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phrider said:
Any revised parts list? Any special hints or suggestions?
This is what we have for text so far. It is not complete. We will revise and repost with pics some time in the future.

3.46 Differential Installation

Tools Required:

12mm wrench/socket
13mm wrench/socket
16mm wrench/socket
16mm Gear Wrench or flat ratchet or 12" or greater pipe to fit 16mm combination wrench
19mm wrench and socket
E12 socket
Torque wrench with range up to 110 Nm
17mm hex (male) socket

Parts Required:

Z3 3.0i 3.46 rebuilt differential, 33 10 7 508 262, qty 1, $2200.00 retail plus core
Z3 3.0i 3.46 speed sensor, 62 16 8 357 020, qty 1, $29.50 retail
O-ring for speed sensor, 33 11 1 206 166, qty 1, $0.67 retail
Fill/Drain crush washers, 07 11 9 963 355, qty 4. You need 2 when you build up the diff to install and 2 more at break in change at 600 miles on new differential, $0.07 retail each
Gasket, 33 11 1 211 708, qty 1, $3.56 retail
Diff Mounting Bolts M12x1.5x32, 34 11 1 156 982, qty 4, $1.83 retail each
Wave washer, 07 11 9 932 112, qty 8, $0.08 retail each
Self locking hex nut M12x1.5, 07 12 9 900 047, qty 1, $0.24 retail each
Driveshaft hex nuts with ribs, qty 4, 26 11 1 227 843, $0.64 retail each
Output shaft bolts, qty 12, E12 Torx screws with ribs, 33 21 1 227 664, $1.79 retail each
Lock ring, 33 13 1 207 280, qty 2, $0.38 each
Copper exhaust system nuts, 11 62 1 744 323, qty 4, $0.92 retail each

Parts Optional:
M output flanges, 33 13 2 227 265, qty 2, $70.50 retail each
M rear diff cover, XXXXXXXXXXX

Shop Materials Required:
Differential oil, 83 22 1 467 993, qty 4 quarts, $14.10 retail per quart.
Copper paste for exhaust bolt threads, XXXXX

And so it begins***8230;

I. Removal of stock differential

1. Chock front wheels. Use quality chocks with chains.

2. Jack up rear of car. Install Jack Stands (Reference this link) and ramps under rear wheels for additional safety.

3. Remove exhaust system. Do driver's side first. Remove XXmm bolts and XXmm copper nuts at flanges. Note the copper nuts are one use only and BMW recommends copper anti-seize compound on the bolt threads. Remove 13mm bolts (qty 2 each) at forward and aft muffler hangers. Unhook exhaust system from final hanger. Do not adjust hangers or you will have to re-align everything later, which will be a pain. Remove passenger side exhaust system next.



4. Support each output shaft. We used 3 very high strength tie wraps on each of the 2 shafts. Tie wraps are nice because they are easy to install, they do not scratch any components, and they are easy to cut off and remove later. We tied to the rear sway bar.



5. Remove 6 E12 bolts on each output shaft. With the car on jackstands, you can easily remove the half shafts from the diff output flanges.

6. Remove 16mm driveshaft nuts. The remove torque is much greater than the install torque. This is why. Note: in order to access all 4 of the bolts, have someone push in the clutch and you will be able to turn the driveshaft.

7. Drain differential oil. We think it is easier to do this while the differential is mounted to the car. Note the crush washers are a one-use-only item. Do not re-install new crush washers yet. Re-install fill and drain plugs so you do not lose them or get their positions confused.

8. Disconnect speed sensor on differential cover.

9. Support differential with floor jack. Put jack pad just forward of rear aluminum diff cover.

10. Remove horizontal diff mounting bolt through rubber mount. On my car, I had a 19mm nut and a 19mm bolt. This is different than Ron's car. Note there are washers on each side.



