end play.
Or you could count the amount of turns it takes to undo the nut and do itt up the same amount
Or you could use an old school torque wrench to measure how much torque it takes to undo the nut then tighten it back up a tiny bit more

(note: I accept no responsibility for someone else doing this in case they mess it up which is easy to do )


or there is the option of a solid crush collar http://www.rsmfg.co.uk/page7.html

Either way he's going for the option of drilling the flange now so it doesn't really matter.

I haven't said the service manual is wrong, it just does not cover replacing the crush collar & seal without completely stripping the diff.