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I'm swapping my stock ZHP diff with a 3.46 diff from a 325i. I need to swap the input flanges but neither my craftsman nor gearwrench 30mm socket will fit around the nut on the pinion shaft. Any suggestions? How has anyone else here done it?
 

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Taking that nut off will put you in the position where you need to check and adjust the gear mesh between the ring and the pinion. Even if you don't replace the pinion gear, you will be relieving the thrust pressure on the bearings, this means that the gears will be affected.

Also, you will want to be sure that the flanges are interchangeable before you set about to take the one off that is mounted to the car.

I'm confused as to the upside of taking the 330 ZHP diff out of the car and putting in the diff from a 325.
 

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I'm confused as to the upside of taking the 330 ZHP diff out of the car and putting in the diff from a 325.
I was wondering the same.
Would be far easier to put in a regular 3.46.

Sell the ZHP diff you have, buy a regular 3.46. You'll come out with a profit, and won't have to mess with flanges.
 

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I was attempting the same thing, swap the input flange from a different differential to mine but unable to do so because none of my sockets would fit that damn nut. Also, I was afraid that it would mess up the ring and pinion so I gave up. If anybody knows the exact procedure on how to do this, I'm sure the OP and me would greatly appreciate it.
 

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OEM ///PLUS
2003 M3 6MT Slicktop
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I'm swapping my stock ZHP diff with a 3.46 diff from a 325i. I need to swap the input flanges but neither my craftsman nor gearwrench 30mm socket will fit around the nut on the pinion shaft. Any suggestions? How has anyone else here done it?
i've done this a few times on diffs. not sure which one you have, but Craftsman socket fit. not sure how many points my 30mm socket is but it's thin enough to fit. now if Craftsman made them thicker later i do not know.

i've must have posted this procedure over 15 times over the years.

basically it goes something like this:
there is a thick circumference locking plate/washer you unbend to get to the nut. you mark the nut edge next to the pinion shaft tip. you count how many turns (revolutions/movement) it is to remove it from that point. you keep the nut with the diff it's removed from. same goes for the donor diff flange and it's turns. pull off the flange and do the same for the other donor diff flange. swap and then put the nut back on the same way and turns ending with it matching up to the mark on the tip to the one on the nut. this way it's the same amount as it was before. it's not pulling the pinion up by being over torqued and not too loose by being under. it's the same as it was since the thickness of the flange mounting face is the same across both.
don't forget to bend the locking plate/safety washer again to keep from moving. i usually buy a new one in case the old one is destroyed(P/N 23211490120). because i don't want to start the job only to have this hold me up. i always have an extra in my garage. i don't think it's even a $2 part.
side flanges just pop out and back in. if you notice a leak, now would be the time to replace any seals and also super easy to replace the diff fluid now too.
 

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2003 M3 6MT Slicktop
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Taking that nut off will put you in the position where you need to check and adjust the gear mesh between the ring and the pinion. Even if you don't replace the pinion gear, you will be relieving the thrust pressure on the bearings, this means that the gears will be affected.

I'm confused as to the upside of taking the 330 ZHP diff out of the car and putting in the diff from a 325.
because the 330 ZHP has a 3.07 ratio diff for it's manual 6 speed while a 3.46 diff will be a much better performance ratio mated to a overdriven six speed. Almost all magazines who tested the 330ZHP published how they wished BMW would have fitted the 3.38 or 3.46 for the ratio instead of 3.07. stock was 2.93

as for swaping the diff flange. one can measure the drag on it but that's way to tricky and excessive work. just putting it back where it was is so much easier and have never heard of anyone Ever having an issue. it's when it's completely taken apart to swap internals, swap R&P, or LS unit added that it needs to be thoroughly measured and "set-up" again.
 

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In the old days, BMW said that whenever you took the pinion flange off, you had to replace the crush sleeve.
Which involves taking the carrier out, pulling the pinion stack, and then re- crushing and resetting preload drag.
Which takes an amateur an afternoon, and might involve several crush sleeves.
Sometime around the E30, they started saying that IF you were only replacing the seal, you could get away with
putting the pinion nut back exactly where you found it, re- establishing the preload on the pinion.
Many of us had already been doing that, and USUALLY the pinion nut had enough load against the crush
sleeve that it stayed tight. Every so often, one would back off, and unless you caught it right away,
chew up the flange, and sometimes the splines on the pinion shaft.

Now, if you change the flange, and the flange is EXACTLY the same thickness as the one you took off,
in THEORY the preload can be re- established by getting the nut back to where it was when you started.
As far as I know, BMW has not signed up for this level of adventure, saying instead that any time any
component in the pinion stack is changed, it's time to replace the sleeve, re- blue the gears, the whole
9 yards.

In THEORY it might work. I've never needed to change just the flange, so I've never tried.

t
 
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