11. Lower jack approx ½" - 1". This will give you access to the 16mm mounting bolts on the top of the differential.



12. Remove four 16mm diff mounting bolts. You can use a combination wrench to do this if you enjoy laying under your car for long periods of time. A Gear Wrench or a thin ratcheting combination wrench will make life a lot easier. Be aware that the diff is heavy. Verify it is stable on your floor jack before removing the last 2 bolts. Diff is now free to come off of car. You will have to drop the diff down to clear the sheet metal mounting bracket that had the 19mm nut/bolt and also move the jack aft at the same time. This way you can clear the driveshaft studs.





II. Build up of 3.46 Differential

1. Remove qty 8 16mm bolts on rear diff cover of 3.15 stock diff. Remove 2 XXmm bolts on stock speed sensor. Install new O-ring and 3.46 speed sensor into 3.15 M diff cover. If you want to keep your M 3.15 diff complete, you will need to buy a new rear diff cover. Note for the O-ring, install it onto the outer edge of the speed sensor, then push the speed sensor in place and let the O-ring go where it wants.

2. Remove 17mm fill and drain plugs on 3.46 diff. Drain. Re-install fill and drain plugs without crush washers.

3. Remove qty 8 16mm bolts on rear diff cover of 3.46 diff. Remove and install new gasket onto 3.46 diff. Install 3.15 M diff cover with new speed sensor onto 3.46 diff unit. We used the OEM 3.46 diff cover mounting bolts again. Install torque is 45 Nm. You could replace them with new or order chrome ones from Ron Stygar if you are thinking ahead. You could powdercoat or whatever finish your diff cover for fun too. Note that there is no differential oil installed at this time, nor are the fill & drain crush washers in place.

4. Install 3.46 diff cover onto 3.15 M diff. No need to replace gasket or torque the fasteners all the way. This will keep dirt out of your 3.15 in case you ever want to re-install it.

5. Remove 3.46 output flanges. A large flat blade screw driver, twisted 90 degrees (do not pry) will easily unsnap the lock ring that is holding the output flanges to the diff. Replace the lock ring on each side of the diff with a new one.

6. Install M output flanges. If you purchased new output flanges, you can leave your 3.15 intact. If not, you will have to remove the output flanges from your 3.15 and install them into the 3.46. Note the bolt patterns are different, so are the overall lengths of the output flanges. This is why it is necessary to change to the M 3.15 output flanges. To install the M output flanges, coat the bearing surfaces with a light coat of differential oil, slide into diff insuring teeth are aligned until you hear the lock ring snap onto the flange.

III. Installation of 3.46

Installation is reverse of removal. You will spend (possibly) a great deal of time lining up the 2 aft/upper 16mm diff mounting bolts. Go slow. Hand start all bolts. If you cannot get them after the first few minutes, quit. Go do something else for a while and then try again later.

Install new diff fluid. Install torque on differential fill and drain bolts is 77 Nm. Replace crush washers on fill and drain bolts.

Drive car for 600 miles. Keep speed under 100mph. Replace differential fluid and crush washers and retorque to 77 Nm.
 

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I definitely want to see the performance gains this achieves, as in before and after comparisons. Excellent work Jon.
 

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Wanna borrow my G-tech PRO? ...

Hi Jon ... If you ever want to borrow my G-tech PRO to get some 0-60 ETs with the 3.46's, let me know and I'll bring it to work and we can meet at lunch. OR, if you have any reason to come over to Bellevue, drop me an e-mail and I'll give you directions.

For reference, I did a couple 0-60's with my S52 Coupe and got a 5.17. The S54 would be approx. the same to that speed, but with the 3.46's, you might be frustrated in trying to "hook" the street rubber. High-4's would be realistic, though.

Like to see that Coupe of yours, too!
 

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He"ll have no trouble hooking up with the 3.46.....


its sooo much nicer at higher speeds..... :)

Congrats Jon!! Nice writeup :thumbup:
 

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Finished mine. A few comments...

