DIY Front Differential Fluid Change Complete

[Proflyer]

Originally Posted by garagelogician

Just gutentight. Don't go crazy on it.

I thought the same thing but wanted to make sure.

[msan]

Originally Posted by Proflyer

I thought the same thing but wanted to make sure.

Torque spec for fill and drain bolts is 60 Nm or ~44 ft/lbs

Reinforcement plate bolts should be replaced with new and torqued to 54 Nm or ~40 ft/lbs and then a 90 degree rotation

Important!
If oil is filled up to the lower edge of the oil filler opening, the front axle differential would be overfilled and in rare individual cases oil could emerge from the ventilation opening on the front axle differential.
After draining front axle differential oil or when carrying out the initial filling of a new replacement front axle differential, the transmission must be filled with 600 ml oil.
Only use the approved front axle oil in the front axle differential.
Failure to comply with this requirement will result in serious damage to the front axle differential!

Note:
Only change oil when front axle differential is at normal operating temperature.

[Lambeau]

I re-used the bolts and filled it to the bottom of the fill hole and now have 73,000 miles driven since I did this with ZERO issues. BMW specifies exactly 600ml and to re-use the bolts so it discourages owners from performing their own work so they can overcharge like they do everything else. I also used Pentosin instead of BMW fluid when I changed my trans fluid and the cheapest trans pan/filter I could find on Ebay and now have 75,000 miles driven since trans fluid change (175,000 total miles on trans) with ZERO issues. I do all of my own work and use the cheapest parts I can find on Ebay for wheel bearings and suspension pieces with zero issues. Pi$$ on BMW and their overpriced rip-off scheme.

[wsmeyer]

Originally Posted by Lambeau

The hardened bolts holding a thin aluminum plate are not going to be "one use only". If BMW states that they are, it's just another means of screwing BMW owners who typically know nothing about vehicles and they fork over more money just because BMW says to.

Damn dude, it's guys like you that make mechanics cringe when you tell them you do your own work.

You obviously have no idea what TTY or TTT bolts are and that's fine, if you don't know, you don't know. Being too lazy though to look them up and learn something makes you a really bad mechanic.

This thread came up in a Google search because I knew they were single use and I was trying to look up the torque for them.

Several places said 45ft/lbs + 90 degrees which is odd as that is a TTT spec but when I did it they all yielded roughly at 90 degrees so they are definitely TTY bolts and the spec is just a guide. Basically just do them all in two steps to yield.

[Lambeau]

If you want to fall for the BS BMW pushes to screw as many people as possible that's fine. I have almost 100,000 miles on the RE-USED bolts which is more valuable testament than your opinion.

[wsmeyer]

Originally Posted by Lambeau

If you want to fall for the BS BMW pushes to screw as many people as possible that's fine. I have almost 100,000 miles on the RE-USED bolts which is more valuable testament than your opinion.

That just means you didn't tighten them enough, if you did they would snap. Just because YOU don't understand something does not make it BS.

[Lambeau]

Real-world 100,000 miles of proof Trumps opinions every time.

[wsmeyer]

That TTY bolts cannot be reused is not an opinion, it is a fact, and the reasoning is because of physics and what happens when you tighten them to yield.

That TTY bolts need to be used there is an opinion. It's not MY opinion though, it was the opinion of the mechanical engineer that designed the part. His is what's called an EXPERT OPINION as he his highly trained and qualified. He also had access to any and all data needed to form an opinion on the clamping force necessary for that plate to do it's job. He also had very specific, quantitative data on what exactly that plates "job" was.

For the opposing view, we have "Lambeau". A home mechanic with no engineering degree, no access to any data on the forces the plate is subjected to, and no idea what a TTY bolt is as he thinks they are reusable, who is justifying his opinion based on the anecdotal evidence that he reused the bolts and has driven 100,00 miles now with no negative effects that he can see.

[Lambeau]

There are many in this thread to prove you otherwise with not one instance of reusing the bolts causing an issue. There is in fact many more instances that they didn't fail than did. You have zero knowledge of what my degree is and you personally attacked me. Grow up.

[stltri]

Was reading some info on the ISTA+ regarding recommended fluids for the differentials. I know different DIY'ers have used different kinds. But I was curious about any drawbacks to using cheaper alternatives over the more expensive fluids recommended by BMW (for e70 N55 motor, per ISTA+ updated 2016) before I tackle this DIY:

1. Front differential: Hypoid Axle Oil G2 (BMW part no. 83-22-2-413-511)

2. Rear differential: Final-Drive Gear Oil Saf-Xo 832514 (BMW part no. 33-11-7-695-240)

3. Transfer case: Transfer Case Fluid - DTF 1 (SAE 75W GL-4) (BMW part no. 83-22-2-409-710)