[superfishyall]

1. What gauge is the sheet metal where the subframe bolts to chassis?
2. I have subframe out and trying to detach axles from the differential. The six bolts on each are out and the outside ends of the control arms are detached from the trailing arms, but the axles don't come off. Should I pry where indicated in picture below?
3. I've been reading about input flange swaps. Pinion preload is critical. When removing and putting back on the same flange, you mark the nut to the flange and reinstall to the mark. But what if the input flange is different? Does the following sound like a reasonable approach? On new differential with incorrect flange, mark nut to flange. Loosen nut. Tighten nut with torque wrench set at estimated needed torque. Tighten nut to mark. If wrench clicks at same instant, stop. If it does not click at mark, repeat loosening, setting torque, tightening nut until wrench clicks exactly when nut aligns to mark. Remove nut and install new flange to final torque setting.

 

[mjdarg]

1. What gauge is the sheet metal where the subframe bolts to chassis?
2. I have subframe out and trying to detach axles from the differential. The six bolts on each are out and the outside ends of the control arms are detached from the trailing arms, but the axles don't come off. Should I pry where indicated in picture below?
3. I've been reading about input flange swaps. Pinion preload is critical. When removing and putting back on the same flange, you mark the nut to the flange and reinstall to the mark. But what if the input flange is different? Does the following sound like a reasonable approach? On new differential with incorrect flange, mark nut to flange. Loosen nut. Tighten nut with torque wrench set at estimated needed torque. Tighten nut to mark. Repeat loosening, setting torque, tightening nut until wrench clicks exactly when nut aligns to mark. Remove nut and install new flange to final torque setting.

The RACP is quite thin from memory. I think it was 1.0 - 1.2 mm thick. Maybe a maximum of 1.5 mm. Where you indicated with your pick is the correct location to separate the half shafts from the output flanges. You can try marking the nut, but if the input flange nut face thickness is different between the two flanges, the correct preload will be at different positions. The best way to do this is check the drag with just the input flange and input bearing installed. You could probably get away with checking this measurement on a fully assembly differential before you disassembly the diff and matching it when you re-install the new input flange.

 

[M.Blacktree]

As mentioned above, marking the nut may not be helpful if you're installing a different input flange. It won't be exactly the same thickness as the old one, so the nut probably won't land on the same spot. IMO it would be wiser to test the drag, as mentioned above. Also, if you over-torque the nut you'll compress the crush sleeve some more, which will affect the gear mesh in the differential. Start off with reduced torque on the nut, and increase it gradually until you get the desired drag.

 

[superfishyall]

Thank you for the replies. I did not suggest installing the new flange to the mark. Please take a look at the process I described. The mark would just be used to measure the torque required to get to the mark with the original flange. Then that torque value would be used to install the new flange, not a mark. I think it may be a crude method of measuring the drag. In the meantime, I will research how to measure drag more directly, as you suggest.

 

[superfishyall]

Here are a couple of links I found re measuring the pinion preload:

3.46 Diff on 330 Install- HELP NEEDED

Grettings all, Today my 3.46 diff arrived and I took it to my BMW Mechanic for the install. He called me a few hours later and said that he could not locate a torque spec/preload figure for the Input Flange that mates to the pinion bearings? He told me he is very concerned with the warranty...

www.e46fanatics.com

pinion preload measurement - Google Search

www.google.com

 

[Sapote]

I've been reading about input flange swaps. Pinion preload is critical. When removing and putting back on the same flange, you mark the nut to the flange and reinstall to the mark. But what if the input flange is different? Does the following sound like a reasonable approach? On new differential with incorrect flange, mark nut to flange. Loosen nut. Tighten nut with torque wrench set at estimated needed torque. Tighten nut to mark. If wrench clicks at same instant, stop. If it does not click at mark, repeat loosening, setting torque, tightening nut until wrench clicks exactly when nut aligns to mark. Remove nut and install new flange to final torque setting.

NO. In this case, you should tighten the nut to achieve the correct bearing drag -- a few inches lbs I will look up.
To remove the diff output flange, pry here:

 

[TobyB]

But what if the input flange is different?

then you should strip down the diff and install a new crush sleeve, to reset
the pinion bearing preload.
But that's a drag. So the usual procedure is to mark the nut to the pinion
shaft as usual, and then measure (carefully, with a mic that's good to 0.001mm ideally)
the new flange and see if it's the same depth as the old one.

If it is, proceed as usual for a seal replacement.

If it's not, yes, tighten the nut to where the drag on the pinion
(which is the only indication of bearing preload you get)
is in the right range, and hope for the best. It seems to work,
usually, anecdotally, most of the time.

The torque on the pinion flange nut is entirely immaterial.
As long as it's got enough to keep things from moving in the pinion bearing stack.
Once that starts to happen, the whole mess wears itself loose in short
order, and it's back to step #1, strip down diff and install new crush sleeve.

The off- roaders with similar design diffs make up solid spacers
because this style is such a pain in the super swampers.

t

 

[Sapote]

The diff input bearing preload drag is [0.6 to 0.8Nm]. This drag is by the bearings only, not the ring/pinion, so you must measure the drag in between ring/pinion plays.

 

[Sapote]

then you should strip down the diff and install a new crush sleeve, to reset
the pinion bearing preload.

I don't think this is necessary. The old bearings must became less preload, so I would just torque the nut more on the old crushed sleeve to get to [0.6 to 0.8Nm] drag. Done.
OP, no need to buy special torque wrench for this; just hang 70g on a meter long bar, or 140g on 0.5m bar, or whatever you can find in the kitchen to hang on.

 

[superfishyall]

NO. In this case, you should tighten the nut to achieve the correct bearing drag -- a few inches lbs I will look up.
To remove the diff output flange, pry here:
View attachment 971433

Hey Sapote - For now, I am trying to remove the axle from the output flange, not remove the output flange itself.

 

[superfishyall]

It's all disassembled except the damn axles, which looked like easiest part in the videos. Judging by how disgusting the differential is and how clean the flanges are, I suspect this is not the original differential. Also, I don't have my replacement subframe bushings yet but I'm pretty sure the holes aren't supposed to be oval. The one on the other side is round.

 

[Sapote]

Should I pry where indicated in picture below?

Hammer around the CV thick disc with a block of wood to loosen it from the output flange, then it will come out.

 

[M.Blacktree]

I think that one oval hole is supposed to be like that.

 

[Inlajnsiksbenzin]

I think that one oval hole is supposed to be like that.

Yes, mine was also oval. It’s by design

 

[superfishyall]

It did look quite precise!

 

[superfishyall]

I still can't get those freaking axles off.

 

[Sapote]

I still can't get those freaking axles off.

Trim off those long cat claws and get some beef!!! The half shaft held to the output flange by the bolts and nothing else.

 

[t.er]

Typical locating datum setup. One hole as the locator, one two-way slot, and (haven't looked this up for the bushings specifically, but generally how it works) the other two are oversized holes to allow for looser tolerances

 

[Inlajnsiksbenzin]

What about putting the car in 1st gear and trying to drive forward with handbrake engaged or pushing the brake pedal after you drove off? There should be a lot of force to pop them off the output flanges? But depends if you have an auto or manual gearbox

 

[superfishyall]

The differential and axles are on the floor of the garage, and not attached to the car. If I can't find someone locally to properly swap the input flange on the differential, I may abandon the differential swap and then I won't absolutely have to remove the axles, although I think it will be easier to replace the bushings on the trailing arm if the axles are disconnected from the differential. Sapote is giving me a hard time about not using enough force but it the way everything is configured, you can't really exert much force at that location, except with a BFH, which I try to avoid.