- The diff mounting nuts can be a :nono::nono::nono::nono::nono: - do them in good light when you are well rested, not at night when you are tired. Start with the hard ones - the upper ones towards the front of the car. Once those are done you can do the lower ones at the back of the car as they are easy to line up - you can see thru the mount to line things up. Look for the "footprint" of the old diff when lining up the first bolts. The trick is getting the diff jacked up to just the right height - high enough to line it up and give you some "wiggle" but not so high that you can't get above the diff with your hand to manipulate the bolt. If all else fails dump the spacers long enough to get 3 bolts started, then remove the bolts one by one and add the spacers back in. Remember to breathe.

I heard one good suggestion after I finished this. Loosen the subframe mounts so that the entire subframe can droop. That should make getting at those top bolts 100x easier. Why didn't I think of that?!

- Make sure you have the correct tool for the fill and drain plugs before you get started. Odds are you will not find it locally. Quite the oddball part. I found a long S&K socket, but will be ordering a proper Facom stubby socket from Ultimate Garage. I recommend you do the same.

Note - the instructions above show this is a 17mm nut. That is incorrect. It is 14mm. The tranny is 17mm.

- Figure out the filling bit before you get started too. I got a Sta-Lube pump setup like Ron shows. Works great.

- DON'T OVER-TORQUE THE FILL/DRAIN PLUGS. Install them to 70 newton-meters (51.6 foot-pounds). No more. Make sure the plug threads, crush washers, and the boss on the cover are clean and dry. Diff lube on these surfaces can screw up the torque reading.

I overtorqued the drain plug after changing the 600 mile break-in fluid change - it split the diff cover (aluminum) and started leaking. This happened at Homecoming and I spent 2 hours under the car in the parking lot of an Advanced Auto Parts patching it with 2 part quick-dry epoxy putty (like JB Weld). I'm going to have to replace the cover.



It's a great upgrade. Don't hesitate.
 

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3.46 DIFF from E46 325iA ? will it work?

3.46 DIFF from E46 325iA ? will it work?

The reason I ask is that I can get a reman unit from a 325i for about $1000 less than the cost of the unit from the Z3 3.0 Coupe. Does anyone know if this will work?
 

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Discussion Starter · #15 ·
samer555 said:
3.46 DIFF from E46 325iA ? will it work?

The reason I ask is that I can get a reman unit from a 325i for about $1000 less than the cost of the unit from the Z3 3.0 Coupe. Does anyone know if this will work?
It might work, but I don't think you want it. I thought the E46 was non-LSD. Maybe an E46 person will chime in here.
 

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Andy and I got the 3.46 in tonight. No problems. About 12 hours of work between the two of us, including beer.

Car is faster than snot.
You swapped a 3.15/1 for a 3.46/1
How is the car faster? That being said: There are two types of cars, street cars and highway cars.
Street cars are quick and highway cars are fast.
A "fast" car is a car for highway use, 2.76/1 would yield the highest speed on the highway but acceleration would suffer.
A quick car for street use would use the 3.46/1, 3.73/1, 456/1 these gear ratios offer quick acceleration but top end speed suffers. A 2.76/1 would walk away from you on the highway, that's a fast car. My stock 3.15/1 ratio would walk away from you on the highway because my 3.15 would reach a higher top speed in the long run.
The car will accelerate quicker off the line with the 3.46/1 vs a 3.15/1, but the top end will be slower than a 3.15 to 1 ratio. Guess what, if you put the 4.56/1 in the diff your car would accelerate even faster than the 3.46/1 but your top end would be even slower.

If you prefer top speed (Highway) "fast as snot" to dragstrip performance (Street), then higher axle gears, like 2.76:1 or 3.08:1, may be called for. The higher gears will reduce engine rpm versus road speed. Another way to look at it is that the car will go faster at the engine's rpm limit than it would with lower gears. So putting a 3.46 did not make your car as fast as snot, it actually slowed your car down.

Just saying so people don't go waste money thinking they will achieve higher speeds.

Your car is not faster than snot, it is quicker than snot.
 
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